How to connect a Summing Mixer ? Setting up a summing box for OTB mix.

Analogue – analog summing boxes have their uses beyond simply combining (sum) signals.

That’s great but what is OTB?

Basically, instead of having your tracks merged digitally into a stereo mix in your DAW – ITB (in the box), you run each track individually out to the analog summing mixer OTB (out of box) and do it all there, then bring it back into your DAW

Signal flow in order: DAW OUT – SUMMING – DAW REC

DAW stems
DA converter (outputs)
Summing mixer (inputs)
Stereo mix from the summing mixer (outputs)
AD converter (inputs)
DAW (rec)

Identical connection DAW – SUM – DAW 8 channel connection example:

DAW out 1Left /2Right —- SUM input 1Left /2Right
DAW out 3Left /4Right —- SUM input 3Left /4Right
DAW out 5Left /6Right —- SUM input 5Left /6Right
DAW out 7Left /8Right —- SUM input 7Left /8Right

Basic simple setup (example) for stereo stems

1/2: Bass/Drums
3/4: Vocals
5/6: Guitars
7/8: Keys/Effects

Youtube quick signal routing

Basic routing example for a Summing Mixer with Stereo to mono input conversion switch:

1: Mono Kick
2: Mono Bass
3/4: Snare, hats some percs > stereo
5/6: Percs\toms\synth blips etc. > stereo
7/8: Synths\Effects\pads\Guitars\Piano\Vocals etc > stereo

Customer example:

Pro Tools HD Native with Avid HD 16×16 converter

Master Insert Send/Return by switch control

Roughly this function allows to SEND master signal to external processors like EQ, Comp, Limiter, then RETURN to master out (print / record)

That’s great but what is an insert?

An insert is used when you want to process a signal directly. You can insert an effect, such as a compressor or EQ directly onto the master summed stereo chain. This is when you want to change the loudness balance of ranges of frequencies by an Equalizer (EQ) or you want to add a compressor to change the dynamic range of your master stereo before Main Rec. (DAW 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

Let’s jump a big one to see there are large opportunities for a more complex signal processing by a Matrix Summing mixer

Multi-bus compression routing Matrix

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

You can route your inputs to desired sub group for external process, then return the processed BUS signals for master summig.

A – Instruments that are in the upper midrange of a song, such as vocals or keyboards, synths, percussion.
B – Instruments that anchor the song such as drums, bass, maybe cello, congas, 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.

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 : www.mbrauer.com/q-a

Channel	Signal	Analog Processing	Subgroup
1	Kick		A
2	Snare		A
3 – 4	Drumset		A
5 – 6	Instruments		B
7 – 8	Instruments		B
9 – 10	Backing Vox		C
11	Lead Vox	API 525	C
12	–		C
13	Bass	DBX 160A	D
14	Solo Guitar		D
15 – 16	Guitars		D

Channel	Signal	Analog Processing
Subgroup A	Drum-Bus	TK Audio BC 501
Subgroup B	Instrumenten-Bus	–
Subgroup C	Vocal-Bus	Wes Audio Mimas
Subgroup D	Guitar-Bus	Elysia Xpressor
L/R	Master	Wes Audio Dione SPL Tube Vitalizer