[sdiy] favorite adsr?

[Tom Wiltshire]

Stewart,

I wasn't making any specific claims about my own PIC design. It's  
pretty good, certainly, and for the price I don't think you can  
argue, but it only has a 10-bit output. This means that for very slow  
envelopes (10 secs) to critical destinations (like pitch or highly- 
resonant filters) you can hear a little bit of digital stepping. This  
disappears when you speed things up a bit. But in all honesty, I  
can't claim that it's perfect. For a quick, cheap, simple VCADSR that  
only uses a few components, it's pretty good, and you'd mostly never  
know it's digital. Ultimately, I'd recommend you knock one up on a  
breadboard and try it.

I've built other envelope generators with 12-bit DACs and the  
stepping disappears on these. My current designs are based on the  
33FJ128GP802 chip that I was raving about earlier, and this has a 16- 
bit DAC accurate to 14-bits. With a sample rate of 10KHz+ and some  
post-DAC filtering this is entirely indistinguishable from analogue.

Regards,
Tom



On 29 May 2009, at 12:56, Stewart Pye wrote:

> Hi Tom,
>
> If you reckon it's as good or better than an analogue one, I'll try  
> out your ADSR. I use AVR micros here but I'll program a chip at  
> work. it certainly "looks" impressive on your website.
>
> Dan,
>
> If you want to try Tom's ADSR PIC, and you can't find someone to  
> program it locally, I'd happily send you some programmed chips for  
> the price of chips and postage from Australia (if it's OK with Tom).
>
> Cheers,
> Stew.
>
>
> Tom Wiltshire wrote:
>>
>> I'd be extremely sceptically about any claims made purely on the  
>> basis of one technology or another.
>> You can use CMOS switches or transistors of one sort or another in  
>> an analogue ADSR, and I doubt you could generalise. Some will be  
>> faster, some slower. Usually there is a trade-off between being  
>> able to reach long segment times and being able to produce an  
>> extremely short segment time. This is down to the charging  
>> capacitor required. A big cap can give you very long times, but  
>> even with minimum resistance will still take a few mSecs to charge.
>>
>> Myself, I gave up on analogue ADSRs some time ago. They use a lot  
>> of components and are relatively complicated compared to a digital  
>> solution, on top of which digital is more flexible (any curve  
>> shape you like, for instance). There was a time back in the early  
>> days when digital envelopes were pretty basic, used sample rates  
>> of 100Hz, and got a reputation for being sluggish and not sounding  
>> good, but that was years ago. It's easy to design a far better  
>> envelope than appears in the Waldorf Wave, say.
>>
>> Finally, it is worth saying that any time under 1mS or so is just  
>> a "click" sound anyway, so you might not find it that appealing.
>>
>> Regards,
>> Tom
>>
>>
>> On 29 May 2009, at 12:02, Dan Snazelle wrote:
>>
>>>
>>>
>>>
>>> i am going to be testing out ADSR'S all weekend and i have heard  
>>> (maybe wrongly) that transistor based ADSR's are quicker/snappier.
>>>
>>> is this true? any recommendations on circuits to try?
>>>
>>> thanks
>>>
>>> --------------------------------------------
>>> check out various dan music at:
>>>
>>>  http://www.myspace.com/lossnyc
>>>
>>> (updated monthly)
>>>
>>> http://www.soundclick.com/lossnyc.htm
>>>
>>>
>>>
>>> http://www.indie911.com/dan-snazelle
>>>
>>> (or for techno) http://www.myspace.com/snazelle
>>>
>>> ALSO check out Dan synth/Fx projects:
>>>
>>> AUDIO ARK:
>>>
>>> www.youtube.com/watch?v=TJRpvaOcUic
>>>
>>> www.youtube.com/watch?v=BqIa_lXQNTA&feature=channel_page
>>>
>>> www.youtube.com/watch?v=V4nJPjGgOcU&feature=channel_page
>>>
>>> and soundtrack/design work:
>>>
>>> NEW: check out Dan's sound design from the 1998 award winning  
>>> film SAFARI by catherine chalmers
>>>
>>> http://www.catherinechalmers.com/videos.cfm
>>>
>>>
>>>
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