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Lilo
Reference Manual
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Speck Lilo Reference Manual

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Page 1
LiLo
16 Channel Line Mixer 24 Channel Line Mixer
Reference Manual
speck electronics
Page 2
Page 3
Warranty
ii
Speck Electronics products are warranted to the original owner to be free of defects in material or workmanship.
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 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.
Notice
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.
All trademarks are the property of their respective owners.
First Printing - June 2004 Edition 2 - June 2008
Speck Electronics 341 East Alvarado Street Fallbrook, California 92028 USA 760-723-4281 www.speck.com
Page 4
Contents
Chapter 1 Introduction
Chapter 2 Installation
General .................................................................................
Unpacking and inspection ....................................................
Repacking ............................................................................
Standard Accessories.............................................................
Operator safety summary .....................................................
LiLo general description ......................................................
LiLo features.........................................................................
"Dual Path" signal routing feature ........................................
Dimensions .................................................................................
Specifications..............................................................................
Signal flow diagrams.................................................................
General .......................................................................................
Power supply installation .....................................................
Environmental considerations ..............................................
Physical placement of adjacent equipment ..........................
Hooking up the mixer ..........................................................
Removing modules for service ............................................
Cleaning ...............................................................................
iii
1 1 1 2 2 2 3 4 5 6 7
9 9 10 10 10 11 12
Chapter 3 Operation
Chapter 4 Wiring
and Other
General..................................................................................
Default control settings.........................................................
Input Channel Controls ............................................................
Input Channel I/O Connectors.................................................
Master Module Controls...........................................................
Master Module I/O Connectors ...............................................
General .................................................................................
AC Distribution and safety ......................................................
Proper AC grounding ...........................................................
Quality AC system ...............................................................
AC distribution .....................................................................
Clock noise and AC .............................................................
Safety earth connection ........................................................
Audio earth ...........................................................................
Proper audio grounding and shielding ...................................
EMI and RFI .............................................................................
Sources of EMI ....................................................................
Reducing EMI ......................................................................
13 14
15 18 21 26
31 31 31 31 31 32 32 32 32 33 33 33
Page 5
Chapter 1Chapter 1Chapter 1 Introduction SectionIntroduction SectionIntroduction Section 111
Introduction
General
Unpacking & Inspection
Thank you for purchasing our LiLo Mixer. The LiLo has operational features that are easy to understand and you should be up and running in no time. If you are unfamiliar with audio equipment or audio signal flow, it is recommended that you read this manual. If you have any questions regarding the LiLo or any Speck product, do not hesitate to contact Speck Electronics.
Speck Electronics 341 E. Alvarado Street Fallbrook, CA 92028 Phone +760-723-4281 email sales@speck.com www.speck.com
The LiLo is delivered in a special, protective container and was carefully inspected both mechanically and electrically before shipment. The power supply, cable, and manual are packed in a separate container. All items should be physically free of mars and scratches and in perfect electrical order upon receipt. To confirm this, the mixer and power supply 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.
Repacking
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.
Page 6
Chapter 1 Introduction Section
2
Standard Accessories
Operator Safety
Summary
The LiLo is supplied with the following list of accessories:
- External regulated power supply: Model PS5-3 for LiLo-16 Model PS5-5 for LiLo-24
- DC Power supply cable (10 foot, 7 conductor)
- AC Power cord (NA version only)
- Operations Manual
This product and its power supply are intended to operate from a single phase 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 LiLo is grounded through the “earth” conductor of the power cord. To avoid electrical shock, plug the power cord into a properly wired receptacle before making any connection from the power supply to the mixer. A protective ground connection, by the way of the grounding conductor in the power cord, is essential for safe operation.
The three conductor line cord and plug assembly is wired in accordance with NEMA convention (line - black, Neutral - white, and safety earth - green). When using the LiLo and its power supply outside North America, it may be necessary to adapt a different power cord for that specific country. To avoid a fire hazard, use only a fuse of the correct type, voltage rating and current rating as specified in this manual. See Figure 7 on Page 10 for fuse chart.
To avoid personal injury, do not remove the top cover from the power supply, and never operate the external power supply without the cover properly installed. If it becomes necessary to service any part of the mixer, always unplug the AC power and disconnect the DC interface cable before proceeding.
LiLo General
Description
Short for “Line-in/Line-out”, the LiLo is a high-definition desktop analog line mixer for routing and blending your external gear. With more than 100 balanced input/output connections, this modular console will mix over 36 signals with unmatched signal routing, generous amounts of headroom, and a neutral signal path. The LiLo is targeted at recording studios, project studios, and audio post-production installations.
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.
Page 7
Chapter 1 Introduction Section 3
LiLo Features
The LiLo is a modular mixer design with 16 or 24 input channels and a master module fit into a solid frame.
balanced with transformers on the mix and group outputs. All input channels have secondary configuration switches as well as configuration jumpers on the circuit board.
Each input module is designed with plug-in preamp PC boards for Line-A, Line-B, and direct out. The master module is also designed with plug-in preamp PC
group
future circuit upgrades from Speck Electronics and/or 3 party manufacturers.
The locations and types of the plug-in preamp cards are shown in Figures 1a, 1b, and 1c below.
Figure 1a. Input channel PCA
All inputs, outputs, and bussing are fully
boards for most of the critical circuit stages including the mix and
summing amps, and output line amps.
