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-   -   Replacement for NE5532 (http://www.diyaudio.com/forums/solid-state/176509-replacement-ne5532.html)

bmoraru 2nd November 2010 05:39 PM

Replacement for NE5532
 
Would like to replace my Denon's DCD-1500AE opamps of the NE5532 type with something better, OPA2604 and AD823 are two candidates with identical pin layouts - which should i choose? i also need a SMD version (is it called SOIC?) for my PCB, are they available in such packaging?

any other suggestion?

greierasul 3rd November 2010 10:59 AM

NE5532 it is a very good opamp. The only drawback it's the input stage which is on bipolars. That input stage it is not properly for a volume potentiometer. If your opamp it is not in that place, after a potentiometer, then you leave it , dont change it. If you have NE5532 after the volume potentiometer, than exchange it with OPA2134

djk 3rd November 2010 11:12 AM

Try a pull-down load to the negative supply rail to force the NE5532 into class A, just a few mA will really make it sound better. Use a simple resistor, or a J-fet with the IDSS trimmed to 3mA~5mA.

The OPA2604 and AD823 are both good too, how good are you at soldering SMDs? The AD823 is a bit more neutral, the OPA2604 may be more hi-fi sounding.

DarpMalone 9th November 2010 07:06 PM

Quote:

Originally Posted by greierasul (Post 2352784)
If you have NE5532 after the volume potentiometer, than exchange it with OPA2134

I'm about to install a transformer into my amplifier to convert balanced from an unbalanced signal (in order to bridge chips)... This transformer uses NE5532 chip which will be fed directly by a passive volume pot.

Can you please explain how this negatively affects the NE5532? Is it due to loss of resolution?
Thanks

Tekko 9th November 2010 07:19 PM

This is the way to go for excellent sound: http://www.national.com/ds/LM/LM4562.pdf

Now compare to NE5532: http://www.experimentalistsanonymous...ets/NE5532.pdf

Which would you pick ?

DarpMalone 9th November 2010 08:13 PM

Well, the LM4562 numbers certainly look better... I'll admit though, I don't know what most of those #'s mean :)

Thanks for the suggestion. I'll try it out

Bonsai 10th November 2010 04:55 AM

"I'm about to install a transformer into my amplifier to convert balanced from an unbalanced signal (in order to bridge chips)... This transformer uses NE5532 chip which will be fed directly by a passive volume pot.

Can you please explain how this negatively affects the NE5532? Is it due to loss of resolution?"
__________________________________________________ ______________

It has nothing to do with resolution.

The input bias current on the NE5532 is nominally 200nA, 1uA worst case.

If you feed a volume pot directly into this, you will probably get noise ('scratching sound') as you adjust the volume - this is because there is DC appearing across the pot due to the 5532 bias current I mentioned above. The affect gets worse the higher the pot resistance, and is also worst with cheap pots.

This issue has nothing to do with resolution or anything like that.

If your potentiometer is capacitively coupled into the input of the 5532, you will not have this problem, and this is how most designs that use this op-amp deal with the issue.

If you want a DC coupled design, then ideally you want to use a JFET input op-amp, where the bias currents at room temperature are in the pA range. The new LM4562 also has very low input bias currents, and you can safely direct couple low value pots (10k or less) into its input stage. If you go on my website below and look at the X-Altra Mini Preamp, you can see an example.

If you are using a swithed type volume control, then you CAN direct couple into the NE5532 - no problem. You just need a high value bias resistor between ground and the input pin of the op-amp to provide a bias path between the switch break before make periods. The value should be 10 times the value of your pot - so for a 10k pot, use a 100k bias resistor.

That said, the NE5532 is now over 30 years old, but it still is a very fine op-amp for audio. Take a look at Samuel Groners site, or read up in Self's latest book to see just how far ahead of its time this device was (launched in 1978!). I remain a 5532 fan - some things are great, no matter how old.

sumaudioguy 10th November 2010 08:40 PM

This has been covered in a lot of threads. The 5532 sounds pretty bad but better than most of the opamps which are just plain terrible. Try an NJM2068. Straight drop in and sounding much better.

As a suggestion, you should have searched the forums to find these answers because of the many threads discussing this subject. Search first, ask second.

bmoraru 12th November 2010 04:22 PM

Bonsai, can i please send you the schematic so as to tell me whether i can replace the 5532 with 4562 without issues? thanks!

Bonsai 13th November 2010 01:33 AM

yes - just post it up here on the forum.


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