#21

tracking is (in this context) the special analog “joy” of making sure 1. that each synth agrees that an octave is actually an octave (e.g. low note being in tune but then getting out of tune as you play higher notes) and 2. how well the synth does at actually holding on to the tuning you’ve set (that famous “drift,” for good or ill)

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#22

I am thinking about buying the TM50. So you think it could be use with any kind of synth?

#23

@WhiteNoise Yes, I haven’t had any issues tuning instruments with it at both line and euro levels.

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#24

Thanks a lot I’ll do that

#25

You say “the theory behind it” but there is not a lot of what I’d call theory to setting the base pitch of an analog synthesizer. You’re just choosing the pitch when no control voltage is applied - ie, what note 0V maps to. Then, each volt of CV maps to an increase in pitch of an octave. This is why some people will adjust the pitch knob whilst feeding in a known voltage, eg 2V or 3V, to map 3V to, say, C3 (nicely audible) and then still be in tune down to C0 (which is a much harder note to tune by ear). (If you set them to C3 when they had no CV applied, the only way to go to a lower note would be to apply negative voltage, which isn’t always as easy on many systems).

If they’re both in tune with no voltage applied (or with the same voltage applied), then, if they both track V/Octave, they should be at the same pitch for the same voltages. But they might not be! Reasons they wouldn’t be come down to issues of calibration, and which we might describe as ‘bad tracking’; sometimes this is user-servicable, sometimes not (for instance, on a CEM3340-based VCO I made, it’s a dance that requires a tuner and adjusting two trimpots until the VCO tracks across many octaves). As mentioned earlier, synths can also drift with temperature, which is why analog synths often really do need to literally warm up.

Of course, if you’re only playing the instruments with each other, does it matter if the unmodified base note of the instrument is an actual note in a western scale? Not necessarily! The only time it matters that you’re tuned to a known key, on an analog synthesizer, is when you wish to play with other musicians at the same key. Then you can’t just tune one instrument to another; you’d have to tune them both to a known pitch - eg, tuning to A=440 - rather than just “they both are the same”.

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#26

Tracking can be a factor in tuning. I usually tune so that 0V is the lowest note I’m going to use for that oscillator, rather than 0V = C0 or something like that. That way I can use lower voltage pitch CVs, which tend to be more accurate if the tracking isn’t perfect.

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#27

Turns out it wasnt a silly question at all- i certainly hadnt given it half as much thought as has been revealed in thie thread so far…

#28

Thank you fro the detailed reply! Well maybe I need to explain myself more clearly…my issue is that when I twist the pitch knob on the 0 coast it seems to me that the disposition of the notes on my keyboard is shifting and I am not able to play melodies I played earlier on another angle of the pitch knob. For example I am playing a C on my keystep then I twist the pitch knob on the 0 coast and that same note has become a D…I suppose I need a tuner to make sure that when I twist the knob I am always on a C…am I making sense?

#29

ahhh. for this reason I often fix the pitch knob at the start and then never touch it again if I can help it.

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#30

That sounds like what should be happening. The pitch knob changes the mapping of voltages to pitches. You could think of it as a transpose knob.

The keys of a keyboard don’t correspond to pitches as such but to voltages. Turning the pitch knob of an oscillator changes what pitch the voltages (keys) cause.

Using a tuner to make sure that the keys produce the expected pitches is a good idea. As @alanza also said, I don’t use the pitch knob after tuning a VCO.

#31

Yes, that’s correct behaviour. You’ve set a point of reference with the pitch knobs; the voltage or midi from your keyboard just adds or subtracts to that. There’s literally no guarantee on a 0 coast that C3 on your keyboard is C3 coming out of it - that’s all down to the pitch knob.

Question: what were you expecting to happen when you adjusted the VCO pitch knob?

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#32

Then what’s the point of the pitch knob? Why would we need that at all?

#33

Not sure…I now understand it is like the shif octave button on the keystep, but with too much range. I will probably not touch it again

#34

It sets the base note of the oscillator before any other CV is applied to it.
Also useful if you are not using a keyboard/note based approach and want to have things in tune for drones etc.

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#35

This may fall squarely into the “it goes without saying” category, but if your oscillators include a lot of timbre / waveshaping capability, try to minimize those parameters as much as possible before tuning. I’m thinking specifically of your 0-Coast, here. If you have access to a raw sine or triangle output that is solely affect by pitch, that’s your best bet.

Once the oscillators are in tune you can start to gradually add in grit and modulation.