This type of design will facilitate
rd
P/N LPCPRE1
Line Amp
(Line-A)
P/N LPCPRE1
Line Amp
(Line-B)
P/N LPCPRE2
Output Amp
(Direct Out)
Figure 1b. Master 1 PCA
P/N LPCPRE2
Output Amp
(Mix Left)
P/N LPCPRE2
Output Amp
(Mix Right)
P/N LPCACN
Summing Amp
(Mix Right)
Figure 1c. Master 2 PCA
P/N LPCACN Summing Amp
(Mix Left)
P/N LPCPRE2
(Mon. Left)
Output Amp
(Mon. Right)
P/N LPCPRE2
Output Amp
(Aux 2)
P/N LPCPRE2
Output Amp
(Aux 3)
P/N LPCPRE2
Output Amp
P/N LPCPRE2
Output Amp
(Group 2)
P/N LPCACN
Summing Amp
(Group 2)
P/N LPCPRE2
Output Amp
(Group 1)
P/N LPCACN
Summing Amp
(Group 1)
P/N LPCPRE2
Output Amp
(Aux 1)
P/N LPCPRE2
Output Amp
(Aux 4)
Page 8
Chapter 1 Introduction Section 4
LINE A
LINE B
Dual Path Signal
Routing Feature
LINE A LINE B
INPUT
TRIM A
TRIM B
SELECT
LINE-A LINE-B
An important benefit of the LiLo is the ability to mix 32 line signals in “real time” from the standard 16 channel mixer (or 48 with the 24 channel LiLo). You could, for example, have the 16 outputs from D/A converters (Protools, Radar, etc.) connected to the 16 "Line-B's" and at the same time the "Line­A's" can be used for 16 other line signals such as mic preamps, samplers, or additional outputs from D/A converters...all ending up at the stereo and group mix busses.
The dual path signal routing is possible because the LiLo's input channels use separate line preamps for Line-A and Line-B rather than switching XLR inputs into a common preamp stage. This combination of dual channel line amps, Group Select switch [12], and Aux Select switch [20] can virtually double the input capacity of the LiLo.
Figure 2 shows one example of the “dual path” signal flow. In this example, the Group Select switch is pushed to select Line-B as the source for the GRP 1 and GRP 2 assign switches. The group assigns are then routed to their respective master that are then mixed to the stereo mix output. At the same time, Line-A is mixed through the channels fader, pan, and mix assign.
MONO
MIX-L
MIX BUS
GROUP SELECT
FADER
LINE-B
MIX
GRP 1
GROUP BUS
INSERT
O
CHANNEL
INSERT
FADER
A/B SELECT
GROUP SWITCH CONFIG.
(GSC)
LINE-B
MUTE
PAN
INSERT
MASTER
S
S
MIX-R
INSERT
S
FADER
GROUP
LEVEL
PAN
MONITOR
LEVEL
MONITOR
OUTPUT
MIX
OUTPUT
MIX
The signal flow for Line A is as follows:
Line-A input à Input Select “Line-A” à Fader à Pan à Mix assign à Stereo mix
The signal flow for Line B is as follows:
Line-B input à Grp select “Line B” à Grp 1 or Grp 2 assigned à Group master à Group pan à Mix assign à Stereo mix
GRP 2
AUX BUS
AUX 1
AUX 2
AUX
FADER
LINE B
SELECT
AUX 3
AUX 4
Figure 2. Dual path signal flow
GROUP INSERT
GROUP
S
GROUP INSERT
LEVEL
S
LEVEL
S
LEVEL
S
LEVEL
S
LEVEL
PAN
AUX SEND 1
AUX SEND 2
AUX SEND 3
AUX SEND 4
GROUP
OUT
MIX
GROUP
OUT
Page 9
Chapter 1 Introduction Section 5
Dimensions
3.56" [90.3]
18.29" [464.6]
9.99" [253.7]
8.59" [218.2]
28.07" [712.9]
28.57" [725.6]
17.00" [431.8]
1.91" [48.5]
3.74" [95.0]
7.08" [179.7]
5.50" [139.7]
2.93" [74.5]
2.34" [59.4]
Figure 4. Power supply dimensions
10.05" [255.3]
6.68" [169.5]
24.55" [623.6]
Figure 3. Mixer dimensions
Page 10
Chapter 1 Introduction Section 6
Specifications
Line input impedance
Line-A and Line-B Insert returns 2T, DAW, and Aux returns
Maximum input level
Line A Line B Channel insert return Mix insert return
Output Impedance
All Active-balanced outputs All transformer-balanced outputs
Maximum output level (2k load)
All Active-balanced outputs All transformer-balanced outputs
15K ohms 30K ohms 20K ohms
+28dBu +28dBu +28dBu +28dBu
60 ohms 600 ohms
+28dBu (Balanced) +24dBu (Balanced)
Frequency Response (12 dB gain)
(Any line input to mix output)
THD+n
(+4dBu any line input, Gain 0, +4dBu mix out) (+12dBu any line input, Gain 12, +24dBu mix out)
Crosstalk (1kHz)
Channel to channel Input to Mix out, channel muted Input to Mix out, channel fader off
Noise (22Hz-22kHz)
Residual Mix and Group output noise Mix output - 16 channels routed, faders up Mix output - 16 channels routed, faders off Mix output - 16 channels routed, faders off, muted
DC Power Requirements (Mixer)
AC Power Requirements (External supply)
Dimensions (Mixer)
10Hz-30kHz (+0/-.5dB)
.0032% .0024%
-100dBu
-95dBu
-89dBu
-102dBu
-81dBu
-84dBu
-90dBu
+/- 17.5 VDC @ 1.7A +6.5 VDC @ 3.8A
100-120 VAC 50/60Hz 5 amp 220-240 VAC 50/60Hz 3 Amp
WxDxH=28.5" x 24.5" x 10" (724mm x 645mm x 254mm)
Dimensions (External supply)
Weight (Mixer)
Weight (External supply)
Total shipping weight
WxDxH=7" x 17" x 5.5" (178mm x 432mm x 140mm)
50 Lbs (22.7kg)
19 Lbs (8.6kg)
86 Lbs (39kg)
Page 11
Chapter 1 Introduction Section 7
AUX BUS
SOLO BUS
SOLO
MIX
MUTE
MIX BUS
GRP 1
LEFT
RIGHT
PAN
FADER
RELAY
PAN
(GFP)
GROUP
FOLLOW
GROUP
SELECT
(GSC)
GROUP
SWITCH
CONFIG.
