Page 1
XTRAMIX
~ Version 5b ~
Ultra Compact Studio Line Mixer
Reference Manual
cxi
speck
electronics
Page 2
ii
Notice
Warranty
Edition
Speck Electronics makes no warranty of any kind with regard to this material,
including, but not limited to, the implied warranties of merchantability and
fitness for a particular purpose. Speck Electronics shall not be liable for errors
contained herein or for incidental consequential damages in connection with the
furnishing, performance, or use of this material.
This document contains proprietary information which is protected by
copyright. All rights are reserved. No part of this document may be
photocopied, reproduced, or translated into another language without the prior
written consent of Speck Electronics.
The information contained in this document is subject to change without notice.
Speck Electronics products are warranted to the original owner to be free of
defects in material or workmanship.
This warranty does not apply to incandescent lamps, slide potentiometers, or
any product subject to accident, misuse, neglect or failure to comply with
normal maintenance procedures or if the serial number has been defaced,
altered, or removed; nor will Speck Electronics accept responsibility for
damages resulting from improper installation, alteration or unauthorized parts
or repairs. If the product is modified by the customer without permission, the
customer agrees to pay for parts and labor necessary to remove the modification
before repair. The cause of the defect is in the sole judgment of Speck
Electronics.
Should a defect develop within one year of purchase from Speck Electronics or
an authorized dealer, Speck Electronics will supply the part or parts necessary
at no charge. Labor is covered in this warranty for a period of one year.
Outside service, repairs or pickups are not covered under this warranty.
Any item returned for warranty repair should be sent, if possible, in the original
packing container, prepaid to Speck Electronics, 341 E. Alvarado Street,
Fallbrook, California, 92028. If in our opinion the packing container is
improper for return shipping, we reserve the right to supply a new container at a
minimal charge.
In the interest of improving Speck Mixers and related products; designs and
specifications are subject to change without notice. It should be mentioned that
if a change is necessary for any reason, we make every effort to document
that change and send an "update notice" to all customers at no charge.
First Printing - May 1992
Edition 2 - July 1994
Edition 3 - June 1995 (Xtramix-cx)
Edition 4 - August 1997 (Xtramix-cxi)
Edition 5 - April 2000 (Xtramix-cxi Version 5)
Edition 6 - December 2004 (Xtramix-cxi Version 5b)
Speck Electronics
341 East Alvarado Street
Fallbrook, California 92028
USA
760-723-4281
www.speck.com
Page 3
Contents
Contents
iii
Chapter 1 Introduction
Chapter 2 Initial
Chapter 3 Installation
General ......................................................................................
Operator Safety Summary .........................................................
Power Source ......................................................................
Grounding the product ........................................................
Use the proper power cord ..................................................
Use the proper fuse .............................................................
Panels and Covers ...............................................................
General Description ...................................................................
Input section ........................................................................
Effects section .....................................................................
Master section .....................................................................
Features .....................................................................................
Standard Accessories .................................................................
Regulated power supply ......................................................
Rack mount adapters ...........................................................
Rubber Protectors ................................................................
Specifications ............................................................................
Unpacking and Inspection .........................................................
Environmental Considerations ..................................................
Grounding ...........................................................................
Rack grounding ...................................................................
Repacking for Shipment ............................................................
General ......................................................................................
Mechanical Installation .............................................................
Physical Placement of Adjacent Equipment ..............................
Power supply .............................................................................
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1
1
1
1
1
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3
4
4
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4
5
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7
7
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9
9
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Page 4
Contents
iv
Chapter 4 Operation
Configuring the AC
Mounting location ...............................................................
AC wiring chart ...................................................................
Fuse chart ............................................................................
Connecting the Power Supply ...................................................
Power Supply DC pin assignment .......................................
Rack Mount Adapters ................................................................
Installation ..........................................................................
Default Control Settings ............................................................
Cleaning ....................................................................................
General ......................................................................................
Front Panel Controls ...............................................................
Input Channel ............................................................................
Channel Subgroup Assign/Mute Section ...................................
Effects Send Section ..................................................................
Odd Effects Sends .....................................................................
Even Effects Sends ....................................................................
Stereo Effects Return Section ....................................................
Monitor Section .........................................................................
Master Section ...........................................................................
Stereo Cue Return Section .........................................................
Stereo Aux Return Section ........................................................
Talkback Section .......................................................................
Rear Panel Controls ................................................................
Input Channel Connections and Switches .................................
Effects Send Connections and Switches ....................................
Effects Return Connections .......................................................
Assign Subgroup Connections ...................................................
Monitor Section Connections and Switches ..............................
Tuner Section Connection and Control .....................................
Master Input/Output Connections ..............................................
10
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Page 5
Contents
Chapter 5 Wiring and Other
v
General ......................................................................................
Start simple .........................................................................
Audio Cable ...............................................................................
Multipair wire harnesses .....................................................
Connectors .................................................................................
Proper AC Grounding ................................................................
Quality AC system ..............................................................
AC distribution ....................................................................
Clock noise and AC ............................................................
Safety earth connection .......................................................
Electronics earth ..................................................................
Proper Audio Grounding and Shielding ....................................
EMI and RFI ..............................................................................
Sources of EMI ...................................................................
Reducing EMI .....................................................................
44
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Page 6
Chapter 1 Introduction Section
Introduction
General
Operator Safety
Summary
Power source
Grounding the product
Use the proper power cord
Use the proper fuse
Thank you for purchasing our Xtramix Ultra Compact Line Mixer. The
Xtramix was designed from the ground up as a high performance mixer
dedicated to the project studio owner, recording studio, touring, or
professional keyboard player.
The Xtramix has operational features that are unique to our products and
are somewhat technical in nature. We hope this manual is easy to
understand. If you have any questions regarding the Xtramix or any
Speck product, do not hesitate to contact Speck Electronics. Our phone
number is +760-723-4281.
This product and its power supply are intended to operate from an AC
power source that does not apply more than 240 Volts RMS between the
supply conductors or between either supply conductor and ground.
The external power supply for the Xtramix is grounded through the
grounding conductor of the power cord. To avoid electrical shock, plug
the power cord into a properly wired receptacle before making any audio
connection to the mixer. A protective ground connection, by the way of
the grounding conductor in the power cord, is essential for safe
operation.
Upon loss of the protective ground connection, all accessible conductive
parts, including knobs and controls that may appear to be insulating, can
render an electric shock.
Use only the power cord and connector that is supplied with your power
supply. The power cord must be in good condition.
To avoid a fire hazard, use only a fuse of the correct type, voltage rating
and current rating as specified on the chassis of the power supply and
this manual.
Refer to the section in this manual regarding specific details on fuses.
1
Page 7
Chapter 1 Introduction Section
2
Figure 1a. Front Panel Layout
XTRAMIX
cxi
Figure 1b. Rear Panel Layout
XTRAMIX
cxi
Page 8
Chapter 1 Introduction Section
3
Do not remove covers or panels
General Description
Input section
Effects section
To avoid personal injury, do not remove the top cover from the power
supply, or the rear panel of the Xtramix and never operate the external
power supply without the cover properly installed. If it becomes
necessary to remove the rear panel of the Xtramix for service, always
unplug the AC power and disconnect the DC interface cable before
proceeding.
The Xtramix is a high performance line audio mixer that may be used
separately or as part of a larger mixing system.
When used as a rack mount recording mixer, the Xtramix provides 40
synth inputs (20 stereo inputs), 8 subgroup assign capability, and the
ability to access up to 8 stereo effects devices. A complete 8 x 2
monitor and mix section allows the input channels and effects channels
to be mixed to the stereo program, monitor and headphone outputs.
When used as a traditional synth/sampler mixer the Xtramix has the
ability to be operated in many configurations. It may be used as a 70
input, 2 output compact keyboard mixer; or as a 56 input, 8 subgroup, 2
output keyboard mixer; or as a 40 synth or line input, 16 subgroup, 2
output mixer; or any combination of the above mentioned
configurations.
The mixer is divided into three basic sections. The input section, the
effects send and return section, and the master section.
The input section consists of 20 stereo input channels and has all the
controls necessary to effectively control synth and sampler operation.
Channels include level control with 8 subgroup assign, a pan/balance
control, 2 effects sends that are assignable to 8 effects busses, and the
ability to solo the signal. The rear panel for each input channel offers
balanced 1/4" TRS connectors for synth or line interface, an effects
stereo/mono select switch, and a low/high input level select switch.
The effects section provides total control for up to 8 stereo effects
devices.
Each of the effects channels include an effects send master for its
respective effects buss and associated effects sum input. The effects
return includes a stereo effects return level, 8 subgroup assign, pan, inplace solo, and mono select switch. Each effects channel has a 1/4"
TRS send jack, a 1/4" TRS effects sum in jack, and (2) balanced 1/4"
TRS jacks for the left and right effects returns.
Page 9
Chapter 1 Introduction Section
4
Master section
Features
Standard Accessories
Regulated power supply
The master section provides the Xtramix with many choices for routing
and controlling the line signals from the input section and effects
devices from the effects section.
The master section includes 8 discrete subgroup level controls, a stereo
program, stereo monitor, and stereo headphone controls. A stereo cue
and stereo aux return allow a variety of signals to be mixed with the
synth signals to the monitor and headphone outputs. The master section
provides a full compliment of balanced 1/4" TRS input and output
connectors that allow the Xtramix to adapt to a wide range of
professional situations.
