[sdiy] LM13700 Noise

[Tim Ressel]

Thanks for all the info, but I am concerned about broadband noise. I'm 
already using the lin diodes.

I am making a wave folder that has a ridiculous amount of gain on the 
back end, and the VCAs are making too much noise for my customer. I'm 
trying to minimize the noise through optimizing the LM13700 circuit if 
possible. The alternative is to switch to a linearized 2164 VCA, but I 
am trying to avoid the redesign.

I'd like to know if there is a 'sweet spot' on the 13700. Less input, 
more control current, or vice-versa. that kind of thing.

--timbo


On 7/6/2017 5:33 AM, Tom Wiltshire wrote:
> There's a great paper on minimising *distortion* in the LM13700:
>
> http://www.openmusiclabs.com/2015/10/my-summer-vacation-by-guest/trackback/index.html
>
> It covers noise in passing, but you might learn something useful.
>
> In short, I'd agree with Richie. Maximise the signal level, accept some distortion (just call it "warm analog character") and be sure to use a decent op-amp I-to-V convertor on the output not just a resistor to ground.
>
> HTH,
> Tom
>
> ==================
>         Electric Druid
> Synth & Stompbox DIY
> ==================
>
>
>
>
> On 6 Jul 2017, at 12:51, Tim Ressel <timr at circuitabbey.com> wrote:
>
>> Hi,
>>
>> Does anyone know how to minimize noise in an LM13700 design? I've been playing with the balance between input level, control current, and output I/V conversion gain trying to minimize noise but with limited success. The datasheet doesn't seem to cover this.
>>
>> Thanks!
>>
>> -- 
>> --Tim Ressel
>> Circuit Abbey
>> timr at circuitabbey.com
>>
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>

-- 
--Tim Ressel
Circuit Abbey
timr at circuitabbey.com