Indulge me with a stupid question

If you combine 2 unbalanced signals without a transformer or active circuit it’s still going to be unbalanced. A simple Y cable + and + to ground s to ground is going to be a mono unbalanced, a + to + with the other + to negative and grounds combined is going to be a stereo unbalanced cable.

if you don't mind an impertinent question... 

FEA gives nice demos for mono applications and stereo/dual mono applications, is it budget driving the question on how to (re)purpose a mono unit for stereo work? Meaning, can't get two at this point in time? So, want to bare-wire sum to mono into one of these?

If you can't get two at this point but want to do stereo work, you may consider the 2-pass technique were you split the stereo track L/R and process the L and R separately (sequentially, one at a time) through the mono device then recombine (*not* sum) in the DAW.

Or were you summing to mono to go into this particular device for another reason? Like, what would you maybe do with the resultant wire-summed signal that was processed by this device?

Stereo:


Mono:

I re-read your post. Something like this would get you a balanced mono output from stereo:
www.radialeng.com/product/mix-21

THx for your help guys

The main question mark for me is, "can the EQ52 rack500 eq module receive, treat and output two unbalanced signals via its MONO balanced I/O and signal path ?" Let's ask the manufacturer.

"The EQ52 features differential input and output. Both input and output can operate in differential or single-ended, unbalanced modes. A high current active output buffer mimics the behavior of a transformer, providing constant gain for balanced or unbalanced operation, when either the positive or negative output signals are grounded. Therefore, the output can drive differential or single ended output with no extra user configuration needed."

@ poppaflavor : can't make 2 pass. My goal here is to find a cost effective very capable stereo sidechain eq. It's not in the audio path. I wouldn't want to spend more than 350/400 euros on a stereo sidechain eq, so two EQ52 units wouldn't cut it budget-wise. It's actually quite expensive as is, one EQ52, but the curves are so great that I could justify that, plus the fact that I could also use the EQ52 for mono audio tasks if not needed for SC duties. & I like the fact that it's a small unit. Versus a DBX graphic eq that takes 2RU space for example.

@ bossanova & doubledog : my goal here is to stay right under 300/400 euros for a flexible stereo sidechain eq solution, so I'd have to do without any fancy mergers & spitters. What would work in the budget target is Y cables (two unbalanced TS turned into one balanced TRS) to interconnect the eq and the compressor SC I/O (via BAL/UNBAL patchbay I/O connections).

My impression is that the compressor threshold setting could accommodate level discrepancies caused by the cable trickeries. I suspect I'd need to lower the compression threshold quite a bit. I don't even care if the SC signal gets noisy or hummy (as long as it's not overpowering the control signal itself). It's totally punk, but maybe it could work !

I guess there are other cheap stereo eqs out there to mangle sidechains. But if one can get one EQ52 module to work in a stereo setting, then it's quite a cost effective solution, with very interesting eq curves. If you have another small cheap capable SC stereo eq in mind I'm all ears !

res.cloudinary.com/ie-proaudio/image/upload/v1661386156/IE-literature/IngramEngineeringEQ52-OwnersManualRevB_agzwxa.pdf

what about using a plugin (or two) to sculpt the side-chain EQ?  then just run that out to your compressor?

I think Softube (or UA) Tilt has about the same controls?   www.softube.com/tilt 

Yes it becomes single ended at some point in the circuit, he told me. Too bad. It would have been the ultimate stereo SC eq.