Tuning problems / how to know if a module is misbehaving

Hi everyone,
I’ve been building my first rack in an Intellijel 104HP 7U case. Here is where I am at now: 1st rack progress: April 14, 2022 - Eurorack Modular System from adamj on ModularGrid

I’ve been struggling a bit with keeping my oscillators in tune and wanted a reality check on what is normal.

Some context: I like harmony so having multiple quantizers is important. I got a Doepfer dual quantizer but concluded it was malfunctioning. It mostly worked fine, but the jack for transposing the quantized signal was outputting fluxuating (even with a constant voltage input) out-of-tune notes whenever it received a non-zero voltage. I consulted customer support (from the retailer, Sweetwater, so not probably not an “expert”) and, although they thought it could potentially be a power problem, since everything else in my rack seems to be working normally they agreed there seemed to be something wrong with the jack/module. So I am exchanging it. But now I am having more difficulties, and this experience has made me paranoid something is wrong with my rack. Next week I’ll have a replacement quantizer so I can at least see if this one works properly and that will ease some of my concerns.

I suppose it comes with the territory that there are occasion hardware problems, and it’s not out of the realm of possibility that a module is 90% functional and one jack or whatever isn’t working properly?

In the meantime I’m using my Disting as a dual quantizer. That’s been working fine.

The latest difficulty is I got an Intellijel Shifty and I am often struggling to get musical results out of it. I am aware that a delay between the gate and CV signals can cause out-of-tune voltages to be sampled, so I turned on the maximum sample delay compensation. That only partially helped, so I am also using track & hold instead of sample & hold. That helps more but things are still often noticeably out of tune. Sometimes it seems ok though.

This has made me hyper aware of the tuning of my oscillators and how easy it is for things to get out-of-tune. I believe my Doepfer A-111-3 and Intellijel Dixie 2+ are both analog, so tuning difficulties are to be expected. I just don’t know what is considered normal.

I have experienced the oscillators being out of tune when the modular is turned on after being off a while. I believe this is completely normal and it could take maybe 20-ish minutes to stabilize. I’m not worried about this.

I am starting to get the impression the Dixie may continue to go in and out of tune even after a warm-up period though. Not wildly so, but I have to retune it periodically. However, that may be directly related to the fact that the Dixie’s octaves are not exactly double the frequency, and I sometimes retune because of that. I can tune the Dixie against the other oscillators, and if I increase its pitch by two octaves, it is slightly (but often pleasantly) out of tune. If I go more than a few octaves, it gets noticeably out of tune and needs to be re-tuned to sound good. Is this normal? In that case, I suppose I need to mindfully choose the octave range I want to play in and tune the oscillator to that. That’s fine if it’s a normal part of the analog experience. I just want some confidence my modules are working as best they can. Also, the Dixie generally needs it’s “Fine” knob at about 1:00 - 2:00 instead of near 12:00. Is that normal?

By comparison, the Doepfer oscillator tracks the Plaits a lot better, and I trust the Plaits since it’s digital. Both those modules are in tune with their “Fine” at 12:00, if that has anything to do with anything. I should probably take measurements and get actual Hertz values and be scientific about all this. But I am definitely getting the sense the Dixie can’t stay as in tune as the Doepfer across the full voltage range for pitches.

Back to the Shifty: As an experiment I ran the Disting quantized output to my buffered mult and then to the Plaits, Doepfer, and Dixie. I tuned them and they sound good. Then I put the Shifty in shift register mode, plug the quantized signal into the Shifty CV, hit the gate a few times (so it should be working like the buffered mult at this point) and things are slightly (but acceptably) out of tune. I just don’t know what I should be expecting here. All I know is once I start trying to sequence pitch changes, I often can’t get the results I want and things sound worse then going through the buffered mult and bypassing Shifty. Again I’m not sure what my expectations should be. Maybe this is the analog world and I need to learn to embrace it. Or maybe the Shifty just isn’t meant for my setup.

Is it possible the Dixie and/or the Shifty and/or other modules could stand to be re-calibrated? What does re-calibrating a module even do?

Another thing my paranoia is doing is making me question whether these tuning problems have been getting worse as I’ve added more modules. I could definitely be imaging this because I am so focused on tuning issues now. But could there be some sort of issue with my rack’s power? I don’t think my power usage with 1st rack progress: April 14, 2022 - Eurorack Modular System from adamj on ModularGrid is anywhere close to the limit with the TPS80W MAX power supply. (Side note, here’s my plan for the full rack, which I think is still fine regarding power: 7U 104HP rack (v10) - Eurorack Modular System from adamj on ModularGrid).