GROUP BUS
GRP 2
POST/PRE
PAN
AUX
(AFP)
FOLLOW
LINE-B
FADER
LINE-B
A/B SELECT
AUX 2
AUX 1
AUX 3
AUX 4
AUX
SELECT
FADER
LINE B
POST/PRE
AUX PRE
CONFIG. JUMPER
PRE FADER
PRE INSERT
Dwg: LILOFLOW INPUT
Date: 4-1-04
Drawing By: V. M. Poulos
Rev. No.
LiLo Line Mixer
Speck Electronics
INPUT CHANNEL SIGNAL FLOW
Copyright © 2001-2004 Speck Electronics by
INSERT
O
Speck Electronics LiLo - Input Channel Signal Flow
INPUT
SELECT
PLUG-IN
MODULE
LEGEND
BALANCED SIGNAL
UNBALANCED SIGNAL
RELAY
RELAY
TRIM A
SWITCH
CONFIGURATION
(ACCESSABLE VIA
TOP PANEL HOLES)
LOGIC CONTROL SIGNAL
SWITCH
LINE-B
LINE-A
TRIM B
LINE INPUT MODULE
LINE A
LINE INPUT MODULE
RTN
LINE B
SEND
INSERT
CHANNEL
Figure 5. Input Channel signal Flow
LINE A
LINE B
NORMAL
AUX 2
AUX 4
DIRECT OUT
CONFIG. JUMPER
LINE AMP MODULE
PLUG ACTIVATES RELAY
(LINE C)
DIRECT OUT
Page 12
Chapter 1 Introduction Section 8
MIX BUS
MIX
PAN
LEVEL
GROUP
SOLO
LINE AMP MODULE
OUT
SOLO BUS
GROUP
METER
SELECT
Typical of 2
RELAY
S
SUMMING AMP MODULE
PLUG ACTIVATES RELAY
VU
OUT
FROM MIX L-R
FROM GROUP 1-2
RELAY
PLUG ACTIVATES RELAY
MIX
LEFT
LINE AMP MODULE
FADER
MASTER
S
RIGHT
OUTPUT
LINE AMP MODULE
LEFT
LEVEL
MONITOR
MONO
RELAY
RELAY
RELAY
RIGHT
OUTPUT
MONITOR
Dwg: LILOFLOW MASTER
Date: 4-1-04
Drawing By: V. M. Poulos
Rev. No.
LINE AMP MODULE
LINE AMP MODULE
LiLo Line Mixer
Speck Electronics
SOLO
INDICATOR
SOLO
2.T.
DAW+MIX
MASTER SECTION SIGNAL FLOW
Copyright © 2001-2004 Speck Electronics by
S
SUMMING AMP MODULE
SUMMING AMP MODULE
RELAY
PLUG ACTIVATES RELAY
DAW
S
S
RTN
SEND
INSERT
GROUP BUS
GROUP
SOLO BUS
SOLO
RTN
SEND
MIX-L
INSERT
MIX BUSGROUP BUS
MIX
LEFT
MIX BUS
GRP 1-2
RIGHT
GRP 1
RTN
SEND
MIX-R
INSERT
IX
M
DAW
W
+DA
IX
M
MONITOR SWITCH LOGIC
2.T.
GRP 2
Speck Electronics LiLo - Master Section Signal Flow
MODULE
PLUG-IN
RELAY
RELAY
LINE AMP MODULE
LEVEL
Typical of 4
LEGEND
BALANCED SIGNAL
UNBALANCED SIGNAL
LOGIC CONTROL SIGNAL
SWITCH
S
AUX BUS
AUX SEND
PAN
DAW
LEVEL
Typical of 2
LEVEL
L
R
INPUTS
AUX RTN
L
DAW
2 TRK
LEVEL
SOLO
LEVEL
S
S
R
INPUTS
R
L
2 TRK
INPUTS
SOLO BUS
Figure 6. Master Module Signal Flow
Page 13
Chapter 2 Installation & Setup 9
Installation
& Setup
General
Power Supply
Installation
The following information should give you the basics on how to install the LiLo mixer and power supply. The proper installation of the LiLo requires a clear understanding of audio wiring, AC distribution, grounding, and shielding techniques.
If the LiLo is being installed into a larger studio or as a sidecar/expander to a host console, it may be necessary to retain the services of someone experienced in these matters.
One of the primary reasons that the power supply of the LiLo 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 LiLo. For that matter, any device that has a strong magnetic power field should be kept at a reasonable distance from the LiLo and its audio cables.
Because the power supply does not use a cooling fan, it is silent and can be located in the same room as the mixer. It is important that the ventilation holes are not obstructed and that the unit is operated in free air to prevent overheating. Allow a minimum of 4”(100mm) of clearance from all ventilation holes.
The LiLo's power supply can operate with 100 VAC, 120 VAC, 220 VAC, 230 VAC, or 240 VAC 50/60hz. Before switching “on” the power, you should verify that the voltage setting on your power supply is configured to match the AC mains requirements of your country. If the AC mains voltage needs to be changed, this procedure should be performed and checked by a qualified technician.
Before connecting the DC power supply cable to the LiLo, make certain the power switch is set to the “off” position.
To connect the power supply to the mixer, fit the circular connectors at each end of the DC power supply cable to the chassis mount receptacles that are mounted on the power supply and the rear of the Lilo. The respective connectors are keyed so the plug and chassis mount receptacle can fit in only one direction. When the connectors have been mated, rotate the circular locking ring clockwise until it stops.
Page 14
Chapter 2 Installation & Setup 10
In the unlikely event that a fuse blows, it is EXTREMELY important that a fuse of the same type and current rating be replaced. The chart below in Figure 7 lists the fuse current ratings to be used for your countries mains voltage. All fuses are 20mm x 5mm slow blow type.
Fuse Chart for PS5-3 Power Supply
100 VAC 120 VAC 220 VAC 230 VAC 240 VAC
5 Amp 5 Amp 3 Amp 3 Amp 3 Amp
Figure 7.
