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 Forum index » Instruments and Equipment » DSI Synths
Low frequency poping noise
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EdisonRex
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PostPosted: Wed Jun 24, 2009 4:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

welcome to the forums Urosh. That is a very interesting and thoughtful post. I will try out your tests. I might even post the results here Wink If someone else doesn't do it first.
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torsig1967



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PostPosted: Sun Jun 28, 2009 1:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

recnsci wrote:

Hi there,

IMHO reason is not poor or cheap circuit design, it's one of side effects of using DCO ...


Interesting reading. Seems like there's no easy way to recreate old analogue oscillators using modern stuff like DCO then. In my opinion the whole point of using analogue oscillators is lost if there are artefacts like this (cheap or not).

How is this solved in the modern Moogs?
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recnsci



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PostPosted: Mon Jun 29, 2009 11:57 am    Post subject: Reply with quote  Mark this post and the followings unread

torsig1967 wrote:
recnsci wrote:

Hi there,

IMHO reason is not poor or cheap circuit design, it's one of side effects of using DCO ...


Interesting reading. Seems like there's no easy way to recreate old analogue oscillators using modern stuff like DCO then. In my opinion the whole point of using analogue oscillators is lost if there are artefacts like this (cheap or not).

How is this solved in the modern Moogs?


Sorry, I wasn't clear enough. "Cheapness" of DCO versus VCO is more historical reason. Today, it is not much more expensive to make true VCO synth, compared to DCO approach. Dave Smith, on the other hand, was forced to use DCOs because he uses custom manufactured CEM chips (AFAIK). Heart of evolvers and pro08s are chips similar to CEM 3396, used in Matrix 6 and Matrix 1000. "Waveshaper" part in those chips is analog portion of DCO.

And, AFAIK new Moogs use VCOs, as well as Andromeda and all SE synths. Probably cheapest VCO synth is that semi modular tabletop from MFB (KRAFTZWERG). You should check that one if you can.

cheerz
urosh
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torsig1967



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PostPosted: Tue Jun 30, 2009 2:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

recnsci wrote:
Probably cheapest VCO synth is that semi modular tabletop from MFB (KRAFTZWERG). You should check that one if you can.


There are some other MFB synths (Synth II, Synth Lite II e.t.c.) are these VCO as well?

Thanks for the info anyhow.
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recnsci



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PostPosted: Thu Jul 02, 2009 3:14 am    Post subject: Reply with quote  Mark this post and the followings unread

torsig1967 wrote:
recnsci wrote:
Probably cheapest VCO synth is that semi modular tabletop from MFB (KRAFTZWERG). You should check that one if you can.


There are some other MFB synths (Synth II, Synth Lite II e.t.c.) are these VCO as well?

Thanks for the info anyhow.


As far as I know, only Kraftzwerg and Eurorack modules are VCO based. You should check this as well: http://www.spectralaudio.ch/neptuneII.htm .
Or, simply shop here: http://www.schneidersbuero.de/
(owner, Andreas Schneider, is one hell of a great guy). They have quite an extensive catalog.

cheerz
Urosh
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Munchausen



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PostPosted: Sun Jul 05, 2009 3:29 am    Post subject: Reply with quote  Mark this post and the followings unread

Urosh,

Please send your message to DSI support. You seem quite knowledgable about it and maybe they could tell you if an update would actually be possible.

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gd



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PostPosted: Mon Jul 06, 2009 7:02 am    Post subject: Reply with quote  Mark this post and the followings unread

I agree with the above assessment as the P 08 suffers from the same so it must be due to the nature of the DCO's vs. the VCO.
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Jinsai



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PostPosted: Tue Jul 14, 2009 12:51 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well, here's an MP3 where it's fairly clear: http://www.chillproductions.com/anu/temp/DCOglitch.mp3

Here's what a non-glitched attack looks like:
Posted Image, might have been reduced in size. Click Image to view fullscreen.

Here's what a glitched attack looks like:
Posted Image, might have been reduced in size. Click Image to view fullscreen.
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Barely



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PostPosted: Thu Jul 07, 2011 3:05 am    Post subject: Reply with quote  Mark this post and the followings unread

recnsci wrote:
torsig1967 wrote:

Seems they are well aware of the problem.

So I got myself a Novation Super Bass Station instead (analog too) and it's quite funny (or annoying) but this machine has a similar problem but less noticeable.

None of my truly vintage analog synths (MicroMoog, Korg MP, Pro One and others) has this artefact. So it has nothing to do with being "vintage" or being "analog". It's just poor and cheap circuit design.


Hi there,

IMHO reason is not poor or cheap circuit design, it's one of side effects of using DCO (whitch Bassstation uses as well).
Classical VCO has circuit that converts voltage into current, and that current charges capacitor, which results in linear rise of capacitor voltage. When voltage reaches some threshold, electronic switch of some sort is triggered that discharges capacitor. Thus, you have sawtooth waveform on capacitor with constant amplitude, but with ramp rise rate (and thus VCO frequency) proportional to capacitor current. Problem is (among other things) that you need high quality voltage to current converter at VCO input, which means its expensive and a bit trickie to do.
(...)
Urosh


Hi there and sorry for digging out such an old post.
I can hear the Oscillator clicking, yes.
But might I just draw your attention to this little song:
http://www.youtube.com/watch?v=RyLmV1yQJFg&feature=related
It's the almighty ARP2600, and it clicks as hell.
I actually like it that way Wink So I'd say that the evolver is in best company sonically Smile
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Antimon



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PostPosted: Thu Jul 07, 2011 3:23 am    Post subject: Reply with quote  Mark this post and the followings unread

If you mean the faint sequence that opens the sound, that sounds like common clicks due to a steep attack to me. The noise you get on an Evolver is due to the pitch gliding, and is only apparent when you play two successive notes that have a large difference in pitch.

