[sdiy] Arp 2600 replacement op amps

[James R. Coplin]

What I can say about the opamp upgrade in the 2600 is that it makes an
enormous improvement in the audio.  I had my 2600 completely gone over by
Phil Cirocco of CMS and this is one of the things he did.  However, I can't
tell you what he used because my 2600 is in storage because of an impending
move.

There are some other areas in the 2600 that need addressing as well though.
The power supply should be replaced and the filter needs to be fixed to
extend the frequency range.

James R. Coplin

> -----Original Message-----
> From: owner-synth-diy at dropmix.xs4all.nl [mailto:owner-synth-
> diy at dropmix.xs4all.nl] On Behalf Of James Patchell
> Sent: Sunday, October 01, 2006 7:56 AM
> To: James Dunn; synth diy
> Subject: Re: [sdiy] Arp 2600 replacement op amps
> 
> It depends on what the LM301 was used for...
> 
> If the LM301 is in a DC path (CV summers, etc.), I would leave it
> alone.  The DC performance of the LM301, while dated, was still pretty
> good.  You will have a hard time improving on that.
> 
> For audio paths... TL07x would be fine...
> 
> TO-5 to dip...yeah, there are converters out there...not cheap though.
> 
> My personal opinion...if there is no reason to change it...don't do it.
> 
> I would not consider, in general, a CA3140 as an improvement over an
> LM301... The main thing the CA3140 has going for it is the low bias
> current
> and speed...the LM301 has much better DC performance.  Using a CA3140 in a
> DC summer would degrade the instrument, rather than improve it.
> 
> At 01:07 PM 10/1/2006 +0100, James Dunn wrote:
> >Hi all,
> >
> >I want to replace the 301 op amps in my 2600 with better ones - I've
> >looked through the synth-diy / analogue heaven archives as well as the
> >music machines website and they seem to recommend LF411 or similar FET op
> >amp. I am also aware that I would need to disconnect the frequency
> >compensation caps. as modern op amps have this internally.
> >
> >My question is: where can I get some op amps that would be suitable BUT
> in
> >a metal can? There are some metal can CA3140's on ebay, but they're not
> so
> >cheap, and I will need lots!
> >Or, is there such a thing as DIL to TO-5 package socket converter?
> >Or do I have to have to insert loads of stripboard and wire DIL op amps
> in?
> >
> >Any advice gratefully appreciated.
> >
> >James
> >
> 
>          -Jim
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