Environmental
Considerations
Physical Placement of
Adjacent Equipment
The LiLo will operate satisfactorily over a wide range of ambient temperatures, and the external power supply will operate from -10º C to +30 º C. If the power supply is installed in an equipment rack that also contains heat producing equipment, adequate ventilation should be provided. This will prolong component life and maximize operational stability.
While the internal circuitry of the Lilo is fully shielded by the chassis, installation should nevertheless be planned to avoid locating the LiLo immediately adjacent to power amplifiers, power supplies, or any source of Electromagnetic emissions.
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 4.
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 LiLo 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.
Hooking up the Mixer
A quality installation is essential when wiring any audio system. When the time comes to actually interconnect your equipment, proceed slowly. Interfacing the many pieces of electronic equipment to your mixer and audio system should be a logical, methodical process.
Start by connecting only the monitor power amp (or powered speakers) to the mixer, and then add one line signal 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.
Page 15
Chapter 2 Installation & Setup 11
Due to the high performance of the LiLo, 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 LiLo 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.
All wire and cable interfaced to the LiLo should be terminated with high quality connectors. A ¼" 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.
Removing Modules
for Service
Always turn the power supply “off” and disconnect
!
Removing the Input Module
To remove an input module for maintenance, remove the Philips screws at the top and bottom of the module. Carefully pull the input module straight up by holding the knobs. Once the module is clear of the main chassis, remove the ribbon cable at the rear of the module by releasing the ejector tabs, and then remove the larger ribbon cable at the bottom. To re-install the module just reverse the procedure being certain than the ribbon connectors have been inserted completely into the receptacles and that the ejector tabs “snap” back into position.
Removing the Master Module
Before removing the master module, it is recommended that some kind of protective material is laid over the input modules adjacent to the master module. A small towel would work fine.
To remove the master module, remove the Phillips screws (4) at the top and bottom of the module. The module will need to be lifted up and the front tilted up slightly until the module completely clears the main chassis. Once the module is clear of the chassis, lay the module on its side. Remove the (6) ribbon cables that are identified “A through E” by releasing the ejector tabs. Next, remove the (2) larger ribbon cable connectors at the bottom of each circuit board.
the DC power cable before servicing the LiLo mixer.
To re-install the module just reverse the procedure being certain that the ribbon connectors have been inserted completely into the receptacles and that the ejector tabs “snap” back into position. All cables are labeled to match the label on the module's receptacles.
Page 16
Chapter 2 Installation & Setup 12
Cleaning
The module and chassis are a high quality painted surface and the panel lettering is applied using a silkscreen printing technique.
To clean the top or rear panel, wipe the surface gently using a soft lint-free 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 17
Chapter 3 Operation Section 13
Mixer Operation
Overview
Default Control
Settings
In this section we hope to give you basic information on the operation of the LiLo and adequately describe its controls, switches, and connectors.
The information in this section of the manual is intended to help with the technical process when using your LiLo. Words alone could not adequately describe how to adjust the controls for every situation you might encounter with the Lilo. You should experiment with settings and routing techniques to achieve the best results for any particular situation. Your ears should be your best gauge of how to adjust the settings on the LiLo to make the sound fit your requirements.
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 aux sends, aux returns, and master level controls should be set to their full counter­clockwise setting. All pan controls should be set centered. All pushbutton switches on the input channels and master module should be set to the out position.
When any future reference is made to the controls or switches of the LiLo, it will be assumed that they have been set to their neutral positions.
Page 18
Chapter 3 Operation Section 14
Input Channel Signal
Flow Diagram
LEGEND
BALANCED SIGNAL
UNBALANCED SIGNAL
LOGIC CONTROL SIGNAL
TRIM A
TRIM B
RELAY
RELAY
CONFIG. JUMPER
LINE A
LINE B
SEND
CHANNEL
INSERT
(LINE C)
DIRECT OUT
SWITCH
21
22
RTN
23
24
CONFIGURATION
SWITCH
(ACCESSABLE VIA
TOP PANEL HOLES)
2
LINE INPUT MODULE
3
LINE INPUT MODULE
PLUG ACTIVATES RELAY
LINE AMP MODULE
PLUG-IN MODULE
DIRECT OUT
Use this input channel signal flow diagram shown below in Figure 8 as a reference when reading the descriptions of the controls, switches, and connectors [1] through [24] in this chapter.
7
SOLO
1
LINE A LINE B NORMAL AUX 2 AUX 4
LINE-A
LINE-B
INPUT
SELECT
5
O
INSERT
6
RELAY
15
LINE-B
A/B SELECT
4
FADER
GROUP SWITCH CONFIG.
(GSC)
8
MUTE
12
FADER
LINE-B
PRE FADER
PRE INSERT
9
PAN
GROUP SELECT
AUX PRE
CONFIG. JUMPER
14
FOLLOW
AUX PAN
(AFP)
10
FOLLOW
19
RIGHT
GROUP
PAN
(GFP)
13
MIX
LEFT
11
POST/PRE
POST/PRE
GRP 1
GRP 2
20
LINE B
17
FADER
AUX
SELECT
16
18
SOLO BUS
MIX BUS
GROUP BUS
AUX 1
AUX 2
AUX 3
AUX 4
AUX BUS
Figure 8. Input module signal flow
Page 19
Chapter 3 Operation Section 15
Input Channel
1. Line Input Select
2. Line-A Gain Trim
3. Line-B Gain
4. Insert Select
The Lilo has separate line amp modules for each input as well as separate trim controls. This switch selects the Line-A or Line-B line amp module. Two yellow LED's display the status of the switch.
This control provides up to 12dB of gain for the Line-A
3 2 1
input. The factory setting is fully counter-clockwise (0 dB). A small flat blade screwdriver can be used to adjust this pot.
This control provides up to 12dB of gain for the Line-B
5
4
input.
