[sdiy] Temperature Compensated Exponential Converter Using SSM2164

[cheater cheater]

>> A lot of classic synth circuits worked just fine with rail refs.
>
> A lot of classic synth circuits were also horribly out of tune on gigs.

Yes, and what Richard might be talking about - minimoogs, microkorgs,
etc - is just very simple stuff.
Not huge modulars with dozens of modules.

Now that I think about it, most modulars I see are at least 3x as
complicated as a Model D.

(model) D.

On Tue, Sep 8, 2009 at 1:41 PM, Antti Huovilainen<ajhuovil at cc.hut.fi> wrote:
> On Tue, 8 Sep 2009, Richard Wentk wrote:
>
>> A lot of classic synth circuits worked just fine with rail refs.
>
> A lot of classic synth circuits were also horribly out of tune on gigs.
>
>> Yes, they're theoretically crappy. But some of that analogue sound comes
>> from unpredictable random variations. If you start putting atomic-precision
>> Vrefs throughout a circuit you'll lose some of that character.
>
> Do you? Have you made A/B comparisons with otherwise equivalent circuits?
> Are the PSU variations truly random and not strongly correlated with VCO
> resets and LFO cycles?... (rhetoric question)
>
>> There's also the cost/complexity issue. If your PSU is designed properly,
>> rails should be stable enough. It's cheaper to design a PSU with reasonable
>> quality than it is to start sprinkling Vrefs throughout every circuit.
>
> I doubt this. References are dirt cheap (you only need stability and lowish
> tempco, not absolute accuracy). "Stable PSU" is an oxymoron at microsecond
> switching speeds (rails have finite impedance).
>
> Finally and IMO most importantly: using local references is much easier to
> get right than making sure 100% of your PSU wiring is optimized to minimize
> interference.
>
> Antti
>
> "No boom today. Boom tomorrow. There's always a boom tomorrow"
>  -- Lt. Cmdr. Ivanova
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