•
Twenty balanced stereo inputs may individually operate as mono input
channels.
Input channels offer high and low operating levels.
•
Eight stereo effects returns with individual mono switching.
•
•
Eight assignable subgroups available for all input channels and effects
returns.
•
Effects send outputs have summing points so that other mixers' aux
outputs may be combined with the Xtramix sends.
The solo circuit for input channels, effects returns and monitor section
•
can feed headphones only or both headphones and monitor output.
•
A separate tuner output follows the solo for quick isolation.
The Xtramix is supplied with an external rack mount Model PS3-1.5
regulated power supply that is capable of powering the Xtramix.
The PS3-1.5 power supply is supplied with a IEC power entry
connector, a 3 conductor AC power cord, and a 6 foot DC cable. The
DC cable has a 6 pin connector at one end that plugs into the power
supply, and a 4 pin connector at the other end that plugs into the
Xtramix. The cable may be secured to the rear chassis of the Xtramix
for a positive connection.
Page 10
Chapter 1 Introduction Section
5
CAUTION!
IMPORTANT!
Rack mount adapters
Specifications
ALWAYS CHECK THE PROPER OPERATING VOLTAGE
BEFORE OPERATING THE XTRAMIX.
USE ONLY THE POWER SUPPLY THAT IS
SPECIFIED FOR YOUR PRODUCT.
The Xtramix is supplied with a set of rack mount adapters. If the
intention is to mount the Xtramix in a standard 19" equipment rack,
these adapters must be mounted to the left and right sides of the mixer.
Line Input Impedance
Effects Return Input Impedance
Cue Return Input Impedance
Aux Return Input Impedance
Subgroup Insert Return Impedance
Effects Sum In Impedance
15k Ohms
15k Ohms
15k Ohms
15k Ohms
5k Ohms
10k Ohms
Effect Send Output Impedance
Program Feed Output Impedance
Monitor Feed Output Impedance
Tuner Feed Output Impedance
Subgroup Feed Output Impedance
Subgroup Insert Send Impedance
Line Input Level (High Level)
Line Input Level (Low Level)
Effects Return Input Level
Subgroup Insert Return Level
Cue Return Input Level
Aux Return Input Level
All line outputs are designed to drive a
600 ohm load and may be operated
into any load 600 ohms or greater.
Normal
0dBu
-20dBu
+4dBu
+4dBu
+4dBu
+4dBu
Maximum
+28dBu
+10dBu
+21dBu
+21dBu
+21dBu
+21dBu
Page 11
Chapter 1 Introduction Section
Specifications (Cont.)
6
Subgroup Feed Output Level
Subgroup Insert Send Output Level
Program Feed Output Level
Monitor Feed Output Level
Effects Send Output Level
Tuner Feed Output Level
Headphone Output Level
Output Distortion(THD+n)
22Hz to 22KHz
Frequency Response
(Any primary line In to Program Out)
Test Conditions:
0dBu signal at left input.
Input level control set to 3 o'clock position.
Input channel assigned to subgroup #1.
Subgroup master #1adjusted to indicate 0 VU.
Monitor channel #1 level set to 3 o'clock position.
Monitor pan pot centered.
Program master adjusted to indicate 0 VU.
Frequency response measured at program feed-left.
Normal
+4 dBu=0VU
+4 dBu
+4 dBu=0VU
+4dBu
+4dBu
+4dBu
Unweighted
.0067%
Maximum
+28dbu
+20dBu
+28dBu
+21.5dBu
+21.5dBu
+20dBu
4 Watts
6Hz(-3dB) to 154kHz(-3dB)
A-weighted
.0037%
Residual Noise Measurement
(Any primary line In to Program Out)
Test Conditions:
0dBu signal at left input.
Input level control set to 3 o'clock position.
Input channel assigned to subgroup #1.
Subgroup master #1adjusted to indicate 0 VU.
Monitor channel #1 level set to 3 o'clock position.
Monitor pan pot centered.
Program master adjusted to indicate 0 VU.
Input signal removed and terminated with 100
Ohms.
Noise measured at program feed-left.
Power requirements (Mixer)
Power requirements (Power Supply)
Dimensions (Xtramix)
Dimensions (Power Supply)
Shipping weight Approximately 33 lbs (14.9Kg)
Bi-polar 16.25 volts DC, 1.3 Amp
-89 dBu (unweighted)
-95 dBu (A-weighted)
120/240 VAC, 1/.5 Amp
HxWxD = 7" x 19" x 7"
(178mm x 483mm x 178mm)
HxWxD = 3.75 x 11.25 x 5.25
(95mm x 286mm x 133mm)
ALL MEASUREMENTS WERE PERFORMED WITH AN AUDIO PRECISION SYSTEM ONE TEST SET.
Page 12
Chapter 2 Initial Preparation
Initial Preparation
Unpacking and
Inspection
Environmental
Considerations
Grounding
8
The Xtramix is delivered in a special, protective container and was
carefully inspected both mechanically and electrically before shipment.
It should be physically free of mars and scratches and in perfect
electrical order upon receipt. To confirm this, the product should be
inspected for physical damage that may have occurred in transit. Any
damage should be reported to your dealer and delivery company as soon
as possible.
The Xtramix will operate satisfactorily over a wide range of ambient
temperatures, and the power supply will operate from 10 to 50 degrees
C. If the power supply is installed in an equipment rack that also
contains heat producing equipment such as power amplifiers or other
power supplies, adequate ventilation should be provided. This will
prolong component life and maximize operational stability.
While the internal circuitry of the Xtramix is fully shielded by the steel
chassis, installation should nevertheless be planned to avoid locating the
Xtramix or any low level audio equipment immediately adjacent to
power amplifiers, power supplies, or any source of Electromagnetic
emissions.
To protect operating personnel, the National Electrical Manufacturers
Association (NEMA) recommends that the instrument panel and rack
cabinet be grounded. All Speck power supplies are equipped with a
three conductor power cord which, when plugged into an appropriate
receptacle, grounds the power supply. The offset pin on the power cord's
three-prong plug is the ground wire.
The three conductor line cord and plug assembly is wired in accordance
with NEMA convention (line - black, Neutral - white, and safety earth green). Audio signal grounds and DC grounds from the mixer are
isolated from the AC safety earth.
When using the Xtramix and its power supply outside North America, it
may be necessary to adapt a different power cord for that specific
country.
CAUTION!
DO NOT REMOVE, DEFEAT, OR DISABLE THE SAFETY
EARTH TERMINAL ON THE POWER CORD. DO NOT USE
A GROUND LIFT ON THE POWER SUPPLY.
Page 13
Chapter 2 Initial Preparation
8
Rack grounding
Repacking For
Shipment
Merely affixing the Xtramix into an equipment rack is no guarantee that
the product is making a reliable ground connection. The mounting rails
in the equipment rack should never be depended upon for a ground
connection.
The following information is provided as a general guide for
repackaging your Xtramix for shipment. If you have any questions,
contact Speck Electronics direct. Our phone number is +760-723-4281.
If the product is to be shipped to Speck Electronics for service or repair,
attach a tag to the product, identifying the owner and indicating the
service or repair to be accomplished. Include the model number and
serial number of the product. Place the product in the original container
if available. If the original container in not available, a suitable one can
be purchased from Speck Electronics.
If the original container is not used, wrap the product in heavy plastic
before placing in an inner container. Use plenty of packing material
around all sides of the product and protect panel faces with cardboard
strips. Mark shipping container with "Delicate Instrument" or "Fragile",
and insure the shipment for the proper amount.
In most cases, it will be necessary to remove the rack mount adapters if
the unit is returned in its original shipping container. When remounting
the rack mount adapters, make certain you use the original mounting
screws supplied with the Xtramix.
Page 14
Chapter 3 Installation Section
Installation
General
Mechanical Installation
Physical Placement of
Adjacent Equipment
Power Supply
The following information should give you the basics on how to install
the Xtramix and Power Supply. The proper installation of the Xtramix
as a part of a larger system requires a clear understanding of audio
wiring, AC distribution, grounding, and shielding techniques.
When the Xtramix is being installed into a larger system it may be
necessary to retain the services of someone experienced in these matters.
Before the mixer may be placed into its normal operating position, it
will be necessary to install the rack mount adapters.
The Xtramix may be installed into any 19" wide equipment rack that
uses standard E.I.A. universal spacing. The Xtramix may be affixed to
standard E.I.A. rack rails using (4) 10-32 machine screws.
The location of the Xtramix should be such that the operator has a clear,
unobstructed view of the front panel from his normal operating position.
The unit should also be within easy reach of the operators normal
position in order to facilitate the use of the front panel controls.
Any device that emits a high EMI (Electro Magnetic Interference) or
RFI (Radio Frequency Interference) energy field should be treated with
suspicion. EMI is considered any unwanted signal which adversely
affects the operation of the mixer or the mixing system. This subject is
discussed in Chapter 5.
Electronic equipment such as power amplifiers, power supplies
(especially wall mount type), video monitors, computers, certain synths
and samplers must be located away from the Xtramix and its associated
cables. It may be necessary to alter the positions of certain equipment
that you feel would cause buzzes or hums in the mixer system.
