Analog Drift

[SocProf]

Does anyone know if there is both slow and fast drifting occurring in analog oscillators (comparable to wow and flutter in a tape deck)? If so, most of the VA attempts to replicate drift focus on the "wow" part.

[ricard]

In the sense that wow and flutter, while just being two frequency bands of a general pitch variation, come from different sources (such as wow being due to uneven idlers, for instance, in an analog tape recorder, and flutter being due to, for instance, uneven surfaces causing the tape to vibrate as it passes over them), there are several components in an oscillator (and the rest of the circuitry) which can account for drift. The power supply voltage is one, tending to start at one value, and then eventually settle down at another after a while, when the unit has warmed up. Then there's the temperature sensitivity of critical components, such as timing capacitors and semiconductors in the oscillator kernel, which is partly linked to the machine warming up, and partly to the ambient temperature in the room. And then there would be a general randomness in component parameters, a type of ultra low frequency noise. I would think that it is the last of these that 'oscillator drift' in VA's try to replicate.

Then apart from the drift itself, some oscillators in an analogue machine would drift more than others, each having its own 'personality' so to speak. It can be either due to individual component variation, or the location of components in the machine. I think very few VA's try to emulate it on this level, but since there is a certain structure to the randomness, I think just adding random 'slop' seems useless, you really need to try and emulate specific behavior (such as "an 8 voice synth where voices 5 and 7 drift more than the others") on order to get that analog synth "feeling".

[Ledbetter]

Very good post above by ricard.

[SocProf]

Thanks, Ricard.

[Mr_-G-]

Emulating oscillator random pitch drift sounds in principle like a good idea, unless you used a synth that drifted...
You can do this with very low frequency black or brown noise with bouncing at a set range (so it does not end up drifting too far away).
Not sure I wish this feature in a new instrument.

[Cornopean]

I had an Arp Axxe once that drifted. We left it set to a low bass sound and went out for lunch. When we returned, it was about eight octaves higher.

I had a Sequential Circuits Prophet 600 also. The oscillators on that drifted so much that the Tune button was the most-used membrane one, and they did not sound in any way attractive when they drifted. You would play a few notes and suddenly get one that sounded awful, as the board assigned each oscillator in turn, and the drift was certainly not uniform. Still a fantastic board though, the synth I miss the most, despite it being far too unreliable, at times just locking up completely.

[Ledbetter]

Isn't this a little bit like missing the horse poop after switching from a carriage to a Model T?

[SocProf]

Only if your Model T is trying to pass as a horse and carriage.

Every VA I've seen with a drift feature allows the user to control the amount. So it can be kept to modest levels, and of course you can turn it off when you don't want it.

[tripbeat]

miss this function in my nl4, make sense to implement this in a good way (prophet 12 is not bad for this). maybe to less processor power or a lack of philosophy. i love my jupiter 4 are bit out of tune,
nord lead is the analog copy per se! sound in tradition of jupiter 6 (dco) and prophet 5. team of clavia would do us a favour to add this drift in the way they like;)
beside that, quality synth!

[cl516]

Didn't wanna start a new thread, but just wanna ask:

Is there any global tuning on new NL4?
Is there a way for keytracking to slightly affect detuning of an octave?

thx