Need a opamp suggestion to replace a NJM4558D

gaetan8888 · 4th August 2007, 10:14 PM

Hello

Any much better opamps suggestions for a drop-in replacement of a NJM4558D ?

That opamp output are following a PCM1710 dac, in a Denon DCM-260 CD player.

I include the schematic I have just get of that output.

Thank

Gaetan

gaetan8888 · 4th August 2007, 11:18 PM

Hello

The line between the output line goes to another part of the circuit. It's not shorting the output.

Gaetan

Cobra2 · 4th August 2007, 11:54 PM

NJM4558 is a dual opamp, nothing special, can be replaced with almost any other dual opamp...
You could also replace the caps C429/C430 with some better bipolar or film-caps.

Arne K

Ric Schultz · 5th August 2007, 12:29 AM

If the 4558 is a dip package I would use a AD827 and bias the output into class a with about 7ma with a fet and resistor or current source and resistor. I would remove all the other parts in the output stage except for the feedback resistors and output cap.....use nude damped blackgate for coupling cap (33uf 16V N) and vishay/dale one eighth watt RN55 resistors. You do not need any output filtering whatsoever with these simple TI DAC chips.....you will get very transparent sound this way. Also use separate regulated 5 v supply for left and right analog power supplies on the DAC chip....makes a difference sonically. I used to modify MSB DACs and they used the very similar PCM 1716.

gaetan8888 · 5th August 2007, 01:14 AM

Hello

I have some Texas NE5532 but it's old tech ic's. Maby the OPA2134 but it's a fet op amp and I'm not sure it would be a drop-in replacement for the NJM4558 ?

Gaetan

jaycee · 5th August 2007, 04:28 AM

If all you want is drop in replacements then ne5532 should be fine. It might be "old tech" but it's also a very good op amp.

Adding in much newer opamps like the AD827 into an existing design is, IMO, asking for trouble. These new opamps are very fast, and are likely to just oscillate without due care and attention.

If you can live without the mute function, pull the two Mute transistors TR400/401. This is known to improve sound quality in many cases.

gaetan8888 · 5th August 2007, 04:46 AM

Quote:

Originally posted by jaycee
If all you want is drop in replacements then ne5532 should be fine. It might be "old tech" but it's also a very good op amp.

Adding in much newer opamps like the AD827 into an existing design is, IMO, asking for trouble. These new opamps are very fast, and are likely to just oscillate without due care and attention.

If you can live without the mute function, pull the two Mute transistors TR400/401. This is known to improve sound quality in many cases.

Hello

About that mute fonction, is it an auto muting ? It seem that most cd player have that mute fonction, I don't see any mute buton on most cd player remote control.

Thank

Gaetan

jaycee · 5th August 2007, 04:52 AM

Yeah.. could be. You can try removing them, and if you notice strange and nasty noises when idle, you can always put them back

gaetan8888 · 5th August 2007, 04:55 AM

Hello

Ok, it cut noise between cd track reading.

Gaetan

sandyK · 5th August 2007, 05:00 AM

gaetan
OPA2134 may not be quite as good as the LM4562 etc. but should plug straight in withpot any stability problems. If the inputs to the IC are well balanced you may be able to get rid of the O/P capacitors, as the OPA2134 has a very low DC out.
The muting is auto. Any gain made by pulling them out will be very small,and may not be obvious in your system. However, if one goes leaky, a fault I have had twice over the years, channel balance may be affected.
SandyK

4th August 2007, 10:14 PM	#1
gaetan8888 diyAudio Member Join Date: Apr 2007	Need a opamp suggestion to replace a NJM4558D Hello Any much better opamps suggestions for a drop-in replacement of a NJM4558D ? That opamp output are following a PCM1710 dac, in a Denon DCM-260 CD player. I include the schematic I have just get of that output. Thank Gaetan

4th August 2007, 11:54 PM	#3
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	NJM4558 is a dual opamp, nothing special, can be replaced with almost any other dual opamp... You could also replace the caps C429/C430 with some better bipolar or film-caps. Arne K __________________ Ars longa, vita brevis

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5th August 2007, 12:29 AM	#4
Ric Schultz diyAudio Member Join Date: Mar 2002 Location: Boulder Creek, CA	If the 4558 is a dip package I would use a AD827 and bias the output into class a with about 7ma with a fet and resistor or current source and resistor. I would remove all the other parts in the output stage except for the feedback resistors and output cap.....use nude damped blackgate for coupling cap (33uf 16V N) and vishay/dale one eighth watt RN55 resistors. You do not need any output filtering whatsoever with these simple TI DAC chips.....you will get very transparent sound this way. Also use separate regulated 5 v supply for left and right analog power supplies on the DAC chip....makes a difference sonically. I used to modify MSB DACs and they used the very similar PCM 1716.

5th August 2007, 01:14 AM	#5
gaetan8888 diyAudio Member Join Date: Apr 2007	Hello I have some Texas NE5532 but it's old tech ic's. Maby the OPA2134 but it's a fet op amp and I'm not sure it would be a drop-in replacement for the NJM4558 ? Gaetan

5th August 2007, 04:28 AM	#6
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	If all you want is drop in replacements then ne5532 should be fine. It might be "old tech" but it's also a very good op amp. Adding in much newer opamps like the AD827 into an existing design is, IMO, asking for trouble. These new opamps are very fast, and are likely to just oscillate without due care and attention. If you can live without the mute function, pull the two Mute transistors TR400/401. This is known to improve sound quality in many cases.

5th August 2007, 04:52 AM	#8
jaycee diyAudio Member Join Date: Apr 2004 Location: Norwich, UK	Yeah.. could be. You can try removing them, and if you notice strange and nasty noises when idle, you can always put them back

5th August 2007, 04:55 AM	#9
gaetan8888 diyAudio Member Join Date: Apr 2007	Hello Ok, it cut noise between cd track reading. Gaetan

5th August 2007, 05:00 AM	#10
sandyK diyAudio Member Join Date: Apr 2007 Location: Sydney	gaetan OPA2134 may not be quite as good as the LM4562 etc. but should plug straight in withpot any stability problems. If the inputs to the IC are well balanced you may be able to get rid of the O/P capacitors, as the OPA2134 has a very low DC out. The muting is auto. Any gain made by pulling them out will be very small,and may not be obvious in your system. However, if one goes leaky, a fault I have had twice over the years, channel balance may be affected. SandyK

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