[sdiy] ALFA clone chips?

Michael E Caloroso mec.forumreader at gmail.com
Sat Mar 27 21:15:20 CET 2021


Uncovered a bad CEM3310 in a vintage poly synth some years ago.  I
replaced it with an AS3310.  No difference.

MC

On 3/27/21, 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.
>
> 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
> <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.
>
>
>> 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 4:46 PM Benjamin Tremblay <btremblay at me.com>
>> wrote:
>>>
>>> I have not tried the VCO, but have had great results with the 3320 VCF
>>> and the 3360 VCA. It’s pretty much Pro One for the masses.
>>> The 3320 is easy to damage if you over-power the resonance control.
>>> The 3360 can be tamed once you work within the correct control voltage
>>> range.
>>> I’m an idiot. I don’t have a scope. But they sound great and I was able
>>> to get them stood up and move on to the rest of my project.
>>>
>>> I’m also using a number of AS2164 chips. I have never used other brands,
>>> but these work great for computer-controlled mixers of analog signals.
>>> I made no effort to squeeze any gain out of them using negative voltage
>>> bias on the control pins. They work fine for my application.
>>>
>>> I still have some 3330 VCA chips. They were very frustrating to use.
>>> They seem to require a low-impedance voltage divider that gets very noisy
>>> without careful placement of capacitors.
>>> Maybe if I go back and try to breadboard them after having learned the
>>> 3360 I could be more successful.
>>>
>>> On Mar 27, 2021, at 11:19 AM, cheater cheater <cheater00social at gmail.com>
>>> wrote:
>>>
>>> I was wondering if anyone had any experiences with ALFA clones of
>>> classic chips. Are they good? Is anything missing? Are they very crap?
>>> No difference at all? Any specific ones to watch out for?
>>>
>>> Thanks
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>>
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