M6 Retro
Portable Audio Mixer

Operation Manual for Mixers with PCB V1.1
Copyright 2002
Professional Sound Corporation
Printed in the U.S.A.

TABLE OF CONTENTSDESCRIPTION……………………………………………………………………………4
SAFETY WARNINGS……………………………………………………………………4
APPLICATIONS…………………………………………………………………………..4
FUNCTIONSINPUTS……………………………………………………………………………7
A.

BALANCED INPUTSB.

INPUT LEVELSC.

MICROPHONE POWERINGD.

LOW CUT FILTERE.

CHANNEL GAINF.

CHANNEL PANSG.

AUX SENDSH.

CHANNEL FADEROUTPUTS…………………………………………………………………………7-8
A.

BALANCED OUTPUTSB.

OUTPUT LIMITERSC.

HEADPHONE OUTPUTSD.

PRIVATE LINE

E.

BOOM COMMUNICATIONF.

TAPE RETURNSMETERS…………………………………………………………………………….9
A.

PEAK READING METERS

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ADDITIONAL FEATURES…………………………………………………………9A.

SLATE MICROPHONEB.

REFERENCE OSCILATOR

POWERING………………………………………………………………………..9-10
A.

INTERNAL BATTERY POWER

B.

EXTERNAL POWERCONSTRUCTION……………………………………………………………………10
A.

CHASSISB.

ELECTRONIC TOPOLOGYC.

ENVIRONMENTAL OPERATIONINTERFACING………………………………………………………………………11A.

TO RDAT RECORDERSB.

TO NAGRA RECORDERSWARRANTY AND NON-WARRANTY SERVICE…………………………………11
SPECIFICATIONS…………………………………………………………………….12

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DESCRIPTION
Thank you for purchasing the Professional Sound Corporation M6 Portable Audio
Mixer. We are confident that this M6 Mixer has set new standards for portablemixer technologies and features while incorporating a timeless housing design.
Please feel free to contact us if you have any comments or questions concerning
your new mixer. Additionally, we invite you to share your suggestions for new
products you would like to see developed.
Professional Sound Corporation extends a one-year warranty on parts and labor
to all M6 Mixer owners who return their warranty cards at the time of purchase.
This warranty gives you specific rights, which are stated on the card, and enables
us to keep you informed of product updates.
The PSC M6 Mixer provides all the functions necessary to produce studio quality
recordings in the field. It’s user friendly features, rugged design and sonic purity
make the M6 Mixer perfect for feature film recording, remote broadcast, andmany types of electronic field production (EFP).
HEARING SAFETY WARNINGS:
Please be sure that you have read this entire manual before operating thismixer.
While special attention has been given to your safety and hearing
protection, the operator determines proper and safe operating levels.
Please note the following:
Always turn down the headphone volume before plugging in yourheadphones.
Always operate your headphones at the lowest practical level.
Be especially cautious in unknown or widely varying environments.
Remember, your ears are your livelihood. Turn it down!
APPLICATIONS
•
•
•
•
•

Feature Film Sound Recording
Location recording (Dialogue and Music)
Digital Recording and Playback
Broadcast remotes
Desktop Mixing for Video Post Production

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INPUTS:A.

BALANCED INPUTSThe PSC M6 Audio Mixer provides six input channels utilizing female XLR
connectors. The studio grade input circuitry is transformer balanced for improved
RF rejection and in-field practicality. The XLR connectors are wired as follows:
Pin 1 shield (ground), Pin 2 Audio high (in phase), Pin 3 Audio low (out of phase).
Balanced wiring enables longer cable runs without the worry of excessive noisedue to nearby electromagnetic and radio frequency interference. Thesebalanced inputs may be unbalanced if desired. Either pin 2 or 3 may be tied to
ground (pin 1) to unbalance the inputs of the M6 Mixer. Note: The AES standard
for unbalancing an XLR connector is to tie pin 3 to ground (pin 1).
B.

