Crane Song AVOCET II User Manual

With REMOTE II

OPERATOR'S MANUAL

Version (8.0)

20140630

LTD.

2117 East 5th Street

Superior, WI 54880 USA

tel: [phone]

fax: [phone]

www.cranesong.com

© 2004, 2005, 2006, 2009, 2014 Crane Song, LTD. Subject to change without notice. Printed in

the U.S.A.

1

First time power up 6
Main Functions 8
Talk back 9,12
Gain Trims 10
Shift Mode 11
Headphone controls 13
Output 3 mode select 14
Surround mode 17
Reboot 22
Internal configuration jumpers 24
Back panel 30
Surround interconnect 31
Remote control size 33
Accessory connector 34
Revision History 35

5.1 interconnect cable pin out 36
Subwoofer alignment alignment 39

by Bob Katz
Headphones setup - external amplifier 47
External audio output 51
Avocet alignment 53
Signal flow diagram 55
Digital Metering cable pin out 56

2

IMPORTANT SAFETY INSTRUCTIONS

1. Read these instructions

2. Keep these instructions

3. Heed all warnings

4. Follow all instructions

5. Do not use this apparatus near water

6. Clean only with dry cloth

7. Install in accordance with the manufacturer's instructions

8. Do not install near any heat sources such as radiators, heat registers, stoves, or other
apparatus (including amplifiers) that produce heat

9. Protect the power cord from being walked on or pinched particularly at plugs and the
point where they exit from the apparatus

10. Only use attachments/accessories specified by the manufacturer

11. Unplug this apparatus during lightning storms or when unused for long periods of
time

12. Refer all servicing to qualified service personnel. Servicing is required when the
apparatus has been damaged in any way, such as power-supply cord or plug is dam­aged, liquid has been spilled or objects have fallen into the apparatus, the apparatus
has been exposed to rain or moisture, does not operate normally, or has been dropped

13. CAUTION: To disconnect the unit completely from the MAINS, unplug the unit. Turn­ing the power switch off does not disconnect the unit completely from the MAINS.

3

“Avocet” is designed to solve the problems of accurate monitoring and volume control as
required by workstation users, studios and mastering rooms alike. Avocet is a stereo
controller with three digital inputs, three analog inputs and a headphone system. All
digital signals are up-sampled and jitter reduced to ensure highest accuracy during D/A
conversion. Options are available to change the D/A mode, all though the default mode
has been chosen as more accurate.

Avocet’s many features including; dim, mute, phase, mono, and 16 bit truncation func­tions, plus a speaker select switch that sends line level balanced audio to one of three
outputs. The six input sources have on the fly gain trim capability.

An accessory connector has extra functions for the technically minded. They are; buff­ered stereo output, mono output, talk back mic output, headphone bus output, and
several input control functions such as; talk back enable, mute and input selection
control that could be used for a pre-listen or solo command. This connector is also used
to tie audio boxes together for surround operation.

The internal headphone amplifier can be fed from the program source or an external
input. Provisions for a talk back function are included.
The three headphone sources are;

• The analog AUX input

• Main, meaning the audio source selected by the input button

• Program, meaning the audio source selected by the input button.
However the level control, mono and phase buttons also apply to the program
source.

All three phone sources have individual gain settings controlled by the green knob.

The talkback mic
the remote. The talk back mic signal is mixed into the headphone amplifier along with
the selected headphone source. By sending a cue mix to the Aux input you can use the
headphone system for doing overdubs in the studio and have communication to the
artist. At the same time the main audio path can operate independently of the head­phone system

(not supplied and there is no phantom power) is hooked into the xlr connector on

SURROUND

By using 3 two channel audio boxes Avocet will function as a 5.1 system, and 4 audio
boxes makes a 7.1 system. See the speaker setup information. This function allows
intergrating, both surround and stereo speaker systems. A metering system is under
discussion. A specially made accessory cable connects the audio boxes when working
surround.

Systems that ship surround from the factory have lables on them as to how the audio
boxes are configured.

4

Notes:
When configuring the units for Surround, if the system was not purchased as Surround please consult
the factory

This manual applies to Avocet version 1.5 with remote II, the older manual is available on the web site

5

FIRST TIME POWER UP

The first time that Avocet is powered up, it should be initialized. This is done by pushing
all three output select buttons at the same time. This sets up the remote for proper
operation. It also resets the user settings:

All gains, main and phones are set to zero
Output 1 is the selected output
DAW is the input selected
Phones are set to the Aux input
Stereo speaker selection is selected
All offsets are cleared

The remote cable must be attached and screwed down before power up.

Take the time to look at the following pages and see show how the buttons work. After
that, you should be good to go.

Almost all user selections and gains are remembered by Avocet and restored on power
up. The headphone button and the talk button positions are not remembered

Configuration information for surround or stereo only systems are in the back pages of
this manual.

AUDIO PATH

The main audio path is discrete class A electronics with a stepped attenuator for gain
control. All switching and gain control functions in the main audio path is done with
relays. Yes they make acoustic clicks when operating.

The headphone audio path is done with high quality integrated circuits. The D/A con­vertor uses the latest technology intergated circuits.

POWERED MONITORS, POWER AMPS WITH NO GAIN CONTROL

Most powered monitors do not have a level control that is meaningful. This results in the
need to trim Avocet’s output gain. In order to do this and not add any amplifier stages
an output pad is supplied. This pad is to be placed at the input of the power amp. Not
at Avocet’s connector. The pad has a range of 6 to 20 db of loss and is preset to a 10
db loss.

6

BUTTON FEEDBACK
When holding down a button for gain trim; or speaker setup, the led now provides
feedback that the button was held for the required time. The led will wink out for 1/2
second and then come back on. In the previous version there was no feedback to
the user on mode change. This applies to the 6 input select buttons, the mono
button, and the speaker buttons for selecting the mono output channel.

7

MAIN FUNCTIONS

Truncates the digital input to 16 bits. For
checking what 16 bits sounds like

Channel Selection
to 7.1 surround

SHIFT MODE
to reach the setup
functions (they have the
smaller text on the panel)

Selects which
speaker output
1 of 3

Changes the
phase of one
channel, disabled
in surround mode

Talk back button sends the
talk mic into the head­phone output. It is push-on
push-off, however holding
it for 2 seconds allows
quick release - non latching

Monos the
stereo source

Dims the main audio path. The dim level
is set by turning the level while dim mode
is active.
Selection of phones is over ridden by
selecting dim.

