[sdiy] Prophet 10 op-amp swaps?

[Eric Frampton]

I just swapped the LM458 out for a TL074 as Paul suggested (pinouts duly checked!) and recorded a little 20-second snippet.

If you have Pro Tools 9 or 10 (or want to line up 4 different stereo audio files manually), I've ZIPped and uploaded the session so you can hear for yourself. I -think- I can make out a difference between the 458 and the 074, particularly in the clarity of internal voices in the strings.

On all 4 stereo tracks, the left channel is the old LF356's, right channel is the new LME49710 (half an LM4562).

http://www.ericframpton.com/Prophet_10_test_1.zip

e

On Jul 18, 2013, at 3:03 PM, Paul Schreiber <synth1 at airmail.net> wrote:

> I'm the idiot, forgetting back then all op amps were singles!
> 
> The other suspect is the LM348 quad op amps. TL074 there (CHECK THE PINOUTS)
> should be an improvement.
> 
> Paul S.
> 
> 
> -----Original Message-----
> From: synth-diy-bounces at dropmix.xs4all.nl
> [mailto:synth-diy-bounces at dropmix.xs4all.nl] On Behalf Of Eric Frampton
> Sent: Thursday, July 18, 2013 11:56 AM
> To: Oakley Sound
> Cc: Synth DIY
> Subject: Re: [sdiy] Prophet 10 op-amp swaps?
> 
> On Jul 10, 2013, at 5:06 AM, Oakley Sound <oakleylist at btinternet.com> wrote:
> 
>> It's been a while, but I replaced all the EQ op-amps with OPA134s on my
> old P10. I also did some other things too but I'm not sure of the details
> now.
> 
> The LM4562 that Paul S. recommended is actually a dual op-amp (silly me!),
> so I've got some of the single version, the LME49710, on order.
> 
> I swapped out the LF356 in the EQ section on the Upper board, and left Lower
> alone for comparison. Just dropping a TL071 in that spot (until the 49710's
> arrive) made a huge difference. Can't wait to see what swapping all the rest
> of 'em out - and with the better part - could do.
> 
>> I'm assuming those six 560K resistors on the outputs of the balanced
> output drivers on the schematic are actually 560R. If they are really 560K,
> I'd get them swapped out straight away.
> 
> Good catch. The schemo is labeled wrong, and they really are 560R as
> installed.
> 
> e