INPUT LEVELSThe PSC M6 Mixer can accommodate a wide range in input levels. Microphonelevels of all types can be handled as well as line level signals. The input range ofthe M6 Mixer is –60dBu to +4dBu. Thus the M6 is compatible with all forms of
consumer and professional audio equipment. The input level switches arelocated on the front panel. These input level switches provide for two levelsettings: “M” Microphone level (0dB attenuation), and “L” Line level (50dB
attenuation) This input level attenuation settings are used to correctly interface
sources of varying levels to the M6’s preamplifiers. Correct level matchingensures maximum headroom and lowest possible noise floor.

C.

MICROPHONE POWERINGThe M6 Mixer can accommodate the most popular microphones used today.
The microphone powering switches are located directly below the input XLR
connectors. They can be switched to either Dynamic (D) or 48Phantom (48) or
Tornador (12T).
In the Dynamic position the mixer provides no microphone powering. This
position is used with Dynamic Microphones, Line Level inputs and when using
Wireless Receivers.
In the 48 Phantom Position the mixer provides 48 volts DC to pins 2 and 3 of the
XLR connector. 48PH microphones or simplex powered microphones with arange of 9 to 52 volts or 12 to 52 volts may be powered by the M6 Mixer. Pin 1 isshield to ground while pins 2 and 3 carry 48 volts DC. The term “phantom” isderived from the fact that there is no voltage potential developed across pins 2
and 3 thus a dynamic microphone transducer can be operated with 48PH turnedon. However, most portable wireless receivers will not operate with 48PH turned
on. We strongly recommend setting inputs to dynamic for use with all wirelesssystems.

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Because of the PSC M6 Mixer’s “retro” design, we have included the 12T
microphone powering. When set to 12T, 12 VDC is applied across pins 2 and 3.
Pin 2 being positive and pin 3 being negative. This polarity is know as “standard
phase” and is the excepted A.E.S. standard. Some older 12T microphones may
have been wired as “Red Dot”. This is the reverse polarity of standard phaseand is still in use by a small percentage of 12T microphones world-wide. Any“Red Dot” microphone can easily be converted to standard phase to bring it into
the A.E.S standards of operation. If you own 12T microphones wired “Red Dot”
and do not wish to change their wiring, you can still operate them from the PSC
M6 Mixer by using a simple phase cable or phase barrel. PSC part numbers are
as follows:
FPSC0010C Phase Reversal Barrel
FPSC1017
Phase Reversal CableD.

LOW CUT FILTERS

Each input channel of the M6 Mixer is equipped with an active low cut (highpass) filter. These filters are activated via the three way switches located near
the adjacent channel fader knobs. These filters will attenuate all frequencies
below a preset frequency at a rate of 12dB per octave. When set at “20Hz”,
frequencies below 20 Hz are effectively rolled off with the mixer operating at full
frequency response. Optional low cut filter settings of 100Hz and 140Hz will roll
off the frequencies below these figures at a rate of 12dB per octave (-3dB level at
100Hz and 140Hz respectively. Low cut filtering is important in location
recording where wind noise can cause pre-amplifier overload. This effect can be
minimized by switching the low cut filter setting to either 100Hz or 140Hz cutoff.
The low cut filter switches are located on the front of the M6 Mixer.
E.

CHANNEL GAIN

In order to limit noise and increase headroom, the channel gain controls arelocated in the feedback path of the pre-amplifiers. This provides continuously
variable gain rather than just a decrease in channel output level when an
overload situation occurs. This results in increased headroom and lower chanceof signal clipping (severe distortion). These pots have an adjustment range ofapproximately 50dB.
F.

CHANNEL PANS

The new M6 Audio Mixer contains signal routing pan pots. These pan pots areused to route the individual input channel’s signal to either the left or rightsumming buss or any combination in between.
G.

AUX SENDS:

In addition to the two left and right summing busses, the M6 Mixer offers two
additional auxiliary summing busses that can be used for aux sends to Comtek
tm transmitters , Directors feeds, Video Assist audio feeds etc. Each input
channel contains two auxiliary send pots that control the level from that individual
input channel to the auxiliary busses.

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H.