The Xtramix is supplied with the Model PS3-1.5 power supply that
offers a variety of mounting options. The power supply may be placed
on any flat surface, permanently affixed to a flat surface, or mounted on
a single rack rail with the optional rack mount adapter.
9
Page 15
Chapter 3 Installation Section
Mounting location
Configuring the AC Mains
10
One of the primary reasons that the power supply of the Xtramix is
external is to insure that the power transformer enclosed within the
power supply chassis maintains a safe distance from the active
electronics of the Xtramix. For that matter, any power supply
(especially the small wall mount supplies), power amplifiers, or any
strong power field device should be kept at a reasonable distance from
the Xtramix. It is also important to keep the above mentioned devices
clear of all interface cables, audio cables and harnesses.
The external power supply for the Xtramix does not provide an AC
power switch. It is recommended the power supply be plugged into an
AC strip that uses a power switch.
The power supply should not be installed directly above or below the
mixer. It is recommended that it be installed in the rear of the
equipment rack, providing that it remains at a reasonable distance from
the mixer and cables, and has adequate ventilation.
The power supply normally generates a small amount of heat during
operation. It is important that adequate ventilation is provided when
planning the mounting location.
The power supply may be wired to operate with 100 VAC, 120 VAC,
220 VAC, 230 VAC, or 240 VAC 50/60hz. Before applying AC power,
you should verify that the voltage setting on your power supply is
configured to match the AC requirements of your country. This
procedure should be performed and checked by a qualified technician.
Unless otherwise specified on the panel of the supply, the power supply
is wired for 120 VAC 50/60Hz operation and uses a North American
IEC style AC plug.
To gain access to the inside of the power supply, it will be necessary to
remove the top cover. This is accomplished by removing the 4 screws
on the bottom of the power supply chassis. Make certain that the power
supply is unplugged before proceeding.
There are 5 terminals available on the power transformer of the power
supply. The configuration of the five terminals determine the operating
voltage of the power supply. It is only necessary to change the black
(line) and white (neutral) AC wires. Do not attempt to remove or
change the Green AC safety wire or the multicolored wires used at the
DC terminals. It is recommended that you measure the DC voltages at
the DC connector before reconnection to the mixer.
Page 16
Chapter 3 Installation Section
11
AC wiring chart
Fuse chart
CAUTION!
CAUTION!
Connecting the
Power Supply
The following chart represents the proper AC terminal configuration for
the Model PS3-1.5 power supply.
FOR USE AT:
JUMPER AT:
APPLY A.C. AT:
100 VAC
1 & 3
2 & 4
5 & 1
120 VAC
1 & 3
2 & 4
4 & 1
220 VAC
2 & 3
1 & 5
230 VAC
2 & 3
4 & 1
240 VAC
2 & 3
4 & 1
The following chart represents the proper fuse rating for the
Model PS3-1.5 power supply. All fuses are 5 x 20mm Slow-Blow type.
100 VOLTS AC
120 VOLTS AC
220 VOLTS AC
230 VOLTS AC
240 VOLTS AC
1 AMP
1 AMP
.5 AMP
.5 AMP
.5 AMP
ALWAYS CHECK THE PROPER OPERATING VOLTAGE
BEFORE OPERATING THE XTRAMIX.
DO NOT REMOVE, DEFEAT, OR DISABLE THE SAFETY
EARTH TERMINAL ON THE POWER CORD. DO NOT USE
A GROUND LIFT ON THE POWER SUPPLY.
Before connecting the DC power supply connector to the Xtramix, make
certain the power supply is not plugged in.
The power supply interface cable is a 3 conductor wire with a square
plug on one end and a rectangular plug on the other end. Do not attempt
to extend or modify this cable. Any attempt to modify this cable could
result in severe damage to the Xtramix or power supply.
To connect the power supply to the mixer, first fit the square plug into
the receptacle on the power supply. The connectors are keyed so they
will only fit in one direction. Next, fit the rectangular plug into the
connector at the rear of the Xtramix. These connectors are also keyed to
fit in only one direction. Once the plug has been connected to the
Xtramix, it may be secured with a cable tie to the adjacent cable tie
holder.
Page 17
Chapter 3 Installation Section
12
Power supply DC pin
assignment
Rack Mount Adapters
Installation
IMPORTANT!
Default Control
Settings
The following chart represents the DC voltages available at the 6 pin
connector on the Model PS3-1.5 Power Supply.
1
4
3
2
5
6
PIN 1 - DC COMMON
PIN 2 - MINUS 16.25 VOLTS DC
PIN 3 - N/C
PIN 4 - N/C
PIN 5 - N/C
PIN 6 - PLUS 16.25 VOLTS DC
In order to install the Xtramix in a 19" equipment rack, it will be
necessary to attach the two rack mount adapters to the main chassis of
the Xtramix. Each rack mount adapter is attached to the main chassis of
the mixer with (3) 6-32 x 3/16" Phillips machine screws.
Using a Phillips screwdriver, remove the (6) screws installed on both
sides of the mixer. Position the adapters so the side with the small round
holes match the threaded holes on the sides of the Xtramix, and the side
with the oval shaped holes are towards the front panel of the mixer.
Attach the rack mount adapters to the left and right sides of the chassis
with the (6) screws and tighten.
ONLY USE THE SHORT SCREWS THAT ARE SUPPLIED
WITH THE MIXER. USING LONGER SCREWS WILL
DAMAGE THE INTERNAL CIRCUITRY OF THE MIXER.
Before any attempt is made to operate the mixer, it would be a good idea
to set all the mixers controls to their neutral positions. This gives you a
reference point to work from when adjusting controls and switches.
All volume controls including effects sends, effects returns, and master
level controls should be set to their full counter-clockwise setting. All
pan controls should be set centered. All pushbutton switches on the
front and rear panel should be set to the out position.
When any future reference is made to the controls or switches of the
Xtramix, is will be assumed that they have been set to their neutral
positions.
Page 18
Chapter 3 Installation Section
13
Cleaning
IMPORTANT!
The front and rear panels are a high quality painted surface and the panel
lettering is applied using a silkscreen printing technique.
To clean the front or rear panel, wipe the surface gently using a soft lintfree cloth to avoid scratching the panel or markings. Paper towels are
not recommended. Commercially available window cleaner solutions
may be used; however, the solution should be applied to the cloth and
not the panel to avoid the seepage of liquid to the inside of the
enclosure.
DO NOT USE BRUSHES OR FEATHER DUSTERS TO REMOVE
DUST. THIS MAY CAUSE DUST TO FALL INTO THE OPENINGS
AROUND THE PUSHBUTTON SWITCHES.
Page 19
Chapter 3 Installation Section
~This page intentionally left blank~
14
Page 20
Chapter 4 Operation Section
Operation
General
Input Channel
15
We hope to give you basic information on the operation of the Xtramix
and adequately describe its controls, switches, and connectors.
It is assumed that you have a working knowledge of audio and signal
flow. If this is your first mixer it is suggested that you purchase a book
on the basic operation of audio mixers. Speck Electronics will be happy
to suggest some publications on this subject.
FRONT PANEL CONTROLS
The input channel of the Xtramix is designed to accept most balanced or
unbalanced stereo synth or line signals. Each input channel incorporates
a stereo level and pan/balance on a dual concentric rotary potentiometer.
3 pushbutton switches are used in combination with the level and pan
for assignment to the 8 subgroup busses. There are 2 effects sends on a
dual concentric rotary pot, and 4 effects assign switches that are used in
conjunction with the effects send pots for assignment to 8 effects send
busses. Each channel also incorporates an in-place solo switch on the
front panel, and high/low level select and effects stereo/mono select on
the rear panel.
In order to monitor any active input channel at the Xtramix's monitor
and program feeds, it must first be assigned to a subgroup or subgroup
pair (see Subgroup Assign Section below). The only exception to this
rule is when an input channel is soloed. Soloing an input channel will
yield the same results whether it is assigned or not.
Throughout this manual, many references are made to the terms
"Subgroup", "Bus", or "Bus/Subgroup". Depending on the context of
the description, any one of these terms may be used. The terms
"Subgroup", "Bus", or "Bus/Subgroup" generally apply to the 8
subgroups of the Xtramix, its pushbutton assign switches, respective
controls, and connectors.
Page 21
Chapter 4 Operation Section
16
Figure 2. Input Channel
Page 22
Chapter 4 Operation Section
17
Refer to Figure 2 for location of items 1 thru 15.
1. Input Level Control
2. Input Balance/Pan Control
D
3. Solo LED
4. In-Place Solo Switch
The smaller (inner) knob of the gray capped concentric is a dual rotary
potentiometer that simultaneously and equally adjusts both the left and
right channel levels.
The larger (outer) knob of the gray capped concentric when used in
conjunction with the Channel Subgroup Assign Section (see below),
allows an input channel to be assigned to any of eight individual
subgroups or any of four subgroup pairs.
When an input channel is operated in the stereo mode, this control acts
as an odd/even (left/right) balance for the selected subgroup pair.
If the channel is operated in the mono mode, then this control acts as a
traditional assign pan for the selected odd/even subgroup pair. When
panned to the left, this allows a mono signal to be assigned to any odd
subgroup (1,3,5,7). When panned to the right it allows a mono signal to
be assigned to any even subgroup (2,4,6,8). When placed to its
center position, the mono signal may be assigned to an odd/even
subgroup pair.
