[sdiy] ALFA clone chips?

[Tom Wiltshire]

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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