Summing Mixer Setup - Documentation - Additional Options

Summing Mixer Connections

DB25 (D-Sub) – TRS – XLR balanced (optional)

  • D-Sub DB25 Tascam Standard Analog Balanced

  • TRS  1/4″ balanced : Tip=hot (+), Ring=cold(-) Sleeve=GND

  • XLR balanced: 1=GND, 2=hot (+), 3=cold (-)

Be sure you’re using Analog DB-25 – NOT (AES/EBU digital)! 

AES/EBU pinout scheme follows the analog one closely. The original AES/EBU pinout was indeed based on the analog pinout, but using the first four balanced lines for AES/EBU in, and the last four balanced lines for AES/EBU out.

Always use Compatible cable with standard Analogue Tascam

Please note!

Balanced XLR and TRS are exactly the same electronically, the only difference is the connectors.

Input channels

Number and type  (optional)

1U Rack:

  • DSUB: up to 40-48 ch input
  • TRS: up to 32 ch input
  • XLR: 8 ch input

2U Rack:

  • DSUB: up to 96 ch input
  • TRS: up to 64 ch input
  • XLR: up to 16 ch input

3U Rack: temporary out of stock

  • DSUB: up to 128 ch input
  • TRS: up to 96 ch input
  • XLR: up to 32 ch input

*free to choose mixed mode (d-sub+trs+xrl)

Output channels

Number and type  (optional)

1U Rack:

  • DSUB: up to 16 ch out (8 stereo)
  • TRS: up to 8 ch out (4 stereo)
  • XLR: up to 6 ch out (3 stereo)
  • * in case of 16ch input by D-Sub input

2U Rack:

  • order (there is no theoretical limitation)

3U Rack: (temporary out of stock)

  • order (there is no theoretical limitation)
  • limited availability 2020

*free to choose mixed mode (d-sub+trs+xrl)

Master Active Passive switch

What’s the 2 in 1 (two in one) Active Passive?

  • this function enables to connect different kind of mic preamp instead of internal amp
  • freely can use a completely different sounding amplifier for gain makeup

There are two ways to control by A/P switch:

  1. Active mode: gain makeup by inside amp Neumann/Filtek/Lawo/NE2OX
  2. Passive mode: gain makeup by Your external micpres or DAW amplifiers

Benefits: Different amp = Different sound character

Active mode: both switches Up

  • 1st switch: signal to Inside amp (passive mode disabled)
  • 2nd switch: Inside amp signal to master out (passive excluded from signal chain)

Passive mode: both switches Down

  • 1st switch: signal to 2nd (bypass Internal amp)
  • 2nd switch:  signal to master out (Inside amp excluded from signal chain)
  • use your DAW inputs or mic pres for the gain, that way you have flexibility over the character. 

free to choose and use completely different sounding amplifier

FAQ – Why two switches instead of one?
  • Discrete dual balanced signal require 2 x 12  = 24 point solid state dual stereo balanced switching network
  • Dual switch: keeps it clean and isolated the dual balanced stereo signal flow from input to output

Horizontal Switch placement – YouTube video

Vertical Switch placement – YouTube video

Stereo to Mono input conversion switch

STM – stereo to mono function

This function converts a Stereo input L/R (two hard panned L/R Input) signals to absolute center placed Mono signal. (1 x Stereo to 2 Mono)
  • (mono) SNARE on channel 1Left,
  • (mono) KICK on channel 2Right

However, for mono signals (such as kick, snares, lead vocals or bass that should appear in the middle of a mix), it would be a waste to use Stereo L/R panned channels what would amount to two (2) required converters for a mono result.

For example, channel pairs 1L & 2R switched to mono (ST1 stereo to 1/2) both instruments become  placed in the center of the panorama.

Routing from DAW to Sum

  • DAW Mono Snare: —-Left side of stereo out—  (interface Ch 1 Left out)—- sum Left 1IN
  • DAW Mono Kick:—-Right side of stereo out  (interface Ch 2 Right out)—–sum Right 2IN
  • Then switch to mono mode to place Snare and Kick in the  center of  panorama.

Please note!

Panning for instruments in the DAW sequencer (Steinberg cubase, pro tools, flstudio, reaper, logic pro, Ableton etc.) should place the kick hard left, the bass hard on the right, and so on.
* with STM(Stereo to mono)option can save a lot of DAW interface out
** no need to waste precious stereo CH’s for mono instruments
***clarity of position in the stereo field (mono is true mono)

With mono signals one should switch these to mono mode to combine them to single D/A converter, thereby avoiding the waste of having to use a D/A pair for one mono track.