CHANNEL FADER:

The PSC M6 Mixer is equipped with traditional rotary knob faders. This “retro”
design is ideal for field use as it is dust and dirt resistant just like your trusty old
Sela mixer. Ya baby, it’s 1975 all over again! Typical operating range of thefaders is from #4 to #9 position on the fader.
OUTPUTS:A.

BALANCED OUTPUTSThe M6 Mixer contains very high quality custom-made audio output transformers.
These transformers have been designed to provide wide bandwidth, lowdistortion and real-world ease of use. Transformers have been chosen over atransformerless design because of their inherent ability to interface with virtually
any other device, especially RF based products. This is very important in thisday and age in consideration of the frequent use of multiple RF receivers andtransmitters. The PSC M6 Mixer contains three separate balanced outputs.
These include Left Main output, Right Main Output and a third balanced output
labeled as Video Assist. This output is switch-able to feed either Left, Right or a
Mono Sum of left and right. The switch is located on the front panel of the mixer
near the meter.
B.

OUTPUT LIMITERS.

The limit threshold (activation level) is factory set at +3 on the meter. The limiters
compress the signal at approximately 2.7 to 1 ratio. This is to say an increase of
2.7dB in input signal will result in only a 1dB increase in output signal. Output
channel limiting is indicated by the front panel mounted red LED’s..
The M6 contains two separate limiters that are controlled by one front panel
mounted switch. This switch has three settings: Off, Separate (S), and Ganged(G). In the off position, no limiting occurs.
In the separate position, the limiters act independently of each other. This isespecially useful when recording split tracks. I.E. interviewer and interviewee on
separate channels. Thus, if one person un-expectantly raises their voice, that
limiter will activate, but the other will not. In the ganged mode, both limiters aretied together and can be triggered by either input. This is useful in recording
stereo as independent limiting would alter the stereo image.
C.

HEADPHONE OUTPUTSThe Main or “Mixer” headphone output is located directly on the front edge of themixer. This location was chosen to allow the operator to easily plug/unplug thephones from the M6 Mixer and other devices. The M6 Mixer’s headphone7

amplifier circuitry is designed to drive virtually any headphone with an impedance
rating of 32 to 600 Ohms. The headphone circuitry is controlled by the use of afront panel selection switch and a volume control. The rotary switches are used
to control what the operator listens to. These choices include: Left channel toboth ears, Right channel to both ears, normal Stereo, a Mono sum of the twochannels, Auxiliary 1 and Auxiliary 2. There is second switch located on the righthand side of the front panel of the mixer and is used to control the “tape” or“direct” monitoring sources. This switch controls only the monitoring of the“mixers” headphones.
The PSC M6 mixer also contains three additional headphone outputs labeled as“Director”, “Boom 1” and “Boom 2” These three headphone feeds also offer thesame selection of monitoring choices with the exception of monitoring “tape”
D.

PRIVATE LINE:

The two headphone feeds labeled Boom 1 and Boom 2 also are equipped with
“Private Line” circuitry. This allows the mixer operator to speak directly to theboom operators via the slate microphone without the audio going out any other
outputs such as the main outputs. This is helpful if the mixer operator is locatedout of sight of the boom operator. To use the “Private Line” function, you must
simply press the private line button located on the front panel of the M6 mixer.
The private line function will only operate as long as the button is pressed down.
E.

BOOM COMM:

The M6 mixer also contains a complete duplex communication system built in.
This system allows the mixer operator and boom operators to communicate
freely with each other in a full duplex mode (similar to telephone conversation).
The rear panel of the M6 mixer contains two “TT” (tiny telephone) connectors thatare labeled Com 1 and Com 2. These connectors have two purposes. They
provide a microphone input and corresponding pre-amplifier and also a logic
signal input to control the comm function. The PSC Duplex communicator cables
are similar to our standard duplex cables in that they provide a talent (boom)
input as well as a boom operator headphone feed. In addition to these common
features, they contain a built in microphone and push to talk switch. This
microphone and push to talk switch are used when ever the boom operator
wishes to speak to the mixer operator. Conversely, there is another commswitch located on the front panel of the mixer used by the mixer operator tocommunicate with the boom operator(s). When any of the comm switches ispressed, the communication system is activated. When the communication
system is in use, the slate microphone is routed to the two boom headphonefeeds and the two boom operators talk back microphones are routed to themixers headphone feeds. As soon as the communication button(s) are released,
all headphone monitoring functions return to normal.
*SAFETY NOTE* ALWAYS TURN DOWN THE HEADPHONE VOLUMEBEFORE PLUGGING IN YOUR HEADPHONES.

