Q Compensation has no effect?

[acemonvw]

Hello -

So first thing to be clear about: I'm not sure in what way I would notice Q Compensation, but when I ran through settings based on what I believe it's supposed to do (keep low frequencies elevated when filter resonance is increased), I don't hear any differences at any setting.

Sounds identical, looks identical on graphs...

So here's the test I did.

Filter cutoff max, Resonance sweep, ENV at 0% First REV1/2 filter at Q comp of 1, then 8. Repeat with REV3 filter. 
There will be 4 filter sweeps you hear.

Then I moved cutoff to 50%, same order. 
There will be 4 filter sweeps you hear.

Moved ENV amount to 100%, cutoff 0%, res sweeps, but only on the REV3 filter. 
There are 2 filter sweeps you hear.

I don't hear any differences, but maybe what I'm testing you wouldn't hear the difference.

And yes, I have confirmed I'm on the latest Main and Panel OSes.

Of course - I could never tell the difference between REV 1/2 and 3 filters so... I dunno. 

[LPF83]

If you just start with default patch while in Prg mode, turn up resonance until you hear audible drop in the lower harmonics, then toggle back and forth between setting 1 and 8, you don't hear a difference?

But yes the difference is something like the difference between the Rev 1/2 and 3 filters...  barely noticeable on some sounds and night and day on others.

[acemonvw]

Ok, so I went back and tested what you suggested. Set resonance to 50% (12 o clock) and then toggle between 1 and 8. I can hear the oscillator being louder at 8. Yes. At resonance to 75% and up to 100%, there is no audible difference.

I thought it would have been pronounced at 100%, otherwise, I didn't see the purpose, as you could just dial back the resonance as needed. But I guess I'm not super knowledgeable about these things.

I did record it to show the differences I hear. I think this was with REV 1/2 filter.

[LPF83]

Ok, so I went back and tested what you suggested. Set resonance to 50% (12 o clock) and then toggle between 1 and 8. I can hear the oscillator being louder at 8. Yes. At resonance to 75% and up to 100%, there is no audible difference.

I thought it would have been pronounced at 100%, otherwise, I didn't see the purpose, as you could just dial back the resonance as needed. But I guess I'm not super knowledgeable about these things.

I did record it to show the differences I hear. I think this was with REV 1/2 filter.

The Prophet filter is self-oscillating (definitely look that one up and understand what it means, because its an important sound design feature).  Basically when you set the resonance very high, you're getting sound from the filter itself and not just shaping the tone of the oscillators.  The Q compensation doesn't really come into play once you get into audible self oscillation, its for the settings below that.

One way to hear the potential impact of Q compensation is to create a sound where you hear a very noticable difference between setting 1 and 8, then record a riff into the DAW or whatever you use to record MIDI, and play that back in a loop while listening to the difference in how it sounds on 1, 8, and the numbers in between.  It can be subtle to fairly profound.  My own ears interpret the difference generally as 1=more vintage sounding, 8=more modern but maybe that varies.

[g3o2]

According to information floating around in the gearspace forum, when set to VIN in the third global page, Q comp kicks in with the vintage knob. This suggests that the original behaviour would not relate to any of the new 8 settings of q comp.

[LPF83]

According to information floating around in the gearspace forum, when set to VIN in the third global page, Q comp kicks in with the vintage knob. This suggests that the original behaviour would not relate to any of the new 8 settings of q comp.

That's interesting if the case, but the inner "spock" in me has trouble working out the logic of that, because it would somehow imply that on vintage Prophets the filter somehow gets more bass compensated with age, which would be weird.

[g3o2]

who knows, maybe it’s indeed the other way around when turning the vintage knob

[LPF83]

who knows, maybe it’s indeed the other way around when turning the vintage knob

Perhaps, but to my feeble mind it would be an equally strange feature of the vintage knob, because Q compensation was reallly either a feature of the synth design or it wasn't.  One way I like to think of it is sort of like a "Jupiter/Juno" option for the Rev4, as Q compensation was a popular feature of those designs.

[g3o2]

and now a feature of the P rev 4 :-D

[LPF83]

For those questioning the level of difference Q compenstation can make, even if you're not a keyboard player/writer of music, go get a MIDI track and play it through your DAW and the Rev4 with a resonance involved sound and listen to the difference Q comp can make.  Back in 1983, this level of difference in tone would be the difference in buying one synth versus another.. if you had one $5k synth (adjusted for inflation would be about $15k today) and another one created this much variation in tone, many would conclude you needed yet another $5k purchase. 

Not that with Q comp is better than without -- sometimes I prefer with it off..  but it's still a massive bonus to Rev4 owners in terms of variability of the sounds that can come out of the thing.  And it's somewhat hidden such that someone demo'ing in a store would have no idea that this level of variability even exists.

[verstaerker]

According to information floating around in the gearspace forum, when set to VIN in the third global page, Q comp kicks in with the vintage knob. This suggests that the original behaviour would not relate to any of the new 8 settings of q comp.

thats true.. but the vintage knob does a few "minor" other things at the same time

[g3o2]

thats true.. but the vintage knob does a few "minor" other things at the same time

obviously