Each input channel on the LiLo has a balanced send and return available via separate ¼” TRS jacks on the rear connector panel. The insert signal path is immediately after the Polarity switch and just before the fader. When this insert switch is depressed, any audio device connected to the insert connectors is inserted in the channel's audio path. If the insert switch is pushed in and nothing is plugged into the send/return jacks, the signal will pass through the channel since the jacks have switching (normaling) contacts that are only broken by the insertion of a plug. A green LED on this switch illuminates indicating that the insert is enabled.
5. Polarity
6. Slide Fader
7. Solo
8. Mute Switch
9. Pan Control
This switch reverses the polarity of the Line-A and Line-B input signal by 180 degrees.
This 100mm slider adjusts the level for the input channel. The operation of the slide fader will control the level to the stereo mix, aux sends, group assigns, and the direct output. A good starting position for this slide fader is to align the slider knob to the #10 mark on the panel.
Depressing this switch allows you to isolate any input channel to the monitor outputs while maintaining stereo perspective.
Any combination of input channels, group assign, or aux returns may be soloed without interrupting the flow of the signal to the main mix feed. A red LED on this switch as well as the master Solo indicator will illuminate if a channel is soloed.
Depressing this button eliminates all signal flow to the channels left/right mix, group assigns, as well as the aux sends.
This center detent pan control places the channel anywhere in the stereo left/right mix when the Mix Assign is enabled.
9
7 8
6
Page 20
Chapter 3 Operation Section 16
10. Mix Assign
11. Group Assigns
12. Group Select
The Mix Assign switch, in conjunction with the Pan control, allows an input channel to be mixed to the left/right main output.
The GRP 1 and GRP 2 pushbutton switches allow an input channel to be assigned and mixed to the two individual subgroups. The group assigns normally operate independent of the channel's pan and L-R mix assign, although when the "GFP" configuration switch [14] is set, the group assigns will follow the pan control.
This switch selects the source for the GRP 1 and GRP 2 assigns. In the "Fader position, the source for the group
á"
assigns are the channels fader. When depressed to the "Line-B position, the source for the group assign switches is “exclusively” the channel's Line-B line amp.
â"
The GSC switch [15] will change the “Line-B” designation to “A/B select”.
When the “GFP” switch is pushed, the pan control allows
15 11
12
14
13
the signal to be panned across the 1 and 2 group. The "GFP" function is described below.
13. AFP
(Aux Follow Pan)
14. GFP
(Group Follow Pan)
15. GSC
(Group Switch
Configuration)
AFP, GFP, GSC Configuration Switches
Each input channel on the LiLo has a secondary level of signal routing that is made possible with three push switches that are accessible via small holes in the panel. These
10
switches change the configuration of the aux sends and group assigns. Any small diameter object (like a paper clip) can be used to push this switch.
When this switch is pushed to the down position, the levels set at Aux Send 1 and Aux Send 2 will follow the position on the channels pan control. The AFP switch does not affect Aux Sends 3 & 4.
When this switch is pushed to the down position, GRP 1 and GRP 2 assign will follow the position on the channels pan control.
This switch changes the operation of the Group Select switch. When the GSC switch is pushed to the down position, the Group Select is no longer “Fader á/ Line-B â” but instead becomes "Fader á / A-B Select â” What this means is that when the group switch is pushed to the “Line-B” position, it is no longer exclusively Line -B, but rather the opposite input selected at the Line Select. Example: If the Input Select is set to “Line-B”, then the Group Select will function as "Fader á/ Line-A â".
Page 21
Chapter 3 Operation Section 17
Aux Sends
Each input channel has four aux sends that can be switched pre or post the faders. The Pre/Post functions can be configured to accommodate different mixing applications.
16. Aux Sends 1&2
17. Aux Post/Pre Select
18. Aux Send 3&4
19. Aux Post/Pre Select
Adjusts the level to the Aux busses 1 and 2.
Aux 2 can be configured to send a signal to the direct output. (See jumper configuration Figure 9b on Page 19)
This switch selects the source of Aux Sends 1 & 2. In the “Post á” position, the aux sends reflect any adjustment to the fader or mute. In the “Pre â” position, the channels fader has no effect on the level set at the Aux sends.
When the “AFP” switch is pushed, the pan control allows the signal to be panned across the 1 and 2 Aux Sends. The "AFP" function is described on page 16.
Adjusts the level to the Aux busses 3 and 4.
Aux 4 can be configured to send a signal to the direct output. (See jumper
16
17
configuration Figure 9b on Page 19)
18
This switch selects the source of Aux Sends 3 & 4. In the “Post á” position, the Aux Sends reflect any adjustment to the fader or mute. In the “Pre â” position, the channels fader has no effect on the level set at the Aux Sends.
19 20
20. Aux 3&4
Source Select
The source of the “Pre” switch position for Aux Sends 3-4 can be pre-fader (default) or pre-insert using a push-jumper as shown in Figure 9a on page 19.
This function is similar to the Group Select in that it selects the source for the Aux Sends 3 and 4. In the up position, the source for the send is the channels fader. When depressed to the Line-B position, the source for Aux Sends 3 & 4 is “exclusively” the channels Line-B line amp.
Page 22
Chapter 3 Operation Section 18
Input Channel
I/O Connectors
Each of the input channels has a balanced XLR Line-A input connector, balanced XLR and TRS connectors for Line-B, balanced ¼" TRS connectors for the Inserts, and a balanced ¼" TRS Direct Out.
The pin configuration for all XLR connectors is:
Pin 1=Ground, Pin 2=High (+), Pin 3=Low (-)
The pin configuration for all ¼" TRS jacks is:
Tip=High (+), Ring=Low (-), Sleeve=Ground
21. Line-A Input
22. Line-B Input
23. Insert Send and Return
Input Channel
Relay Option
This XLR active-balanced input is suitable for any high level line source.
This active-balanced input is suitable for any high level line source. The XLR connector and ¼” TRS jack are wired in parallel.
