[sdiy] LAG circuit de-tuning VCO question

[Dave Kendall]

Thanks Tony.

I'll stick with the TL072 in this circuit then, as it's working with no 
noticeable (to my ears) droop.

Is the LT1013 a good choice for CV summing, or should I look at the 
AD711 instead?
Many circuits simply specify a TLxx, and so far I've had no problems, 
but I wonder if it would be worth going the extra mile for a CV summer 
to handle VCO control CVs....

cheers,
Dave

On Nov 6, 2011, at 09:33, Oakley Sound wrote:

> Don't use the LT1013 for this. It's an excellent op-amp but it's a 
> bipolar input device and will have measurable input bias currents.
>
> Driving a LT1013 voltage follower with a variable source impedance of 
> up to 1M will introduce voltage errors at the output. And those errors 
> will significantly change as you alter pot's value.
>
> Use a high quality FET input op-amp instead, AD711 etc.
>
> I haven't done the maths but I bet even a TL071 would be better than a 
> LT1013 in this case.
>
> Tony
>
> www.oakleysound.com
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