[sdiy] JX3P Metal Sync (was Re: Idea - Triangle wave DCO core)

[Tom Wiltshire]

On 14 Mar 2012, at 13:19, Florian Anwander wrote:

> Hello Richie
> 
>> Florian, have you ever worked out how the "Metal" setting on the JX-3P
>> works? I haven't sat down and figured it out, but I'm guessing it's
>> something like that the master resets the slave's integrator state but
>> doesn't reset it's digital counter as well. Or maybe the other way
>> around: The master resets the slave's digital counter, but doesn't reset
>> the integrator state back to zero?
> In the schematics there are two controlling signals: the signal 'Sync' enables the reset of the programmable counter of the slave DCO. The signal 'Met/Syn' enables the reset of the integrator of DCO2 by the counter of DCO1. I never checked that in the real synth, but considering the naming of those two control signals it is most likely, that sync causes a reset of both, counter and integrator, while metal causes only the reset of the counter.

Very interesting. That sounds very likely, and drawing a few waveforms that you'd get out of it, it produces an interesting result.

Since the slave's counter isn't reset, the frequency isn't locked to the master, so the underlying pitch gets a bit scrambled. This would explain why people think it's a ring modulator, and why it sounds "metallic".

It'd be an easy addition to any Ramp DCO design. I might try it.

Thanks both.

Tom