[sdiy] EH frequency analyzer

[harrybissell at wowway.com]

Just to repeat for those who might have missed classic threads...

The LM13600 has a buffer amp whose impedance is fixed at an
'average- good for most applications" level.

The LM13700 has a buffer whose impedance is changed with the Gm
bias. This means the 13700 will perform better in wide range applications,
especially at really low Gm biases...

BUT - the bias connection to the buffer might give more control 'breakthrough'
(think less CV voltage rejection) and could thump in some cases.

In practice, they are usually interchangable.

If you want to dig in, look carefully at the spice model listings for each and
note the differences in the output transistor parameters. This are the only
clues I have found to what is really going on.

H^) harry


On Fri, 8 Aug 2008 15:00:04 +0100, Tom Wiltshire wrote
> On 8 Aug 2008, at 14:40, John Mahoney wrote:
> >
> > The Moogerfooger ring mod looks to be based on the LM13600. (Hey,  
> > isn't the 13600 all but extinct? I wonder what Moog is using now in  
> > these pedals. Maybe they've got a stockpile.)
> 
> National Seminconductor still have the LM13700 listed. I never  
> understood exactly what the difference was supposed to be between  
> LM13600/LM13700 ( was 13700 a later upgrade?) but they seem to be  
> pretty much interchangeable.
> 
> T.
> 
> (http://www.national.com/mpf/LM/LM13700.html)
> 
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Harry Bissell & Nora Abdullah 4eva