Vintage Synth Repair

--- In vintagesynthrepair@yahoogroups.com, "ethanzer0 
<ethanzer0@y...>" <ethanzer0@y...> wrote:
> Hello,
> 
> Does anybody know if a LF411a is a 
> safe substitute for a LM301?
> 
> I have read an article that claims
> the LF411a can be subsituted for the
> LM301 in Arp 2600s.
> 
> TIA,
> 
> Ethan


These chips are very different: The 301 is a bipolar opamp
that needs external compensation (and which can be optimized
for speed, depending on the voltage gain in the circuit).
The 411 is a low offset BiFet amp (low offset for a cheap Fet
input, that is ...) with internal compensation.
Nothing could be farther from being a drop in replacement.
But of course there are a lot of circuits where you _could_
use both chips, especially if you remove the 301's external
copensation cap(s). OTOH, if you have any cap in your 301
circuit with a value other than 30 ... 33pF (or if you even
have two compensation caps for feedforward compensation),
don't think about replacing it with a 411.

Why would you even want to use a 411 instead of a 301?

If memory serves, the ARP has LM308's somewhere - now here
it might make more sense to replace them with LF411 ...

JH.