Input selection
The DAW input will be S/PDIF,
AES or Optical selected in
Shift mode. Digi- 1, 2 are AES,
the analog inputs are Bal­anced

Input level when
Phones or Dim modes are
not selected
1 DB steps through most of
the range

Mute kills the main output.
On power up Avocet is
muted

8

Talkback Operation

Talk mic is on when
the LED is on. It has
push-on, push-off operation
or latching. However if the
talk button is held for one half
second, talk back releases
when the button is released,
non latching

The monitor level can be set when the
talkback button is pushed. The monitors can
be dimmed to off or a level that is below
feedback. This will allow comminution in
both directions while in talk mode.

When in talkback all other buttons are
locked until talkback is released

9

Gain Trim

Shift key to enable gain trim, offset control

Gain trim offset clear

Gain trim offset lock

Gain trim unoffset lock

must be in shift mode
to enable these functions

If one presses and holds the input select button a second time it will enable the input
gain trim mode. It requires about one half second of hold time to enter the trim mode.
Trim mode allows changing the input level on the selected input relative to all other
inputs. Gain trim has an offset range of plus or minus 10 db in 1 db steps. By pressing
the input button a third time, the input will return to normal operation while remembering
the gain trim. Selecting any other input will also exit the trim adjust mode.

Gain trim can be cleared, locked or enabled by using the Shift key to reach the desired
selection.

The mono function also has a gain trim for level matching in surround. After selecting
mono, if one presses and holds (for one half second) the mono select button it will enter
the input gain trim mode. To leave the gain trim mode press and hold the button for one
half second. Pressing the button for less time will cause the gain trim to be remem­bered and the mono mode to be exit.

In normal operation all input gains will track. At the end of the stepped attenuator range
the offset gains could reach a limit where they will not change. As an example if you
trim an input up by 10 db and then move the main gain to max that input will be max
+10 which is not possible. Bringing the main gain back down, the 10db offset will still
exist. The same thing will happen on the bottom end of the control range.

10

SHIFT MODE SETUP FUNCTIONS

In the Shift Mode Select the source

for the DAW input between

AES, SPDIF, OPTICAL

.

Changes DIM
from relative LEVEL
to absoulte LEVEL

Changes output 3
to work in parallel
with outputs 1 and 2
for use as a sub woofer
output

Functions F1, F2, F3
for future features

11

SHIFT MODE SETUP FUNCTIONS

TALK BACK MIC GAIN

TALK BACK MIC GAIN is changed by
selecting the TALK button
when in the SHIFT MODE.
Turning the gain knob
changes the mic gain. The gain steps
are 3 db steps to 72 db of gain

GAIN

12

SHIFT MODE

Headphone Setup

Headphones / shift to select phones control

Dim Button over rides
Headphone mode

Headphone Level

Selects direct AUX analog
input for the Headphone
output

The headphone source is
selected by the main input
buttons. It’s level does not
change with the main
system level

The headphone source
is selected by the main
input buttons. It’s level
changes with the main
system level

13

Shift Mode Output 3 Mode

as sub woofer on-off

With this button selected in the shift mode. OUT 3 is converted to work
as a Sub Woofer output. It is full range unfiltered audio that can be
turned ON or OFF with OUT 3. Thus allowing outputs 1and 3, or 2 and 3
to be on at the same time. If this is not selected, OUT 3 works as a
normal third speaker system output

Shift to select control

Output 3 does not provide any filtering or mono summing. Using this as
an output to turn a sub woofer on or off assumes that either there is
external summing and filters for the sub woofer or that there is stereo
sub woofers with filtering which is a better method.

14

In normal operation one should set the power amp gain, so that your normal listening
level is with the gain knob at 1 o’clock. There is a supplied adjustable pad for powered
monitors and power amps that have no gain control.

Speaker selects - Mute and Solo

Channel or speaker control is determained by the top row of buttons.
The channel is on when the led is on. This applies to all modes of
operation. The channels are Left, Right, Center, LFE, Surround Left,
Surround Right, Extra Left, Extra Right.

If one holds down a channel select button for one half second or more
the selected channel will be soloed. The led on the soloed channel
will flash indicating that this is the soloed channel. Other channels
can be turned on and off in the solo mode. By holding down the
flashing / soloed channel a second time ( for one half second) the
system will return to the pre-soloed speaker selection. If one holds
down a different channel select for the one half second time period
un-soloing returns to the selected channels prior to having selected a
new soloed channel.

15

Speaker select buttons now allow multiple selection
at a time

Mute will over ride
all functions including Talk
Back

16

Changing the speaker setup

from Stereo to Surround

Default mode

By pressing any one of the speaker select buttons and holding it for
about 0.5 seconds will put Avocet into the speaker set up mode.
If SHIFT is selected the speaker setup is disallowed.

Selecting the center channel button will cause the center channel be
the mono speaker when selecting mono. This is the surround mode
of operation

Selecting the left, right, or both, (left and right) will disable the sur­round channels. This selects which speaker is the mono speaker,
when the mono function is selected. This is the stereo mode of
operation

To exit the setup mode touch the output select button a second time
During Speaker setup the Sub Woofer mode is disabled.

Once set up, switching between the speaker systems is user trans­parent.

17

Transparent Surround Mode

MONO SPEAKER SELECT

Selects which speaker
is the mono output
when mono is selected

Speaker Setup

In OUT 1 SETUP SELECT
turning this button on
will cause the unit to be in
surround mode at all times
(Transparent Surround `Mode)
the mono speaker select
function determines the
active speakers when mono is
selected

18

Group Function

This showes the key grouping

The group function is reached by the phones / shift
button and then selecting the group button. What it
does, is in surround mode, it groups together Left,
Right, Center to function as one button, Surround
Left and Surround Right as one button, and Extra
Left and Extra Right as one button

19

Changing the speaker setup

from Stereo to Surround

By pressing any one of the speaker select buttons and holding it for
5 seconds will put Avocet into the speaker set up mode.

Pressing the center channel button will make the center channel be
the mono speaker when the mono function is selected. This is the
surround mode of operation

Selecting the left, right, or both, left and right will disable the sur­round channels and select which channel is the mono speaker, or
speakers, when the mono function is selected. This is the stereo
mode of operation

To exit the setup mode touch the output select a second time

Once set up, switching between the speaker systems will be trans­parent.

There is no channel summing when going from surround down to
stereo.

