I have had my current DVD player for about 5 years now. I’m quite happy with the CD sound, but I wanted to try out whether it would improve the sound by changing the op-amps in the stereo output stage to something better.

 

 

The player is using a PCM1796 DAC per channel in differential mode. This feeds into a differential I/U stage and a filter section using in all 3 dual op-amps per channel. The op-amps used are MJM2068.

 

There are many pages on the net describing the sound of op-amps and as many pages about moding your CD or DVD to better sound.

Well I ordered some samples of the new National op-amps LM4562 which have some of the industry’s best distortion performance , and has been announced as one of the best sounding op-amps for audio. I got 4 samples delivered for free (4 is the max and you have to pay for shipping).

 

I changed all the opa-mps in the filter section, which doesn’t take more than 15 minutes if you know which opamps to change (You’ll need a service manual with the schematics and print layout).

 

This is what I found:

 

Step 1

Changing IC303-IC306 from NJM2068 to LM4562

 Sound improvement/change:

• Less aggressive in the treble
• Larger sound stage, but moved further away
• Can play louder without discomfort
• More relaxed sound
• More details which are more distinct and easier to pinpoint in the sound stage

 Improvement (on a scale from 0 to 5) : 2

Next I changed the I/U converter opamp to a OP275. I have used OP275 before, and have found their sound to be a little less correct, but creating a bigger feeling of room, which I think was what was needed now.

 

Result: 

 

Step 2

Changing IC301 – IC302 from MJM2068 to OP275G

Sound improvement/change:

• Sound was maybe more direct, and more present.
• A bit less relaxed.
• Room was maybe a bit bigger but maybe also a bit less well defined

Improvement: 0-1

 

Overall

Overall I think the improvements are ok for the little money spent. It’s way better than changing cables (which I think belongs on a 0 on my scale). The more expensive LM 4562, seems to be better than the standard MJM2068 in all respects, and gave a good improvement. Changing the last two MJM2068 to OP275, is not that clear. The change is so small that you have to set up a real A/B situation to make a fair comparison, so to me MJM equals OP275.

 

I think I’ll try changing the I/U op-amp to something else maybe the AD8066 which have been said to be very good especially in the bass, or maybe also use the LM4562, which for sure did pose an improvement.

 Should you do it … yes it’s worth a try, but don’t expect miracles …. do something for your room to achieve that

 Good reading about op-amps:

http://www.sg-acoustics.ch/analogue_audio/ic_opamps/pdf/opamp_distortion.pdf

 

http://www.sgheadphones.net/index.php?showtopic=2628&mode=threaded

 

http://members.cox.net/alexhardware/opa.htm

 

http://www.tangentsoft.net/audio/opamps.html

 

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My scale of improvements:

• 0 = None
• 1 = Small but noticeable
• 2 = I can also hear the difference tomorrow!
• 3 = Definitely better
• 4 = Big … my wife tells me unprovoked that something have changed for the better!

5 = Huge  … new speakers, new room