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How to connect summing mixer to audio daw interface soundcard FAQ

General and Technical questions user manual troubleshooting signal loss ground loop noise


audio transformer

Can I connect Unbalanced synth and drum machine ?

Yes you can connect because Vintage Maker summing is “all purpose” mixer.
Can handle both balanced/unbalanced signal from synth like Moog, Nord, Yamaha etc.
Can handle large external instruments like samplers, tape machines, drum machines etc.

Daw interface sound card type ?

Can fit to all brand of DAW interfaces like Digidesign 192, Avid HD I/O 16X16,Universal Audio, RME Fireface, Prism, Lynx Aurora, Apogee, Motu, Focusrite, Metric Halo, Steinberg MR816, and so on..

Mic preamp type ?

Can fit to all brand of mic pre like Neve 1073, Aphex Channel, Great River, Avalon, Chandler Limited, Crane Song, SPL, Focusrite, Presonus, Midas, Summit Audio, ART Pro and so on…

Can I use my DAW mic preamp inputs for gain makeup ?

Yes, you can, by prior consultation the mixer will be designed for your DAW mic preamp working range, so you can use your DAW interface micpres without any compromises.

I need expensive mic preamp for passive summing? Or I can use my own DAW line / mic preamp inputs?

No, you don’t need expensive Mic Pres, by prior consultation the mixer will be designed for your DAW mic preamp or amp work range.
So Please let me know about your DAW interface brand, type or external mic pre type dB (decibels) gain range.

Can I use my DAW line instrument inputs for gain makeup ?

Yes, you can, by prior consultation the mixer will be designed for your DAW instrument input working range, so you can use your DAW inputs without any compromises.

Can I connect External gears like equaliser compressor or limiter ?

Can handle external signal processors like EQ, Compressor, Limiter, Multi Effects Processors like Massenburg, Drawmer S3, Lexicon, Alesis, Tube-Tech LCA2B, JoeMeek, FMR Audio RNC DBX, ART and so on
balanced and unbalanced compatible

If all the inputs are not plugged in at any one time, that doesn’t effect the impedance or anything in a negative way does it?

You can leave free unconnected inputs without any issue!
No noise on unused mixer inputs!
There is not affect the stereo image!
Can be left “free” unconnected inputs 4 – 8 – 12 or more inputs! 

Signal noise rate – SNR?

Signal/ Noise rate: -110dB
Absolutely NOISE FREE  due to custom-developed dual shielded discrete stereo balanced summing network. read more:

Why No Channel Input level controls and pan pots ?

Level controls and pan pots on the inputs = is a line mixer, but not a summing mixer
Pan pot and level controls prevent the complete 100% accurate recall provided by simply opening a session in your DAW.

connect summing mixer
Youtube - loop back - Unity Gain
how to connect summing mixer to computer
Youtube - DAW audio signal routing


1. Signal loss – Wrong type D-SUB cable

Be sure to check that the cables you’re using are rated for analog audio use. Many cables look the same on the outside.

TASCAM developed the standard for multi-pin DB-25 cables:

  • Analog DB-25 Connectors (GOOD for summing)
  • Digital AES/EBU DB-25 Connectors (WRONG for summing)
  • Tascam pinouts

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

More about – Active Passive Documentation and Diagrams

2. No signal or missing signal on Left / Right  In/Out

Make sure your cables and connectors are wired correctly for balanced (or  unbalanced) signals, same for your patchbay or external processors, always make sure that the XLR  TRS D’SUB connectors are plugged correctly!
  1. Fault DAW interface output
  2. Improper DAW mixer settings – signal routing
  3. Check Master out –  DAW (main rec) return mixer settings

Exclude possible errors (the most common failure points)

  • faulty connector
  • faulty cable
  • improper cable – soldering
  • faulty soldering points on cable

Do a Simple Loop Back – Cable Test – Youtube

Test all your connectors in the signal chain:

  1. DAW — to — SUM cables
  2. SUM — to — DAW cables

Always use identical connection for L/R Stereo in or out:

  • Balanced (L/R) cable
  • or
  • Unbalanced (L/R) cable

It may cause signal loss:

  • wrong unbalanced cable
  • unbalanced connector
  • poor contact cable
  • poor contact connector

Insert send return loop back simple cable test

send return test

This test verifies the functionality and signal quality of the audio ports.

loop back insert

Always exclude cable error. If the cable test fails one side, unplug then test it out with already tested cable. Eg. Left side SND/RET test done successful, unplug that cable then put it to the Right side SND/RET then test.

loop back trs

3. Switch contact loss – Two position 12 pin toggle switch

Solution: switch 20-30 times fast and strong between 2 positions

  • Silver plated contacts of solid state switch prevent sticking 
  • Designed for more than 5000 switching cycles 

Exclude possible errors (the most common failure points)

  • faulty connector
  • faulty cable
  • improper soldering
  • faulty soldering points

Quick and Easy troubleshooting - Fix stuck audio switch

Although the switch is designed for more than 15.000 switching cycles but sometimes gets stuck, so you can easy fix

Easy Fix Attenuator issue - bad connection - see error malfuinctions

4. Ground loops hum noise and static interference

1st step exclude noise source: unplug – disconnect all summing inputs (DAW -SUM) cables then listen / check.

