Discussion about the Korg PolySix synthesizer

Hi all,

I wondered about the quality of the little VCAs in the P6. So I changed
one of the voices to a VCA based around the BA662 Roland OTA. The BA
part is similar in operation to the well known 3080, but its an inline
package and easier to put onto strip board designs.

The sound from the new circuit was better, although this is very
subjective. The CV breakthrough click with fast attacks and decays is
only slightly reduced but it somehow sounds cleaner. Hard to describe. I
think the VCA law is different too, the BA662's are configured to be
linear. They clip softer too. Its also increased the overall signal
level on the voice board, which should help increase overall S/N. I
haven't added trimming to the BA662, since they seem to be very well
spec'd for offset. This may be the reason for their inclusion in Roland
gear over the 3080. However, I did try trimming one of them and it does
make a small difference. Not worth doing though.

So I built a little board and replaced all six of the VCAs. The result
is excellent, but hard to describe. Overall, its smoother but still
sounds like the Polysix.

I thought it rather amusing using the BA662 instead of BA6110s or even
the 13700. Hey, I've got a 'Rolorg'...


Regards,

Tony Allgood  Penrith, Cumbria, England

Oakley Modular Synth and TB3030:
www.techrepairs.freeserve.co.uk/projects.htm
My music: www.mp3.com/taklamakan