[sdiy] Best AVAILABLE OTA for building new designs?

[Tom Wiltshire]

I'd say the situation is a *lot* better than it was in 2017. There are three manufacturers of synth chips, beyond TI still banging out the LM13700 (but only in SMD these days - DIP version is no longer available).

Alfa Rpar:
They're making a load of clones of many of the old CEM designs, including the 3310, 3320, 3330, 3340, 3350, 3360, 3372(with additions) and others. They also make the quad 13700 clone you noticed, which is four of the 13700 OTA without the darlington buffer, and also a 3280 OTA clone. There's also an excellent 3080 clone, but it's a bit expensive and probably not cost-effective for using large numbers. And then there's the 2164 too.
They've also done some new designs which push the envelope a bit, like the AS3363 which is a whole bunch of interconnected VCAs - some kind of crazy programmable mod matrix on a chip? Or a multi-4-quad-multiplier? It's an interesting chip, but I just can't work out exactly *what* to do with it!
There's also some old-school matched-pairs if you want to go back to basics.

Coolaudio:
Coolaudio also make clones of some of the CEM stuff, the 3320 and the 3340, plus the 13700 and 2164.

Sound Semiconductor:
They've started making new versions of various SSM chips (2040 and 2044 notably) but also producing new and improved designs that go beyond, including an amazing oscillator chip.

In short, there's an absolute ton of stuff out there these days. Most cost effective is probably the 2164 quad VCA, and the 13700 dual OTA.

HTH,
Tom

==================
       Electric Druid
Synth & Stompbox DIY
==================



> On 8 Aug 2024, at 19:08, Dan Snazelle via Synth-diy <synth-diy at synth-diy.org> wrote:
> 
> imagine someone asked you to make some new synth modules.
> then imagine that the last time you did so in any quantity above one---  it was 2017. 
> 
> 
> I am trying to get a handle on what the parts landscape is like now for cost-effective CV control. Back in 2017 the lm13700 was really the only available OTA . I was just starting to work with the ssm2164 at the time but never used it extensively.
> 
> In the interim I have built synth circuits but only in quantities of one where cost was no object and I was able to rely on my own extensive parts supply. 
> 
> 
> So my question is this-- if I am thinking about design for manufacturing—what do you think the best option is? 
> 
> Has anyone tried the quad ALFA OTA? Is it even readily available? Same for the new SSM2040​.  
> 
> OR would you just use the 2164 instead? 
> OR would you just try to make discrete OTAS out of say the  BCM856DS //BCM847BS
> 
> thanks for any and all opinions on this. 
> 
> 
> 
> 
> 
> 
> 
> 
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