[sdiy] LM13600 gone? NE5517 or XR13600!

[Grant Richter]

The LM13600 seems to modulate the darlington stage along with Iabc, to
reduce darlington draw for low values of Iabc. This would extend the low end
range of the LM13600 for slow moving modulation signals like phase shifters.

But it causes control voltage feed through (popping) for fast moving signals
like envelopes in VCAs or VCFs.

For a phase shifter like the Moogerfooger, the LM13600 works best, for most
other circuits a LM13700 would be preferred.

A separate FET buffer eliminates the problem altogether.

> From: "Czech Martin" <Martin.Czech at Micronas.com>
> Date: Thu, 10 Apr 2003 16:12:59 +0200
> To: <synth-diy at dropmix.xs4all.nl>
> Subject: [sdiy] LM13600 gone? NE5517 or XR13600!
> 
> There has been a long thread about the LM13600 OTA and
> the differences to the LM13700. The basic ciircuit
> of this dual ota is the same, but the Darlington
> stage differs (biasing inluded in 13600, no biasing in
> 13700). All from my head.
> 
> Some people think that some filters need a 13600 to sound
> *good*, or to be a clone, whatever that means.
> Unfortunately National Semiconductor has discuntinued
> (what a nice typo!) the LM13600.
> 
> I have:
> 
> 1. been able to obtain 5 XR13600 (at least this is what
> I read from the laser print on the package) @ www.reichelt.de.
> I hope that it is the same circuit.
> Exar today has no hint on that circuit on their web site.
> 
> 2. learned, that the NE5517 is similar, if not equal, from
> the datasheet.
> 
> So there is some hope that some filters can still be built
> with a similar or identical circuit without emulating
> the ota with discrete or other components.
> 
> Still, there are similar japanese OTAs arround.
> 
> 
> Yes, you're rigth: I'm just hunting down rare components
> in order to be able to build something if I have more time
> in the future. Buy now, as long as you can get them,
> solder later.
> 
> 
> 
> m.c.
> 
> 
> 
> 
>