Triangle wave looks more like a square wave

The Dave Smith Instruments Prophet-12 Analogue Synthesizer

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pelican
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Re: Triangle wave looks more like a square wave

Post by pelican » Sat Nov 30, 2013 11:51 pm

seriously? I think you guys are being a little unrealistic. Do you not think dave spent much much time looking at the waveforms on an oscilloscope. He chose them for a reason and obviously believes them to be good. I doubt you will get your beloved waveforms added anytime soon :roll:

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Re: Triangle wave looks more like a square wave

Post by Mefistophelees » Sun Dec 01, 2013 12:34 am

Someone did something similar with some modular oscillators on anther site recently and it turns out one oscillator produces a decidedly impure sine wave. It's quite capable of a pure sine wave but it's deliberately calibrated that way.
What might surprise you is that it's a very high end oscillator - a Macbeth.

NewsFromTheSky
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Re: Triangle wave looks more like a square wave

Post by NewsFromTheSky » Wed Dec 04, 2013 3:52 am

jasonswe wrote:A smoother, more ideal triangle should be a possibility by emmploying FM, because the OSC can modulate themselves for finer tweaking. I may try later. Not easy since OSC frequency is given as note value and not ratios between operators.
You can map transposition to frequency ratios (1:2 = +12, 1:3 = +19, 1:4 = +24, 1:5 = +28, though the odd numbers are slightly off). However, oscillator self-FM will change the fundamental frequency, because it's logarithmic FM, not linear phase modulation (as on the Yamahas). But try it and see what you get.

Linear phase modulation is one of my top feature requests for the P12. You could have a 4-operator FM synth with analog filters.

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Re: Triangle wave looks more like a square wave

Post by Soundquest » Fri Dec 06, 2013 6:50 pm

Maybe it'd be easier just to change the name from Triangle to Rhombus...or somethin' like that :wink: Seriously though...that's wierd. Do each of the various P12 oscillators "Triangle" waves look like that (I mean similarly skewed)?

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Mr Kay
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Re: Triangle wave looks more like a square wave

Post by Mr Kay » Sat Dec 07, 2013 11:24 am

Hey, if there's an update for this, 'wanna keep the existing shape, 'used it on some of my patches :P

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Re: Triangle wave looks more like a square wave

Post by Fuseball » Sat Dec 07, 2013 12:13 pm

Mr Kay wrote:Hey, if there's an update for this, 'wanna keep the existing shape, 'used it on some of my patches :P
I can't imagine they would change any of the existing waveforms, given that the sound of everyone's patches is based upon them. In my dreams, perhaps, we get additional waveforms added. I'd love a set of "classic" waves based upon the P08's saw, triangle and saw-tri. They wouldn't even need to be necessarily shape mod-able. I'm not holding my breath though. The P12 is what it is and the sounds I get from it don't really encroach on the sounds I get from my fully analog synths.

I was talking to Kent Spong (much respected synth repairer) yesterday. I described the P12's triangle to him and he said it sounded like it was modelled on a CS-80's square wave, which also has rounded corners. Probably a coincidence but interesting nonetheless.
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Mr Kay
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Re: Triangle wave looks more like a square wave

Post by Mr Kay » Sun Dec 08, 2013 12:20 pm

Actuelly, the P'12 is the only synth on witch I manage to make sounds I like with the triangle wave.

Most of the time, I use the sawtooth, the square and the sine, and the lack of sine wave really annoyed me on the Mopho Kb.

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Re: Triangle wave looks more like a square wave

Post by Dorimar » Sun Dec 15, 2013 10:23 am

I dont own a prophet 12 but it is a very tempting instrument. I read all the comments in this interesting thread carefully.

The only thing I am missing is an official statement about this opportunity to improve the product.
I don't think that this is a wanted feature

So:

Where does it come from?
What can be done on user part to minimize the effect?
What does Dsi think about this and what can they do to deliver a triangular triangle?

