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DPW experiments

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antto
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2474 posts since 4 Sep, 2006, from 127.0.0.1

Postby antto; Tue Dec 18, 2012 9:56 am

i just demonstrated the final waveform for a single cycle of a single sawtooth with that shape (the last picture, from my previous post)

the theory about reducing aliasing <- who said that? ;]
my nose tells me that the JP-8000 has a sampling rate of more than 48KHz, probably 64K at least

while i know Roland had some very clever math for practical digital IIR filters, i still think having a good resonant HPF tracking an oscillator is not what they have there in the supersaw
It doesn't matter how it sounds..
..as long as it has BASS and it's LOUD!

irc.freenode.net >>> #kvr
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Ichad.c
KVRian
 
1002 posts since 8 Feb, 2012, from South - Africa

Postby Ichad.c; Tue Dec 18, 2012 10:37 am

antto wrote:the theory about reducing aliasing <- who said that? ;]


One research blog and one research article - I read alot :) Have to go and dig around to find it though - the artical does a pretty good analysis. Will try and find it for you - my "Research" folder look like a Lorenz attractor.
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Ichad.c
KVRian
 
1002 posts since 8 Feb, 2012, from South - Africa

Postby Ichad.c; Tue Dec 18, 2012 10:50 am

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antto
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2474 posts since 4 Sep, 2006, from 127.0.0.1

Postby antto; Tue Dec 18, 2012 12:11 pm

yes, i remember now

i really don't agree with what is written there about the HP filter
tho, i agree that you can get the same type of shape by running the supersaw thru a 2nd order resonant HP filter (i tried it myself, with an SVF HP)

szabo paper wrote:Research showed that oscillators used in the Super Saw are in fact saw oscillators, but the added signal of the 7 waveforms goes through a high pass filter.

did someone reverse-engineer the JP-8000 code? ;]
szabo paper wrote:A way to achieve such a waveform without a high pass filter is through a wavetable oscillator. This method cannot be the one used by the Super Saw, because a wavetable oscillator is band limited, and the oscillators found in the Super Saw are not.

:o :uhuhuh:
who said it can't be done with a wavetable?
who said a wavetable is bandlimited?
i really disagree on that
you can make this waveform in many ways, and he is right to believe it's a HP filter, but i don't think so ;]
in my supersaw aproximation, i use a simple wavetable (a very short one in fact) and absolutely no interpolation

that wavetable can be replaced by (or stuffed with the data from) the funky polynomial which i posted pictures of earlier
i originally found the curve when i was working on the triangle waveform, then i figured the same curve can be used to make the supersaw too, coincidence? ;]
It doesn't matter how it sounds..
..as long as it has BASS and it's LOUD!

irc.freenode.net >>> #kvr
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Ichad.c
KVRian
 
1002 posts since 8 Feb, 2012, from South - Africa

Postby Ichad.c; Tue Dec 18, 2012 1:16 pm

antto wrote:
szabo paper wrote:A way to achieve such a waveform without a high pass filter is through a wavetable oscillator. This method cannot be the one used by the Super Saw, because a wavetable oscillator is band limited, and the oscillators found in the Super Saw are not.

:o :uhuhuh:
who said it can't be done with a wavetable?
who said a wavetable is bandlimited?
i really disagree on that


I agree with you on that.(Getting really off-topic :hihi: ) But does your approximation sufficiently estimate the alias/noise slope/level - below the fundamental?
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antto
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2474 posts since 4 Sep, 2006, from 127.0.0.1

Postby antto; Tue Dec 18, 2012 1:28 pm

i don't think recordings sampled at 44.1kHz are sufficient to make such analysis
nor that the aliasing is the key component of the supersaw, it *could* hint what the JP sampling rate is tho

i think szabo has had access to a JP during his analysis
if so, why didn't he record at a much higher sampling rate?
bleh, anyway, i didn't mean to argue
i just see other possible ways of doing things ;]
It doesn't matter how it sounds..
..as long as it has BASS and it's LOUD!

irc.freenode.net >>> #kvr
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Sendy
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5233 posts since 20 Jul, 2010

Postby Sendy; Tue Dec 18, 2012 1:31 pm

Szabo's Supersaw emulation is REALLY good. I have a JP-8000 standing right next to me and I honestly found no discernable differences between his oscillator and the supersaw sounds coming from the JP. Just as well considering my JP just recently succumbed to the "weak outputs" fault which makes it now hard to get a decent sound out of it :/

The other waveforms on the JP aren't so interesting - Feedback is a comb filter with feedback and a metric ton of aliasing, Tri Mod is simple wraparound on the Y axis which can be done much better in other synths (and is actually a really cool sound when you can modulate it properly), Sawtooth shaping just changes the level and polarity of the fundamental - it looks far more drastic on the wave plot than it ever sounds... about as exciting as doing AM on a sine wave... Pulse is the same old story... noise is blah... That only leaves the regular Triangle which I've posted about already - really interesting sound and the only waveform on the board that can't be emulated.
http://sendy.bandcamp.com/releases < My new album at Bandcamp! Now pay what you like!
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EvilDragon
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14940 posts since 6 Jan, 2009, from Croatia

Postby EvilDragon; Tue Dec 18, 2012 1:42 pm

Is Feedback osc really just a comb with feedback? I've always wondered what is it exactly.

Shame Szabo didn't emulate it in JP6K. I'd totally be all over that plugin if all waveforms were emulated.
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Ichad.c
KVRian
 
1002 posts since 8 Feb, 2012, from South - Africa

Postby Ichad.c; Tue Dec 18, 2012 1:44 pm

antto wrote:bleh, anyway, i didn't mean to argue
i just see other possible ways of doing things ;]


Me neither! Not a 'moddeling' man myself - I prefer 'new/different' things - I have the attention span of a 3year old. I greatly respect the work - you and others do, though.
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Ichad.c
KVRian
 
1002 posts since 8 Feb, 2012, from South - Africa

Postby Ichad.c; Tue Dec 18, 2012 1:53 pm

Sendy wrote:The other waveforms on the JP aren't so interesting - Feedback is a comb filter with feedback and a metric ton of aliasing...


I've tried that approach - can't even get close, all I get is the 'noisy' part. :cry:
To me - it's the most interisting waveform/process in the JP8000! (I like odd things).

As for it's unique triangle - the top and bottom image - I got done with DPW, but the middle image (with it's asymmetry) is still a mystery to me. But it seems like antto already solved that one!
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