Without Osc. Retrig, what causes sound inconsistency?

L

Libertine Lush

New member
Hi everyone,

I have a simple question about a specific sound behavior.

On a synth with 2 oscillators and Oscillator Retrig. turned off, when you repeatedly press the same note, it will sound just slightly different some of the time. What's the reason for this?

I understand that with Osc. Retrig. on the phase of the 2 oscillators are always in phase at the beginning of key depression, and so the same note played repeatedly will sound the same. I also recall reading somewhere that most synths set the 2 oscillators to be slightly out of phase by default. Does that mean that they are always out of phase by the same amount, because if they are, should the same note played repeatedly always sound the same, with the same amount of out-of-phase difference each time?

I figure I must be missing some crucial foundational info which is why I can't understand this behavior.

Thanks for any help.
 
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Not too sure myself but retrigger should restart the whole sound everytime it's triggered.
Polyphony is probably just multiple notes at the same time, legato...not sure wtf legato is.

If most synths have their [I'm not sure why they did this in the first place] phases somewhat different by default, it should still stay the same but not having them at the same phase they'd basically start from square one if that's what you mean.
 
KonKossKang said:
If most synths have their [I'm not sure why they did this in the first place] phases somewhat different by default, it should still stay the same but not having them at the same phase they'd basically start from square one if that's what you mean.
Click to expand...

Yea, I believe you understand what I'm trying to say: that with the 2 oscillator phase difference with Osc. Retrig off, the phase difference should be the same with every key depression, and yet for some reason, at least of the synths I observed this on, the sound is not consistently the same each time.
 
Libertine Lush said:
Hi everyone,

I have a simple question about a specific sound behavior.

On a synth with 2 oscillators and Oscillator Retrig. turned off, when you repeatedly press the same note, it will sound just slightly different some of the time. What's the reason for this?
Click to expand...

if osc retrig/synch is off the oscillators are free-wheeling never aligning again (well not quite never, but taking a lot of time). The lack of alignment can be due to phase drift (true for hardware more than software).

bottom line, oscillators unless phase locked will de-synch over time

I understand that with Osc. Retrig. on the phase of the 2 oscillators are always in phase at the beginning of key depression, and so the same note played repeatedly will sound the same.
Click to expand...

True

I also recall reading somewhere that most synths set the 2 oscillators to be slightly out of phase by default. Does that mean that they are always out of phase by the same amount, because if they are, should the same note played repeatedly always sound the same, with the same amount of out-of-phase difference each time?
Click to expand...

I've never heard of that particular practice in hardware or software unless you change the phase (the position in the wavetable the oscillator starts from). You can get some phase related issues (beat tones) by using microtuning to make the sound wider (e.g. one osc is +5 cents, the other is -5 cents), but these should remain fixed unless you turn off retrigger/synch

@kkk: and legato means to play smoothly and connectedly i.e. as little break between each successive note as possible, so not related to this topic
 
bandcoach said:
if osc retrig/synch is off the oscillators are free-wheeling never aligning again (well not quite never, but taking a lot of time). The lack of alignment can be due to phase drift (true for hardware more than software).
Click to expand...

Could you go into further detail about this free-wheeling nature? For example, which part(s) of the oscillator behavior is random, responsible for this initial key depression sound difference? Is it that the starting phase of an oscillator following a key played isn't always the same?

Is phase drift referring to the same thing as oscillator drift?

Thank you.
 
I guess it's important to understand that on an analog synth (dunno to what extent this is modelled on VAs), the oscillators don't start making sound when you hit the key(s), but rather that they're constantly outputting a signal, which is shaped into discrete notes by the envelopes. So the oscillators are "running" whether or not anything is being played.
 
^^this is part of that free-wheeling aspect, especially in hardware synths, so when a key is depressed the phase position of the oscillator can be anywhere from 0[sup]0[/sup] to 359[sup]o[/sup] through the cycle. Some software emulations mimic this behaviour, others don't.

re-triggering/synching all oscillators to start at 0[sup]o[/sup] is one method for ensuring that the relationship between all oscillators in a patch remains constant for each new note; especially helpful for lfos that are providing specific forms of modulation to the sound

as for oscillator drift, I usually associate this with movement in tuning, especially in older hardware synths which had a fine tuning knob to bring the entire synth back into concert pitch or not as the user decided)
 
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Ah, okay! I had actually considered, when trying to figure out this behavior, whether the oscillators are actually quietly operating the entire time or only when keys are played. I thought maybe it was the latter.

So now it totally makes sense. Thank you to both of you for the wonderful info.
 
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