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Bald Eagle
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Re: Triangle wave looks more like a square wave

Post by Bald Eagle » Sun Dec 15, 2013 11:23 am

It getting close to 3 weeks since this thread was started and still no official response from DSI. It's beginning to look as if they are just going to ignore this.

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Re: Triangle wave looks more like a square wave

Post by Flux302 » Thu Sep 03, 2015 7:47 pm

WAY old thread but I am a synth nerd who likes investigating this sort of thing. was there every any info about why the waveforms in the P12 don't look like what they are pro ported to be? main reason I ask is I believe it maybe up to a few other factors. are the oscillators AC coupled inside the synth before they go through each stage? that would certainly pull the slopes of the square toward the zero crossing. the triangle looks like an overdriven triangle or something. but certainly not a true triangle, the square is heavily sloped (more so than any other synth I own). the saw also has a heavy slope to it. the wavetables all seem to look very close to what the OLED screen indicates.
So I tried to recreate this shape using my Modular synth (yes I said it I am a nerd when it comes to this stuff). and I was able to pretty quickly approximate a similar wave form using a Triangle wave into the DSI character module which I had girth turned up to about 10'oclock, and drive just slightly turned up. then I ran that into a SEM 12db filter which I used no resonance and slightly filtered down. this gave me a VERY similar shape and tone.
Only reason I really wonder is because DSI never actually answered the question about it and I like to actually know synthesis wise what is going on in my sound design. (I really hate evasive tactics intentionally or not... like REALLY hate it)
It would just be nice to know why the choices were made. maybe go into a little detail as to 1) is it a result of sending through the character mod and filters? is it at the raw oscillator level that the signal looks like this? is the DAC being over driven at all? any chance this has some what of thing to do with the very easy to get overdriven sound? whats the deal... inquiring minds want to know. surely an honest answer can't be against the rules? :?: :?: :?: :D

again nothing wrong with the fact that the waveforms aren't at all "pure" its just a curious character that I would like to better understand.
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Re: Triangle wave looks more like a square wave

Post by Flux302 » Thu Sep 03, 2015 8:10 pm

for anyone interested here are the waves I see. (couple notes this is an init patch with only 1 oscillator at level 64 program level is 64 , no delay free back distortion etc)

Here are the waves... and I even include a moog triangle for perspective :)

now if I am doing something wrong I would love to know. I have a friend sending me a shot of his Pro2 waveforms (and I do not see this behavior with my tempest)

again this is for the nerds... not a gripe. please see included attachments
Attachments
p12saw.jpeg
p12 saw
p12saw.jpeg (1.32 MiB) Viewed 2534 times
p12square.jpeg
p12 square
p12square.jpeg (1.27 MiB) Viewed 2534 times
p12triangle.jpeg
p12 triangle
p12triangle.jpeg (1.13 MiB) Viewed 2534 times
trianglemoog.jpeg
moog triangle
trianglemoog.jpeg (1.05 MiB) Viewed 2534 times
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oldgearguy
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Re: Triangle wave looks more like a square wave

Post by oldgearguy » Fri Sep 04, 2015 10:42 am

I got something similar for the square and saw. I posted a couple of boring tech videos on YouTube (search for oldgearguy, sawtooth, square) comparing a few different synths (including the P-12).

Given DSI's response to the triangle wave discussion, I've moved past the waveform (and filter) design choices and just work with the sounds as they are. Most of the time I'm not using the classic waveforms anyway, but when I do, I can make them work in context.

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Re: Triangle wave looks more like a square wave

Post by Pym » Fri Sep 04, 2015 5:52 pm

Note that regardless of the way it appears on the final ouptput (due to the filtering effects of the circuitry and so on) when used a modulation source it is a pure waveform. If you took an oscilloscope and put it on the final output from the DSP you'd see a pure triangle wave
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Re: Triangle wave looks more like a square wave

Post by nikwal » Fri Sep 04, 2015 7:41 pm

Cool, pure is how i like them, even though people say they pure are boring. Depends on what you DO with them..