Input channels and effect return channels do not automatically mix
to the program, monitor, and headphone outputs -- They must be
assigned to a subgroup first. Once assigned to a subgroup, the
monitor level and pan for that respective subgroup is then adjusted
to produce a stereo mix to the program, monitor and headphone
outputs.
This red LED illuminates any time its associated solo switch is
depressed. The master solo LED will also illuminate, changing from
green to red, when the solo switch is depressed.
In-Place soloing allows you to isolate any stereo channel while
maintaining its stereo perspective.
The source of the solo signal is the stereo or mono synth signal post
(after) the channel's level control. When a solo switch is enabled, any
adjustment to the channels level control will be evident in the monitor
and/or headphone playback.
Any combination of input channels, effects returns, and monitor
channels may be soloed without interrupting the flow of the signal to the
Program Master Feed. A red LED directly below this switch will
illuminate when the channel is soloed.
Page 23
Chapter 4 Operation Section
Channel Subgroup
Assign/Mute Section
5. 1-2/5-6 Subgroup Assign/
Mute Switch
18
There are two types of In-Place solo incorporated into the Xtramix:
Absolute and True. All input channel solos are Absolute In-place. This
means that a soloed signal will be perceived in the same stereo or mono
perspective being produced by the instrument itself. The solos on the
effects returns and the monitor channels are True In-Place
and follow the position of the channels pan/balance control.
Unlike True In-Place solo, the position of the input channel Balance/Pan
control will have no bearing on the left/right perspective in the Absolute
solo mode. Additionally, if a stereo instrument is connected to a
channel being operated in the stereo mode (see Stereo/Mono Switch and
Channel Input Connectors description, Rear Panel), then soloing that
channel yields a stereo solo signal. If the channel is set to operate in
mono, then soloing that channel will yield a centered mono solo signal.
The solo listening level can be controlled by either adjusting the Input
Level Control, the Master Monitor or Headphone level, although
adjusting the Master Monitor or Headphone level will not affect any
relative balance created with the Input Level Control.
Be aware that the solo circuit activated by this or any other solo switch
on the Xtramix will feed the Monitor Master and/or Headphones as well
as the Tuner Feed outputs. The stereo program outputs are unaffected
by the solo function.
This bank of pushbutton switches, in conjunction with the input channel
Balance/Pan Control (see above), allows an input channel to be assigned
to any of eight individual subgroups or any of four subgroup pairs.
A channel is “Muted” as long as it is not assigned to any subgroup(s).
When the Subgroup Assign Changeover Switch (see below) is in the up
position, pressing the 1-2/5-6 Assign Switch routes the input channel
signal to the 1-2 subgroup pair. When the Subgroup Assign Changeover
Switch is in the down position, pressing the 1-2/5-6 Assign button routes
the input channel signal to the 5-6 subgroup pair. In the up position, all
signal flow to the 1-2 or 5-6 subgroups is muted.
Page 24
19 Chapter 4 Operation Section
6. 3-4/7-8 Subgroup Assign/
Mute Switch
7. Assign Changeover Switch
8. Presence of Signal LED
9. Mono LED
Effects Send Section
When the Subgroup Assign Changeover Switch (see below) is in the up
position, pressing the 3-4/7-8 Assign Switch routes the input channel
signal to the 3-4 subgroup pair. When the Subgroup Assign Changeover
Switch is in the down position, pressing the 3-4/7-8 Assign button routes
the input channel signal to the 7-8 subgroup pair. In the up position, all
signal flow to the 3-4 or 7-8 subgroups is muted.
In the up position the Subgroup Assign Switches will select subgroups
1 thru 4. When depressed the Subgroup Assign Switches will select
subgroups 5 thru 8.
This green LED will illuminate when a signal is present at the left or
right channel. This provides for easy identification of an active synth
even when a channel is unassigned (muted) and sound is inaudible.
This yellow LED illuminates when the channel's effects Stereo/Mono
switch (See rear panel description) is depressed. This indicates that the
left and right signals are being summed together creating a mono
composite for the effects sends.
There are two Effects Send Controls available per input channel in the
form of a black capped dual concentric potentiometer. The smaller
(inner) knob is labeled as the "Odd" effects send and the outer (larger)
knob is labeled as the "Even" effects send.
Each send can be selectively assigned to one of four effects busses,
"Odd" (1/3/5/7) and "Even" (2/4/6/8). This is accomplished by the
selection of the four black Effects Assign Switches.
Each stereo channel also incorporates an effects Stereo/Mono switch
(located at the rear). When this switch is in the Mono position, the
source for effects sends 1 thru 8 is the algebraic sum of the left and right
synth signals, post (after) the input level control. When the Stereo/
Mono switch is in the Stereo position, the source for odd effects sends
(1,3,5,&7) is the left synth signal, and the source for the even effects
sends (2,4,6,&8) is the right synth signal.
The effects sends are designed to operate only when a Subgroup Assign
Switch is depressed.
Page 25
Chapter 4 Operation Section
Odd Effects Sends
20
10. Odd Level Control
11. Odd Effects Assign Switch
12. Odd Effects Changeover
Switch
Even Effects Sends
13. Even Level Control
14. Even Effects Assign Switch
15. Even Effects Changeover
Switch
The smaller (inner) knob of the black capped concentric adjusts the level
being sent to the selected "Odd" effects bus. This control is used in
conjunction with the Odd Effects Assign Switch and Odd Assign
Changeover Switch.
When this button and the Odd Effects Changeover Switch (see below)
are both in the up position, then effects send #1 is selected. Depressing
only the Odd Effects Assign Switch changes the selection to effects #3.
Note that the 1/3 symbol immediately to the right of the Assign Switch
is meant to be read as 1 or 3.
Depressing this button accesses the 5/7 (5 or 7) effects sends. With this
switch down, and the Odd Effects Assign Switch in the up position,
effects send #5 is selected. When both buttons are depressed, then
effects send #7 is selected.
The larger (outer) knob of the black capped concentric adjusts the level
being sent to the selected "Even" effects bus. This control is used in
conjunction with the Even Effects Assign Switch and Even Assign
Changeover Switch.
When this button and the Even Effects Changeover Switch (see below)
are both in the up position, then effects send #2 is selected. Depressing
only the Even Effects Assign Switch changes the selection to effects
send #4. Note that the 2/4 symbol immediately to the right of the Assign
Switch is meant to be read as 2 or 4.
Depressing this button accesses the 6/8 (6 or 8) effects sends. With this
switch down and the Even Effects Assign Switch in the up position,
effects send #6 is selected. When both buttons are depressed, then
effects send #8 is selected.
Page 26
Chapter 4 Operation Section
21
Figure 3. Stereo Effects Return Channel
Page 27
Chapter 4 Operation Section
22
Stereo Effects
Return Section
16. Stereo Effects Return Level
17. Effects Return Balance/ Pan
Control
D
18. Mono LED
There are eight stereo effects returns incorporated into the Xtramix.
Each of the effects returns are individually assignable, in stereo or
mono, to the eight subgroups. Each return channel also incorporates a
stereo return level control, pan/balance control, stereo/mono select
switch and in-place solo switch.
When not being used for an effects device, it is perfectly acceptable to
connect a synth or sampler to an available effects return.
In order to monitor any active effects return at the Xtramix's monitor
and program feeds, it must first be assigned to a subgroup or subgroup
pair (refer to the Subgroup Assign Section). The only exception to this
rule is when an effects return is soloed. Soloing an effects return will
yield the same results whether it is assigned or unassigned.
Refer to Figure 3 for location of items 16 thru 24
This control is a dual rotary potentiometer that simultaneously and
equally adjusts both the left and right channel levels. A Return Level
setting of approximately two to three o'clock will yield an adequate level
of effect when matched with an effects unit that is properly operated at a
professional input/output level of +4dbu.
This control when used in conjunction with the Channel Subgroup
Assign Switches, allows the effects return to be assigned to any of eight
individual subgroups or any of four subgroup pairs. When an effects
return is operated in the stereo mode, this control acts as an odd/even
(left/right) balance for the selected subgroup pair.
If the effects return is operated in the mono mode (see Effects Return
Mono Switch), then this control acts as a traditional assign pan for the
selected subgroup pair. When panned to the left this control allows a
mono signal to be assigned to any odd subgroup (1,3,5,7). When
panned to the right it allows a mono signal to be assigned to any even
subgroup (2,4,6,8). When placed to its center position, the mono signal
may be assigned to an odd/even subgroup pair.
Effects return channels and input channels do not automatically
mix to the program, monitor, and headphone outputs -- They must
be assigned to a subgroup first. Once assigned to a subgroup, the
monitor level and pan for that respective subgroup is then adjusted
to produce a stereo mix to the program, monitor and headphone
outputs.
This yellow LED illuminates when the Effects Return Stereo/Mono
Switch (see below) is depressed. This indicates that the left and right
signals are being summed together creating a mono composite.