  • DAW interface output amplifiers can generate noise
  • DAW RTAS/VST/VSI plugins can generate noise

Ground loops are a major cause of noise, hum, and interference in audio  and computer systems
You may also want to make sure all of the devices are physically plugged into the same electrical outlet. 
If you have some gear on one outlet and some on another, those may be on different legs of the electrical circuit and that might be causing the hum as well.

Most common causes of hum or other noise

Wrong cable shield
Ungrounded outlets for gear
Potential difference between gears
Improper cable grounding and isolation

Ground loops are a major cause of noise, hum, and interference in audio  and computer systems

The summing unit come by double ground shield isolation, so make sure to use good balanced cable with proper ground -shield. 

Cable length

The biggest downside to unbalanced cables is the distortion. The ground wire meant to protect the unbalanced cable can, at longer lengths of cable, actually act as an antenna or amplifier for surrounding noise. The hum from a nearby television or audio system could be picked up by the cable heard in your audio capture. As a general rule, this effect is only noticeable with cables beyond ~20 feet in length.

With balanced cables, you don’t get the same distortions, so they can be much longer without any detriment to your sound quality. That said, when the cord length is under 10 feet, unbalanced cables actually have a stronger signal than balanced cables. A passive switcher or summing mixer like the LittleOne or LittleKnob should not be introducing any noise, merely passing it along if it’s present at the input.

5. Passive Attenuator or Switch – click – pop sound

By proper line level setting You can minimize the switching contact sound

Because of physics of solid state switch and resistor based attenuator –  may occur a minimal, negligible click sound.

That’s absolutely normal, when the solid state components creates switch contact between different resistance and impedance values.

ATTENTION: it seems that audio interfaces that have DC-coupled outputs can produce this kind of pop/clicks with some passive monitor controllers like the Little Knob, similar as Heritage Baby Ram and so on (due to passive analog switch contactors)


Causes of click sound:

  • high  gained active monitors speakers

  • low level signal from (DAW) output


Solution: (controller or passive summing)

  • Increase DAW output gain level 

  • Decrease Monitor speaker levels

Different Ground potential  
Usually the same Electrical ground (or isolated ground) must be present on all instruments.
Solution: Convert the system alimentation to a single point ground.
Potential Difference (between gears) can be a major cause. The audio signal grounds between two pieces of gear are dependent on the AC outlets ground (and sometimes the gear itself can be a factor)

Passive Attenuator effective working range from -6dB to -58dB

Because of its physics of passive attenuator first 1 to 6 steps are under -58dB and under this value it has a frequency dissipation at low frequencies.

Solution: (controller or passive summing)

  • Increase DAW output gain level 

  • Decrease Monitor speaker levels


Stereo to Mono routing STM switch quick setup test Vu meter phase check proper studio operation

Analog Summing Mixer Active / Passive switch operation

Read more about A/P Documentation (click here)

Multi Insert 4 x Send Return stereo balanced in chain

Read more about Multiple Insert Send Return Documentation (click here)

It’s a dual mode summing mixer feature, like you have 2 type of mixers inside the box

  • this function enable to use 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

This function allows to SEND master 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
  • 2nd switch: enable Return from external
  • 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
  • Simply because Neumann is a dual stereo amp
  • Neumann 2C/2B electronic circuit require 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 equally set both L/R side gain by 2 x Stereo pot 
  • see db step diagram 

Single (one) pot solution?

  • VintageMaker is a small manufacture who deals directly with You without markups from distribution and retail channels.

  • VintageMaker use the same high grade components used by all the other manufacturers. There is no compromise there!

  • High quality components result the correct and low noise operation of the popular summing network designed / developed by Vintage Maker, therefore is the most liked summing solution since 2010!


Custom order

  1. Check configuration setup option list then send me your desired setup
  2. Check additional options documentation tutorial

You get the best electronically fitted summing mixer designed for Your studio (DAW Interface) working range! (let me know about your DAW interface soundcard type / brand)

Power Supply PSU and plug adaptor

  • Neumann, Lawo and Filtek transformer summing amps are equipped with a huge voltage regulator stabilizer circuit.

  • The provided small Switching PSU it provide a stable 18 – 24VDC alimentation, therefore you dont need to use another one.

  • Please dont change the original PSU!

  • PSU: 110-240VAC to 18-24 VDC 0,6-1,5A (world wide) EU plug

  • *out of Europe requires EU to US/UK/AU plug travel power adaptor