Each input channel on the LiLo has a balanced send and return available via separate ¼” TRS jacks. The inserts signal path is located immediately after the Polarity switch and just before the Fader . When the channel's Insert switch is depressed, any audio device (such as an equalizer or filter) connected to the send/return connectors is inserted in the channel's audio path. If the Insert switch is enabled and nothing is plugged into the return jack, the signal will pass through because the jacks have switching (normalling) contacts that are only broken by the insertion of a plug. The insert send/return operates at nominal level of +4dBu.
21
The insert return can also be used as a “Line-C” input by connecting a source to the insert return jack and depressing the Insert switch.
23
As an option, the input channels can be ordered with a relay installed that will bypass the insert return electronic circuitry when not in use. The active-balanced return
24
circuitry will only be activated when a plug is inserted into the return jack.
24. Direct Output
The Direct Output provides an active-balanced line level signal from the channel and operates at a nominal level of +4dBu. The Direct Output is ideal for minimum signal path connection to multitrack recorder. Although the source of the direct out is the channels fader, it can be easily configured so the signal source is the Line-A preamp, Line-B preamp, Aux 2 send, or Aux 4 send. See the circuit board configuration jumpers shown in Figure 9b.
22
Page 23
Chapter 3 Operation Section 19
Note - All active-balanced output circuits of the LiLo were designed for
balanced lines and should only be connected to balanced inputs. If that is not possible and it is necessary to connect to an unbalanced input, care must be taken not to connect the low (-) terminal to ground. If the low (-) terminal of these outputs is connected to ground, the result will be a high level of audio distortion.
Circuit board configuration jumpers
Figures 9a and 9b below show the locations and designation of the configuration push-jumpers for the Direct Out and the Aux Sends.
Direct Out
By default the Direct Out push jumper is set to the “Normal” (fader) position. The other settings may be the Line-A preamp, Line-B preamp, Aux 2 send, or Aux 4 send as shown below in Figure 9b.
Aux pre configuration
The Aux pre configuration jumper will allow the “Pre” position on both Post/Pre switches [17] & [19] to be set at either "Pre Fader" or "Pre Insert". By default, the LiLo is shipped with this jumper in the "Pre Fader" position. This push jumper affects the “Pre” setting for Aux Sends 1 through 4. Refer to Figure 9a below for the location and setting of this jumper.
LL RR
YY
10K-B10K-B
Pre FaderPre Fader
Pre InsertPre Insert
GG
Figure 9a.
Aux configuration jumper
YY
RR
GG
GG
10K-A10K-A10K-A10K-A10K-A10K-A10K-A10K-A
Pre FaderPre Fader
Pre InsertPre Insert
11
HH LL
InIn
AA
PowerPower
CC
++
--
AA
YY
GG
360360
1K1K
360360
2.1K2.1K
HH LL
T-T- T+T+
InIn
TrimTrim
PowerPower
OutOut
CC
++
--
HH LL
HH
LL
Line ALine A
OutOut
Line BLine B
NormalNormal
Aux 2Aux 2
Aux 4Aux 4
ININ
10K-A10K-A
360360
10K-A10K-A
909909
T-T- T+T+
TrimTrim
BB
11 22
OutOut
HH LL
BB
1919 2020
++
--
CC
PowerPower
Line ALine A Line BLine B NormalNormal
(Fader)
Aux 2Aux 2 Aux 4Aux 4
Figure 9b.
Direct Out configuration jumper
Page 24
Chapter 3 Operation Section 20
Master Module Signal
Flow Diagram
LEGEND
AUX SEND
51
AUX RTN
INPUTS
52
49
DAW
INPUTS
2 TRK
INPUTS
49
SWITCH
AUX BUS
L
R
L
R
L
R
BALANCED SIGNAL
UNBALANCED SIGNAL
LOGIC CONTROL SIGNAL
S
SOLO BUS
33
34
LEVEL
LEVEL
29
30
31
S
S
RELAY
LINE AMP MODULE
Typical of 4
Typical of 2
DAW LEVEL
2 TRK
LEVEL
SOLO LEVEL
RELAY
PLUG-IN MODULE
35
PAN
Use the master section signal flow diagram shown below in Figure 10 as a reference when reading the descriptions of the controls, switches, and connectors [25] through [54] in this chapter.
MIX
LEVEL
41
42
LINE AMP MODULE
LINE AMP MODULE
SOLO
38
36
37
RIGHT
GRP 1
GRP 2
32
SOLO
MONO
METER
SELECT
LINE AMP MODULE
27
40
PAN
LINE AMP MODULE
MONITOR
GROUP
RELAY
LEVEL
S
MIX BUS
SEND
RTN
47
45
SEND
RTN
SEND
RTN
SUMMING AMP MODULE
PLUG ACTIVATES RELAY
PLUG ACTIVATES RELAY
S
SUMMING AMP MODULE
S
SUMMING AMP MODULE
PLUG ACTIVATES RELAY
RELAY
DAW
S
RELAY
DAW+MIX
RELAY
2.T.
GROUP BUS
GROUP INSERT
SOLO
SOLO BUS
MIX
LEFT
MIX BUSGROUP BUS
GRP 1-2
AW
26
+D
IX
.T.
2
MONITOR SWITCH LOGIC
MIX-L
INSERT
MIX-R
INSERT
MIXDAWM
S
39
Typical of 2
RELAY
RELAY
SOLO
LINE AMP MODULE
FROM GROUP 1-2
25
MASTER FADER
28
FROM MIX L-R
INDICATOR
MIX BUS
SOLO BUS
GROUP
OUT
46
VU
OUT
50
LEFT
MIX
OUTPUT
RIGHT
44
LEFT
MONITOR
OUTPUT
RIGHT
48
Figure 10. Master section signal flow
Page 25
Chapter 3 Operation Section 21
Master Module
25. Stereo Master
26. Monitor
Source Select
This 100mm dual slider is the master volume to the transformer balanced mix outputs. The VU meters will display any adjustment to this Stereo Master control when the Meter Select switch is set to the "Mix L-R" position.
Under normal operating conditions the fader should always be set at maximum. If it has to be pulled down a significant distance it indicates that the levels at the input channels are too high and should be reduced.
