Roland Alpha Juno-2 pwm sawtooth

DSP, Plug-in and Host development discussion.
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KVRian
1160 posts since 21 Apr, 2017 from Bahia, Brazil

Post Mon May 24, 2021 8:07 am

Thanks URS.

I loaded up the file Chappelle attached. Though similar. It is not what the earlier discussion was struggling with.

There is a curve to the Alpha Juno Saw pulse it seems. Now.....I understand some of that conversation but I don't have a full grasp of it.

Thanks for the WT Chapelle. It is still quite usable.
We jumped the fence because it was a fence not be cause the grass was greener.
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Urs
u-he
25746 posts since 8 Aug, 2002 from Berlin

Post Mon May 24, 2021 8:14 am

a curve?

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Urs
u-he
25746 posts since 8 Aug, 2002 from Berlin

Post Mon May 24, 2021 8:15 am

ah, the highpass?

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Urs
u-he
25746 posts since 8 Aug, 2002 from Berlin

Post Mon May 24, 2021 8:31 am

Like these?

https://u-he.com/urs/SawPWMx1-4WavetablesHighpassed.zip

Just had to roughly estimate where the cutoff of the HP would be, based on the OP.

Note that these won't always sound correct as the alpha-Juno has a fixed highpass before (or after? Can't remember) the chorus section. Such that, the perceived "curve" of the sawtooth depends on the frequency of the oscillator. It's probably better to use the "perfect" waveforms I posted before and add a highpass filter in the synth (or after) to match the "belly" of the waveform. Just like one would for a Minimoog sawtooth (but there definitely before the lowpass filter).

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KVRAF
2774 posts since 8 Jul, 2008 from UK

Post Mon May 24, 2021 9:56 am

Thanks Urs, those wavetables are pretty cool too. So the Alpha Juno's Saw PWM was a pretty wierd thing at the time then ? I don't know the AJunos full history, but this has caught my attention, obviously thanks to the What The patch.
Forward ever, Backward never

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Urs
u-he
25746 posts since 8 Aug, 2002 from Berlin

Post Mon May 24, 2021 10:33 am

It was pretty novel, sure. I haven't followed the prior argument in this thread, but I'm pretty sure we came to the conclusion that Roland used the bits of the digital phase counter to "chop" the waveform, or the PWM signal. The dual PWM can be obtained for instance by subtracting the highest bit of the phase counter from the normal pulse signal (saw + bias) before the comparator.

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KVRian
1160 posts since 21 Apr, 2017 from Bahia, Brazil

Post Mon May 24, 2021 10:57 am

Urs wrote:
Mon May 24, 2021 8:14 am
a curve?
Yeah.....
The OP first post has some pics that show a slight parabolic curve and depending on the PW the curve flattens out and almost appears to go in the opposite direction.

A few seem to agree it is keytracked hi pass making the curve.

Thanks for sharing the WTs. A bit different than the pics but they quite beefy all the same.

The WT in Ana2 has a similar parabolic curve to the pictures. But the curve seems to remain constant through PW changes. It sounds a bit more delicate than the ones you shared. It has 2 pulses.

Lol...... I'm not sure any of us could tell what's what if we did a blind test.
We jumped the fence because it was a fence not be cause the grass was greener.
https://scrubbingmonkeys.bandcamp.com/
https://www.scrubbingmonkeys.com/

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Urs
u-he
25746 posts since 8 Aug, 2002 from Berlin

Post Mon May 24, 2021 11:04 am

Well, thing is, the "curve" depends on the setting of the highpass filter in the synth, and the note you play... analogue oscillators are commonly pretty perfect. But as people hardly ever see them in isolation, people attribute the waveform they see to the oscillator. Most of the time, the quirk of the visible oscillator waveform is actually a highness filter or some other process in the chain...

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KVRian
1160 posts since 21 Apr, 2017 from Bahia, Brazil

Post Mon May 24, 2021 11:05 am

These WT make me wanna open up Bazille and see if I can get close.
We jumped the fence because it was a fence not be cause the grass was greener.
https://scrubbingmonkeys.bandcamp.com/
https://www.scrubbingmonkeys.com/

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KVRian
1160 posts since 21 Apr, 2017 from Bahia, Brazil

Post Mon May 24, 2021 11:07 am

Urs wrote:
Mon May 24, 2021 11:04 am
Well, thing is, the "curve" depends on the :hyper: setting of the highpass filter in the synth, and the note you play... analogue oscillators are commonly pretty perfect. But as people hardly ever see them in isolation, people attribute the waveform they see to the oscillator. Most of the time, the quirk of the visible oscillator waveform is actually a highness filter or some other process in the chain...

Kkkkkkl

You just summed up 7 pages of arguing. :hyper:
We jumped the fence because it was a fence not be cause the grass was greener.
https://scrubbingmonkeys.bandcamp.com/
https://www.scrubbingmonkeys.com/

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Urs
u-he
25746 posts since 8 Aug, 2002 from Berlin

Post Mon May 24, 2021 1:10 pm

:lol: :lol: :lol:

KVRer
2 posts since 21 Jan, 2021

Post Sun Jun 13, 2021 12:52 pm

so they're not Alpha Juno saw pwm wavetables but on another thread about Alpha Juno pwm saw there was some info on D-50 saws and how they could be pwm'd. i set it up the same way in vital, but that had too much level difference, so i remade it with line source. i've really been enjoying the sound they have, def going to use these a lot.
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KVRian
1160 posts since 21 Apr, 2017 from Bahia, Brazil

Post Mon Jun 14, 2021 3:05 am

Cool. What is the frame count and sample per frame of these?
We jumped the fence because it was a fence not be cause the grass was greener.
https://scrubbingmonkeys.bandcamp.com/
https://www.scrubbingmonkeys.com/

KVRer
2 posts since 21 Jan, 2021

Post Sat Jun 19, 2021 2:25 pm

Scrubbing Monkeys wrote:
Mon Jun 14, 2021 3:05 am
Cool. What is the frame count and sample per frame of these?
i believe the wavs are exported in the same format serum uses

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KVRian
1160 posts since 21 Apr, 2017 from Bahia, Brazil

Post Sat Jun 19, 2021 2:31 pm

alixp wrote:
Sat Jun 19, 2021 2:25 pm
Scrubbing Monkeys wrote:
Mon Jun 14, 2021 3:05 am
Cool. What is the frame count and sample per frame of these?
i believe the wavs are exported in the same format serum uses
256 frames at 2048 samples/frame?

I don't have Serum but I think it can use various frame count and sample. Not sure.
We jumped the fence because it was a fence not be cause the grass was greener.
https://scrubbingmonkeys.bandcamp.com/
https://www.scrubbingmonkeys.com/

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