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TAPE RETURN

The M6 Mixer is equipped with tape returns used to monitor tape confidence
heads from most any recording device. These tape monitor amplifiers can be
adjusted to match the signal levels of most any device. These levels areadjusted using a small jewelers screwdriver (or “Greenie” screwdriver). The
adjustment points are located on the bottom panel of the M6 mixer. The
tape/direct switch is located on the upper right hand corner of the front panel.
When set to ”D” (Direct) the phone amplifiers to monitor the mixers output signal.
If switched to “T” (Tape), then the phone amplifies monitor the external sourcesuch as the RDAT recorders.
PLEASE NOTE The tape returns are only
available for the “Left”, “Right” and “Stereo” monitor settings. There is no tapereturn function for the “Mono”, “Aux 1” or “Aux 2” settings.
METERS:A.

PEAK READING METERS

The M6 Mixer is equipped with a custom made LCD meter. We designed thismeter to be easy to read. Because the most common use of this type of mixer iswith RDAT’s, we designed the M6’s meters to emulate the peak reading
attributes found on many RDATs.
ADDITIONAL FEATURES:A.

SLATE MICROPHONE

The M6 Mixer is equipped with a slate microphone. This microphone is activatedwhen the front panel “slate” momentary push button switch is pressed. The slate
microphone allows the operator to put voice slates (notes) on tape for later
reference. These are normally notes for editing tape. A level adjustment trim pot
is located near the slate button on the M6 Mixer. Turning the adjustment
clockwise will increase the slate microphone level. Turning the adjustment
counter-clockwise will lower the level.
B.

REFERENCE OSCILLATORThe M6 Mixer is equipped with a reference oscillator used for setting of levels
between the mixer and recorder. This known reference level is also used whentransferring tape during editing. The M6’s oscillator operates at 440Hz at “0” on
the meters. We have chosen 440Hz simply because it is much more pleasant inyour headphones than the typical 1Khz used by other manufactures. We haveused 440 Hz on our mixers for many years. The reference oscillator is equippedwith a level adjustment trim pot located internally. This adjustment is factory
calibrated and should not be adjusted without proper measurement equipment.
POWERING:
A. INTERNAL POWER, ALKALINE BATTERIES

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Ten “D” alkaline batteries can power the M6 Mixer. These batteries areaccessed via the battery door located on the side panel of the M6 mixer. Whenusing alkaline batteries, you can expect 6 to 10 hours of operation under normal
circumstances. Always observe correct polarity when installing batteries!
Note: Never store your M6 Mixer for extended periods of time with alkaline
batteries installed in the mixer. There is a possibility that the batteries mayleak causing corrosion of the mixer. Battery leakage and the resulting
corrosion damage is not covered under the M6 Mixer warranty.
B. EXTERNAL POWER
The PSC M6 Mixer can also be externally powered from any source of DC powerfrom 10 to 16 VDC. Do not exceed 16VDC or mixer damage will result. Over
voltage and the resulting damage is not covered under the M6 warranty.
The mixer consumes approximately 10 watts of power over this voltage range.
The external power connector is located on the rear of the mixer. Pin outs of thisMale XLR 4 pin connector are as follows:
Pin 4 (+) Positive
Pin 1 (-) Negative
This external DC input is protected from reverse polarity up to 6 amps. If you
inadvertently connect external power of the incorrect polarity, the mixer will not
be damaged, it simply will not power up.
CONSTRUCTIONA.