One other thing I’m wondering is if a problem module could appear to be functioning ok but causing problems in other modules, due to power spikes or something. Or maybe modules/power cables can cause signal interference of some sort? Do I have to be careful no power cables touch the backs of any modules? Is there any reason to unplug every modules and slowly add some back in and test very carefully? Like I wonder what would happen if I tested the Shifty with the minimum of modules plugged in. Worth investigating or waste of time?

Regarding testing things, I have a 1U zeroscope and it’s been helpful (the tuner is really finicky though), but I wonder if I should get a standalone oscilloscope and/or multimeter and/or tuner. Especially if there is some issue with my rack/power that’s affecting the zeroscope too. Any recommendations?

That is all for now. I appreciate any insights anyone can share.

That sounds like a module that is out of calibration; most analog VCOs have a “scale adjust” or similar to ensure 1V/octave response.

Based on this documentation, the Dixie has two separate adjustments (CVGAIN and OCT-ADJ):

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Thanks @al2o3cr, the 1v/octave tracking calibration sounds like exactly the solution for the Dixie. Reading that article:

If you are not sure of what you are doing do not attempt to change the calibration on your module.

lol, that’s me! I’ll reach out to Intellijel support. Regardless of what they recommend, I think I should invest in a multimeter and try to start learning how to do this. I expect it will be a valuable skill.

Any recommenations on these requirements for callibration? Ideally I could invest in a high quality device that does everything, if such things exist.

You will need:

  • An accurate voltage source capable of exact 1 V intervals from 0 to 10 V.
  • A multimeter / frequency counter. The higher the resolution the better.

Hiya @adamj
I’ve really been trying to lock in a solidly pitched system with quantizers for a while now. Mostly positive results with some maddening “never in tune for more than an octave” moments.
I have a bunch of oscillators in the mix (partially for sonic flavors but also just to simply see what ones hold up the best with tuning woes) and for what it’s worth I always end up being happiest with the tuning stability of the Intellijel 1U VCOs and the Befaco Even VCO.
I can relate to much of what you’re talking about in your initial post.
Basically just saying don’t get discouraged and you’ll start to get a good flow once you try out a few diff mods. Those tuning woes are real but it’ll start to make more sense when you connect with certain mods and their quirks/personality.

:call_me_hand::v:

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I can’t speak for all oscillators, but I’ve got a Dixie 2+, and despite being all-analogue the tracking’s pretty stable. That said, it responds to temperature slightly: PW and flip are a bit more stable after it’s been running continuously for a while; pitch tracks better after it has warmed up, too, but the pitch tracking seems to be much more stable in general—the tuning response is marginally different and barely noticeable. That said, some other analogue oscillators might not have as good temperature-stable tracking as the Dixie’s do. I agree it’s probably calibration, but I just wanted to remind you that things need to warm up, and it’s just something to keep in consideration.

Caltrans by Klavis sorts the tracking on all my analog oscillators with the added bonus of offering semitone offset and octaves, portamento/glissando check it out

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Thanks everyone!

Thanks for the words of encrouagement. Over the weekend I spent some time just making cool sounds and trying not to worry about tuning so much and feel a lot less freaked out about the whole thing. At least I think my rack is fine and there’s just one problematic module (the Shifty) that I’m going to contact Intellijel about. My Dixie’s octave tracking could use some 1V/octave calibration, but it’s still workable right now if I don’t spread my pitches across too many octaves.

I just need more time to learn my module’s quirks and how to work with those quirks (or in some cases reach out to the manufacturer for support and calibration)

Interesting, I will check this out.

It turns out there’s a calibration procedure explained in Shifty’s manual that is easy for anyone to do with no special equipment (It’s basically automatic by connecting the input to the outputs). I guess after looking at things like Dixie’s calibration procedure, which is beyond my skills, I stopped reading these sections of the manuals carefully.

Anyway thanks to Intellijel support recommending I do the calibration, my Shifty is working well now! :+1:

Now I know: Reading the manuals front-to-back is valuable even if you don’t understand everything or think it’s not relevant. And re-reading them is good too since it’s a lot of info to absorb (especially if you buy too many modules too quickly… which I did… even though I was warned not to…).

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