20

Functions that can change

There are trim pots on the back of the main unit
for the analog gain trim. These have a range of
8 db

There is a high gain mode selected by an
internal jumper. This will add 14 db of gain to
the Analog 2 input. There is a small pop that
can be heard when the gain changes by 14 db.
This is a result of the switch contacts and
happens only when high gain is selected

20

Clearing the internal settings -

System Reset

By pressing all three output selection buttons
at the same time Avocet will reset all of it’s
internal settings. This is the same as rebooting
the remote.

All gains, main and phones are set to zero
Output 1 is the selected output
DAW is the input selected
Phones are set to the Aux input
Stereo speaker selection is selected
All offsets are cleared

22

Rev 8 D/A jumpers and Trims

Main Audio Path Digital level trims

Meter mute off = enabled
on = disabled

Meter level trims for digital metering output
analog inputs only

This jumper on for master or stereo operation
It is on for a stereo system
In a surround system this jumper in on, on the
left right channels
It is off on all other units. This allows the A/D to
sync to the master or stereo unit

23

JUMPER FOR HIGH GAIN ON ANALOG 2 DEFAULT IS OFF LOW GAIN

JUMPERS FOR SURROUND

OFF OFF - LEFT, RIGHT

FAULT

JUMPER ON THESE 2 METER = INPUT DE-

JUMPER ON THESE 2 METER = OUTPUT

JUMPER ON = STEREO, OFF = SURROUND OPERATION

JUMPER ON SOLO = ANA1 INPUT

JUMPER OFF SOLO = DAW INPUT

ON OFF - SURROUND LEFT, RIGHT

OFF ON - CENTER REV 5 AND UP ONLY

ON ON - EXTRA

REV 4 pcb

Do not change jumpers or adjust the trim pots unless you are sure of what you are doing

24

JUMPER FOR HIGH GAIN ON ANALOG 2 DEFAULT IS OFF LOW GAIN

JUMPERS FOR SURROUND

OFF OFF - LEFT, RIGHT

FAULT

JUMPER ON THESE 2 METER = INPUT DE-

JUMPER ON THESE 2 METER = OUTPUT

JUMPER ON = STEREO, OFF = SURROUND OPERATION

JUMPER ON SOLO = ANA1 INPUT

JUMPER OFF SOLO = DAW INPUT

NOT ASSIGNED

ON OFF - SURROUND LEFT, RIGHT

OFF ON - CENTER REV 5 AND UP ONLY

ON ON - EXTRA

REV 5 pcb

Do not change jumpers or adjust the trim pots unless you are sure of what you are doing

25

REV 5 pcb Center Channel Jumpers

Do not change jumpers or adjust the trim pots unless you are sure of what you are doing. This
controls what happens with the center channel and LFE channel when in the mono mode. The
settings below is for stereo operation, and in surround mode, the front and surround channels.

Center Channel Surround

The settings below is for LFE and center channel operation.

26

JUMPERS POSITIONS FOR STEREO OPERATION

JUMPERS POSITIONS FOR SURROUND

LEFT - RIGHT FRONT

27

JUMPERS POSITIONS FOR SURROUND

CENTER - LFE

JUMPERS POSITIONS FOR SURROUND

LEFT - RIGHT SURROUNDS

28

JUMPERS POSITIONS FOR SURROUND

EXTRA CHANNELS

29

Power entry

Analog Outputs

Remote connector

and fuse location

Power Switch

Second headphone output

Analog Outputs

Analog input

Gain Trims

Digital inputs

Analog inputs

30

5.1 INTERCONNECT

link cable

Surround Left, Right channels

Center = Left, LFE = Right

Left and Right channels

Connect Remote here

When powering the system up. If they are not all powered at the same time, the audio box
with the remote connected to it must be powered on last. If any of the units are not pow­ered the remote will not work correctly.

The internal jumpers must be set correctly. See the page with the jumper settings

31

STEREO INTERCONNECT

Connect Remote here

The internal jumpers must be set correctly. See the page with the jumper settings

32

7.53 inches

Depth not counting the knob is 1.62 inches

8 inches

PAD LOSS ADJUST

OUTPUT

INPUT

XLR OUTPUT PAD

This is an adjustable pad for use with amplifiers or powered monitors that have no

gain control. The pad has a range of 6 to 20 db of loss. It is preset to 10 db

33

ACCESSORY CONNECTOR

1 Right Channel Source Output
2 gnd
3 gnd
4 talk mic output - When talk button is pushed (Mic Output)
5 Right phones out (Line level phone bus)
6 Left phones out (Line level phone bus)
7 gnd / ground
8 data I/O do not connect
9 gnd
10 gnd
11 gnd
12 Surround mono input 6
13 Surround mono input 5
14 Left Channel Source Output
15 mono out
16 talk command in - enable by tying to gnd
17 mute+
18 mute-, solo­19 solo+
20 used in surround wiring from left-right to center channel
21 gnd
22 Surround mono input 1
23 Surround mono input 2
24 Surround mono input 3
25 Surround mono input 4

To use the external mute or solo inputs 5 to 15 volts needs to be applied to the control
input lines. Polarity must be followed. These inputs are optical isolated.

The mute control is push on - push off, the talk input is also push on - push off
or latching. The solo switching remains in the soloed state as long as the control volt­age is applied. A jumper is provided on the main pcb that selects either the solo is the
DAW or ANA1 input as the solo input.

All audio signals are unbalanced

Starting with the rev5 pcb the low connection for mute and solo has changed

See the section on headphone setup and the external wiring connections.

34

Revision History

Rev3 main pcb Non Surround Remote

This version will not upgrade to surround operation. New everything is required. This version has a
db15 connector accessory on it’s back all others have a db 25 pin connector
This is units with serial numbers to A682840

Rev4 main pcb Non Surround Remote

The Rev 4 main boards will work for front or surround channels only. This version should have 2
relays changed, it also requires a circuit modification to allow operation of the surround channel select
buttons and the firmware updated for surround operation. The D/A converter will need to be up­graded to the Rev 6 D/A or later. In surround operation all the D/A’s must be the same. Surround
operation is then enables by installing the proper jumpers to configure the system

Rev4 main pcb Surround Remote

The Rev 4 main boards will work for front or surround channels only. This version should have 2
relays changed and the firmware updated for surround operation. The D/A converter should also be
checked for the Rev 6 D/A or later. In surround operation all the D/A’s must be the same. Surround
operation is then enables by installing the proper jumpers to configure the system
This is units with serial numbers starting with A682881

Rev5 main pcb Surround Remote

This version is required for center channel and LFE operation. The Rev 4 main boards will work for
front or surround channels only. This version is shipping with the latest firmware and the latest D/A
converter, Rev 6 D/A or later and is ready for surround operation by selection the proper jumpers to
configure the system. The Accessory connector has a small pin out change from the rev 4 pcb. This
is units starting with serial numbers A682941.