Four momentary pushbutton switches select the source to the Monitor Master control. Each switch has a red LED.
The source for the monitor can be:
Mix- This is the stereo mix of the LiLo post the stereo master fader DAW- This is any mono/or stereo signal that is connected to the DAW return. Mix+DAW - When pressed, any signal from the DAW return is combined with the overall mix, post the stereo fader. 2T - This is any mono/or stereo signal that is connected to the 2 Track return.
28
27. Monitor Master
This adjusts the overall level to the stereo monitor outputs on the rear panel. The Monitor Master typically controls the volume to a stereo power amplifier or powered speakers.
28. Mono Select
When depressed, this switch sums the left and right signal together, creating a mono composite for the monitor mix. The operation of the Mono switch does not affect the main stereo mix.
The Mono switch allows the user to check for any out-of-phase signals or simply monitoring your mix in monaural.
26
27
25
Page 26
Chapter 3 Operation Section 22
29. DAW Return Level
30. 2 Track Return Level
31. Solo Master
This trim pot adjusts the level of any external
32
stereo source connected to the DAW returns on the rear panel. This could be the stereo mix of a DAW or any other stereo source. This return is selected with the DAW, or the Mix+DAW Monitor Source Select switch.
33
The factory setting for this pot is about the 2 o'clock position. A small flat blade screwdriver can be used to adjust this pot.
This controls the level of any stereo source connected to the 2T returns on the rear panel. This could be a DAT recorder, CD player/recorder or any stereo audio signal. This return is selected with the 2T Monitor Source Switch.
This control adjusts the overall solo listening level to the monitor outputs. The adjustment of this control permits the volume of a soloed signal to match the level of the normal stereo mix. An associated LED illuminates when a solo switch on any input channel, group assign,
29
or aux return is soloed.
30
32. VU Meter Select
33. Aux Masters
This switch selects the source to the VU meter
31
pod as well as the ¼” VU output on the rear panel. This switch can be either the "L-R Mix" outputs or "Group 1-2" outputs. Two yellow LED's display the status of the selected outputs.
The four Aux Masters provide master level control to the balanced aux send outputs on the rear panel. 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.
Page 27
Chapter 3 Operation Section 23
Aux Return Section
There are two aux return sections incorporated into the LiLo. Each stereo return includes a stereo Return
Level control, Pan control, Mix Assign, Group Assign, and in-place Solo switch.
34. Aux Return Level
35. Pan/Balance Control
36. Mix Assign
37. Group Assign
38. Solo
This dual pot simultaneously and equally adjusts the left and right aux return level.
This center detent control acts as the left/right balance for any stereo output effects device connected to an aux return. When a mono output effects device is connected to the aux return, then this control would act as a traditional pan.
The Mix Assign switch, in conjunction with the Pan control, allows an aux return to be mixed to the left/right main output.
The GRP 1-2 pushbutton switch allows the aux return to be assigned and mixed to the two individual subgroups. This switch operates
38 37 36
under the control of the pan/balance control.
35
Depressing this switch allows you to isolate any aux return to the monitor outputs while
34
maintaining stereo perspective. The source for the in-place solo circuit is post (after) the aux Return Level control. This allows you to solo multiple effects returns while retaining their relative levels. A red LED above this switch, as well as the master Solo LED, will illuminate when the return is soloed.
Page 28
Chapter 3 Operation Section 24
Group Section
There are two group master sections on the LiLo mixer. Each section includes a Group Master level that controls a balanced XLR output on the rear panel. Each group section also includes a Pan control, Mix Assign that in conjunction with the pan control assigns the group mix to the main left/right mix, and In-place Solo.
39. Group Master Level
40. Pan Control
41. Group Mix Assign
42. Solo
43. Mix Assign LED Display
This control is the master to the group output on the rear panel. The VU meters will display any adjustment to the Group Master controls when the meter select switch is selected to the
42
GRP 1-2 position.
41
This center detent pan control places the group
43
master anywhere in the stereo left/right mix when the Mix Assign is enabled.
40
This switch, in conjunction with the Pan control, assigns the group mix to the main
39
left/right mix.
Depressing this In-place solo switch allows you to isolate the groups panned signal to the monitor outputs while maintaining stereo perspective.
When a group Mix Assign switch is depressed, this dual color LED will illuminate either green or red depending on the combination of switches that are assigned on any input channel. The reason for this display is to alert the user that a common signal from any input channel has been assigned to both the Mix and Group. Only when the group mix switch [41] is assigned is this LED relevant.
Group Mix Assign Channel Mix assign Channel Group 1 Assign Channel GRP Select LED color
G=Green, R=Red, X=Irrelevant, â=Switch Down, á=Switch Up
Logic Truth Table
[41]
[10]
[11]
[12]
[43]
Figure 11. Mix assign LED truth table
á â â â â
á â â â
X
â á â â
X
á á â á
X
Off G G G R
Page 29
Chapter 3 Operation Section 25
VU Meters
The LiLo may be ordered with a choice of two types of VU meters: A dual LED style, or dual analog style. Both types are calibrated to indicate 0VU for an output level of +4dBu.
LED Style
The LED style meter pod uses two 18 segment LED arrays and are sensitive from -31db to +5db. This circuit is designed to approximate the ballistics of a "taut band" analog style VU meter.
Analog Style
The Analog style meter pod uses two high quality illuminated Sifam VU meters.
Replacing lamps on the analog meter requires removing the cover of the VU pod by removing the (6) phillips screws. After the cover has been removed, carefully rotate the copper tab on the rear of the meter until it is clear of the lamp. Remove the old lamp and replace with a flange base, #7332, 5 volt incandescent lamp.
Page 30
Chapter 3 Operation Section 26
Master Module I/O connectors
The master section has a full compliment of XLR and 1/4" TRS jacks for the main Mix Outputs, Group Outputs, Monitor Outputs, Aux sends and Aux
returns, the stereo DAW Return and 2 Track Return, and a external V.U. Meter Output.
