[sdiy] Prophet 600 tuning question

[Tom Wiltshire]

On 29 Feb 2012, at 11:35, Andre Majorel wrote:

> On 2012-02-26 13:32 +0000, Tom Wiltshire wrote:
> 
>> Given that the uP is using its own clock frequency as the
>> basic time reference, presumably you could retune the whole
>> instrument a little by tweaking the 8MHz master uP clock. It's
>> possible that this has drifted a bit over the years. Aside
>> from that, I can't really see a way to do it.
> 
> f_osc = f(f_cpu) ? The Prophet 600 has DCOs ? Colour me amazed.
> It certainly doesn't sound like it.

I didn't say that. I just meant that the uP will use some timer to measure the frequency for the tuning routine. That timer will probably depend on the master system clock.
Once it's got tuning tables worked out, it can use them to generate adjusted CVs for the entirely-analog not-entirely-linear VCOs.

I agree about f_osc = f(f_cpu) though. That's true in any uP-tuned synth.

T.