I typically prefer tube amps, but I have a Music Man amp from about 1979 that sounds great. It has a solid state preamp section and tube power section. The preamp section uses LM 1458 op amps. Any thoughts on better replacements that offer a warm, clean, rich tube'ish sound?
Thanks
Thanks
Don't overvalue the op-amp. Probably you won't hear much difference. Guitar amplification adds loads of harmonic distortion and sound is still 'clean', so only thing I think you may look for is low noise.
regards
regards
There really is no point, but NE5532's are cheap and may be quieter. I would not go further than that.
-Chris
-Chris
Being far more familiar with tubes, I inferred from the various negative comments regarding LM1458 and the comments on this board comparing one op amp to another that op amps color the sound much as do tubes. i.e. lots of positive comments about OPA2604, OAP2134, NE5532, and JRC4558. But, based on this feedback, op amps are not a noteworthy factor in the color of the sound in a guitar amp preamp? One is as good as another is for this application?
Buckeye Sound said:
LM1458 is about the cheapest opamp sold, extra bargain as it's dual, so it's basically you get what you pay for. Things have moved on, even at the budget end. The NE5532 mentioned is usually a drop-in swap and, though double the price, still only about 50 pence/cents.
Fit sockets and try a few.
Hey Buckeye,
It's not the sound so much as the amount of noise you hear with no signal. I suggested the NE5532 as it does sound good and is quiet. The TL072 can be quiet depending on the circuit, but the output drive current is lower than the NE5532. Either one should be better in all respects over what you are using. I wouldn't use sockets, but that's your choice. If you do, get some nice Augates. Don't use cheap parts. They will cost the same or more than the op amps. Hmmmmm.
-Chris
It's not the sound so much as the amount of noise you hear with no signal. I suggested the NE5532 as it does sound good and is quiet. The TL072 can be quiet depending on the circuit, but the output drive current is lower than the NE5532. Either one should be better in all respects over what you are using. I wouldn't use sockets, but that's your choice. If you do, get some nice Augates. Don't use cheap parts. They will cost the same or more than the op amps. Hmmmmm.
-Chris
Howdy,
THe 4558 is close to the 1458 you are replacing. Buy name brand only. If the printing is bad and / or it's a brand that is not well know I would not touch it. Basically, if they are being sold cheap compared to the market in your area, they are most likely remarks, pulls or rejects.
-Chris
THe 4558 is close to the 1458 you are replacing. Buy name brand only. If the printing is bad and / or it's a brand that is not well know I would not touch it. Basically, if they are being sold cheap compared to the market in your area, they are most likely remarks, pulls or rejects.
-Chris
Or order any of them from MOuser. They are all cheap in cost.
The 5532 is a low noise op amp, bt it will use about twice the current as the 4558. This is not likely a problem in this guitar amp, but in a mixer with a hundred chips it would be an issue.
I agree with the others that "upgrading" the op amps might lower noise more than offer tonal improvements.
The 5532 is a low noise op amp, bt it will use about twice the current as the 4558. This is not likely a problem in this guitar amp, but in a mixer with a hundred chips it would be an issue.
I agree with the others that "upgrading" the op amps might lower noise more than offer tonal improvements.
Thanks
I ordered these from Mouser and should get them Friday. The TL072 & NE5532 are TI and the 4558 is New JRC.
Locally, there are two suppliers that primarily sell NTE stuff, which tends to be pricy compared to the Mouser prices.
I ordered these from Mouser and should get them Friday. The TL072 & NE5532 are TI and the 4558 is New JRC.
Locally, there are two suppliers that primarily sell NTE stuff, which tends to be pricy compared to the Mouser prices.
Here's what I've found. I tried four different op amps in lieu of the LM1458. I tried a JRC4558, NE5532, TL072, & OPA2228. All were new parts. I have a Music Man 112 RP 65 with 7 ops amps. The phaser uses 3, pretty much. All of the op amps were functional in the amp, except in the phase inverter position, IC-7 on my amp. The newer faster chips created funky bad sounds in IC-7. Here's how they did otherwise.
OPA2228: worked fine, did sound a hair thin, but not real noticable.
NE5532: I had high hopes for this chip, but it overdrove the preamp -- clean sound was not possible. Not a bad overdriven sound however. Might be a good chip for the OD in an RP amp?
JRC4558: Maybe a bit punchier -- nominal difference from the LM1458
TL072: Maybe a bit thin -- nominal difference from the LM1458
Lesson I learned: LM1458 op amps are the cheapest around, they work find in my amp -- put them in and forget them.
OPA2228: worked fine, did sound a hair thin, but not real noticable.
NE5532: I had high hopes for this chip, but it overdrove the preamp -- clean sound was not possible. Not a bad overdriven sound however. Might be a good chip for the OD in an RP amp?
JRC4558: Maybe a bit punchier -- nominal difference from the LM1458
TL072: Maybe a bit thin -- nominal difference from the LM1458
Lesson I learned: LM1458 op amps are the cheapest around, they work find in my amp -- put them in and forget them.
Hi Buckeye,
Sounds like the NE5532 was oscillating. The gain will be no different as the circuit determines that. Should have sounded very similar to the others. What you should have been looking at was the noise floor.
Anyway, I agree. Leave the originals in.
-Chris
Sounds like the NE5532 was oscillating. The gain will be no different as the circuit determines that. Should have sounded very similar to the others. What you should have been looking at was the noise floor.
Anyway, I agree. Leave the originals in.
-Chris
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