Master Insert Send Return

Master Send/Return by switch control

This function allows to SEND master stereo L/R signal to external processors like EQ, Comp, Limiter, then RETURN to master out (print / record)
  • allows to switch between processed or unprocessed signals (comparison purposes)
  • Master SND/RET placed before master out
  • 100% of the signal routed to SEND
  • 1st switch: enable Send to external (route master to SND)
  • 2nd switch: enable Return from external (route return to master out)

Active mode: both switch UP (ACTIVE)

  • 1st switch: signal to External (enable send out)
  • 2nd switch: Return signal to master out (enable return)

Bypass mode: both switch Down (Bypass)

  • 1st switch: signal to 2nd switch (bypass send)
  • 2nd switch:  signal to master out (bypass return)

the 100% of master signal forwarded to send out

Available by TRS DSUB XLR balanced

FAQ – Why two switches instead of one?
  • Discrete dual balanced signal require 2 x 12  = 24 point solid state dual stereo balanced switching network
  • Dual switch: keeps it clean and isolated the dual balanced stereo signal flow from input to output

Multi Master Insert Send Return chain


  • Connect  in CHAIN more than one external processor like Eq, Comp,Limiter or Mic Preamp
  • Dedicated Send Return connection and control before master out
  • Select or deselect – exclude or include – Send or Bypass the desired external gear within the chain

Passive summing 2 x Insert example:

  • SND A/RET A: Mic Pre 1
  • SND B/RET B: Compressor

Active summing 4 x Insert example:

  • SND A/RET A: Equalizer
  • SND B/RET B: Compressor
  • SND C/RET C: Limiter
  • SND D/RET D: Reverb

the 100% of master signal forwarded to send out

with BYPASS option can compare differences (eg. with compressor and without compressor)

Available by TRS DSUB XLR balanced

FAQ – Why two switches instead of one?
  • Discrete dual balanced signal require 2 x 12  = 24 point solid state dual stereo balanced switching network
  • Dual switch: keeps it clean and isolated the dual balanced stereo signal flow from input to output

Auto TRS Master Insert Send Return


  • the signal was non interrupted if nothing connected to SEND
  • AUTO TRS SWITCH – internally switched balanced routing network

As soon as you connect something to the SEND OUTPUTS the main signal gets interrupted, is then processed through an external device and is brought back to the summing mixer via the RETURN INPUTS – whether it is an INSERT or a SEND FX.  The amount of SEND FX signal (like the amount of a reverb) then depends on the DRY/WET signal of the SEND FX device)

Master Out On/Off switch control

Master out On/Off switch

By this option you can enable or disable (on/off) one or more than one of multiple master outputs 
  • Master Out A (on/off)
  • Master Out B (on/off)
  • Master Out C (on/off)

Master Stereo to Mono switch

Mix Mono compatibility test 

  • placed before master outputs

The word ‘Mono’ is panned absolutely center. This means both Left and Right speakers reproduce the same word ‘Mono’ at the same volume. This also sounds ‘mono’ and so panned to the middle.

Checking your mix for Mono compatibility as you go is a good preventative measure.

Sometimes just because a mix sounds good in stereo doesn’t mean it will sound good when the left and right channels are combined into a mono signal. In some cases, you may hear what is known as comb-filtering, which will color the sound of your mix and cause peaks and dips in its frequency response. In some cases, instruments may lose their integrity or even seem to completely disappear from the mix!

Phase Invert switch

Phase Invert R side of stereo signal

Phase inversion is a subtle, yet versatile music production tool capable of many distinguished feats. First, what is phase inversion? Inverting a wave’s phase means swapping the location of its peaks and troughs. This creates cancellation when peaks of one wave coincide with the troughs of the other wave.

Phase Invert R + Master Mono mode

Reversing the phase of the right channel and mono-ing it with the left and sending the result to both speakers is particularly useful for assessing the width content of your mix and distortion characteristic by effectively replacing the ‘centre image’ with the out-of-phase information.
This provides an excellent way to check mono compatibility and to also learn spatial tricks from your favourite reference material.

Direct Monitoring - input to output switch

No Mix switch – route desired stereo L/R input to *Output 

For example this is really useful in case when audio editing in DAW and there is no need the mixer for summing – mixing purposes, you can use by default DAW interface 1/2 dedicated monitor outputs for direct monitoring.

“Direct Monitoring.”

This refers to the ability to monitor signal directly from the interface, bypasses selected Input by DIR SWITCH from summing network then route signal to summing amp / or / master outputs.

Important note!

  1. Power off internal amp to avoid speaker damage! 
  2. Set Summing to Passive mode
  3. Active mode (first time) operate with low level DAW signals!
  4. The other inputs are still active and works as regular summing inputs.

By Direct out switch option can route a dedicated stereo channel input to master out, bypassing the summing network

  • Direct Monitor out switch on desired input (usually on stereo 1/2)
  • Stereo input 1 (ST1) L/R ——route to Master output  (or to summing amp inputs —Master Out)

Direct Monitoring + Bypass Summing

Total Bypass:  Direct Switch + Bypass Sum Switch

Switch 1.  Route desired stereo L/R input to Master out

Switch 2. Mute/Bypass Exclude the other summing inputs

Important note!