CHASSISThe new M6 Mixer chassis has been designed for demanding field use. The
complete chassis is formed from 0.125” aircraft aluminum. All punching is doneon a computer controlled “Trump” rotary turret punch press for extreme accuracy.
In addition, through careful design, we have managed to keep the overall weightof the M6 Mixer to 12 lbs. (5.4Kg) total.
The mixers sheet metal is hand-formed using various press brake setups before
the stainless steel threaded inserts (Pem Nuts tm) are pressed permanently into
place. The housing parts are then Chem Film TM plated for superior corrosion
resistance before being electro-statically coated with an epoxy powder coating.
This powder coat paint is then baked on in an oven. Powder coating was chosen
for its durability and environmental friendly characteristics.
All silk-screening is printed sub-surface (below) a hardface lexan tm overlay.
This process provides a silk-screened label that is virtually wear proof. The
lettering will not wear off as on other mixers.
B.

ELECTRONIC TOPOLOGYThe new M6 audio mixer was designed from a clean sheet of paper. It utilizes
completely new circuitry designs based upon the latest advances in semi
conductor technology. In addition, it features surface mount technology for
reduced size and weight.
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The M6 Mixer uses high quality transformers on its inputs and outputs.
Transformer topology was chosen for its inherent ability to reject RF, thus making
this new mixer perfect for use with multiple RF systems.
This new design uses modern semi-conductors from Maxim, Linear Technology
National Semiconductor and Burr-Brown to name but a few. These operational
amplifiers, voltage regulators and precision voltage references feature low power
consumption, low noise and low distortion.
C.

ENVIRONMENTAL OPERATIONYour new M6 Audio Mixer has been designed to operate under extreme field
conditions. The electronics have been designed to operate over a temperature
range of -4 to 158 degrees Fahrenheit (-20 to +70C) less the affects on batteries.
This in addition to the M6’s ability to operate under high humidity conditions
makes it perfect for harsh field conditions.
INTERFACINGA:TO RDAT RECORDERS:

The M6 Mixer can be interfaced to virtually any professional recorder via thestandard XLR outputs.
B:

TO WIRELESS MICROPHONES:The M6 Mixer will easily accept the output signal from virtually any wirelessreceiver. It can accept microphone or line level signal via a simple switch setting.
Please note that most wireless receivers are not compatible with 48PH or 12T
mic power. You should always set the M6’s mic powering switch to “D” dynamic
when using wireless receivers.
WARRANTY AND NON-WARRANTY SERVICE
In the unlikely event your M6 Mixer requires service it should be carefully packed
and shipped prepaid to:Professional Sound Corporation
Service Department
28085 Smyth Drive
Valencia, CA 91355 USA
PH 661-295-9395
FAX 661-295-8398
e-mail techsupport@professionalsound.com
Please call before shipping your mixer. We may be able to solve yourproblem via the phone. We are always willing to help you with your M6 Mixer
11questions. Complete details of the PSC M6 Mixer warranty are given on theenclosed blue warranty registration card. If you did not receive one, pleasecontact your local dealer or call us directly.
SPECIFICATIONS
Size:14” W x 15” D x 2.25” H(35.5cm x 38.1cm x 5.7cm)

Weight:

12Lbs. (5.4Kg)

Temp Range:-4 to +158F (-20 to +70C)

Batteries:

10x D Alkaline

Case Material:

0.125” (3mm) Aircraft Aluminum

Finish:Epoxy Powder Coat

Overlays:0.005” Hardface Lexan tm with
Sub-surface Epoxy silk screening

Global Gain:

80dB

Freq. Response:

20-20Khz +/-1dB

Signal to Noise:

131dB EIN 150 Ohms

Distortion:

00.08% THD

Low Cut Filter:

100Hz, 140Hz 12dB/Octave

Mic Power:

DYN, 12T, 48 PH

Oscillator:

440Hz

Limiter:

1mS Attack, 100 mS Release
2.7:1 Ratio

Warranty:

1 Year, Limited

Copyright 2002, Professional Sound Corp. This manual and the complete M6
Mixer design is covered under various state, federal and international copyrightlaws. No portion of this manual or any M6 mixer technologies may be reproduced
without the specific written permission of PSC. All rights reserved. This manualand all M6 Mixer specifications subject to change without notice.

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