[SOLVED] Norns won't record stereo from modular

Here’s a fun one (apparently today is my day to break stuff). Certain combinations of input are producing strange results. I am totally baffled. In both scenarios, Ableton is sending an instrument out of outputs 3/4 on my interface.

SCENARIO #1: AUDIO STRAIGHT FROM DAW

Records just fine in stereo, as expected.

SCENARIO #2: INVOLVING THE MODULAR

Into Intellijel Stereo In
Then into Arbhar (in mono [only option], but will sum to stereo on output), which is set to full dry signal
Then into Strymon AA.1 in stereo (which is just an amplifier/attenuator)
Then into norns
(never mind the rest of the chain, because I’m monitoring from norns, and that’s where things get wonky)

And now, the interesting part
I can hear the piano through both cans of my headphones (while plugged into norns) when MON is turned up, but norns will not record anything in certain scripts. In both MLR and Cheat Codes, nothin’ (or barely nothin’, like very very soft). In Otis? Works just fine.

Also of note, playing back something from Arbhar’s buffers in stereo? Records just fine. So there’s something going on with the dry signal.

Now for even more fun and intrigue

Unplug the RIGHT input on norns and record something in MLR? Works perfectly. MON now only outputs to my left ear, as expected.

My Suspicion
Is that I’m doing something super obtuse.

Can attach a photo if that’s helpful.

MLR sums the left + right inputs to a single channel, but Otis doesn’t (it either feeds L + R to separate Softcut voices, or just L to both). It sounds like your left + right inputs might be out of phase, canceling one another out when they’re summed.

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That thought had crossed my mind, but I suppose it seemed strange to me that a device (Arbhar) that natively takes a mono input and generates a stereo signal would create phase issues. But I think you’re probably right. I stepped away for a few minutes but will noodle more this evening.

Update- skipping Arbhar immediately remedies the problem. Which is a bummer, but not on the part of norns. Looks like this rig is going to take a little more thought, and a few more patch cables. Thanks @synthetivv

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this is gonna sound dumb, but can’t you just swap polarity on a cable or jack? (depending how arbhar is wired, could be a perfectly understandable assembly goof.)

I love Arbhar, but this phase cancellation is my biggest problem with it. Caused me no ends of bafflement similar to yours in the past. Apparently it was introduced to allow for simple handling of the grains being sent out of a single output when running mono (or something). Good news though! There’s an Arbhar update that looks like it fixes this by giving you an option to turn the phase cancellation off. I haven’t had time to install it yet, but from the description in the new manual it looks like exactly what you want.

@SimonKirby that’s good to know, I’ll look into it. I guess I’d assumed that the dry output would be spared, but perhaps not.

@zebra I rethought the chain a bit and decided that I could accomplish what I want to do with Arbhar in parallel, instead of at the front of the chain.

Although, with Arbhar completely out of the chain last night, I still really liked the results. I just felt crazy, then stupid while investigating. Which is not unfamiliar territory.

@SimonKirby I’m tinkering with this this evening, and so far I’m not noticing any difference in the phase relationship in stereo as I toggle this setting on and off. Will report back if I find success.

Oh! That’s puzzling… the description in the manual made it sound like they’d fixed the phase problems with this setting. I haven’t updated yet but was planning to do so in order to start using the Arbhar in stereo again. As it is I’m resigned to using it as a mono effect. (For me, passing the stereo signal into any upstream stereo effects caused all sorts of bizarre phase cancellation effects - was hoping this new firmware would be the solution.) Still love it a lot mind you!

There’s some good info here. Quoth the updated manual (which has a bit more information than the update change log, which is what I was referencing until last night):

Phase Switching

The second output of arbhar is phase-inverted in order to ensure that no phase cancellation occurs when the second output is normalised to first output when monitored in mono. When monitoring in stereo, however, the user might experience that the dry input signal of the arbhar is cancelled out further down the signal chain (i.e. summing a stereo signal to a mono signal some stereo effects, like reverb, that actually process a summed stereo input).

This can be avoided by leaving the Dry/Wet Mix knob fully wet and mixing in the dry signal separately or by engaging the phase switch for the second output.

To do this, press and hold the Shift Button then the Capture Button and turn the Hold knob fully clockwise for stereo patching. For mono patching, press and hold the Shift Button then the Capture Button and turn the Hold knob fully anticlockwise. This is the default state.

This setting can also be changed in the arbhar_config.txt file (See the arbhar_config.txt section for more information).

It is important to note that if the arbhar is patched in mono and the phase switch is engaged, the dry signal will cancel out. This can actually be used to simulate a VCA for the granulated sound when the arbhar is in Stereo Panning Configuration. Just patch a CV signal into the Mod Input. At 0V all grains are heard. At +5V all grains are panned to mono and cancel out.

End quote.

I still love it as well. Very much so, as a matter of fact. I suppose this is good to keep top of mind when working with the module going forward. Lesson learned!