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#36

where you set the pitch knob is your 0 volt point. it can be at any note you choose. this is where a tuner first comes in handy.

every note you press on the keystep adds an amount of voltage. higher notes add more than lower notes.

many analog oscillators dont “track” more than a few octaves correctly. this is normal.

your pitch knob is much like a tuning peg on a string instrument. youll ~probably~ want it in the same place most of the time. but sometimes you want to play drop d, and have to adjust a string or two. on a synth, you might want to play accurately several octaves higher/lower than you were before, or with a (harmonically dangerous) reference point. then you would adjust pitch knobs. this is near impossible to do accurately on-the-fly.

i dont understand why pitch knobs are often featured so prominantly on many oscillators, in places that are easy to bump accidentally.

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#37

Picture the tuning knobs on the headstock of a guitar. Would you start twisting those after you’ve tuned the instrument and begun playing a song? Probably not, unless you were going for something particularly weird, because it would upset the tuning of that string (and possibly other strings) across the entire fretboard. You play the guitar using the fretboard–not by trying to reach each desired note by turning the knobs.

If you’re not sequencing that VCO, or not playing it though a keyboard, and are only making a drone or another sound that can perhaps be a little uneasy and doesn’t have to sync perfectly with other voices, then in that case it’s fine to play by ear.

Yes, it’s definitely tempting when you’re just starting out with modular synths, to keep playing with the pitch knobs (I recall the same feeling), but you get used to it after a while.

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#38

This is definitely one way to think about it, and a common way. Sometimes I think of the the pitch knob, the CV (and in the 0-Coast’s case, MIDI) as all being methods of transposition.

While I’m not saying it’s super easy, I think it gets easier in practice. I’ve used pitch knobs for live key changes etc. Particularly with more drone-like pieces where the pitch knob is the only thing controlling pitch.

(I also grew up with the violin as my first serious instrument, and that’s a horrible interface for specifying pitch, making knobs seem relatively easy by comparison :laughing:)

But it definitely depends on the individual oscillator and the pots and knobs used on them. I owned a Kermit that was tedious and difficult to dial in because it had very little turn resistance, but my second one is much better (despite my wishing for a little more finger room).

Larger knobs are easier to make fine adjustments to without restricting rapid adjustments. They’re also unfortunately easier to bump! So it’s a compromise. I think a lot of designers think “coarse pitch = very important = make big to show importance.”

But having a clear space around the pitch knob would help both with reducing accidental nudges and signifying importance…

#39

Try thinking about it the other way: it’s not a pitch bend, or an ‘octave’ shift: it sets the actual pitch of the oscillator. Ignore the keyboard for a second. A VCO is just emitting sound constantly, oscillating at a frequency. The “pitch” knob on an oscillator like is on the 0-Coast sets the pitch its at.

We can alter the pitch without twisting it by adding control voltage to the Volt per Octave input. We put a voltage in, which represents a certain amount of pitch: one volt represents one octave above the base pitch; two volts two octaves; and so on - a few millivolts represents a tiny increase in pitch. And yes, negative voltage would shift it lower.

So we tune the base pitch, and then feed in voltage to make tunes.

Now - when you plug a midi keyboard into the 0-coast, you’re effectively converting those midi notes to CV internally, and that CV gets added to the pitch that’s set on the pitch knobs.

@Starthief’s point that the pitch knob, the CV, and midi are all methods of transposition is a really good one: essentially, all the voltage gets added, and fed into a thing inside the oscillator called an ‘exponential converter’, and ta-da, the pitch of the oscillator is set. (This is why you can add voltage to a CV input on a VCO to transpose a sequence, for instance).

The 0-coast is an interesting beast in that it’s less rooted in straight up keyboard-based instruments than the Moog - that’s what’s known as the ‘west coast’ influence coming in on it.

Sorry if I’m going on about this, but you’ve stumbled onto a fairly core concept in the land of voltage-controlled synthesis: the relation of voltage to oscillator control. The 0-coast is good at laying this stuff bare, I think. I certainly wouldn’t want you to ‘not ever touch the pitch knob again’ - it’s a control on a synth, and the designer has placed it prominently on the panel, that means it’s got to be for something, right?

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#40

I am actually playing the 0 coast in conjunction with a Moog Mother-32, DFAM and grandmother…so it’s a difficult interaction creating happy accidents, but I just don’t want to find harmony by accident.

This conversation is becoming more and more interesting!