Firmware

As of December 5, 2005 the firmware revesion that is being shipped has a blue dot on the remote
and on the main unit. This firmware will not work correctlly with non blue dot firmware. There
will be a firmware update in early 2006 for the non surround remotes that will allow some additional
operations. Starting with the rev 4 main unit and with either the surround remote on the rev 4 pcb of
the non surround remote, an upgrade in firmware will allow the remote inputs on the accessory con­nector to change the display on the remote when activated.

35

D/A Converter
Starting with Sn A682890 we switched to a new SRC in the D/A converter. This D/A is a big improve­ment in sound quality. This is an upgradable item. In units with serial numbers of A682840 and less it
will require some soldering skills. The later units it is plugin.

Upgrades

Upgrades are factory direct only in the US and in the rest of the world by the local Crane Song
distrubition company.

REV7 FIRMWARE, REV7 D/A

Sarting with the rev 7 D/A board rev 7 firm ware is installed in both the main unit and the remote.

both units must contain the same rev.

If a rev4 or later system has this frimware installed it should be fine.
In other words rev4 and later main boards with the surround remote will run rev7 firmware
The remote must be a surround version

In order to upgrade to the rev7 D/A
the wrap need to change, the digital out requires an extra hole.

This D/A is in units starting with Sn. A683041. The rev7 D/A has the same time delay as as the rev6
and later D/A so they can be mixed in a surround system.
However only rev7 and later has the metering digital output.

THE CHANGES

1. Output #3 can work in parallel with outputs 1 or 2. This is for thoese who need only 2 outputs
and have the desire to turn a sub woofer on or off, the OUT 3 button cab be programmed to allow this
type of operation. Note that when setting up the type of speaker system, stereo or surround, the
system switches to non sub woofer mode. You will then need to reset this mode if you desire it.
At this time, there is not any writting on the front panel for this function

2. The remote talk input is now non latching. This is available on the db 25 connector.
The talk button on the remote will latch if pushed for less than 0.5 seconds, If it is held
for more than 0.5 seconds it will be non latching. The remote input and the button on the remote can
over ride each other.

3. A digital meter output has been added. This is an AES output on a DB-9 connector
which also allows of meter sync in surround mode. It requires a specially made cable

36

This page is being updated

Sn for REMOTE II starts with AR684189
Sn for the main unit with the new D/A start with AM684259

5.1 interface cable wiring diagram

If you wish to use any the other accessory connector connections such as the talk back command
input, they should be connected to the left, right audio box connector.

38

This is avery good starting place for setting up sub woofers. One could go farther and use a RTA and
experment and find the best place in the room for subwoofer placement.

This was written by Bob Katz, www.digido.com and is used with permission

Accurately Set Up a Subwoofer With (Almost) No Test Instruments

Bass frequencies are extremely important to sound reproduction. Everyone is interested in getting
their bass right, but most people haven’t a clue how to proceed. This article will help to settle the
process of integrating an active subwoofer with an existing “satellite” system. If your room and
loudspeakers are good, you’ll only need two test CDs and your ears to adjust your subwoofer. If your
room is not so good, or you want to refine the sound even further, then we’ll discuss the best way to
integrate test equipment measurements with your hearing. The simple listening test will also reveal if
your room has problems and if it’s time to hire an acoustician.

Let’s review the basic requirements for smooth, extended bass response.

Conquering the Room

Many people are proud of the “ideal dimensions” of their listening room. In general, the larger the
room, the fewer audible problems with low frequency standing waves (nodes and antinodes). To
getsmooth and even bass requires ceilings taller than 10 feet, width greater than 12 feet, and length
greater than 25 feet (30 or more for deep bass). Dimensions (including diagonals) should not be
multiples of identical wavelengths, to avoid buildup at octave resonances. Of course, larger rooms
may need absorption to keep the reverberation time down, but standing waves don’t tend to build up
awkwardly in larger rooms. It’s also important to use absorption so that the decay time at low
frequencies is roughly similar to that at mid and high frequencies. This is called a “neutral room.”

Lightweight, flexible walls act as
out the walls, never to return. In my opinion, the ideal is a solid concrete (block) wall, but proper
construction with plaster lathe, wood, and/or double sheet rock can accomplish similar results. But
solid walls create problems of their own; a world-class room usually requires some absorption and/or
diffusion to deal with resonances and echos. Watch out for cavities within the walls, which can cause
resonances. Creating a large room with good bass response, interior acoustics, and outside isolation,
is the role of a professional acoustician. This article will share some secrets in the fine tweaking of
systems in good rooms; don’t dream of building a room from scratch without hiring an acoustician.

Speaker Mounting - Spikes or Isolators?

Soffit-mounting involves recessing loudspeakers into a cavity in the wall, with the edge of the
loudspeaker flush to the wall. Soffit-mounting requires the expertise of an experienced acoustician,
and is beyond the scope of this article. The main loudspeakers must be decoupled from the floor.
Heavy, rigid stands should have a top no larger than the bottom of the loudspeaker to avoid diffraction
(a form of comb filtering). I’ve had great success spiking speaker stands (using spikes, or “tiptoes”)
through holes in the carpet. Some authorities recommend a damping pad underneath a heavy, full

diaphramatic absorbers,

where some bass frequencies will escape

39

range speaker instead of spikes. Whichever mounting method, the goal is to reduce sympathetic
vibrations or traveling waves in cabinets, floor and walls. The resonant frequency of the box and stand
should be extremely low. Hit the box with your fist and confirm it does not have a resonant character;
sweep a sine wave through the system and listen for vibrations. I’ve had great success with a very

thin isolator between the speaker and the stand which compresses almost completely under the

speaker’s weight.

Listener position

If you’re sitting in an antinode, there’s always going to be a dip at that frequency, and no amount of
equalization will correct the acoustic problem.

Speaker position

Ironically, solid walls aggravate the interaction of loudspeaker position and frequency response. The
closer the loudspeaker to walls and especially corners, the greater the bass level. You may have the
“smoothest,” most accurate satellite (main) speakers in the world, but they must be positioned to avoid
side wall reflections and must be far enough from all walls to reduce resonances.

Near Field Monitoring?