Page 28
Chapter 4 Operation Section
23
19. Stereo Effects Return
Mono Switch
20. 1-2/5-6 Subgroup Assign/
Mute Switch
21. 3-4/7-8 Subgroup Assign/
Mute Switch
22. Assign Changeover Switch
23. Effects Return Solo Switch
24. Solo LED
Depressing this switch sums the left and right effects inputs creating a
mono composite. This feature will prove useful if a stereo effect is to be
assigned to a single subgroup or specifically placed somewhere in the
left to right perspective of a stereo subgroup.
When the Subgroup Assign Changeover Switch (see below) is in the up
position, then pressing the 1-2/5-6 Assign Switch routes the effects
return signal to the 1-2 subgroup pair. When the Subgroup Assign
Changeover Switch is in the down position, pressing the 1-2/5-6 Assign
Switch routes the effects return signal to the 5-6 subgroup pair.
In the up position, all signal flow to the 1-2 or 5-6 subgroups is
“Muted”.
When the Subgroup Assign Changeover Switch (see below) is in the up
position, then pressing the 3-4/7-8 Assign Switch routes the effects
return signal to the 3-4 subgroup pair. When the Subgroup Assign
Changeover Switch is in the down position, pressing the 3-4/7-8 Assign
Switch routes the effects return signal to the 7-8 subgroup pair.
In the up position, all signal flow to the 3-4 or 7-8 subgroups is
“Muted”.
In the up position the Subgroup Assign Switches will select subgroups
1 thru 4. When depressed the Subgroup Assign Switches will select
subgroups 5 thru 8.
Depressing this switch allows you to isolate any effect return to the
Monitor and/or Headphone outputs while maintaining stereo
perspective. The source for the In-Place solo circuit is post (after) the
volume control. This allows you to solo multiple effects returns while
retaining their relative levels.
There are two types of In-Place solo incorporated into the Xtramix:
Absolute and True. The stereo effect return solos are True In-Place.
This means that the left/right perspective of a soloed effects return will
be affected by the position of the effects return Balance/Pan control.
Additionally, if a stereo effects device is connected to a return being
operated in the stereo mode, then soloing that channel yields a stereo
solo signal. If the return is set to operate in mono, then soloing that
channel will yield a mono solo signal.
The solo listening level can be controlled by either adjusting the Effects
Return Level Control, the Master Monitor or Headphone level, although
adjusting the Master Monitor or Headphone level will not affect any
relative balance created with the Return Level Control
This red LED illuminates any time its associated Effects Return Solo
Switch is depressed.
Page 29
Chapter 4 Operation Section
24
Figure 4. Monitor Channel
Page 30
Chapter 4 Operation Section
25
Monitor Section
25. Buss/Line Select Switch
26. Monitor Level Control
This is the theoretical heart of the Xtramix. Here is where a stereo mix
of all the subgroups is created, independent of the Bus/Subgroup
Masters. The adjustment of the monitor section's Level and Pan controls
create the stereo mix for the Program outputs, Monitor outputs and
Headphone outputs.
There are three selectable modes of operation for each of the eight
monitor positions:
A. Pre, or independent of the associated Bus/Subgroup Master
(see Monitor Pre/Post switch rear panel).
B. Post, or dependent on the associated Bus/Subgroup Master
(see Monitor Pre/Post switch rear panel).
C. As a stereo/mono input (see Bus/Line Switch below).
Personal requirements will determine whether to select the Pre or Post
mode of operation.
Refer to Figure 4 for location of items 25 thru 30
This switch is the source select for the monitor channel. In the up
position, this switch selects its respective mono assign subgroup bus.
When depressed, this switch selects any stereo or mono signal present at
the rear line input connectors.
This knob determines the relative stereo mix level of all signals assigned
to its associated assign subgroup. With the Monitor's Pre/Post switch
(see rear panel) set to Pre, this control will function independent of the
assign Subgroup Master Control. This means it is possible to send a
subgroup signal to, for instance, an external mixing console while
retaining independent control of that same signal for the monitor or
program feeds of the Xtramix. This is considered to be the normal mode
of operation for the monitor section.
The optimum starting point for this control is the three o'clock position.
This should provide for the greatest range of adjustment for the input
channels and effects returns as well as the Monitor Level Control itself.
If the Monitor's Pre/Post switch (see rear panel) is set to Post, then the
Monitor Level Control will follow the Subgroup Master Control. This
means that any level changes made to the Subgroup Master Control will
directly affect the monitor level. This mode of operation would
typically be reserved for situations where the Monitor and Program
feeds need to directly reflect any changes made to a given Subgroup
Master Control.
Page 31
Chapter 4 Operation Section
26
27. Monitor Pan/Balance Control
28. Monitor Solo Switch
29. Monitor Mute Switch
30. Solo/Mute LED
When the Bus/Line Switch on the monitor channel is selected to the Bus
(subgroup) position, this control acts as a traditional left/right pan for the
stereo Program, Monitor, and Headphone outputs.
When the Bus/Line Switch is selected to the Line position, the
Pan/Balance Control acts as a left/right balance control for an incoming
stereo line signal.
Depressing this switch allows you to isolate any monitor channel to the
Monitor and/or Headphone outputs while maintaining stereo
perspective. The source for the In-Place solo circuit is post (after) the
volume control, this allows you to solo multiple monitor channels while
retaining their relative levels.
Depressing this switch deletes the Bus/Subgroup signal from the
Monitor, Program and Headphone feeds, although its associated
bus/subgroup output will remain unaffected by the operation of this
switch. When the channel's Bus/Line Switch is selected to the Line
position the Mute Switch will delete the stereo line signal.
This dual colored LED indicates the status of the channel's Solo and
Mute switches. When the Mute switch is depressed, the LED will
illuminate green in color. When the In-Place Solo switch is depressed,
the LED will illuminate red in color.
Page 32
Chapter 4 Operation Section
27
XTRAMIX
cxi
Figure 5. Master Section
Page 33
Chapter 4 Operation Section
Master Section
28
Refer to Figure 5 for location of items 31 thru 48.
31. Bus/Subgroup Masters 1-8
32. Power/Master Solo LED
33. Dual VU Displays
34. VU Meter Select Switch
35. Meter Select Indicators
These are the individual master level controls for the eight subgroup
outputs. Metering for the bus/subgroup outputs is provided by two LED
VU meters in selectable pairs (1/2, 3/4, 5/6, 7/8 ).
The optimum starting point for a Bus/Subgroup Master is the three
o'clock position. This should provide for the greatest range of
adjustment at the input channels and effects returns as well as the
Subgroup Master Control itself.
If a Subgroup Master Control is operated at a lower than normal setting,
it may be an indication that the input channels and/or effects returns
assigned to it are either adjusted to high or need to be set to a Low level
status (see Input channel “High/Low” Switch on the rear panel).
When the monitor channel Pre/Post Switch is set to the Pre position, the
operation of the Subgroup Master Control has no affect on the levels set
for the monitor channel. If the Pre/Post switch is set to Post, then any
level changes made to the Subgroup Master Control may be perceived as
a level change to its respective monitor channel.
This LED will illuminate green when the power is applied to the
Xtramix. When any solo is depressed, this LED will change from green
to red.
These 10 segment VU (volume units) meters indicate the relative levels
of the stereo program and 8 subgroup outputs, and are sensitive from 20db to +3db.
Depending on the position of the meter sensitivity trim pots, a meter
reading of zero VU reflects a mixer output level of either +4dbu, the
industry professional standard, -10dbV, or virtually any reference level
you care to set. This VU meter circuit was designed to approximate the
ballistics of a "Taut Band" analog style VU meter.
This momentary switch selects the VU meters for the 8 subgroup
outputs and the program master feed. To select a pair of meters, depress
this switch until the desired pair is indicated on the lower LED's. The
left and right program master feeds are automatically selected when the
Xtramix is initially powered.
The 5 LED's indicate the selection of the respective VU meter pairs. The
L-R, indicates the left/right program master is being displayed. The 1-2,
3-4, 5-6, or 7-8 indicates that the respective subgroup output pairs are
being displayed.
Only one VU pair may be selected at a time.
Page 34
Chapter 4 Operation Section
29
36. Stereo Program Master
37. Stereo Monitor Master
38. Monitor Kill Switch
39. Stereo Headphone
Level Control
This pot acts as the master volume to the stereo program feed. It should
be pointed out that the Left/Right program meters follow this master
control, hence any adjustment to the Program Master Control is
displayed at the program meters. A typical starting point for the
Program Master Control is the three o'clock position. This setting
should make it reasonably easy to achieve a 0 VU reading when using
multiple synth and sampler patches without having to rely on excessive
input level (see input channel) adjustments. If, however, a 0 VU reading
is desired when using only one source (a single synth), it is perfectly
acceptable to set the Program Master Control higher than the three
o'clock position to obtain the necessary output.
The operation of the Program Master Control does not affect the
operation of the Monitor level or Headphone level. If required, the
Xtramix may be configured so the source of the Monitor and Headphone
is post (after) the Program Master Level Control.
This controls overall level to the stereo monitor feed and operates
independent of the Program Master and Headphone Master. Typically,
the monitor outputs would be connected to a stereo power amplifier for
purposes of driving a personal monitoring system. However, in
situations where the Xtramix is interfaced to, for instance, a large frame
recording console and solo capability is desired, then it is completely
acceptable to utilize the solo capable monitor outputs for this purpose.
The integrity of this signal is virtually equivalent to that of the program
outputs.
