[sdiy] ALFA clone chips?

ColinMuirDorward colindorward at gmail.com
Sat Mar 27 21:37:30 CET 2021

 >>Is that just the AS3340 or the CEM3340 as well?

My understanding is that some but not all cem3340 suffered from the same
problem (some early versions?) Even for the as3340, I wondered if there are
varying degrees of the problem.

I chatted with a rep at Alfa Rpar a couple years ago and tried to convince
him to do a TZ 3340 version. He said something like "oh that looks easy
enough", but of course they did the 3396 and whatnot, instead. It would be
amazing if they solved the PWM/pitch issue and added linear TZ in one fell
swoop. Then we might have drop-in TZ upgrades to existing gear that uses
the linear FM input.

On Sat, Mar 27, 2021 at 7:34 PM cheater cheater <cheater00social at gmail.com>

> >> On 27 Mar 2021, at 18:19, cheater cheater <cheater00social at gmail.com>
> wrote:
> >>
> >> Thanks. was the original CEM3320 equally easy to damage? Did the other
> >> chips have similar problems in their original versions?
> >>
> On Sat, Mar 27, 2021 at 7:48 PM Tom Wiltshire <tom at electricdruid.net>
> wrote:
> >
> > Yes, the early CEMs were just the same, and the early SSMs were worse,
> since Dave Smith had to move the Prophet 5 from one chipset to the other to
> get it to stay in tune.
> >
> > The current CEM3340 is Rev.G. My understanding is that Rev.G was only a
> datasheet change and an acknowledgement that some of the claimed figures
> for Rev.F weren’t likely in practice, but that still means there were five
> versions fixing earlier problems. I think that’s worth bearing in mind when
> we compare chips from Coolaudio and Alfa with the originals. We’re
> comparing later versions with early versions in most cases. CEM took a
> decade to get the chips to the final state that we’re judging against.
> I thought what these companies did (CoolAudio aka Uli Behringer, ALFA,
> SSI) was take photos of the old chips and re-issue them based off
> that?
> > BTW, there’s a good application note now for the PWM problem:
> >
> > https://www.alfarzpp.lv/eng/sc/AS3340%20tip%20VCO%20_%20PWM%20.pdf
> >
> > I’m sure it’s not the only solution. I’d like to see something like this
> integrated onto the silicon and an AS3340 Rev.B get released. Fixing things
> is not a failure, but a success. No-one expects everything to be perfect
> first time. It’s what you do next that counts.
> (...which may or may not mean reissues are impossible)
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