I wouldn’t master with near-field monitors, but I will mix with them. Near-field monitoring was devised
to reduce the effects of adverse room acoustics, but if your room acoustics are good, then “Mid-field”
or “Far-field” will provide a more accurate depth and spatial picture. There must be an obstruction-free
path between the monitors and the listener. What is the biggest impediment to good sound
reproductionin a recording studio? The console. No matter how you position the monitors, the
console’s surface reflects sound back to your ears, which causes
effect you get if you put your hand in front of your face and talk into it. Or if you wear a wide-brimmed
hat, which produces an irregular dip around 2 kHz. It amazes me that some engineers aren’t aware of
the deterioration caused by a simple hat brim! Similarly, I shudder when I see a professional
loudspeaker sitting on a shelf inches back from the edge, which compromises the reproduction. The
acoustic compromise of the console can only be minimized, not eliminated, by positioning the
loudspeakers and console to increase the ratio of the direct to reflected path. Lou Burroughs’ 3 to 1
rule can be applied to acoustic reflections as well as microphones, meaning that the reflected path to
the ear should ideally be at least 3 times the distance of the direct path.

comb filtering

, the same tunnel

What about measurements?

Can’t we just measure, adjust the crossovers and speaker position for flattest response, then sit down
and enjoy? Well, since no room or loudspeaker is perfect, measurements are open to interpretation,
and frequency response measurements will always be full of peaks and dips, some of which are more
important to the ear than others. Which of those many peaks and dips in the display are important
and which ones should we ignore?
I’ve found the ear to be the best judge of what’s important, especially in the bass region. The ear will
detect there’s a bass problem faster than any measurement instrument. The measurement instrument
will help to pinpoint the specific problem frequencies, whether they’re peaks or dips, and by supplying
numbers, aid in making changes. The whole process is very frustrating, and it’s inspired my search for
setup and test methods that use the ear. A perfect setup still requires a multistep process: listen,
measure, adjust, listen again, and repeat until satisfied, but it’s possible to streamline that process.
Here’s a listening test for adjusting subwoofer crossovers that uses simple, readily obtainable and
cheap test materials, and that’s generally as precise as most more formal measurement techniques!
If you’re setting up a permanent system, dedicate a day to the process; even the easy doesn’t come
easy. Some brands of subwoofer amplifiers have all the controls or connectors you need; you may
have to adapt the process described below to your particular woofer system.

40

Polarity is not Phase

This is still a confusing topic, perhaps because people are too timid to say
The

polarity

signal, and can be corrected by a simple wire reversal. Remember that
phase shift is actually a time delay. The so-called
switches, they have no effect on the time of the signal! Sometimes this is referred to as

phase

loudspeakers are working together, their polarity must be the same. If they are separated by space, or
if a crossover is involved, there may be a
degrees (at a specific frequency). I have a pair of
There are three controls on the crossover/amplifier: volume (gain), phase (from 0 to 180 degrees),
and low pass crossover frequency (from 35 Hz to over 200 Hz). Notice there is no high pass
adjustment. The
loudspeakers have clean, smooth response down to some bass frequency, and gradually roll off
below that. It’s logical to use the natural bass rolloff of the satellites as the high pass portion of the
system and to avoid adding additional electronics that will affect the delicate midrange frequencies.
So we use a combination of lowpass crossover adjustment and subwoofer positioning to fine-tune the
system.

A good subwoofer crossover/amplifier usually provides more than one method of interconnection with
the satellite system. The best is the one which has the least effect on the sound of the critical main
system. I prefer not to interfere with the line level connections to the (main) power amp feeding the
satellites. If your preamplifier does not have a spare pair of buffered outputs, I recommend using the
speaker-level outputs of the main power amp. The
coupled balanced inputs on banana connectors designed to accept speaker-level signals. Connect
the main power amp’s output to the sub amp’s input with simple zip cord with bananas on each end.
No real current is being drawn, so wire gauge does not have to be heavy. Double-bananas make it
easy to reverse the polarity of the subwoofer, a critical part of the test procedure. Some subwoofers
use a 12 dB/octave crossover, others 18 or more. Interestingly, for reasons we will not discuss here, a
12 dB crossover slope requires woofers that are wired out of polarity with the main system. My subs
use a 12 dB slope, but to make it easy on the mindless, the internal connections are reversed, and
you’re supposed to connect “hot to hot” between the main power amplifier and woofer amplifier. Leave
nothing to doubt-we must confirm the correct polarity.

, but I recommend avoiding the use of the term

of a loudspeaker refers to whether the driver moves outward or inward with positive-going

natural

phase

phase

difference between them, measured in time or

Genesis

approach to subwoofer nirvana assumes that your (small)

switches on consoles are actually

phase

Genesis

when you really mean

subwoofers with separate servo amplifiers.

provides high-impedance transformer-

polarity

phase

when they mean it.

means

relative time

polarity

absolute

polarity

. If two

satellite

;

You have to sit in the “sweet spot” for the listening evaluation. If your subwoofers have an integrated
amplifier, you’ll need a cooperative friend to make adjustments. Since the Genesis amplifier is
physically separate, I was able to move the subwoofer amplifiers to the floor in front of the sweet spot,
and make my own adjustments. Here are the two test CDs:

1. The Mix Reference Disc, Deluxe Edition, MRD2A, available from Music Books Plus, or any
source of 1/3 octave filtered pink noise. Track 71 contains full bandwidth pink noise, and tracks
11 through 41 use multi frequencies in 1/3 octave bands.

2. Rebecca Pidgeon,
stores, or from Chesky Records.

I recorded Rebecca’s disc in 1994. Track 12 is
bass part that makes it easy to identify notes that “stick out” too far and covers the major portion of
the bass spectrum. This record has never failed to reveal the anomalies of different rooms and
loudspeakers in several years of use as a musical reference. The ear is better with instant
comparisons than absolute judgments, and this test relies on our ear’s ability to make comparisons.

The Raven

, Chesky JD115, available at record stores, high-end stereo

Spanish Harlem,

41

which has a slow, deliberate acoustic

All musical instruments and transducers produce harmonics as well as fundamentals. To the best of
our ability to discriminate, we will be concentrating on the fundamental tones in this piece of music. If
your loudspeakers have significant harmonic distortion, they can complicate or confuse the test. Many
studio loudspeakers are designed for high power handling at the expense of tonal accuracy or
distortion. This test is not for them. If you want accurate bass, it’s time to replace the loudspeakers
and probably hire an acoustician with a distortion analyzer.

