[sdiy] Multi-source crossfader

[Scott Nordlund]

I doubt 16 bit waveforms would make a huge improvement.  Since you're (presumably) only going to be storing full-scale raw waveforms, and doing any amplitude processing and crossfading either in the analog domain or with higher-bit digital, 8 bits shouldn't really be that much of a limitation.

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> Date: Wed, 4 Feb 2009 12:19:58 -0800
> From: lightburnx at yahoo.com
> Subject: Re: [sdiy] Multi-source crossfader
> To: synth-diy at dropmix.xs4all.nl
>
> Funny this comes up, as I got on the topic of vector synthesis (mentioned on one of JH's scanner project pages) a few days ago.
>
> I picked up an old motor speed controller at a surplus shop a while back - it's got a nice sloped case, about 12" x 8", with a center-returning joystick in the middle. I gutted out the board and was left to wonder how to best make use of it. After some "research" (see: Wikipedia jumping), the idea of shuffling through wavetables sounds like a great way to wring the most variety out of the two axises of a joystick, a la vector synthesis, ie: the Sequential Circuits Prophet VS.
>
> Apart from reading up on the Prophet VS and its vector interface, I've looked at some existing DIY implementations of wavetables, namely those of Ken Stone (http://www.cgs.synth.net/modules/wavetable.html), and Keith Winstanley (http://home.freeuk.net/lowpass/VCDO.html). There's a .zip available on Keith's page of the original Digisound VCDO module from which both are based.
>
> I'm curious about what kind of modern upgrades could applied to this kind of design. 64-bit eproms would be a bit overkill, but even trying a 16-bit would have some more room for variety with the wavetables (versus the original 8). If I want to get back to that lofi character, I could just drop address lines into the DAC. And if nothing else, a newer eprom would suck less juice - the ones prescribed for the Digisound one took up to 500mA (yes, half an amp!).
>
> All this being said, I get the general theory of the process, less so the specifics of implementation. I've been tackling the VS service manual (http://www.retrosynth.com/docs/pvs/), and some of National Semiconductor's application notes on DACs - any other suggested reading?
>
>
> It's interesting that I pass by Sequential's address listed in the service manual (3051 North First Street, San Jose, CA, USA) on my way to school :3
>
> And Google Maps says Sequential still has a space there:
>
> http://maps.google.com/maps?f=q&source=s_q&hl=en&geocode=&q=3051+N+First+St.,+San+Jose,+CA,+usa&sll=37.394539,-121.934209&sspn=0.007825,0.013819&g=3051+N+First+St.,+San+Jose,+CA,+usa&ie=UTF8&ll=37.396107,-121.934187&spn=0.007825,0.013819&z=16&iwloc=r0
>
>
> _Kyle
>
>
> --- On Tue, 2/3/09, JH.  wrote:
>
>> From: JH. 
>> Subject: Re: [sdiy] Multi-source crossfader
>> To: elektrodwarf at yahoo.se, synth-diy at dropmix.xs4all.nl
>> Date: Tuesday, February 3, 2009, 11:18 PM
>> http://www.jhaible.heim.at/interpolating_scanner_and_scanvib/jh_interpolating_scanner_and_scanvib.html
>>
>> JH.
>>
>> ----- Original Message -----
>> From: "Karl Ekdahl" 
>> To: 
>> Sent: Tuesday, February 03, 2009 10:44 PM
>> Subject: [sdiy] Multi-source crossfader
>>
>>
>> Hi list, i'm in need of a multi-source crossfader,
>> specifically i'm going to
>> have a fader going inbetween four waveforms (square, saw,
>> tri, sine). I
>> started designing some kind of BTJ-contraption but figured
>> perhaps someone
>> here already made one?
>>
>> Thanks
>>
>> Karl
>>
>>
>>
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