In so far as metering the monitor output is concerned (the program
meters follow only the program); as long as the monitor and program
levels, given the same physical adjustment (2, 3, 4 o'clock, etc.), will be
equal. Establishing the monitor output level is simply a matter of
matching the Program and Monitor Master Controls.
This switch Mutes (Kills) the master monitor output without affecting
the Program and Headphone outputs. When depressed, the LED directly
below will illuminate, indicating the monitor signal has been Muted.
This dual potentiometer controls the volume of the stereo headphone
circuit. The operation of the Headphone Master Control does not affect
the operation of the program level or monitor level.
Page 35
Chapter 4 Operation Section
30
40. Stereo Headphone Jack
Stereo Cue
Return Section
D
41. Cue Return Level Control
42. Cue Return Pan Control
43. Cue Mute Switch
This standard 1/4" stereo phone jack will accommodate most popular
stereo headphones.
The tip of the stereo jack is the left headphone signal, and the ring of the
jack is the right headphone signal.
This feature of the Xtramix allows an external Stereo Cue (otherwise
known as headphone or foldback) mix to be integrated into the
Xtramix's monitor and/or headphone feeds (see Solo to Monitor Switch,
rear panel). This makes it possible to customize a balance between the
Xtramix's stereo mix and, for instance, the cue feed from a studio
control room.
The Cue Return is accessed via two unbalanced 1/4" TS phone type
connectors. For more on these connections, see their rear panel
descriptions. Also, as the source for such a signal is most likely the high
level output of a power amplifier (via a dedicated headphone box), the
input sensitivity of the Cue Return has been calibrated accordingly.
Do not attempt to connect the speaker terminals of any power
amplifier directly into the Cue Return of the Xtramix.
The Stereo Cue Return Section includes the return level control, the
return pan control, and the return mute switch. The Cue Return may be
operated in mono when a single signal is plugged into the left input jack.
This dual potentiometer controls the level of an external stereo cue
source and returns only to the Monitor and/or the Headphone outputs.
This control allows the Cue Return to be panned anywhere in the stereo
perspective.
This switch allows Muting of the Stereo Cue Return. Enabling this
switch removes the stereo cue return signal from the Monitor and
Headphone outputs.
Page 36
Chapter 4 Operation Section
31
Stereo Aux
Return Section
44. Aux Return Level Control
45. Aux Return Mute Switch
Talkback Section
46. Talkback Mic
47. Talkback Switch
48. Talkback Trim Control
This section allows an external stereo auxiliary source such as a DAT
recorder, CD player/recorder or any stereo audio signal to be routed to
the Monitor and/or Headphone outputs of the Xtramix.
The Stereo Aux Return Section includes the return level control, and the
return mute switch. The Aux Return may be operated in mono when a
single signal is plugged into the left input jack.
This dual potentiometer controls the level of an external stereo aux
source and returns only to the Monitor and/or the Headphone outputs.
This switch allows the Muting of the Aux Return. Enabling this switch
removes the stereo aux return signal from the Monitor and Headphone
outputs.
The talkback section of the Xtramix incorporates an internal omnidirectional microphone. This sensitive microphone will operate most
efficiently when the operator speaks at a distance of about two feet from
the mike. This mike is activated by the Talkback Switch and is adjusted
with the Talkback Trim Control.
This momentary switch activates the talkback circuit and permits the
operator to talk or slate to the stereo master outputs.
When the Monitor Configuration Switch on the rear panel is set to the
"pre" position, it is possible to talk or slate only to the program master
outputs. When the Monitor Configuration Switch is set to the "post"
position, the talk signal also appears on the monitor outputs.
This control adjusts the volume of the talkback circuit to the program
output. The suggested setting for this control is approximately the two
o'clock range and adjust as necessary.
Page 37
Chapter 4 Operation Section
32
Figure 6. Input Channel Connectors and Switches
Page 38
Chapter 4 Operation Section
Input Channel
Connections and
Switches
1. Left/Mono Channel Input Jack
2. Right Channel Input Jack
Mono or Single Source
Connection
3. Effects Stereo/Mono Select
Switch
33
REAR PANEL CONTROLS
Refer to Figure 6 for location of items 1 thru 4
Typically, this input is used to connect one side of a stereo or dual voice
source. When a channel is operated in the stereo mode, the left input is
assignable via the Input Channel Level and Balance/Pan Controls to the
four odd subgroups; 1,3,5,7.
Typically, this input is utilized to connect the alternate side of a stereo or
dual voice source. An input channel cannot function in stereo unless the
right input is connected. When a channel is operated in the stereo mode,
the right input is assignable via the Input Channel Level and Balance/
Pan Controls to the four even subgroups; 2,4,6,8.
Connections to the 20 stereo input channels of the Xtramix should be
made with standard balanced tip, ring, and sleeve (TRS) 1/4" plugs as
shown in Figure 7.
When connecting a single source (mono signal), to any stereo input
channel, use only the left input connector. Doing so effectively converts
the channel status from stereo to mono thereby eliminating the need for
any external "Y" type connections.
Each stereo channel incorporates an effects Stereo/Mono switch. When
this switch is in the Stereo (out) position, the source for the odd effects
sends (1,3,5, & 7) is the left input signal, and the source for the even
effects sends (2,4,6, & 8) is the right input signal.
When the Stereo/Mono switch is in the Mono (in) position, the source
for effects sends 1 thru 8 is the algebraic sum of the left and right synth
signals, post (after) the input level control.
A yellow LED at the front of the input channel will illuminate whenever
its Stereo/Mono Switch is depressed, indicating the Mono status of
operation.
Fig 7 Stereo (TRS) plug
Page 39
Chapter 4 Operation Section
34
Figure 8. Effects, Monitor, and Subgroup Connectors
Page 40
Chapter 4 Operation Section
35
4. Low/ High Select Switch
Effects Send
Connections and
Switches
5. Effects Send Master Control
6. Effects Send Jack
7. Effects Sum In Jack
Low/High refers to the output operating level of the signal source. It
should be pointed out that the term Low/High has different meanings
from one manufacturer to another. For the Xtramix, the term low and
high refers to a medium strength line signal (-20dbu to 0dbu), and a high
strength signal (0dbu to+28dbu) respectively.
To optimize the input channels of the Xtramix, the Low/High select
circuit was designed to accommodate the wide range of audio signals
that would normally be plugged into this mixer. The Low setting would
be for most synth, samplers, and line level signals that tend to have a
lower output signal amplitude. The High setting is intended for high
output synths and samplers, or any high output audio signal. If you
intend to connect a +4 dbm source into the input channel, the Low/High
switch should be set to the High position.
If you find that the Input Level Control for that respective channel is
always being operated in the lower range, the Low/High switch should
be set to the High position.
Refer to Figure 8 for location of items 5 thru 13
This potentiometer adjusts the output level (to the outboard effects
device itself) of all channel signals routed to an Effects Send Master via
its associated channel's Effects Send Controls. When matched with an
effects unit that is properly operated at a professional input level of +4
dbu, the optimum setting for this pot is typically anywhere from 2 to 3
o'clock.
Each of the 8 effects send channels has a separate 1/4" TRS connector to
interface to the input of an effects device.
It is completely acceptable, from an electronic standpoint, to adapt this
connector to the input of any effects device, regardless of the type of
input connector utilized on the effects unit (unbalanced 1/4” TS, RCA,
XL, barrier strip, etc.)
This standard 1/4" TRS female phone jack allows the Effects or
Auxiliary sends from another mixer, be it a large frame recording
console or a rack mount sub-mixer, to be combined with the Xtramix's
Effects Sends. The purpose of this is to allow simultaneous access to
any effects device from both mixer sources, thereby creating one
integrated system as opposed to having to dedicate separate effects units
to each mixing source.
Page 41
Chapter 4 Operation Section
Effects Return
Connections
8. Left Return Input Jack
9. Right Return Input Jack
Assign Subgroup
Connections
10. Assign Subgroup Feed Jack
36
Simply connect an Effects or Auxiliary send from the external mixer to
the Sum In Jack of any of the eight Xtramix send channels. While it
makes sense, for the sake of continuity, to keep the Effects Send
numbers matched (#1 of the external mixer to the Sum In point of #1 on
the Xtramix, etc.) it is certainly not necessary.
Once the Sum In connection is made, then connect the input of any
effects device to the Xtramix Effects Send Jack. It may take some
experimentation to determine the best settings for each of the Effects
Send Master (Trim) Controls. Try to achieve a situation where an
Effects Send Control on any given input channel needs to be set between
twelve and two o'clock to achieve a healthy effects device input level.
Each Effects Return provides two discrete balanced 1/4" TRS
connectors for connection from the outputs of a left/right stereo effects
device.
Typically, this input is used to connect the left output of a stereo effects
device. When an effects return is operated in the stereo mode, the left
input is assignable to the four odd subgroups; 1, 3, 5, 7, (see Effects
Return Assign Switches on the front panel)
Typically, this input is utilized to connect the right output of a stereo
effects device. When an effects return is operated in the stereo mode,
the right input is assignable to the four even subgroups; 2, 4, 6, 8 (see
Effects Return Assign Switches on the front panel)
When using a single output effects unit, connect its output to either the
left or right Effects Return Input and set the effects return channel for
mono operation (see effects return Mono Switch on the front panel).
