ParasitStudio Guitar Syth - can the Oct up be separated from the Oct down?

[Granny Gremlin]

I like the demos of this thing. Just wondering what part of the circuit (e.g. u2.1 or u3+u2.2) is the Oct up vs the Oct down generator. 

http://www.parasitstudio.se/uploads/2/4/4/9/2449159/0415_guitar_synth_doc.pdf (schem on pg4)

[Nthorn]

vco_out on the cd4046 should be the octave up. 4046 multiplies the signal by feeding the vco_out into a divider then into comp_in. 4046 is an awesome chip and you can get some cool sounds with them.

[Luke51411]

I've built this and it's awesome! I don't think you can separate the octaves. When you activate either octave it effects the other.

[Granny Gremlin]

Yeah, that's what I was worried about.  Seemed too good to be true that it would just be the 4015 doing it (U2.1).  ... but I suppose even easier than my original plan to build just the Oct Up parts on vero/perf, would be to use the PCB but just not populate SW1  and jumper the blend pot pads to be 100% Oct up.  Wondering what else I could get rid of if I don't need the vol control either... could I just jumper the input of R9 (not populate it) directly to output and eliminate the whole blend section altogether?

[maartendh]

The mix pot deactivates the channel you don't want to hear by connecting it to ground. Connecting R9 to C6 should work. Tie pin 9 of U1.4 to + (pin 14 of U1) when you are not using the octave down part - you can let pin 8 be unconnected.

For even higher octaves up, connect SW2 to Q2 (pin 11) or to Q3 (pin 2).

[R.G.]

Search for my mods to the Roctave divider. It used the 4046 PLL to generate several octaves up and a couple down, all at the same time, as well as other things.

A single 4046 can only lock to one note from a guitar at a time. It is keyed to the zero crossings (i.e. signal edges) in the input.  The trick to getting good results from a PLL is in the input filtering to wipe off excessive zero crossings in the input signal and in how you add and filter the resulting logic signals.

[Granny Gremlin]

Connecting R9 to C6 should work. Tie pin 9 of U1.4 to + (pin 14 of U1) when you are not using the octave down part - you can let pin 8 be unconnected.

Hey, thanks a lot; never would have occurred to me about pin 9.

I'll check out that Article RG, thanks.

[Granny Gremlin]

FYI - 20% off everything in the Parasit store today (I grabbed the synth and Corruptor Ring Mod PCBs):

http://www.parasitstudio.se/store/c1/Featured_Products.html