Start by evaluating the satellite system with the subs turned off. Listen to the bass at a moderate level
equal to or slightly louder than the natural level of an acoustic bass. Listen for harmonic distortion: if it
doesn’t sound like a “transparent” acoustic bass, fix the problem with the satellites, first. Listen for
uneven notes. If the lower note(s) of the scale are successively softer in level than the higher notes,
then you have a perfect candidate for a subwoofer. If intermediate bass notes are weak or strong
(uneven bass), the satellite loudspeakers may be too close to the corners, in a node or antinode, the
listening position may be in a standing wave, or the satellites themselves poorly designed. It may be
time to bring in an acoustician. But if the satellite bass is even, you can move on to the next step,
adjusting the subwoofers.

Spanish Harlem

fundamental notes of the bass. If your loudspeaker has sufficiently low harmonic distortion, it will not
affect your judgment of the power of the bass notes, which are already affected by the natural
harmonics of the instrument.

49 62 73 65 82 98 73 93 110

, in the key of G, uses the classic 1, 4, 5 progression. Here are the frequencies of the

As you can see, this covers most of the critical bass range. If the lowest note(s) is weaker than the
rest, then you are a candidate for a subwoofer. My satellites behave in the classic manner, with the
lowest note (G, 49Hz) slightly low in level, but the rest fall in a balanced line. I’ve been in small rooms
where one or more of the intermediate notes are emphasized or weak, which suggests standing wave
problems. Repositioning the satellites may help. Avoid equalization, which is a nasty band aid...proper
acoustic room treatment is the cure. You could conceivably add a subwoofer out of phase at the
frequencies in question, but that’s a technique that should remain confidential between you and your
analyst. Fix the acoustic problems first and you’ll be happier.

If your satellite system passed the initial examination, next step is to decide on a starting
(approximate) subwoofer location. A satellite-subwoofer system has tremendous flexibility, offering in
theory the best of two worlds. The satellites can be placed on rigid stands at ear level, far from
corners and side walls, reducing floor and wall reflections and comb-filtering in the midband. And the
subs can be placed on the floor, in the position that gives the most satisfactory bass response,
integrated with the satellites. If you only have one (mono) subwoofer, start by placing it in the middle
between the stereo speakers. Contrary to popular belief, stereo subwoofers are important, they can
improve the sense of “envelopment”, the concert hall realism that bass waves are passing by you.
Authorities are split on the issue whether a mono or stereo subwoofer setup is more forgiving of room
modes. I prefer the sound of stereo subwoofers. A complete discussion ofhow to place the satellites
would require another article, but let’s start by saying that you may have to deal with reflections from
the side walls by placing absorbers in critical locations. Consider consulting a competent acoustician.

Assuming your satellite system passes the listening test, it’s time to find the right crossover frequency,
phase and woofer amplitude that will just supplement the lower notes of the scale. Start by placing
the subwoofers next to and slightly in front of the satellites. First we must determine the proper
polarity for the subwoofers. If your system uses XLR input connectors, build a polarity reversing
adapter for this part of the test. This is easier with only one channel playing. Put on the MRCD with
full bandwidth pink noise, at a moderate level (70-80 dB SPL). Adjust the crossover to its highest
frequency, the phase to 0, and turn up the subwoofer gain until you’re sure you can hear the woofer’s

42

contribution. Reverse the polarity of the sub. The polarity which produces the loudest bass is the

correct polarity

Next comes an iterative process (“lather, rinse, repeat until clean”). Here’s a summary of the four­steps: (1, 2, & 3) Using filtered pink noise, we’ll determine the precise phase, amplitude and
crossover dial position for
if all the bass notes now sound equally loud. If not equally loud, then we’ll go back to the filtered pink
noise and try a different crossover frequency. We keep repeating this test sequence until the bottom
note(s) has been made “even” without affecting the others. With practice you can do this in less than
half an hour. Adjust each subwoofer individually, playing one channel at a time.
And now in detail:

1) Crossover frequency (lowpass)

Play filtered pink noise (or the Mix CD’s multifrequencies) at your best guess of crossover frequency,
say 63 or 80 Hz. Notice that the signal has a
misadjusted, adding the sub to the satellites will slide the pitch center of the satellite’s signal. Reverse
the sub’s polarity (set it to
frequency, and raise the frequency until you hear the dominant pitch begin to rise (literally, the center
“note” of the pink noise appears to go sharp, to use musical terms). Back it off slightly (to a point just
below where the pitch is affected), and you have correctly set the crossover to this frequency.
Recheck your setting. That’s it.

. Mark it on the plugs, and don’t forget it!

any one crossover frequency

pitch center, or dominant pitch quality.

incorrect polarity).

With the sub gain at a medium level, start at the lowest

. (4) Then we’ll put Rebecca back on and see

If the subwoofer is

2) Phase

The sub should always be on a line with or slightly in front of the satellite. With the woofer a moderate
amount in front of the satellites, the phase will generally need to be set something greater than 0
degrees. Return the sub(s) to
increase the amount of “phase” until you hear the dominant pitch rise. Back it off slightly, recheck your
setting, and that’s it

3) Amplitude

The subwoofer’s settings are exactly correct when its amplitude is identical to the satellite’s at the
crossover frequency. The subwoofer gain is the easiest to get right because there will be a clear
center point, just like focusing a camera. Play the filtered noise, and discover that the pitch is only
correct at a certain gain, above which the pitch goes up (sharp), and slightly below which it goes
down (flat). “Focus” the gain for the center pitch, which will match the pitch of the satellites without the
sub. Recheck your work by disconnecting and reconnecting the sub. The pitch should not change
when you reconnect the sub, otherwise the gain is wrong. To be extremely precise, increase the gain
in tiny increments until you find the point where the pitch rises when the sub is connected, then back
the gain off by the last increment. This process is extremely sensitive.

4) Rebecca

Play

Spanish Harlem

If you hear a rise in level below some low note, then the crossover frequency is too high and vice
versa. Do not attempt to fix the problem with the subwoofer gain, because that has been calibrated by
this procedure, which leaves nothing in doubt except the choice of crossover frequency. Go back to
step one and try again. Once all the notes are even, your crossover is perfectly adjusted. Write that
frequency down. Then, for complete confidence, check the nearest frequency above and below (go
back through steps 1-4), proving you made the right choice. This piece of test music is sufficiently
useful that there will be a clear difference between each 1/3 octave frequency choice and it will be
comparatively easy to determine the winner. The trick is not to rely on our faulty acoustic memory, but
on the ear’s ability to make relative comparisons.

again. If all the levels of the bass notes are even, you’re finished with steps 1-4.

the correct polarity.

