I was wondering how do you guys tune your modular synth. Some systems have quite a lot of VCOs and tuning may take some time, do you tune them one by one? also, do you use something like a guitar tuner or a mobile app?

There seems to be some modules to help with the tuning, are they worth it? or is there any other way to automatically tune the VCOs? I'm not sure if you could just send the VCOs through quantizers and have them tuned with no effort.


It depends on the VCO's pitch controls. In some cases, you have an octave switch and a tuning control, while others use the coarse/fine tune knob pair routine. The former (which began with Moog) can be easier to sort out, since these tend to use the tuning knob over a restricted range, either 12 or 24 semitones as a rule. The other method can be more of a pain...but also allow the VCO to get into frequency ranges that the octave switching method might not allow.

It's worth noting, btw, that if a VCO has NO fine tune control, it's apt to be a real pain to use in a precisely-tuned manner unless it's part of a set of VCOs under a single control set.

As for how I tune, I do it by ear. This is what I recommend, actually, as it helps to increase your pitch acuity over time. The better you can recognize what "in tune" vs. "detuned" vs. "out of tune" sounds like, the quicker you can work and the quicker you can realize when retuning is necessary. I really only use a tuner when working with microtonal intervals...which brings us to...

Quantizers. Now, these do NOT help with tuning. Quantizers are designed to force an incoming CV signal into scalar intervals which can then be used to control VCOs, etc. But they won't help keep the VCOs in tune, they just make them play pitches that conform to the quantizer's scalar parameters. It's still possible to have several VCOs that are totally out of tune with each other, but tracking the same scalar "pitches" equally (which can sound interesting in of itself; see Aphex Twin's "180db_" on "Syro").


Thanks Lugia,

It seems like I got the whole quantizers thing wrong and now I see how I'd still need to tune the VCOs. In fact I've listened the "180db_" track many times before but it never occurred to me why it sounds like that, VCOs out of tune, that makes sense now.

Up until now I've been using an app to tune the VCOs, I guess I'll have to train my ears a bit if I want to do it your way. Time to practice I guess!


The thing you'll want to do is to listen for "beating". When tuning VCOs to unison, octaves, fifths or fourths, the second (and subsequent) VCOs will create a pulsing if they're not precisely on the interval in question. This is due to heterodyning: adding two waveforms will always result in some sort of sum and difference frequency. This is best known with ring modulation, where a carrier and modulator combine in a diode ring to cause only the sum and difference frequencies to be heard, with the original signals (optimally) suppressed.

But with simply mixing VCOs, you still get the sum and difference, but also the original signals. The "sum" is generally harder to hear, but can show up when dealing with very low pitches. The "difference", though...this is MUCH more prominent, and is what causes "beating" between two slightly-detuned oscillators. To get VCOs exactly in tune on those particular intervals, you fine-tune the second VCO so that the beating stops. But slight detunings can also be musically useful for creating the illusion that a sound is more than just the sum of two VCO signals, and thereby making things sound "fat". If doing this, though, the best practice is to tune VCO #2 exactly to VCO #1 (or #3, #4, etc), THEN slightly alter the #2 (etc) VCO's tuning so that you get that bigger, slightly-detuned sound. That way, you're relatively assured that your detuning should track properly.

The only times I use a tuner myself is when establishing a "reference pitch"...my "concert A", more or less. And in a lot of those cases, I'll simply use a synth that gives me a specific A=xxx Hz reference and proceed from there. But if I need to do something more elaborate, such as microtonal intervals or alternate tunings, then I bust out the Strobotuner and a reference table for cents offsets. That sort of tuning issue goes way beyond the "by ear" method above, especially if I need to get it right.


Ah, it makes sense.

A few days ago I was watching DivKid’s video on the Joranalogue Filter 8.Tthe filter has two inputs and I was expecting it to work as a regular audio mixer, but it kind of adds one signal on top of the other and drives the filter, which is also interesting.

However, other filters like the Tonus VCF also have two inputs and the resulting output doesn’t seem to sound louder, so I guessed these are different types of mixers.

Doing some research on this topic this morning I’ve seen some mixing modules calling this ‘unity’ and ‘average’ mode mixers, I’m not sure if that’s the official name though. Anyway, I would say the ring modulator outputs the sum and difference of an ‘average mix’, right? That’s pretty cool.

Regarding the VCOs tuning, I’ve started doing some of those ‘ear training’ exercises and so far is proving to be much harder than I expected, I guess I’ll get it at some point but for now I won’t relay too much on my ears.