JRC 4558 Replacement

[Guitar Dude]

Hey,
I've been looking at a few projects and I've seen that they require a JRC 4558. As I've said a million times before, it's impossible to get odd parts in New Zealand and I wondered if there was a substitute. I've read that substituting other IC's will alter the sound, but to be honest, I don't really care, I just wanna make pedals that do their job 'cause I can't afford the real thing.

Tim

[Aharon]

Subs are among others:
                                 TL072,TL082,NM5532,TL062,LF353....and the list goes on.
They all share one thing,pinout.
Aharon

[Marcos - Munky]

You can use any dual opamp I think, just watch the pinout. You can use two single opamps like the 741, or half of a quad opamp.

[Guitar Dude]

Sweet as, I knew all this, honest...I was just checking :oops:...Are some replacements better than others? I mean, who decides whether a 4558 is better than a TL072?

Tim

[R.G.]

Are some replacements better than others? I mean, who decides whether a 4558 is better than a TL072?

YOU do, dude.

In this case your personal ears are the only ones that matter.

Every eight pin DIP dual opamp I've ever seen had the same pinout, so use a socket, and substitute parts until you like the sound.

[Mark Hammer]

First off, JRC = NJM.  Same company.  JRC = Japanese Radio Company.  The NJ is *New* Japanese something or other.

In truth, many things that list a 4558 (and often they do not name the manufacturer but just say 4558, since there are various alternate manufacturers of that basic chip) do not *require* a 4558.  Rather, the 4558 meets the minimum requirements for whatever needs to fill that slot, and has the appropriate pinout if there is a board layout.  A 4558 could conceivably be replaced with a TL072 or 62, an LM358, an OP275, a pair of NE5534's or CA3140's, or half of an LM4136 quad op-amp if you were building on perfboard.

Elektor magazine, for years, used to have a nomenclature in their published schematics of TUP, TUN, DUG, DUS for "transistor-universal-PNP", "transistor-universal-NPN", "diode-universal-germanium", and "diode-universal-silicon".  In that spirit, the 4558 ought to be listed as DUO for "dual-universal-opamp".

What makes an op-amp "better" can depend on many circumstantial factors.  For instance, is the entire circuit hanging just at the border of being battery-operable vs needing a power supply?  Well, then a lower power op-amp would be recommended.  Is there something about the role of that op-amp that requires it to be able to "swing from rail to rail" (i.e., outputs very close to both the negative and positive supply voltages)?  Then a different op-amp might be selected.  Does the circuit stand to generate a lot of noise unless the op-amp has a very high input impedance?  Then another would be preferred.  Does the circuit need you to be able to adjust (compensate) the gain-bandwidth product of a given op-amp so that it deliberately sluggish with respect to high end (e.g., the Rat)?  Then another one is prefered.

And so on and so on.  For a whole host of reasons, many of which have to do with how legends make things seem better, the JRC4558 has acquired a reputation, primarily via the TS-808 Tube Screamer, and primarily through Stevie Ray Vaughan's use of it.  It was not selected for duty in the TS-808, however, primarily because of tone, but because it was cheap, commonly available and met minimum criteria.  People came to *like* the tone produced by that musician with that pedal with his setup and style and guitar, but that is a far cry from the chip itself having any sort of special sonic qualities.

On my site, I have a fairly thorough (though admittedly not entire up to date or comprehensive) listing of op-amps and their specs-of-interest, scanned from the Hill and Horowitz book "The Art of Electronics".  Look for "Ops, I did it again" at http://hammer.ampage.org and you can see a bit about the range of op-amps out their and what compares with what else.

[WGTP]

Check out my post on op amp evaluation.  It has a list of duals that work.  I tried them all.

[Paul Marossy]

Some opamps use different circuitry, which may contribute to a certain sound - JFET, CMOS, Butler front end, etc.

There are some who claim that chips with a high bandwidth (~10mHz) sound really good. I suppose that is because in theory, they should produce a lot more of the higher harmonics, which are usually virtually absent in solid state devices. Most people would interpret that as "more warm sounding" or "more like a tube".