Sum a Stereo Signal with Cable to go into Mono Input of OT

Hello there,
so I have a live setup with an Octatrack Mk1 as my mixer and sequencer. The C and D input is occupied by drums, and input A is fed by a synth that outputs a mono signal, so I have one free Mono Input.
I have a Dreadbox Typhon, and although the Stereo Effects are great, I would rather have stereo on the Drums since I’m using it mostly for bass and can give a little stereo width to it with the ot’s internal effects.
The Typhon has a L and a R output, but unfortunately you can’t internally set the synth to sum it’s signal internally and output it in mono. So my question is, how should I sum the signal from Typhon’s two Mono outputs to go into the free B input on the octatrack? I guess if I just take the L (or just the R) output of the Typhon I’m losing a lot of volume, right? But I haven’t found a Y-cable that puts two Monos on a single Mono.
What happens if I put a y-cable that puts two monos on a stereo inside input B? Will the octatrack sum the signal, or will it just ignore the second sleeve of the cable?

Hey, you should be fine using only one Typhon output, the volume shouldn’t be that much lower, but just try it for yourself. :slight_smile:

Summing a stereo signal into mono is rarely going to work, the Octatrack inputs are balanced which means it expects the exact same audio signal twice (they’re just inverted from one another if I’m not mistaken, to reduce interferences on longer cables), so you might end up with phase issues. Even if the phase is fine, you won’t get any of the stereo depth so there’s really no point in my opinion.

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Wow, Aldo, it’s you! I love your stuff man! Great use of the OT!

And thanks for the answer, I felt like there was some loss of volume, but I just thought that I can just pan everything in the Typhon hard left/right.

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Yes. Balanced inputs take the L channel and add the inverted R channel to it to cancel out any interferences. When feeding such an input with a balanced signal it has the additional benefit of an implicit 6dB boost (twice the original signal strength due to the adding).

When feeding such inputs with a standard stereo signal you get heavy cancellations (unless L & R are completely different). In the worst case with a dead centered signal you end up with silence + some interference noise.

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Forgive my ignorance, but shouldn’t summing to mono be perfectly fine with mono-compatible material?

In this case, if stereo widening effects are being used, it is not to be recommended, unless phasing is something you’re looking for. But if I have a bass being output as a Stereo L+R, but recorded in mono (like all tracks in ableton work), there shouldn’t be a problem, no?

EDIT: Oh wait, it’s because the input is inverting one of the channels, like you guys both wrote, right, i get it now!

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Balanced inputs do no normal summing. They invert one side (flip the signal upside down) and then add both signals together.

These inputs expects a balanced signal where one side carries the signal of the other side but flipped upside down.

:+1:

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