Another synth where this does appear though, is the Arturia Origin bafflingly enough. I've reported it here:

http://www.arturia.com/evolution/smf/forums.html?topic=3794.0

I can't for the life of me understand how someone could recreate this problem on a VA...

/Stefan

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Barely



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PostPosted: Thu Jul 07, 2011 3:55 am    Post subject: Reply with quote  Mark this post and the followings unread

Antimon wrote:
If you mean the faint sequence that opens the sound, that sounds like common clicks due to a steep attack to me. The noise you get on an Evolver is due to the pitch gliding, and is only apparent when you play two successive notes that have a large difference in pitch.

Another synth where this does appear though, is the Arturia Origin bafflingly enough. I've reported it here:

http://www.arturia.com/evolution/smf/forums.html?topic=3794.0

I can't for the life of me understand how someone could recreate this problem on a VA...

/Stefan


Yeah, now I hear the difference, too. I couldn't reproduce it so quickly on my PEK. Maybe it's because the phase is started again at a new key press, and the oscillator has trouble finding the right phase AND frequency? Just a guess...
Besides that, how do you like your Origin? I stalked around one for some time and then decided to buy a Virus. Which is much better than I expected, btw...
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Antimon



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PostPosted: Thu Jul 07, 2011 4:17 am    Post subject: Reply with quote  Mark this post and the followings unread

The Origin is ok, I guess. I just think that the whole VA deal isn't for me - too often I struggle to make it sound anything else than bland. I was hoping that the Origin would be the polysynth with classic-like structure that fills a space between the PEK and the Nord Modular G2 Engine.

The hardware interface on the Origine is nice. I see it as a template machine - you use (and occasinally make) ready-made structures that are tweakable if you feel the need. Being accustomed to the Nord Modular I don't see the Origin as something you patch from scratch a lot - too cumbersome.

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BobTheDog



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PostPosted: Thu Jul 07, 2011 4:41 am    Post subject: Reply with quote  Mark this post and the followings unread

I quite like patching the Origin.

I think it is because it is fairly simple, there are not that many modules to complicate things. Whereas the G2 makes my mind boggle and steam start appearing form my ears!

I find it easy to make the Origin sound good (to my ears) while I find it very hard to make the G2 sound good, although I know that people here with a bit more savvy than me make exceedingly good sounding G2 patches, if only I could understand them!
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Pym



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PostPosted: Fri Jul 08, 2011 7:01 pm    Post subject: Reply with quote  Mark this post and the followings unread

On page 7 of the 3396 preliminary data sheet (link: http://www.synthtech.com/cem/c3396pdf.pdf) you'll read about range of the oscillator and describing how the chip has a practical range of about 6 octaves with a reasonable error rate. To increase this range it's advisable to use a second resistor to switch over when the range goes from the low to high registers. That's probably what you're hearing. In most instruments using these chips and similar ones the total response time of the voice (envelopes, filters, etc) is pretty slow and thus masks small artifacts like this one. In our gear we err on the side of responsiveness, the envelopes and filter response are extremely quick, with the downside that you hear some artifacts that are naturally inherent in the analog circuitry. It's always a matter of compromise with things like this.
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Barely



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PostPosted: Sat Jul 09, 2011 3:07 am    Post subject:   Reply with quote  Mark this post and the followings unread

Pym wrote:
On page 7 of the 3396 preliminary data sheet (link: http://www.synthtech.com/cem/c3396pdf.pdf) you'll read about range of the oscillator and describing how the chip has a practical range of about 6 octaves with a reasonable error rate. To increase this range it's advisable to use a second resistor to switch over when the range goes from the low to high registers. That's probably what you're hearing. In most instruments using these chips and similar ones the total response time of the voice (envelopes, filters, etc) is pretty slow and thus masks small artifacts like this one. In our gear we err on the side of responsiveness, the envelopes and filter response are extremely quick, with the downside that you hear some artifacts that are naturally inherent in the analog circuitry. It's always a matter of compromise with things like this.


That is the most precise answer we will ever hear about this Wink Thanks for digging that up! Still, I don't find it too terribly bad, I still love my PEK *pat pat* Now I have the sudden urge to test my other analogues on second resistor switches Wink
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recnsci



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PostPosted: Fri Jul 15, 2011 2:03 am    Post subject: Reply with quote  Mark this post and the followings unread

Pym wrote:

Hi Pym, thank you for your response.
...
I have few questions (if OP doesn't mind a bit of hijack). First, if it's not trade secret, what is sample rate of control signals in Evolver (that is, sample rate of DACs that generate Cutoff, Resonance, Pulsewidth, etc Control Voltages) and what is their resolution (in bits)? Second thing, should we expect adding few bits and pieces in firmware, or development of Evo FW has reached it's final phase? I'm interested in just two things, adding signal just after VCA and before Pan as mod source and adding feedback level as mod destination.

Best Regards
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