Play the same frequency of filtered noise and

43

More Refinement
Fine tuning the stereo separation (space between the woofers)

If you have stereo subwoofers, their left-right separation must be adjusted. Play
Listen to the sound of the bass with the subs off. It should be perfectly centered as a phantom image
and and its apparent distance from the listener should subtend a line between the satellites. If it is not
perfectly centered or its image is vague, the satellites are too far apart. Now add the subwoofers. The
bass should not move forward or backward, and its image should not get wider or vaguer. Adjust the
physical separation of the subwoofers until the bass image width is not disturbed when they are
turned on. This “integrates” the system. Go back to step one, recheck the amplitude and phase
settings for the new woofer position. Everything is now spot on.

Congratulations, you’ve just aligned a world-class reproduction system! A subwoofer should not call
attention to itself, either by location or amplitude. When you play music, the combination of the sub
and mains will sound like a single, seamless source.

Now, after logging your settings, sit back, listen and enjoy. You’ve earned the time off. Don’t let anyone
touch those hard-earned adjustments, for you can be confident that they are about as good as they’re
going to get. Play several of your favorite recordings, and listen to the bass. The bass on the best
recordings will be acceptable on your reference system; the worst recordings will have too much or
too little bass. Now you can be reasonably sure the problem is in the recording, not your room or
woofers. What a nice feeling!

Spanish Harlem

.

How The Pitch Detection Method Works

The 1/3 octave pink noise signal (or the multitone test signal) contains a narrow band of frequencies,
whose dominant level is at the center of the band. Thus, you perceive a “pitch” to the signal. When
you add a second loudspeaker driver (the subwoofer) driven by the same signal, if the woofer’s output
does not exactly match the level and distribution of frequencies produced by the main loudspeaker,
there will be a shift in the dominance of the multifrequencies, either towards the high end of the band
or the low end, perceived as a pitch shift. When the two signals are well-matched in level, freqeuency
distribution and phase, you will hear a delicate increase in level, but no change inpitch. By simple
comparative listening, taking the woofer in and out of the circuit, you have confirmed that your drivers
are matched at the crossover frequency, and that the wavefronts of your main speakers and subs are
aligned at the critical crossover frequency.

Of course, we’re making certain assumptions...that:

· your satellite system is well designed, linear and rolls off below some defined frequency.

· your subwoofer system is linear and rolls off above some defined frequency.

· the slopes of the two rolloffs are compatible and will integrate.

Your degree of success depends on how closely the two systems meet those requirements.

44

What To Do When the Results are Less Than Perfect

When interpreting
objectionable to the ear than peaks. First, attack problems with resonant notes and then look at the
dips. Everything may not be rosy the first time around. Supposing that the subwoofer helped the
bottom note(s), which means the crossover is at the right frequency, but some upper note in the
progression has been affected. This means the subwoofer position is not optimized, or the subwoofer
has some frequency response anomaly. As the sub is moved towards the room corners, the low bass
response goes up, previous dips become peaks. There’s cancellation/reinforcement between the subs
and the satellites, which changes complexly as the sub is moved. Thus, adjusting the subwoofer
position is a powerful method to even out the bass, but this type of trial and error is too complicated
without test equipment. You could slide the woofer slightly, adjust the crossover as above, listen, move
it again, readjust, and listen, but our acoustic memory is too short to tell when we’ve hit the perfect
spot.

Advanced Techniques
Integrating the Instruments with the Ears

Here’s where it gets complicated. If you are having problems with uneven bass, we can no longer rely
strictly on our ears. If you’re comfortable with measurement instruments, then let’s proceed. First,
listen to Rebecca and mark down the problem frequency or frequencies, either peaks or dips. You’ll
use that knowledge when you bring in the big guns, the 1/3 octave analyser. The good thing is that
Rebecca has already told you where the problems are, so you’ll know how to separate the forest from
the trees in the 1/3 octave display. I used
transfer function mode with wide band pink noise into both satellites and subs (one channel at a
time).
sound, more accurately representing what the ear hears.
room below 40 Hz, and more important, a little dip in the combined response circa 63 Hz which
corresponded with my perception that note was perhaps a little weak. By moving the sub around very
slightly and watching the display, I was able to exchange the weakness against the surplus without
aggravating any other peaks.

Spectrafoo

Spanish Harlem

time aligns the stimulus and response, which helps to separate direct from reflected

, don’t get too hung up on little “dips” in level. Dips are less

Spectrafoo

(an excellent analysis program for the Mac) in

Spectrafoo

revealed a rising response in my

The strength of this method is we’re continuously integrating our powerful (almost objective) listening
judgments with the “over-powerful” analysis tool. We’re using the analyser for general trends, not
absolute amplitudes; that’s what I mean by separating the forest from the trees. The position of the
test microphone should be in the exact listening position. Wear earplugs to keep your ears fresh when
you’re not required to listen. After moving the woofer, don’t forget to readjust the crossover gain and
phase with our listening technique.

If all goes well,
is really really tweaked. Now sit back and enjoy. Oops, your work is never done. Now that you’ve
adjusted your system, I’ll let you in on one more secret: Servo amplifiers have internal adjustments
that affect woofer damping, make the bass “tighter” or “looser.” but that’s another story.

Spanish Harlem

will be even better adjusted and we can rest assured that our system

45

Acknowledgments:

Jon Marovskis of Janis Subwoofers introduced me to the concept of a pitch detection technique many
years ago. This article refines and expands onhis original idea.

Many thanks to Dave Moulton for insightful technical and editorial comments.

Also, thanks for manuscript review and suggestions by Johnson Knowles of the Russ Berger Design
Group, Eric Bamberg, Greg Simmons and Steven W.Desper.

————

Acoustician Johnson Knowles suggests a viscoelastic polymer pad material like EAR Isodamp C1002
or C1000. The internal damping characteristics ofthe viscoelastics are exceptionally effective as a
speaker to stand interface material.

U.S. Consultant Steve Desper recommends STIK-TAK by Devcon Corporation, available at your local
hardware store. It’s a cheap solution and works well. Australian Greg Simmons has found a similar
product—marketed as
monitor weighing just over 20kg, I used four balls about 15mm in diameter (one under each corner).
With 20kg on top of them, these balls squashed down to about 4mm or 5mm thickness, and held the
monitor very firmly.”

