[sdiy] OTA replacement

[jbv]

thanks for your comments on this topic.
the replacement of the BA662 by the 3080 will actually
take place in Roland SVC-350 vocoder in which that
chip is used only in the compressor...

BTW I was wondering if the 4558 could be replaced by
a TL072, at least in the filter section...

JB

> The 3080 works fine as a replacement for the BA662. I have built 303 clones with both the BA662 and 3080. I have even made a small pcb which converts an SMD 3080 into a 9 pin SIL and is a drop in replacement for the BA662. The only issue is offset, but this can be trimmed out externally.
>
> I have tried this in my JX-3P and could tell no difference - it sounded rubbish before and rubbish after - (only kidding).
>
> ....the 3080 doesn't have the second buffer stage, but you can use a transistor or op-amp to do this.
>
> mark
>
> > -----Original Message-----
> > From: Byron G. Jacquot [SMTP:thescum at surfree.com]
> > Sent: Monday, March 29, 2004 7:52 AM
> > To:   synth-diy at dropmix.xs4all.nl
> > Subject:      Re: [sdiy] OTA replacement
> >
> > > I've just read on a couple of webpages that the
> > > obsolete BA662A (OTA) could be replaced by
> > > the CA3080.
> > > Could anyone confirm this ?
> >
> > I seem to recall people using 3080's in some TB303 clones, and they
> > seemed to work OK.  Not that I ever sat the curcuit  in question
> > alongside a real 303 for sonic comparison, but it wasn't
> > unacceptable.
> >
> > IIRC, The BA662 is in a SIP package, and also has an onboard output
> > buffer, something like a 13600.  The 3080 is usually in a DIP
> > package, and lacks the buffer.
> >
> > Byron Jacquot