Can you suggest a drop in replacement for a socketed 4558 IC

[Snarl 12/8]

Hey,

I've been told that my mixer might sound better if I swap out the 4558 IC's in it. I'd like to try this on a channel or two and see what happens. Can anyone suggest an IC that would pop into those sockets with a minimum of fuss? Something with similar power draw and identical pin configuration so I don't have to change anything else in the circuit?

Thanks,

[winky dinglehoffer]

You could try MC33078. It's not super high slew rate or anything, but it's better than the 4558, similar current draw, & in my unscientific opinion is a step up soundwise.

[Nate Dort]

You could try MC33078. It's not super high slew rate or anything, but it's better than the 4558, similar current draw, & in my unscientific opinion is a step up soundwise.

+1
I use them in a lot of situations where a 4558 is called for in the audio path.

[bipedal]

I noticed this thread because 4558's are common in a lot of overdrive pedals, like Tube Screamers. 8 pin dual op-amp, pretty standard config.

Take a look at this, and scroll down a little more than halfway to find the section The Opamp -- gives a short-list of different "drop-in" substitutes for 4558s that seem to work well in that circuit, and may work well in your application too.

I've read that 4559s can be good, and NE5532s are also supposed to have very low noise...

[Nate Dort]

5532s draw about twice as much current as a 4558 will.

[rwc]

the NE stands for not excellent, and the NG stands for no good.

IMO, the 5532 is awful.

[Nate Dort]

the NE stands for not excellent, and the NG stands for no good.

IMO, the 5532 is awful.

for every application?

[Snarl 12/8]

I ordered a few NE5532's to try out. They haven't gotten here yet, and I started getting cold feet about them with my further googling. In a mixer that has about 100 4558's, I could try a few 5532's on one channel without blowing anything up, right? I'll order some MC33078 and give those a whirl too. Thanks for the suggestions.

ck

[Snarl 12/8]

Hey,

So I replaced each of the 4558's in the mic pre stages of the mixer. I'm assuming that IC1A and IC1B on the schematic are combined into one 4558 chip and that that's the chip involved in the mic pre. I think the mixer is quieter now. I can crank all the channels gain and main faders up about 3/4 of the way and the hiss is less than before. Maybe I'm fooling myself but the mic pres sound a little crisper too.

But I'm realizing that I think it's actually a pair of transistors that's doing the heavy lifting in the mic pre. I've got some questions before I swap those out, since they're not socketed. One channel's hiss actually still has some character to it. It changes a bit over time and has a deeper tone. It almost has the most minute pops and crackles buried in the hiss. I'm thinking if I can get rid of this my pres will sound a lot better.

A) are transistors likely to be a source of noise in my mixer?
B) Can transistors "go bad" over time?
C) Can IC's "go bad" over time?
D) Should I replace those transistors?
E) Is there something better than a 2N4125 that I should use instead?
F) If you were going to replace more IC's throughout the mixer, which would you swap out.
G) Assuming you only used the sends as direct outs on this thing and didn't use the eq, or mains or anything, would you need to swap out anything else to get it quieter?

I'm basically looking to make the mic pres as "usable" as possible on this thing. I think I'm after clean and punchy with as little color as possible.

If you were going to do one more "mod" on this thing to make the pres better what would it be? The transistors, or something else?

Was that too many questions?

Thanks,

[rwc]

the NE stands for not excellent, and the NG stands for no good.

IMO, the 5532 is awful.

for every application?

No, just the ones that pass hi-fi audio.

Everything has its application. One can find a sizzling 4558 in many distortion pedals, but I don't want it in my DAC. One can find a slow/smearing/filtery sounding 5532 in many 80s consoles that did were known for doing edgy sounding rock & pop albums that might benefit from its qualities. stuff has its application.

but, if you want the audio to really come through, get rid of the 5532

it rhymes.

Those have terrible PSNR compared to any modern ICs I see too, on the spec sheet and in practice.