Blue Tak

: “Use enough of it relative to the weight of your speakers. For a small

These HTML documents are Copyright 1999-2003 Digital Domain, Inc. All rights reserved. The
following are trademarks of Digital Domain, Inc.: Digital Domain, Digi-nary. These documents may not
be reproduced in any manner without the permission of the copyright owner. We invite the audio and
music community to link to this web site, which will be periodically revised. Last revised December

2003.

46

HEADPHONE SYSTEM

Method 1 Seperate cue mix

A external cue mix may be feed into the AUX analog input, the internal headphone amp system can
be used

AVOCET MAIN UNIT

HEADPHONE
CUE MIX

Talk back mic

To set this up select the PHONES / SHIFT button. When in this mode select the
“phones / aux” button (this is the phones source), then adjust the phones level
with the big knob. After setting the level leave the PHONES / SHIFT mode by
touching its button a second time. The phones level will not be effected by the
main level.

Aux Analog input

Headphone output
on headphone jack

Headphone output contains, the cue mix
and the talk back mic

The internal headphone amp is capable of driving multiple headphones and in
many cases an external headphone amplifier is not needed.

47

Method 2 Seperate cue mix The phones are not effected by the main level

The main audio source is feed to the internal headphone amp.

AVOCET MAIN UNIT

Talk back mic

Headphone output
on headphone jack

Headphone output contains, the main
audio source and the talk back mic

To set this up select the PHONES / SHIFT button. When in this mode select the
“phones / main” (this is the phones source), then adjust the phones level with the
big knob. After setting the level leave the PHONES / SHIFT mode by touching its
button a second time.

In ths mode the headphones audio will always be what the main audio is. Every
one will hear the same mix. The headphone level will not change when the main
level knob is changed and the headphones will not be effected by the phase, dim,
mono or mute buttons.

48

Method 3 Seperate cue mix The phones are effected by the main level

The main audio source is feed to the internal headphone amp.

AVOCET MAIN UNIT

Talk back mic

Headphone output
on headphone jack

Headphone output contains, the main
audio source and the talk back mic

To set this up select the PHONES / SHIFT button. When in this mode select the
“phones / pgm” (this is the phones source), then adjust the phones level with the
big knob. After setting the level leave the PHONES / SHIFT mode by touching its
button a second time.

In ths mode the headphones audio will always be what the main audio is. Every
one will hear the same mix. The headphone level will change when the main
level knob is changed and the headphones will be effected by the phase, dim,
mono buttons. The mute button will not effect the phones. Mute is a speaker
function.

49

USING AN EXTERNAL HEADPHONE AMPLIFIER

The audio source will be what ever has been defined during setup, see the pervious three pages.
The headphone jack will still operate
The external amplifer and the headphone jack will have the same audio and talk back mic singals.
The external output level is also changed when changing the internal phones level.

DB 25 CONNECTOR

2 gnd
3 gnd
5 Right phones out (Line level phone bus)
6 Left phones out (Line level phone bus)
7 gnd / ground

NOTE: all gnd / ground pins are the same

AVOCET MAIN UNIT

Ground / Shield

EXTERNAL HEADPHONE AMPLIFIER

Audio Left

Audio Right

50

EXTERNAL AUDIO OUTPUT

The audio source will be the selected input
It is not effected by the gain control or other functions

2 gnd
3 gnd
1 Right Audio Out
14 Left Audio Out
7 gnd / ground

NOTE: all gnd / ground pins are the same

DB 25 CONNECTOR

Ground / Shield

Audio Left

Audio Right

EXTERNAL AUDIO OUTPUT

this followes the source and can be used for metering

or other functions

51

SENDING THE TALK MIC SIGNAL TO AN EXTERNAL HEADPHONE SYSTEM

The talk mic signal can be sent to an external headphone system as showen. The mic signal will be
present only when the talk mic button is on.

DB 25 CONNECTOR

3 gnd
4 talk mic output - When talk button is
pushed (Mic Output)

AVOCET MAIN UNIT

Ground / Shield

EXTERNAL HEADPHONE SYSTEM

Talk mic audio only

52

Avocet alignment

The alignment should not be changed unless you are 100 % positive that you know how to do this
and have very good equipment. If not you could mess up the alignment, and the left - right channel
balance. The gain trims will provide a plus or minus 3 db range, which can allow for different configu­rations. Do not attempt to adjust this as a way to reduce the output level. If you do you will mess it
up. If you need to reduce the output level use the provided pads. There is 5 db of analog headroom
above the zero or red led on the remote’s meter.

If the rom has surround frimware set it to stereo operation before power up

Jumper JP1 must be installed on power up
This jumper should not be changed with out power down and power up

With Att at max level, 1khz sine wave

Put the signal into analog 1 and mono the unit

adjust the generator for 1.000V at the (MONO TEST POINT IC7 PIN 1)
ch1 and ch2 should be equal

R166, R167 are the gain trims (CHANNEL GAIN MATCHING)

adjust the output for 1.783 volts in both channels
use 5.1k ohm load on the output, measure the output balanced
turn mono off

ANALOG INPUT TRIMS 1.000v in = 1.000v out

adjust the trims for ANA1, ANA2, and AUX inputs they can be reached by small holes next to the xlr
connectors on the back

DIGITAL INPUT TRIMS

select DAW feed a 1khz sine wave at digital full scale
gain Att. still at max
adjust for 7.70 volts output this is 20db above 0dbm

Jumpers to select input level metering should be installed

REMOTE METER ADJUST with max digital input adjust the meter trims for meter full scale
(R165, R166)

DIGITAL METER OUTPUT WITH ANALOG INPUT

Apply an 1KHz analog input and adjust it for 7.70 volts out with the att. at max
(this is the same level as digital zero on the digital input)
With a digital meter connected to the metering output adjust the meter level trims for digital zero

5353

53

CK the stepped attenuator
analog input 1 apply a square wave 5V p-p, 1KHz
look at the output starting at max output
check for level change in proper sequence anc correct wave shape
If there is a problem at the max setting the other adjustments
may have to be redone

With 1 volt on ANA1 check, both inputs, the phones, main and mono outputs on the aux connector
With PHONES MAIN selected and the phones gain at max

mono = 1.5Vp-p on the scope
If you hit the pase button the mono output should cancel to 0

Phones = 2Vp-p
Phones = jack 3.1 Vp-p
L,R channel output = 1.5Vp-p

.005V rms on the talk mic input should result in 15Vp-p at the phones output on the accessory
connector. Adjust talk mic gain

Test direct control inputs
talk
mute
solo

54

55

STEREO DIGITAL METER CABLE

AES OUTPUT

5.1 DIGITAL METER CABLE

56