If I may ask, is there a special reason you guys went with dsp and not fpga? Programming a dds/nco with "pwm" in a cyclone4 is not hard and does'nt take much space in the circuit if you "timeslot" the calculations. hmm i totally understand if you dont want to talk about it, company secrets and such..

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Re: Triangle wave looks more like a square wave

Post by Pym » Fri Sep 04, 2015 9:52 pm

Easy answer: Sharc DSP chip already has a substantial audio and DSP library and is optimized for a lot of the things we wanted to do. Was the quickest way to market
nikwal wrote:Cool, pure is how i like them, even though people say they pure are boring. Depends on what you DO with them..

If I may ask, is there a special reason you guys went with dsp and not fpga? Programming a dds/nco with "pwm" in a cyclone4 is not hard and does'nt take much space in the circuit if you "timeslot" the calculations. hmm i totally understand if you dont want to talk about it, company secrets and such..
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Flux302
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Re: Triangle wave looks more like a square wave

Post by Flux302 » Sat Sep 05, 2015 2:41 pm

I just want to comment to Pym and DSI that again I am not knocking in any way how it SOUNDS... nor the usability.

I just don't have any other synths that claim a waveform as a triangle or what ever and then put out something totally different at the outs. not a big deal. just makes me get my sleuthing hat on to understand why. on Facebook I spoke about it and came to the conclusion it had to do with DC filtering and the signal chain through the filters?

so bottom line on audio side of things the P12 doesn't output a triangle (and that is fine) but as modulation it does. interesting. does the Pro2 do the same? I know it has a few different waveforms, are they being manipulated in the same way?
I'll see if I can get some Oscope shots from a friends Pro2 ...

Again this is purely for us synth nerds and should not really be taken as a knock agains the tone of the pro12
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Re: Triangle wave looks more like a square wave

Post by Flux302 » Sun Sep 06, 2015 2:21 am

Just another update... Very curiously. The PRO2 waveforms do NOT exibit the same warped behavior. Now that I find more strange.
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sapristico
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Re: Triangle wave looks more like a square wave

Post by sapristico » Sun Sep 06, 2015 2:26 pm

"quickest way to market..."

EXACTLY....you have identified (or finally recognize) the superlative (est) problem (also in some other senses and aspects with this product)...now it's time to provide the remedies...solutions...compensations...to that REAL market...that is: to US...in the BEST way.

Don't take it personal....bussiness is bussiness...and synth love is synth love.

Flux302
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Re: Triangle wave looks more like a square wave

Post by Flux302 » Sun Sep 06, 2015 2:47 pm

I would love to know what voice structure or optimization happened between the pro2 vs p12 that allows for the pro2 to not exhibit the same waveform distortion.

on top of that. I wonder if DSI could have actually sold MORE units by showcasing just how different the two are. Again waveforms don't have to be perfectly traditional to sound good.
That being said, if they aren't a traditional (at output) why not champion that fact instead of kick it under the rug? I mean a lot of the time people spending the kind of money that DSI asks for its instruments are going to be power users, not some average joe picking up a arranger keyboard and doesn't really care whats what. So its not like this stuff will go unnoticed.
regardless I actually like the sound of the P12 (I feel the filters are a bit characterless but I knew that going into it).
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Re: Triangle wave looks more like a square wave

Post by BobTheDog » Sun Sep 06, 2015 4:39 pm

sapristico wrote:"quickest way to market..."

EXACTLY....you have identified (or finally recognize) the superlative (est) problem (also in some other senses and aspects with this product)...now it's time to provide the remedies...solutions...compensations...to that REAL market...that is: to US...in the BEST way.

Don't take it personal....bussiness is bussiness...and synth love is synth love.
What!

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