Each Bus/Subgroup feed has a separate balanced 1/4" TRS connector.
The Subgroup Feed provides a low impedance source for connection to
the input of a multitrack analog, digital, or hard disk recorder.
Each Subgroup Feed is capable of driving three high impedance
bridging inputs without any loading effects. This means that Subgroup
Feed #1 could connect to tape inputs 1, 9, and 17, and Subgroup Feed
#2 could connect to tape inputs 2, 10, and 18, etc. The Subgroup Feed
may also connect to the line inputs of a recording console.
Page 42
Chapter 4 Operation Section
37
11. Assign Subgroup
Insert Jack
Each Bus/Subgroup channel provides a 1/4" T.R.S. (tip, ring, sleeve)
insert jack. The Insert Jack provides line level interstage access to the
assign subgroup bus before (pre) the Subgroup Master Level Control.
This means that any device interfaced to this jack will be processed
before its respective Subgroup Master Control, and will not be affected
by any adjustments of the Subgroup Master Control.
The Insert Jack may be utilized to connect limiters, equalizers, noise
reduction, or automation.
The ring of the 1/4" jack is the unbalanced insert send (pre the assign
Subgroup Master Control), the tip is the unbalanced insert return, and
the sleeve is the signal ground. Any stereo 1/4" plug interfaced to this
jack should be wired accordingly. (See figure 9b)
Fig 9a "Y" Cable
Monitor Section
Connections and
Switches
12. Monitor Line Return Jacks
13. Monitor Pre/Post Select
Switch
Each monitor channel provides a stereo balanced 1/4” TRS input for the
return of any stereo line level signal, such as a analog, digital, or hard
disk recorder. A discrete mono signal may be utilized when plugged
into the left connector only. These 1/4" input connectors may be selected
with the Bus/Line Switch on its respective monitor channel.
This switch selects the subgroup source for its respective monitor
channel. In the Pre position, the source for the monitor channel is before
(Pre) the assign Subgroup Master Control. When set to this position any
adjustment to the Subgroup Master Control will have no direct affect on
the monitor channel volume. In the Post position, the source for the
monitor channel is after (Post) its respective Subgroup Master Control.
This permits the monitor channel to follow any adjustment made to its
respective Subgroup Master.
Fig 9b "Y" Cable schematic
Page 43
Chapter 4 Operation Section
38
23
Figure 10. Master Input/Output Connectors
Page 44
Chapter 4 Operation Section
Tuner Section
Connection and
39
Refer to Figure 10 for location of items 14 thru 24.
14. Tuner Feed Jack
15. Tuner Level Control
Master Input/Output
Connections
16. Program Insert Jacks
This 1/4" TRS phone type connector provides a dedicated feed to an
external tuning device. The source for the output is either the sum of all
signals feeding the program master or any signal(s) that is soloed.
This control adjusts the output volume to a dedicated tuning device. The
source for this output is either the sum of all signals feeding the program
master or any signals that are soloed. If, for example, you need to tune
only one synth module while others are active, then simply depress its
associated Solo Switch and it will be isolated to the Tuner Output Jack.
There is ample gain available at this output so that even the softest synth
patches will trigger the tuners circuitry. Start by positioning this control
at the twelve o'clock mark, and adjust if necessary.
The Insert Jack provides line level interstage access to the program bus
before (pre) the Program Master Level Control. This means that any
device interfaced to this jack will be processed before the Program
Master Level Control and will not be affected by any adjustments of the
Program Master Level Control.
The Insert Jack may be utilized to connect limiters, equalizers, noise
reduction, or automation.
When the Xtramix is used as a recording mixer the insert jacks may be
used to connect an external remote stereo slide fader. A remote slide
fader would permit more precise control of the program level when
fading out music.
When the Xtramix is used a keyboard mixer, the insert jacks may be
used to connect to a stereo foot pedal. The stereo foot pedal would act
as an expression pedal enabling the operator to have a "what you hear is
what you get" control over the program, monitor and headphone output
levels.
Page 45
Chapter 4 Operation Section
40
Each of the left and right program insert jacks employ a T.R.S. (tip, ring,
sleeve) type jack. The ring of the 1/4" jack is the unbalanced insert send
(pre the Program Master Level Control), the tip is the unbalanced insert
return, and the sleeve is the signal ground.
Any stereo 1/4" plug interfaced to this jack should be wired accordingly.
(See figure 11b)
17. Program Feed Jacks
Fig 11a "Y" Cable
Fig 11b "Y" Cable schematic
These balanced 1/4" TRS phone type connectors are the left/right
outputs for the stereo program master. The signal present at these jacks
is adjusted by the Program Master Control on the front panel.
The left and right program feed is capable of driving up to three high
impedance bridging inputs simultaneously. The Program Feed Jacks
are available for interface to the input of an external console, stereo tape
recorder, etc.
Page 46
Chapter 4 Operation Section
18. Solo to Monitor Switch
19. Monitor Configuration
Select Switch
41
Connections to the balanced program feed jacks should be made with
a 1/4" stereo tip, ring and sleeve (TRS) plug as shown below in
figure 12 .
Fig 12. Stereo (TRS) plug
When connecting the balanced program outputs to an unbalanced input,
it will be necessary to configure your cables in order to unbalance the
signal.
This pushbutton switch introduces the Solo function, Cue, and Aux
Returns to the master monitor outputs as well as the headphone outputs.
In the normal position (off), the Solo, Cue, and Aux are removed, and
only the stereo mix is present at the monitor feed. When this switch is
depressed (on), both the monitor and headphone feeds receive the Solo
signal, Cue, and Aux Returns together with the stereo mix. The
operation of this switch does not affect the program feed.
This switch selects the source for the monitor and headphone outputs. In
the Pre position, the source for the monitor and headphones are before
(Pre) the Program Master Control. When set to this position any
adjustment to the Program Master Control will have no direct affect on
the monitor or headphone output levels. In the Post position, the source
for the monitor channel is after (Post) the Program Master Control. This
permits the monitor and headphone level controls to follow any
adjustment made by the Program Master Level Control.
For applications where the Xtramix is being used as a self contained
recording mixer, it may be desirable to set this switch to the "post"
position. In which case, whenever the program maser control on the
front panel is used to fade out music to the Stereo mixdown recorder, the
fadeout will automatically be adjusted to the monitor outputs and
headphone outputs. This is how most recording consoles operate.
For applications where the Xtramix is used more like a conventional
keyboard mixer, it may be desirable to set this switch to the "pre"
position.
Page 47
Chapter 4 Operation Section
20. Monitor Feed Jacks
21. Cue Return Input Jacks
D
22. Aux Return Input Jacks
Left/Right Meter Sensitivity
Trim Controls (Not Shown)
42
When set to the "pre" (factory default) position, level adjustments to the
program level will not affect the monitor or headphone levels.
This switch is recessed behind the rear panel to prevent inadvertent
actuation while plugging or unplugging connectors. The switch may be
depressed by inserting a thin pointed object into the hole (such as a very
small screwdriver).
These 1/4" TRS phone type connectors are available for hooking up a
power amplifier that would be used for the control room monitor
system, keyboard rack speakers , or a stage monitoring system. The
signal present at these jacks is adjusted by the Monitor Master Control
on the front panel.
These standard unbalanced 1/4" TS connectors are available for the
connection of a stereo cue signal or any stereo audio signal. A discrete
mono signal may be utilized when plugged into the left connector only.
Connections to the Cue return stereo input should be made with standard
unbalanced tip and sleeve (TS) 1/4" plugs as shown in
Figure 13.
Do not connect the speaker terminals of any power amplifier
directly into the Cue Return Input Jacks.
These standard unbalanced 1/4" TS connectors allow the interface of an
external stereo signal, such as a DAT, or CD player. A discrete mono
signal may be utilized when plugged into the left connector only.
Connections to the Cue return stereo input should be made with standard
unbalanced tip and sleeve (TS) 1/4" plugs as shown in Figure 13.
There are the two trim pots located at the top of the mixer that adjust the
sensitivity of the Left/Right VU meters. These trim pots in no way
modify the electronic operation of the mixer. The trim pots have been
calibrated at the factory to indicate 0 VU=+4 dbu. This means that
when the VU meter indicates 0 VU, the subgroup outputs and the
program outputs are delivering a +4dbu.
Fig 13. Mono (TS) plug
Page 48
23. Power Supply Connector
43 Chapter 4 Operation Section
If required, the VU meters may be calibrated to indicate -10dbV.
An AC voltmeter and signal generator will be required to perform this
adjustment.
This 4 pin connector will accommodate the connector from the power
supply cable. The connectors are keyed so they will only fit in one
direction. For installation instructions refer to the Installation Section in
Chapter 3 of this manual.
Page 49
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44 Chapter 4 Operation Section
Page 50
Chapter 5 Wiring and Other
Wiring and Other
General
Start Simple
Audio Cable
Multipair Wire Harnesses
It is assumed that in addition to the Xtramix, a considerable investment
has been made in electronic equipment such as synthesizers, samplers,
effects, and computers. We believe that the overall performance of the
Xtramix and your mixing system is dependent on the condition and
quality of this equipment.
A general discussion about AC, AC grounding, audio grounding, EMI,
and quality wiring is discussed in this section. These subjects are very
often overlooked or misunderstood, and should be given consideration
when interfacing your equipment to any Speck product.
