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NJM5532 vs NJM2068, Looking for opinions for replacing an NJM4558

Bratwurst7s

Bratwurst7s

In The Frying Pan
Subscriber
Background:
I have some Marantz MA500 mono amps that I am looking at modding a bit. They are made to be able to be bridged and have a signal inverting circuit that uses a NJM4558DD to do the work to output an inverted signal to the second amp in the pair. The rail voltages are +15v & -15.3v. There is a 10µF/16v stabilizing/local filter cap on each power rail.

The NJM4558 is not a beloved op-amp and I have a lot of NJM5532DD and NJM2068DD parts on hand, so I am considering replacing the 4558 with one of these op-amps. I plan on upping the local filter/stabilization caps to 47µF/35v with a 0.1µF/50v in parallel.

I am looking for opinions from members that have experience with both the 5532 and 2068 as to which they prefer and/or would use in this specific case that I am asking about.

Note that I am aware that there are newer op-amps out there that might be superior to my choices. These are the parts that I have on hand. I am not interested in starting a general op-amp debate. My subject and question is quite limited and defined.

Thanks in advance for any experienced and informed replies.

Cheers,
James
 
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The 5532DD is a reliable and very stable OPamp. It is not prone to instability like some are, especially when inserted into a circuit not specifically designed for it. Like you said, a lot of people knock them against 'better' OPamps that are available, but they are actually pretty good.
I quite like the OPA2143 as well. i have used these in my own preamp circuits and they are very stable and to my ears at least, seem to sound good. The OPA2142 appears to have better specs, but the OPA2143 was designed specifically for audio.
The other important point is to ensure that you have small PSU decoupling capacitors mounted as close to the OPamp supply pins as possible. i put them on the solder side of the PCB right on the socket pins.
 
Powertech said:
The 5532DD is a reliable and very stable OPamp. It is not prone to instability like some are, especially when inserted into a circuit not specifically designed for it. Like you said, a lot of people knock them against 'better' OPamps that are available, but they are actually pretty good.
I quite like the OPA2143 as well. i have used these in my own preamp circuits and they are very stable and to my ears at least, seem to sound good. The OPA2142 appears to have better specs, but the OPA2143 was designed specifically for audio.
The other important point is to ensure that you have small PSU decoupling capacitors mounted as close to the OPamp supply pins as possible. i put them on the solder side of the PCB right on the socket pins.
Click to expand...
I do the same concerning coupling caps. There are 10µF installed originally, 16v, which I replaced with Wima MKS2 10µF/50v but will probably be replaced again with Panasonic FM 47µF/35v along with a 0.1µF in parallel. This is what the Ti datasheet for the LME series recommends and it is what I usually use.

The 2068DD doesn't have quite the supply voltage rating as the 5532, +/-18v vs +/-22v, but they are also actually decent op-amps.

I have also used a lot of different OPA types and like them a lot, but as I said, in this case I am going with what I have on hand and these 2 are proven decent stable parts. I am just very curious as to experience that others have concerning choosing one of these two choices.

Cheers,
James
 
One thing that you should consider is that the 5532 is made with NPN transistors at the input but the 4558 and 2068 are made with PNP transistors at the input. If you have polar capacitors at the input and feedback in your circuit, the 2068 would be preferable.
 
ecluser said:
One thing that you should consider is that the 5532 is made with NPN transistors at the input but the 4558 and 2068 are made with PNP transistors at the input. If you have polar capacitors at the input and feedback in your circuit, the 2068 would be preferable.
Click to expand...
Thank you. This is exactly the type of info that I am looking for. The amps originally had 4.7µF elcos (polarized) in the input path but they have been replaced with film caps.

Cheers,
James
 
I usually run OPamps rated at +/-18V at +/-17 volts even though most commercial circuits run at +/-15V, presumably for safety and long term reliability. I have found that they perform better at that voltage as it gives them a little more headroom without any heating issues. The 5532 will run from about +/-6 v upwards anyway.
 
I like the NJM2068DD for phono preamps but this is a completely different use. You could try installing a socket and see if you can notice a difference.

Good idea what you're doing with decoupling. The 0.1uf should be installed as close to the chip as possible. I tack them on under the board right at the chip power pins. Use ceramic X7R or polypropylene film.

The NJM4580DD is another option as well.

Also change the signal path electrolytics to non-polar. Nichicon ES or Panasonic SU are good choices.
 
WizardWG4 said:
I like the NJM2068DD for phono preamps but this is a completely different use. You could try installing a socket and see if you can notice a difference.

Good idea what you're doing with decoupling. The 0.1uf should be installed as close to the chip as possible. I tack them on under the board right at the chip power pins. Use ceramic X7R or polypropylene film.

The NJM4580DD is another option as well.

Also change the signal path electrolytics to non-polar. Nichicon ES or Panasonic SU are good choices.
Click to expand...

The 0.1µF are TDK MLCC C0G (NPO) ceramic, 50v. I should have stated that earlier. They will go on trace side directly between each supply line pin and ground.
The 4.7µF/16v signal path coupling caps have been replaced with Panasonic ECQ polypropylene film caps. Rather large but I managed to make them fit.

I could, and may, install dip-8 sockets as WizardWG4 suggested, I have lots of them. But the board is installed facing the heat sink and I would still have to disassemble the amp to get at them to swap op-amps.

