AW: Favorite designs

[Haible Juergen]

Very well done.
A few comments / questions, nevertheless:

> ----------
1) 	For VCOs, really can't beat a CEM3340. Extremely well behaved, 
excellent tempreature tracking.

Roland used to select 3340: Better ones for the Monosynths (without 
autotune), the rest for the Polysynths
(with autotune). Are the new ones all "good ones" ?
My OB-8 stays in tune quite well - but not as good as a SEM-VCO clone 
of mine with discrete CA3046
plus tempco resistor, and not as well as my synths with heated chips 
(SSM 2030 was rock stable !!)

Ø	Heating up the transistor (like the uA726 does) is not really 
solving the problem.

Why not ?? Every synth I owned or built with temperature regulated 
chips was very, very stable:
SH-7 (ua726 + some really nasty design tricks), a heated CA3046 DIY 
project, the  Mono/Poly
(SSM2030), and my Minimoog-Clone (which has 2030 as well).
There *is* one drawback for sure: You need lots of power to heat the 
chips up. So It's not the right
choice for large Polysynths, at least.

Ø	4) For VCAs, really can't beat a CEM3381/3382. The OTA approach 
(CA3080/LM13000) are just > too noisy. Cheap, but noisy. Why build a 
whole modular and run it out of a 45dB SNR part??? > The CEMs have 
100dB SNR! At least use MAT-04 matched transistors for the front end.

I think the 3080 is more like 65dB than 45 ... but your point is still 
true. 338x work very quiet and
reliable in my Alesis Micro Gates and Limiters.


For a really good design, the 3 terminal stuff is NO GOOD. Perhaps I 
can address this later.

They are noisy as hell, and to make it worse they tend to latch up. 
 Good old 723 and RC4195 are my parts of choice.

Please, no "your the CEM chip guy" flames. Yes, I am.

You are - and you don't get flames, but our full appreciation for your 
efforts to make them
available again !!

JH.


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