[sdiy] Envelope attack smoothing for drum question

mark verbos markverbos at gmail.com
Mon Aug 24 12:22:09 CEST 2020


In my opinion, that would lead to way too much timing slop. On a low frequency triangle (which is what it is) that could be 50ms, a huge amount even when taken in half. 
What’s wrong with synching the oscillator? It worked for Roland in the TR-909, which I guess is the most established success in the world of synth drums. In fact, I recommend that you simply steal their method of synching, since it works so well. Incidentally, they add some click in as well, I suppose that makes the click consistent.


Mark





> On Aug 21, 2020, at 10:38 PM, Jason Nanna <jasonnanna at gmail.com> wrote:
> 
> Would delaying the trigger until an oscillator zero-crossing be a simpler way to synchronize?  Assuming a bipolar triangle, I don't think it matters whether it's rising or falling.
> 
> On Fri, Aug 21, 2020 at 3:33 PM Jacob Watters <jacobwatters at gmail.com <mailto:jacobwatters at gmail.com>> wrote:
> Right. The linearizing is for noise, but the trimpot is the important part for thumping. I added the diode part to my suggestion because it is a good practice that I often see left out.
> 
> Jacob Watters
> JacobWatters.com <http://jacobwatters.com/>
> Tel: 226-886-3526
> 
> 
> On Fri, Aug 21, 2020 at 3:52 PM Dakota Melin <dksynth at gmail.com <mailto:dksynth at gmail.com>> wrote:
> I think Jacob might be pointing out that if your VCA itself has DC offset problems that’ll thump as well. 
> 
> On Fri, Aug 21, 2020 at 3:41 PM Tom Wiltshire <tom at electricdruid.net <mailto:tom at electricdruid.net>> wrote:
> How does use of the linearising diodes hep with the offset click?
> 
> I agree about eliminating the offset as a source of the click, since if the VCA thumps, it doesn’t;t matter what signal you feed it, or even if you feed it no signal at all, you’ll still hear a click, but I don’t see what the linearising diodes have to do with that.
> 
> Tom
> 
> 
> 
> 
>> On 21 Aug 2020, at 20:25, Jacob Watters <jacobwatters at gmail.com <mailto:jacobwatters at gmail.com>> wrote:
>> 
>> You mentioned an OTA based VCA. I have experienced some clicking with these in the past. Use a linearizing diode and calibrate the 1k trimpot (https://i.stack.imgur.com/5drhW.jpg <https://i.stack.imgur.com/5drhW.jpg>). That will rule out the VCA as the source of the click.
>> 
>> Jacob Watters
>> JacobWatters.com <http://jacobwatters.com/>
>> Tel: 226-886-3526
>> 
>> 
>> On Wed, Aug 19, 2020 at 5:42 PM Didier Leplae via Synth-diy <synth-diy at synth-diy.org <mailto:synth-diy at synth-diy.org>> wrote:
>> We are working on an analog drum module that uses a simple envelope created from a trigger to control the amplitude of a triangle oscillator with a basic OTA based VCA.
>>  
>> We are having a problem with a slight clicking sound at the beginning of many of the drum hits. We think this is because the attack of our envelope is so sharp that the beginning of our drum hit looks like a straight jump from 0V to wherever the triangle wave happens to fall. Therefore the click is somewhat random in that it doesn't occur when the triangle happens to be low at the time of attack.
>> 
>> Can anyone suggest a simple way to deal with this, like adding a slight bit of attack time to the envelope? How could this be done without adding too many parts?
>> 
>> Thanks,
>> 
>> Didier
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