A quality installation is essential when wiring any Speck product. When
the time comes to actually interconnect your equipment, proceed
slowing. Interfacing the many pieces of electronic equipment to your
mixer should be a logical, methodical process.
Start by connecting your headphones or monitor power amplifier, and
then add one synth to the mixer at a time; carefully listening and
monitoring your progress. If a problem arises, such as a buzz, hum,
intermittent signal, or nonexistent signal, stop at that point and solve the
problem before proceeding.
Due to the high performance of the Xtramix mixing system, it is
recommended that you use only the highest quality audio cable. A high
quality cable by definition, is a cable that provides good mechanical
strength, high microphonic noise immunity, high frequency response,
low crosstalk and 100% shielding ability. All audio cable used with the
Xtramix should be a 3 conductor foil shield type (2 inner conductors and
a shield drain conductor). It is not recommended that the 2 conductor
"off the shelf cables" be used.
When multiple cables are necessary (which is generally the case with
our products), multipair cable should be considered as an alternative to
individual cables. Multipair cable and harnesses are generally available
in 4, 8, 12, 16, 24, and 32 pair.
45
Page 51
Chapter 5 Wiring and Other
46
Connectors
Proper AC Grounding
Quality AC System
AC Distribution
All wire and cable interfaced to the Xtramix and Speck products should
be terminated with high quality connectors. A 1/4" plug or XL
connector should make a positive connection to its respective mating
jack and provide adequate strain relief to its cable. All connectors
should also have a metal shell to provide 100% shield for exposed
conductors.
Feel free to check with Speck Electronics for assistance when selecting
cable and connectors. Our phone number is +760-723-4281.
When you are evaluating voltage and current requirements for your
audio system, it is important that your Xtramix mixing system and/or
rack system does not exceed the capacity of your AC service. You
should make certain that the earth (green) wire for the AC system makes
a reliable earth connection, and determine as best as possible that the AC
system is free of noise that could generate unwanted audible sounds or
cause problems in microprocessor based equipment.
When using a larger rack system it is recommended that a dedicated and
isolated AC service be provided. This service should have its own AC
wires, isolated receptacle, and breaker and not be shared with other
unrelated equipment.
Even with an isolated AC system, it may still be necessary to make use
of surge protectors, line filters, isolation transformers, or all of the
above.
Power conditioners should be selected with care, since they sometimes
generate undesirable switching noises in audio systems.
When connecting many pieces of electronic equipment to an AC system
it is important that the AC is properly distributed. It is better to connect
all plugs to a common AC source than to have AC receptacles in
different locations.
When installing a large audio system, it may be necessary to consult a
qualified electrician that is familiar with the specialized style of
electrical wiring required for recording studios.
CAUTION!
DO NOT REMOVE, DEFEAT, OR DISABLE THE SAFETY
EARTH TERMINAL ON THE POWER CORD. DO NOT USE A
GROUND LIFT ON THE POWER SUPPLY.
Page 52
Chapter 5 Wiring and Other
47
Clock Noise and AC
Safety Earth Connection
Electronics Earth
Proper Audio Grounding
and Shielding
Clock noise is one of the greatest enemies of the audio racks AC system.
If a synth or any microprocessor based device emits or somehow
couples its clock signal with the neutral or earth of its own power cable,
it will contaminate your AC system and carry the clock noise into other
equipment; almost always with undesirable results.
The earth connection exists to protect you, your equipment and possibly
your building from an electrical disaster. In a properly wired system, if
a 120 volt AC wire were to break within your equipment's chassis, it
should make contact with the Safety Earth Wire that is connected to the
chassis, and blow the fuse or trip the circuit breaker until the problem
has been corrected. Given the same circumstances, if the AC safety
ground has been defeated with a ground lift or the AC service is
incorrectly wired, the equipment's chassis and quite possibly everything
attached in that rack would be "live" with 120 volts.
In an electronics context, an earth provides a path for unwanted EMI
noise to be carried away from your audio equipment. If you disable
your earth with a ground lift or do not have a reliable earth connection,
the unwanted noise (EMI or RFI), will find an electrical path of least
resistance. That will most likely be your audio equipment and would
result in unwanted buzzes or hums.
In order for any audio signal, such as a synth signal to get from the synth
to the mixer, it requires a minimum of 2 conductors. One conductor is
the hot, or high, or whatever you are familiar with; the other conductor
is the ground or common. Additionally, all audio wires must be
protected from environmental occurrences such as EMI (Electro
Magnetic Interference) and RFI (Radio Frequency Interference) with an
outer shield. An outer shield protects the 2 inner conductors from
outside interference, and prevents that cable from inducing its signal
onto adjacent audio cables.
One common misconception is that the shield of a cable should act as
the common. This may be acceptable for guitar cords or semiprofessional applications, but not for professional applications. The
audio signals must be carried only by the 2 inner conductors and the
shield must act only to cover these 2 conductors without transmitting the
signal from one location to another. It is recommended that the shield
be attached to the common (ground) at one connector's end, and the
shield not be connected at the other connector's end. It is recommended
that all shields be connected at the mixer end, and the shields not be
connected at the other ends (synths, effects, power amps, etc.).
Page 53
Chapter 5 Wiring and Other
EMI and RFI
Sources of EMI
Reducing EMI
48
If a patchbay is utilized in your mixing system, the rules for shielding
may change. With a patchbay, normally all shields are connected at the
patchbay jacks, and not connected at the mixer or external audio
equipment.
The occurrence of EMI (Electro Magnetic Interference) and RFI
(Radio Frequency Interference) in a synth and sampler based system
should be of great concern and not overlooked when installing the
Xtramix. EMI is defined as any unwanted signal which adversely
affects the operation of the mixer or mixing system.
Stated simply, the undesirable effects of EMI may be perceived as a low
frequency smooth sounding 60Hz hum; a low frequency "edgy"
sounding 120Hz buzz; or a higher frequency "whine" caused by the
timing circuits in microprocessor based devices.
Almost every electronic device generates some amount of EMI
emissions. These emissions can be transmitted as electromagnetic
radiation or simply conducted though audio cables and power cords. In
the same respect, most electronic devices are also very susceptible to the
EMI emissions generated by other electronic devices.
There are natural and man made sources of EMI that you can't do
anything about. These sources include radio, TV, and radar transmitters,
as well as motors, lights, and computers. Even the Sun and atmospheric
conditions can be contributors to noise that you experience in your audio
system.
There are generally 3 elements that must be present for EMI to exist.
These include the source of the EMI (conducted or radiated), the
propagation medium by which EMI is transmitted (directly on the cables
or through the air), and the receptor that suffers the adverse affects of
EMI. If any of these 3 elements are eliminated or reduced, the EMI
interference will be eliminated or reduced.
The more electronic equipment operating within an equipment rack, the
higher the EMI emissions. The more audio cable and low level audio
equipment that exists within the same rack, the greater possibility of
unwanted noise. The result of EMI in an audio system manifests itself
as a buzz, hum, whine, or all three.
The most common EMI occurrence in an audio system is radiated
emissions from microprocessors in synths and samplers, and magnetic
field sources from transformers and power supplies.
Page 54
Appendix A 49
Signal Flow Diagram (Part A)
Page 55
Appendix A 50
Signal Flow Diagram (Part B)
Page 56
Connector Matrix for XTRAMIXcxi - Version 5
51 Appendix B
Input / Output
Synth/Line Inputs 1-20 ¼” T.R.S. Switchcraft #297 Balanced
Effects Returns 1-8 ¼” T.R.S. Switchcraft #297 Balanced
Line Returns 1-8 ¼” T.RS. Switchcraft #297 Balanced
Aux Return L & R ¼” T.S Switchcraft #280 Unbalanced
Cue Return L & R ¼” T.S. Switchcraft #280 Unbalanced
Subgroup Outputs 1-8 ¼” T.R.S. Switchcraft #297 Balanced
Subgroup inserts 1-8 ¼” T.R.S. Switchcraft #297 Tip=Return, Ring=Send
Program Outputs L & R ¼” T.R.S. Switchcraft #297 Balanced
Program Inserts L & R ¼” T.R.S. Switchcraft #297 Tip=Return, Ring=Send
Monitor Outputs L & R ¼” T.R.S. Switchcraft #297 Balanced
Effects Sends 1-8 ¼” T.R.S. Switchcraft #297 Balanced
Effects Sum 1-8 ¼” T.R.S. Switchcraft #297 Unbalanced
Tuner Output ¼” T.R.S. Switchcraft #297 Balanced
Headphone Output ¼” T.R.S. Tip=Left, Ring=Right
Important Notes:
All Input and output connectors on the Xtramix use the highest quality Swichcraft SN37A series
jacks. Switchcraft brand mating plugs are therefore recommended because of their 100%
compatibility, reliability and durability.
Neutrik brand plugs may also be used as an alternate.
Cables with molded plugs or any “off-brand” plugs that do not meet the exact mechanical
specifications of Switchcraft are not recommended for use with the Xtramix.
The results from using “off-brand” plugs may vary from intermittent signals to a complete loss of
signal connection or oscillation.
Connection
Connector
Type
Recommend
Connector
Connector
Matrix for
XTRAMIXc
xi
Notes:
All Input and output
connectors on the
Notes
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