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Vintage threads from the first ten years

TS opamp selection

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3/1/2000 6:48 PM

TS opamp selection

I have been messing with chips in my TS9 lately and guys still say the JRC 4558D is the holy grail chip for the Tube Screamers.....Give me some more scoop on this if you could...I have a bunch of different 4558 chips that I have been taste testing through my TS9 to 808 modded pedal.Some of these chips will be Mouser's NJM 4558 D new chips which I hear are supposed to be as good as the original JRC 4558 D's? Sorry to be so anal about this,but I have noticed an actual tonal difference between different op amps and actually the older they are,the noisier they seem to be as far as "hiss" is concerned.....Anyway,I'd love to hear from others on this....Everyone and his or her's brother owns a Tube Screamer! LOL John S....

3/1/2000 11:56 PM
John Greene	The second 'D' means the part has been screened to have a lower MAX noise spec. I wrote down exactly what the spec was for a 'DD' but seemed to have misplaced it. Anyway, any JRC4558 that has a letter after the 'D' has been screened for a particular performance spec. --johng

3/2/2000 12:18 AM
blue	The ones from Mouser are the ones made by the new Japan Radio Company. They are said to be as good as the originals, but they are different in a noticeable way. Do not use these. Try to find an RC4558. I found four in an old Peavey solid state amp. These should be closer to the JRC4558's.

3/2/2000 12:28 AM
John Greene	um, the originals were made by the New Japan Radio Company as well. I have A/B'd 'new' with 'old' and noticed no difference whatsoever. --johng

3/2/2000 1:40 AM

Re: TS opamp selection...Give us more tonal differences John

John.....Could you tell us what it was about the new Mouser 4558's that you didn't like compared to the JRC 4558 D's?
Also....I have been told by a few different sources that Mouser's NJM 4558 D chips are the "real" deal...I am waiting for some to arrive so I can check them out..Right now I have a JRC 4558 DD in my reissue TS9 that sounds good,but I think it is a bit noisier than another good sounding IC (The TI RC 4558) I am still messing around with different chips,but the mod to 808 seems to make the most tonal differences that I've heard.....MHO...John S.

3/2/2000 1:50 AM

quote:
"John.....Could you tell us what it was about the new Mouser 4558's that you didn't like compared to the JRC 4558 D's?"

I didn't say I didn't like the new 4558's. I said I couldn't tell the difference between them.

If anything, the older 4558's with the single 'D' stand more of a chance at being noisier because of the higher MAX noise specification.

--johng

3/2/2000 1:41 AM

That's right, no noticeable differences

John's right, at least to an A-B comparison to my ears and other guitarists that didn't know which they were listening to - they couldn't tell.

I'll give my standard advice - don't get too hung up on getting the perfectly exact "vintage" opamp. Put in a socket and experiment. There's some really good sound in there for TLC2272's, LM833's, and others. The real key - if you read my article on the Technology of the Tube Screamers at http://www.geofex.com is how the opamp responds to overload conditions.

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