Opamp change Now some Disappointments - diyAudio
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Old 18th August 2010, 12:20 PM   #1
ChPuls is offline ChPuls  Germany
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Default Opamp change Now some Disappointments

Hello,

my first post here.
I have changed the Opamps in my CD-Player. The Original-ones were the JRC4565. The sound was ok. They account for the filter and followed by a discret ampflifier current stage.
I tried the BurrBrown OPA2134 and the National Semiconductor LME49720 but was dissapointed by big trade offs. Conclusion: I don't understand why people like opamp swapping!!!!!!!!!!!!!!!!!!

My results compared to each other:
  • JRC4565 - deep bass a little bit bloomy, soundstage wide and deep with nice and longest decay, sometimes at high pitched loud synthesizer or full loud passages distant feeling of distortion and a little bit nervous, but nevertheless most musical and foot tapping yes!
  • OPA2134 - loudness curve, kicking bass but often no real depth and too fast unnatural cut away yes!, the worst soundstage or imaging, the decay is lost! Everything sounds swapped and cleaned, no distortion, but it sounds filtered to sound rounded, even the sometimes silvery highs don't disturb. But the last musical feeling and foot tapping is missing.
  • LME49720 - neutral, people say that it has a good soundstage, the soundstage is indeed deep but only distant, there is no offset in depth no different levels of soundstage depth. And it sounds as if you have but your loudspeaker on a stage with some distant.

I guess the studio mixers have simple JRC4565 or NE5532 in it. And all the effect are best and most musical only with them, because the music was heard and mixed with them in the studio.

Ok, as a conclusion the JRC4565 should be put again in the Player.
But:
Would be there an improvement if i would try the cheap JRC/NJM 2068?
It has better distortion and slew rate than JRC4565! It is said to be an improvement over the NE5532!! But
Will be there the nice decay of the JRC4565 there?
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Old 18th August 2010, 01:45 PM   #2
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Quote:
Originally Posted by ChPuls View Post
I don't understand why people like opamp swapping!!!!!!!!!!!!!!!!!!
Because it is easiest way to get the result, no matter good or bad. Pick the one you like.
The opamp swapping did improve sound on most of the unit that I tested not all.

Last edited by fastvideo; 18th August 2010 at 01:47 PM.
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Old 19th August 2010, 12:58 AM   #3
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There is no spoon! It's just in your mind!
No way an OpAmp can influence the "decay" or act like a "loudness curve". It is physically impossible.
I don't care what you THINK you heard, that is not what happens in real world.
An OpAmp can influence noise, distortion, high-end of the spectrum. Very seldom, in bad designs, a jfet-input OpAmp will have more bass than a regular OpAmp. In decent devices that is not happening.
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Old 19th August 2010, 01:36 AM   #4
sandyK is offline sandyK  Australia
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Later opamps such as the LM4562 and LME49720 or LME49710 are far less forgiving of poor power supply implementation and poor track layout and supply line bypassing.
Get that right and they will outshine the earlier opamps.
The OPA134 and OPA2134 etc. aren't quite as fussy, but will still benefit from the same areas being correctly implemented.
SandyK
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Old 19th August 2010, 03:47 AM   #5
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I am not sure why you tried the OPA2134.
I got one of those to go along with my CMOY headphone amp.
It's not too great.

Surely there are better opamps to try.

Notes on Audio Op-Amps

I don't know what your voltages are like, but that should give you something to look at.

Last edited by nullstring; 19th August 2010 at 03:51 AM.
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Old 19th August 2010, 11:38 AM   #6
Mooly is offline Mooly  United Kingdom
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The JRC/NJM4565 is pretty unique in being rated to deliver 20 volts pk/pk into 400 ohms although I doubt that aspect of it's performance is called for here. In other respects it's very average.

What is the CD player these are fitted too ?
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Old 19th August 2010, 01:25 PM   #7
ChPuls is offline ChPuls  Germany
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It is the small Kenwood DP-1001. It has the Philips TDA1547 (or DAC7) as the DAC. It is from 1994 and was then a good CD-Player. The opamps have even as default a good power supply! And they are followed by an unloading discret current stage.
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Old 19th August 2010, 02:16 PM   #8
ChPuls is offline ChPuls  Germany
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With good power supply i mean not only big elkos and transformer but there are small caps at the opamps even as a default!!!!! Even at 1994 Kenwood still built some good Hifi-ware.

The Kenwood DP-1001 was part of the small but good Kenwood HD 1000 (or 1001) Serie. It is still famous in Japan.


@ SoNic_real_one
Quote:
There is no spoon! It's just in your mind!
No way an OpAmp can influence the "decay" or act like a "loudness curve". It is physically impossible.
YES, you are absolutley right! Even the "cheap" opamps like the NJM4565 have sufficent quality characteristics.

I had this discussion already at the diy-loudspeaker-forum of Visaton - Lautsprecher und Zubehör, Loudspeakers and Accessories "Diskussionsforum".
There is an electric-engineer I respect and he told me the same as you.
But i counter a little bit and say the datas given in the sheets are very statically measured.
I asked, Could it be that when a dynamic and frequence-full signal like music it behaves a little bit different?
The electric-engineer said it could at last the transient-distortion that you can hardly measure!!!!

At next I want only test the also cheap NJM2068 for some lower distortion. (for me that was the only weakness of the original NJM4565 at loud passages)
Otherwise the Original NJM4565 is put in again.
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Old 19th August 2010, 02:44 PM   #9
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Did you give the new opamps a reasonable chance to break in?
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Old 19th August 2010, 06:08 PM   #10
ChPuls is offline ChPuls  Germany
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Yes, i have had the OPA2134 now for 6 month in the CD-Player? I was aware of changing after 1-2 month but now there is no further improvement.
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