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Summing Mixer Setup - Documentation - Additional Options

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Summing Mixer – Connector Type – Studio Standards – TRS – XLR – DSUB DB25 Tascam Analog Balanced

Summing Mixer Input – Customize Input Channels – Select Connector type TRS DSUB XLR – In any order

Summing Mixer OUT – Customize Outputs – Select Connector type TRS DSUB XLR – connect analog mixer

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?

Switch network  provides wide range ANALOG COLOR options you can use:

  1. Passive = External Preamps

  2. Active = Internal Transformer Amp (Neumann/Filtek/Lawo)

  3. Active = use Both  Internal Transformer Amp + External preamps

Benefits: Different amp = Different sound COLOR / Character


Read More…

Stereo to Mono input conversion switch

STM – stereo to mono function

It give an extra stable analog mono base for your mix (Kick / Bass) then a superior separation and 3D depth for additional stereos.

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.

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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)
Read More…

Multi Master Insert Send Return chain


  • CHAINED Connection  Eq + Compressor + Limiter or Mic Preamp
  • Dedicated Send Return connection and control before master out
  • Free Select  – exclude or include – Send or Bypass the desired external gear within the chain
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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

 DIR switch = you can send DAW Monitor out straight to summing output



  • You can configure DAW monitor outputs for: Instrument output / or / Main Mix monitor outputs /see your DAW Mixer routing settings

No Mix (DIR / OUT) switch – route desired stereo L/R input straight to *Output 

You don’t have to unplug the summing when audio editing in DAW and you want to use  your DAW monitor outputs.

Please note: the other summing inputs are still active – you need to mute them from DAW mixer.

Fully exclude “other” inputs see Direct Monitoring switch + Bypass SUM (Total Bypass)

Important note!

  1. Power off the 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 work as regular summing inputs.
  5. DAW solo (DIR/OUT/Channel) or Mute the rest of the remaining outputs from DAW.

Direct Monitoring + Bypass Summing

Total Bypass:  Direct OUT Switch + Bypass Sum Switch

Switch 1.  Route desired stereo 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!

Expansion AUX input

Expansion input:

Linking another (second slave) Passive or Active summing unit or Line Input

Signal process by active summing transformers. (if available) expand up to 100 inputs

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

  • 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 or signal process by active summing transformers.

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
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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

Read 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 the summing mixer and affects main (total) gain reduction – for different applications – gain stage – volume range.

It gives a wide gain – volume range for different applications, gain stages.

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