I do have some LME49860MAX/NOPB and dip-8 adapters for them, as well as a fair amount of different OPA types, but I would rather not go crazy and risk destabilizing the amp. The 5532 and 2068 have a higher slew rate than the 4558 but are known to be pretty stable, which is the main reason that have them in mind to use.

Cheers,
James
 
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ecluser said:
CS02 and CS03 must be non-polar
Click to expand...
CS02 and CS03 were polarized 4.7µF elcos in all 4 of my amps, and are shown so in the schematic, with a + pole on the input side. They have been replaced with bipolar film caps.

Cheers,
James
 
Blue Shadow said:
FIFY.

There are dozens of better sounding chips now.

The 5532 is ubiquitous in the music production industry in boards and such but for playback it can easily be bettered.

I yanked a pair out of a CDP-C705 Sony changer. Sounds very good now. Sounded bland before. I used the OPA2228.

Fortunately the circuit did not need any changes, which some chips might require.
Click to expand...
Please re-read my first post.

Cheers,
James
 
northpaw said:
The ECQ caps are mylar. It's the ECW that are polypropylene. I like both, my favorite coupling caps.
Click to expand...

After thinking about it I realized that I had a brain fart in the first place and actually I did not use ECQ caps at all, but rather ECW. In my MA500 thread I even linked to Mouser with the ECW part and still wrote ECQ. Sorry for the confusion.

Cheers,
James
 
I like both the 5532 and 2068, but my goto for low level audio (either phono or tone controls, etc) is the 2068. It is extremely low noise and sounds excellent. I use the 5532 as well, but usually in areas where I need higher drive voltage/current.

I have a 2068 in my NAD 1240 (single op-amp design) preamp and it sounds great. The LM833 is also a great choice similar to the 2068.
 
Bratwurst7s said:
I did not use ECQ caps at all, but rather ECW
Click to expand...
We are on different continents, or I'd say there was something in the air or water. I had the same confusion about ECW and ECQ a few years ago. I had ordered some ECW in 10's quantities and started using them, and when I needed more (I needed a bunch to replace all the out-of-spec 1µF/50V caps in my old Advent 300 receiver), I ordered ECQ, thinking they were the polypropylene ones I had ordered before. So now I have a selection of both, but would order ECW in the future as the price differential isn't much.

Thanks for mentioning your MA500 thread over in Marantz-land, or I would not have seen it; I look forward to reading through it. I was contemplating getting 3 MA500 a couple of years ago when they came up locally at an attractive price, but demurred when I saw the use of op amps in the schematic. At the time, I questioned such a design, but since then I have become somewhat disabused of that idea, based on my experience with a Kenwood Basic C2 preamp. This was a $5 thrift find. After reworking it, including replacing all the op amps in the line-level circuits with NJM2068DD, I couldn't be happier with the sound of that unit.
 
I have a Kenwood Basic C1 preamp (and another for spare parts) and after going thru it, it is my reference preamp. It has a NJM2068DD in "flat amp" location (first line-level stage) and then a NJM2114D in the "tone control" stage.

Although the C1 was designed as a basic preamp, it has a very neutral sound and adds absolutely nothing to the signal path. Signal to noise is >90dB at unity gain.

I swap out the NAD and Kenwood every few months.
 
THD+N said:
I like both the 5532 and 2068, but my goto for low level audio (either phono or tone controls, etc) is the 2068. It is extremely low noise and sounds excellent. I use the 5532 as well, but usually in areas where I need higher drive voltage/current.

I have a 2068 in my NAD 1240 (single op-amp design) preamp and it sounds great. The LM833 is also a great choice similar to the 2068.
Click to expand...

Thanks for the info. :thumbsup:
At this point I have decided to use the NJM2068DD to start with. Today I installed a socket and should be finished with the modding early next week. Then I will give it a test ride.

Cheers,
James
 
northpaw said:
We are on different continents, or I'd say there was something in the air or water. I had the same confusion about ECW and ECQ a few years ago. I had ordered some ECW in 10's quantities and started using them, and when I needed more (I needed a bunch to replace all the out-of-spec 1µF/50V caps in my old Advent 300 receiver), I ordered ECQ, thinking they were the polypropylene ones I had ordered before. So now I have a selection of both, but would order ECW in the future as the price differential isn't much.

Thanks for mentioning your MA500 thread over in Marantz-land, or I would not have seen it; I look forward to reading through it. I was contemplating getting 3 MA500 a couple of years ago when they came up locally at an attractive price, but demurred when I saw the use of op amps in the schematic. At the time, I questioned such a design, but since then I have become somewhat disabused of that idea, based on my experience with a Kenwood Basic C2 preamp. This was a $5 thrift find. After reworking it, including replacing all the op amps in the line-level circuits with NJM2068DD, I couldn't be happier with the sound of that unit.
Click to expand...

It probably isn't something in the water on my end, but it might be something in the beer. :biggrin:

The op-amp in the MA500 is only used in the signal inverting section used for bridging 2 amps. If you are using the amp as a single unit then the op-amp plays no role at all. My thinking is that any latency whatsoever in the inverting section is going to result in some smearing of the sound when bridging 2 amps. Since both the 2068 and 5532 are enormously faster than the 4558 I am hoping for a little cleaner overall sound. We shall see within a week at the most.

I am amazed at the sound quality of these little things as it is, I never expected them to sound as good as they do. Note that I am using 2 bridged pairs of them.

Cheers,
James
 
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