The pin configuration for all XLR connectors is:
Pin 1=Ground, Pin 2=High (+), Pin 3=Low (-)
The pin configuration for all ¼" TRS jacks is:
Tip=High (+), Ring=Low (-), Sleeve=Ground
The pin configuration for VU output jacks is:
Tip=Left, Ring=Right, Sleeve=Ground
44. Mix Outputs
45. Mix Insert Jacks
The balanced left and right mix outputs are adjusted by the mix Master Control [25] on the front panel.
Transformers are standard on the mix left and right outputs but can be ordered with Active-Balanced outputs.
The Insert Jacks provide line level inter-stage access to the mix bus before (pre) the stereo Master Fader. This means that any device interfaced to this jack will not be affected by any adjustments of the stereo Master Fader.
44
The insert jacks may be utilized to connect processors such as limiters, equalizers,
45
or noise reduction.
The active-balanced electronic circuitry of the left and right insert returns is completely bypassed via a relay until a plug is inserted into either the left or right mix return jack.
Page 31
Chapter 3 Operation Section 27
46. Group Output Connectors
47. Group Insert Jacks
48. Monitor Output Jacks
The balanced group outputs are adjusted by the Group 1 and Group 2 masters [39] on the master module.
Active-Balanced outputs are standard on the group outputs but may be ordered with transformer-balanced outputs.
Each group channel has ¼" TRS send and return insert jacks. The insert jack provides line level inter-stage access to the group bus before (pre) the Group Master level control. This means that any device interfaced to these jacks will not be affected by any adjustments of the Group Master control.
The insert jacks may be utilized to connect processors such as limiters, equalizers, or noise reduction.
The active-balanced electronic circuitry of each group insert return is completely bypassed via a relay until a plug is inserted into its respective insert return jack.
These balanced ¼" TRS jacks are available for hooking up a power amp or powered speakers. The signal present at these jacks is adjusted by the Monitor Master control on the front panel.
49. DAW and
2T Return Jacks
These active-balanced 1/4" TRS connectors allow the interface of an external stereo signal, such as a DAW, DAT, CD recorder/player, or any stereo line level source. These inputs are selected with the Monitor Select [26] on the master module. The 2T and DAW returns may be operated in mono when a single signal is plugged into the left input jack only.
46
47
4849
Page 32
Chapter 3 Operation Section 28
50. VU Meter Output
51. Aux Send Jacks
52. Aux Return Jacks
53. DC Power Input Connector
This ¼” TRS jack is available as an unbalanced output
51 52
for an external stereo VU meter and is selected with the VU Meter Select switch on the master module. The tip of the stereo jack is the left VU signal, and the ring of the jack is the right VU signal.
The use of this output connector does not affect the operation of the VU meter pod on the LiLo.
Each of the four Aux Send channels have an active­balanced ¼" TRS jack to interface to the input of an effects device.
Each Aux Return provides stereo balanced ¼" TRS
50
5354
jacks for connection from the outputs of a stereo effects device. In order to operate the stereo aux return as a mono return, plug into the left input jack only.
The DC power cable that comes from the power supply connects to this 9 pin circular connector. This connector and its respective plug is keyed so they will only fit in one direction. For power supply installation instructions, refer to the Interface & Setup Section in this manual.
The following connector illustration (Figure 12a) and chart (Figure 12b) represents the DC voltages to the 9 pin circular connector required to power the LiLo.
1
4 7
2
8
5
Figure 12a
PIN 1 0 VDC
3 6
9
PIN 2 +17.5 VDC PIN 3 +17.5 VDC PIN 4 0 VDC PIN 5 -17.5 VDC PIN 6 -17.5 VDC PIN 7 0 VDC PIN 8 +6.5 VDC PN 9 N.C.
Figure 12b
Page 33
Chapter 3 Operation Section 29
54. Chassis Ground Lift
When depressed, this switch disconnects the chassis ground of the LiLo from the power DC common. This can reduce the chance of ground loops and eliminate unwanted hums or buzzes.
A few words about hums, buzzes, and the role of a ground lift.
Not to suggest that the reasons for hums in an audio system can't be explained…they can… but the explanation, cure, and costs are very often out of the reach of the average project studio. This is why manufacturers sometimes include a ground lift switch on their products. It just saves you the trouble of clipping or soldering ground wires on your cables. Hence, there is not a right or wrong position for a ground lift switch. If either position improves an otherwise hummy-buzzy situation, that is the right position.
Page 34
Chapter 3 Operation Section 30
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Page 35
Chapter 4 Wiring and Other 31
Wiring & Other
General
AC Distribution
and Safety
Proper AC grounding
The following information is not specific to the operation of the LiLo, but rather general information regarding the “care and feeding” of an audio system.
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 audio product.
When you are evaluating voltage and current requirements for your audio system, it is important that your LiLo and/or audio 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.
Quality AC system
AC distribution
When using a larger studio 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.
Page 36
Chapter 4 Wiring and Other 32
Clock noise and AC
Safety earth connection
Audio earth
Proper Grounding
and Shielding
Clock noise is one of the greatest enemies of the audio racks AC system. If a computer or any microprocessor based device (most samplers and effects are) 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 AC 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 to get from “Point A” to “Point B” requires a cable with 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 semi-professional 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 37
Chapter 4 Wiring and Other 33
If a patchbay is utilized in your mixing system, the rules for shielding change. With a patchbay, normally all shields are connected at the patchbay jacks, and not connected at the mixer or external audio equipment.
EMI and RFI
The occurrence of EMI (Electro Magnetic Interference) and RFI (Radio Frequency Interference) in a contemporary studio system should be of great concern and not overlooked when installing the LiLo. EMI is defined as any unwanted signal which adversely affects the operation of the LiLO or your audio 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.
Sources of EMI
Reducing EMI
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 a studio or equipment rack, the higher the EMI emissions. The more audio cable and low level audio equipment that exists within the same proximity, 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 computers, samplers, and magnetic field sources from transformers and power supplies.
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