Title link takes you to some scans of the KORG Poly61. Interestingly, the Poly61 had a discrete filter. I always assumed it was either an SSM or CEM filter, but I never had reason to look it up.via Florian on AH.
Update: be sure to check out the comments for more info on the filter.
found this in the same site
ReplyDeletehttp://www.dompselaar.org/Korg/P6_overlay.jpg
curious?
um...
ReplyDeletenot a discrete filter, actually an OTA chip filter. pretty standard design.
what's it ca30xx?
ReplyDeleteca30xx refers to a family of integrated circuits. The key part for synthesizer development was the ca3080, an operational transconducatance amplifier, also known by acronym: OTA.
ReplyDeleteIf you're interested browse this app note from Intersil: www.intersil.com/data/an/an6668.pdf
These devices were widely used to build VCAs, VCFs, triangle to sine converters, balanced modulators, etc. In layman terms (but technically incorrect), they allow you to easily make voltage controlled resistors.
After the transistor and opamp, this is one of the most important parts in the history of analog synthesizers.
Other similar parts include the CA3280, LM13600, LM13700.
A minimoog has a discrete filter.
ReplyDeleteThis Korg does not.
Discrete [unfortunately] can mean not monolithic chip based, which is true in this case [no SSM or CEM, or even Korg chip].
ReplyDeleteThe PS-6 does have discrete VCOs, and it probably has Korg's proprietary discrete-but-cheap-and-crappy VCAs.
ReplyDeletePoly-61 uses JRC13600 OTA and SSM for VCA. Sounds fine IMO.
ReplyDelete