  1. Power off internal amp to avoid speaker damage! 
  2. Set Summing to Passive mode
  3. Active mode (first time) operate with low level DAW signals!
  4. The other inputs are still active and works as regular summing inputs.

Expansion input

Expansion input – linking another summing unit

This is another stereo input based on electronically balanced XLR – TRS or D-SUB connectors.

The MainOutputs of the first (slave) Summing mixer outputs are connected to the Expansion Inputs of the second (master) unit.

  • The Expansion Input is an additional stereo input which is routed to current summing network without gain reduction.
  • Typically this stereo input would provide for linking with another Summing unit.

Usually the Main Outputs of another Vintage Maker Summing mixer (or other brand mixer) are connected here to enable summing of up to more channels, but of course any (stereo) summed signal can be connected here.

Channel Insert Send Return

Stereo Input channel send return

Mono conversion by Stereo to Mono switch after return

The input signal  always present on the corespondent send out (stereo ch)
Return bypass switch enable or disable return function:
  • Bypass switch OFF (switch down): Input—> Sum Bus—> Master out (regular summing operation)
  • Bypass switch ON (switch up): Input—> Send—> External Process—> Return—> Sum Bus—> Master out
  • Stereo to Mono signal conversion  performs after stereo signal returns to Sum network

Sending 2 x Mono instruments on a stereo L/R channel:

Panning for instruments in the DAW sequencer (cubase, protools etc.) should place the snare hard left, the kick hard on the right.

Send to external:

  • Input 1L (snare)—Send—Compressor Left in
  • Input 2R (kick)—Send—Compressor Right in

Return from external:

  • Compressor Left out —Return 1L (snare)
  • Compressor Left out —Return 2R (kick)

Convert hard Left/Right instruments to Mono by STM switch

  • switch Stereo to Mono for mono conversion snare/kick 

STM (stereo to mono input conversion switch) read more about

Multibus Group Send with fixed inputs

Sub Group summing for MultiBus Compression technique

Fixed sub mixers (slave sum ABCD) with dedicated inputs, each sub mixer (slave sum) group come with individual send/return for external process – then return to Master for final summing.

for example:

  • 4 x “slave” sum (A B C D)
  • 4 x Send /return
  • 1 x Master sum

*you can order as many channels and options you want


Multi-bus compression routing Matrix

Bus A, Bus B, Bus C and Bus D you can use the matrix swtich to access the MULTIBUS  compression / external routing process. 

See ABCD multi–bus compression routing diagram

STEREO TO MONO conversion switch available only after RETURN / before /signal enter to master summing network

*Stereo to Mono CHANNEL conversion available on fixed group multibus

 Separate instruments into different categories that will allow freedom of movement. (source MICHAEL BRAUER PRODUCTIONS)

  • A – Instruments that are in the upper midrange of a song, such as vocals or keyboards, synths, percussion. Bring up the vocal a lot and it will only effect the instruments assigned to A Choose instruments for a buss that will compliment each other.
  • B – Instruments that anchor the song such as drums, bass, maybe cello, congas. Adding more bass or kick will only have an effect on the other instruments assigned to B. Choose instruments that will compliment each other.
  • C – Instruments that create transient midrange power and will have a lot of rides, such as guitars.
  • D – Instruments that need the warmth of tube and are not played staccato. To be used in combination with other categories for glue factor. 

The process is up to an individual’s taste and of course the application which dictates the approach towards the sound you are looking for. Sometimes only send the drums to B and the samples that support it to B and stereo buss, sometimes I don’t. What’s important is that you try every combination and see which sounds the best. Eventually, you’ll know the sound of the different combinations in your head at which point it becomes instinctual read more about :

See more:

Precision gain control

21 step precision resistor based internal amp gain control potentiometer

  • Number of steps: 21
  • Gold-plated signal path 
  • Extremely short signal path
  • Channel matching: +/-0.1 dB
  • Polished “S” shape wiper and contact pins

FAQ: why 2 pots?

  • Simply because Neumann is a dual stereo amp (2xStereo amplifiers)
  • Neumann 2C/2B electronic circuit requires 2 x stereo potentiometers /side
  • Neumann 2B and 2C is a DUAL STEREO summing amp, 1st one for Left,  2nd one for R side.
  • Easy to set equally the both L/R side gains by 2 x 21 step precision potentiometers



Vari Gain Switch

Placed on passive side of summing mixer and affects main reduction total gain loss.

2 position switch values:

  • -25dB/-35dB

  • -15dB/-25dB

  • -10dB/-20dB

  • -6.5dB/-16.5dB


Knob style and colour

  1.  Solid aluminium regular round black knob

  2. Vintage style White cream “chicken head” knob

  3. Vintage style Black “chicken head” knob

  4. Vintage style Silver “chicken head” knob

  5. Vintage style Bronze “chicken head” knob

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