Op Amp Recommendations

[rhomanski]

I'm in the middle of refurbing an equalizer from the early eighties. It has a bunch of op-amps NJM4558 and M5218's. I can order a bunch of KA4558's from Mouser but was wondering if anyone knows of a different op-amp with better channel separation and less noise.

I would be looking for a drop in, in a dip 8 package. I don't really want to change the look of the unit internally. Thanks.

[Khron]

Re: Op Amp Recommendations

According to

http://nwavguy.blogspot.fi/2011/08/o...surements.html

you should be quite safe with NJM2068's or NE5532's

[budm]

Re: Op Amp Recommendations

I use 5532 for upgrading, they do draw more current, so make sure you do have good power supply and good bypass caps.

[PeteS in CA]

Re: Op Amp Recommendations

Is the 4558 an ancient dual GP op-amp?

[rhomanski]

Re: Op Amp Recommendations

Very nice article. I think I will use the 5532. The caps are 25v and 1000uF. It has a large transformer as well. Should be okay I would think.

Usually I work on equipment that is too old for integrated circuits. Equalizers are the exception. Most companies didn't make equalizers until the late 70's.

I was thinking of trying the Burr Brown after all the hype. I guess after reading that article, it would have been a waste of money.

I do like putting in good components. I used Nichicon KL and PW caps in it and Fairchild 1N4148TA diodes and Fairchild 2SA1815 and 2Sc1015 transistors. Should be good for many years to come when I finish.

When it was built they used 100v low noise capacitors for the op-amps. They have 50v available now so that's what I used.

Thanks guys.

[rhomanski]

Re: Op Amp Recommendations

Yes it is Pete. That's why I wanted to replace them. I knew there was better out there today.

[euromatlox]

Re: Op Amp Recommendations

I have upgraded several integrated (about 1988-93 period) amps using LM4562 (TI/National), it sounds perfect into my ears. Sometimes there are two op amps to be replaced, and in that case I have used LM4562 and TL072 (ST). For phono section I have used LM833 (ST), but if it oscillates (tested by listening) usually just left the original chip there (M5218 is also good there).

Same chips from different manufacturers might sound slightly different, that's why I mention the manufacturers there. Somewhere I have read that ST's TL072 sounds warmer than the TI chip.

I have also tried LME49860 (TI/National), but it has too much bass into my taste, however might have use in car audio. LM4562 sounds much more detailed including middle and treble sections too.

In my opinion NJM4558 and M5218 are just as good as TL072 or NE5532, but these are cheap chips to buy and try. If you want better sound try LM4562 or other more costly alternatives.

[rhomanski]

Re: Op Amp Recommendations

Well, I'm definitely going to put sockets in. That way I can try other chips if I get curious.

[Khron]

Re: Op Amp Recommendations

As per that article, the NJM2068's are 99% as good as the 5532's, but are dirt cheap AND draw less power

[PeteS in CA]

Re: Op Amp Recommendations

I remember working on equipment that used 4558s back in 1977. It's basically a uA741-class dual op-amp in terms of performance.

[rhomanski]

Re: Op Amp Recommendations

Well, this equalizer came out in 78 and lasted until 82 when the new style came out. I figured the op-amps had been improved since it was new.

[PeteS in CA]

Re: Op Amp Recommendations

I promise I didn't work on it. But, yeah, there are better op-amps out there. OTOH, some of the 70s vintage designs are good enough and cheap enough that their usage may extend beyond my lifetime.

[redwire]

Re: Op Amp Recommendations

The 4558 is an awful sounding op-amp, mostly because it's a 70's design with low speed and high cross-over distortion. I've changed out dozens of these and it's totally worth it.
It depends on your budget, there are many better op-amps but some can get expensive. I use the LM833, LM4562. Since these op-amps are much faster compared to the 4558, you might have to add small 22pF caps if it oscillates.

I would not recommend the Texas Instruments NE5532/NE5534 as they have little to do with the Philips/Signetics originals, that are legends. TI engineers told me "it meets the specs but is a different (new) process and design", after I phoned them when their parts did not work like the originals.

[PeteS in CA]

Re: Op Amp Recommendations

I would not recommend the Texas Instruments NE5532/NE5534 as they have little to do with the Philips/Signetics originals, that are legends. TI engineers told me "it meets the specs but is a different (new) process and design", after I phoned them when their parts did not work like the originals.

This is true for pretty much any version of a "classic" part, whether from the inventor of the part or a vendor of an equivalent part. A part created in the 70s or 80s was designed for and manufactured with processes that have evolved substantially or simply changed. Even the basic wafer size is much, much larger. So even the company that invented a classic part has adapted it to modern processes, and in many cases, fit the part onto a smaller die (a larger wafer means more parts from each wafer; smaller dice on that larger wafer means many, many more parts from each wafer!). Whether from the original inventor or another company's equivalent, the modern parts will all meet the published specs, but it's very easy for circuit designs to depend on unspecified behaviors or on parts being significantly better than spec. Thus a modern part may not work as well (or at all!) in a circuit designed a decade or more ago.

[redwire]

Re: Op Amp Recommendations

I vaguely recall the Signetics NE5534 had 26 masks, so of course TI moved it into their standard bipolar process. It's too bad TI cashes in on a legendary part, by choosing to keep it cheap $1 instead of keeping the craftwork.

Looking at the excellent OPA627 - this is a $28 single op-amp! Each die laser trimmed. The part sounds outstanding and is worth it for audiophiles. But $28.

Slightly OT here, but even the 555 timer is an example of the differences on fab (table at far bottom): 555 timer info; The Signetics and National Semi parts behave differently, who knew?

[tom66]

Re: Op Amp Recommendations

OPA1662/OPA1664 is a very good opamp for a very low price, if you're on a budget. Using 8 of them in a design right now with LME49600 as a headphone amp.

[rhomanski]

Re: Op Amp Recommendations

Well, it's up and running. I've played it about 3 hours now. The new capacitors are reforming fairly well. They never sound good for about 2 hours after a recap. I used the NE5532's as suggested. They are quieter than the 4558's it came with. Seems to have a little more clarity. I thought of using the OPA's until I saw the price. Since I need 13 of them the price would make it more expensive than my car. Perhaps in the ouput section later. There's only three of them in that.

I'm using it with my main system. I used blue green led's in the rest of them, so I thought I would throw one in here as well. Didn't work that well. Too dim. So I put in a bright green, luckily with the blue tint of the silk screen, it came out about as bright as the other units and the same tint. Sweet. The red led's in the sliders were dim and I thought it could be just a bad contact. After cleaning the silver plate on the leads and cleaning the sliders, no change. So I just ordered new led's from Mouser this morning.

I had a relay around with the same pinout and threw it in. Most units use that relay. I found out this one doesn't. It needs a 12 volt coil. So I ordered one this morning. The original is still working but, it's an electromechanical device that is thirty years old. I don't trust it.

Bottom line is it's making sweet music. I'll have it finished next week when the last parts come in. Thanks for the recommendations and the help.

[redwire]

Re: Op Amp Recommendations

Hey that sounds like it's working better
My 80's Marantz car EQ (SA-250) had LM358/LM324's and swapped them out for the BB parts and it sounds much cleaner. 80's gear just needs a few tweaks but still higher quality than today's stuff out of China.

[rhomanski]

Re: Op Amp Recommendations

You got that right.

[Khron]

Re: Op Amp Recommendations

They (really) don't make'em like they used to...