[Russtafarian]

I haven't been back to this thread for a while.  I apologize.

Here's what I've changed on my Oppo since my original post.  I've removed the transformers as they added too much noise when I turned up the gain on my preamp.  I've used this pair of transformers in three different players in the past four years and all the soldering and desoldering may have corrupted them. 

I replace the two paralleled 11uf ERSE caps at the front of the PS with a 270uf 250V Nichicon that I hijacked from the switching PS board of my dead Sony ES player.  I've added .1uf polypropylene bypass caps to the two 10uf power supply filter caps next to the DAC.  I've added .22uf PIO (paper in oil) bypass caps to the 11uf ERSE coupling caps.  I've added a 500 ohm caddock load resistor between the coupling cap and the RCA jack.  The Oppo now sounds very clean, clear and detailed.  I've done the same output stage mods to my SB3 with similar excellent results. 

I plan to experiment with Sonicap Gen1's in place of the ERSE caps and maybe even splurge for some Sonicap Platinums or Solen Teflons for bypass caps.

The only caveate to this mod approach is that the Oppo still needs a good preamp or buffer stage with gain to work right.  I went this route knowing I'd be connecting the Oppo to a CAT SL1 preamp.  The cap coupled approach didn't work very well when I connected it to a Promitheus TVC preamp. 

the OpAmp is no longer used... is that correct?

Yup. DAC > coupling cap > 500ohm resistor > RCA jack
 

This is very interesting. Can you provide links that support the fact that the Cary DVD-8 is essentially a dressed up Oppo 970? 

If you go to the Cary website and look at the photos of the DVD-8's remote and insides, I can tell you that it's the exact same stuff as the 970.  I don't know if they've changed the power supply board because they put a shielding box over it.

Russ

[G.Michael]

Hi All,

My modded 970... cap and diode replacement only. 

http://www.audiocircle.com/index.php?action=gallery;area=browse;album=1101

My buddy did the work, replaced nearly 40 capacitors with
--Nichicons (I don't remember which model) on the power supply board
--Blackgates in the output stages
--Nichicon Muse and Elna Cerafine elsewhere on the main board
With everything on the main board being so fragile and tiny, this was a formidible task... probably not something I'd want to undertake. 

( Russ, clearly you downplay your talent as a "parts swapper"! )

I now have a few hours on the unit, not yet close to broken in, but I notice that the sound has improved during that time.  Probably most notable is the background is very quite, similar to higher end transport/dac combos I've heard.

[Russtafarian]

Nice work!  Thanks for posting some great shots.  Good idea laying down those big Nichicons.  Why didn't I think of that? 

Let us know how it sounds when those BGs on the output stage break in.  I could never get the sound to open up with those op amps.  Hopefully you'll succeed with your approach.  If your friend is really good with a soldering iron, maybe you could try better op amps?  I'm not brave enough to try this myself.

For anyone who has any doubt about the Oppo 970 - Cary DVD-8 connection, compare the photos of the circuit board:

Cary DVD-8


G. Michael's Oppo 970


Can you guess which one uses better parts?

Russ

[Monolith]

If your friend is really good with a soldering iron, maybe you could try better op amps?  I'm not brave enough to try this myself.

What op amps does it use?

[fajimr]

don't mean to sidetrack discussion here but does anyone know how similar/different the 970 and 971 (which I have) are?  I haven't opened mine up for a while...

TIA
jim

[G.Michael]

Nice work!  Thanks for posting some great shots.  Good idea laying down those big Nichicons.

Chuck's policy is that if he can't make it look neat, he won't do it.  He was certainly concerned about how this project would go, and generally doesn't like to work with such circuitry this fragile.  His forte is building amps and preamps, and modding such equipment.  Also, speaker crossovers. 

If your friend is really good with a soldering iron, maybe you could try better op amps? 

He won't go near those, either.  Actually, I was shocked by how small those op amps are.  It sure would be nice if those op amps are decent, and that the coupling caps make a big difference.

Also, we chose not to use the Lundahl 1527XL transformers for this project, since there was no way Chuck could neatly fit those in the chassis... which leads me to a posting I'm going to do: "Uses for these new Lundahl 1527XL transformers?"

For anyone who has any doubt about the Oppo 970 - Cary DVD-8 connection, compare the photos of the circuit board:

Well, I see that the Cary unit has a shield over the power supply.

[Russtafarian]

I feel bad that you popped for the transformers on my recommendation only to not use them.  One alternative use is as a splitter to send separate preamp outputs to a main amp and to a sub (or subs).  This would isolate two power amps connected to the same preamp and keep them from interacting with each other. 

Russ

[Russtafarian]

What op amps does it use?

I don't recall. NEC C45.... something.  I've go the notes in a file.

don't mean to sidetrack discussion here but does anyone know how similar/different the 970 and 971 (which I have) are?  I haven't opened mine up for a while...

The 970 plays SACDs.  Don't know what DAC the 971 uses.

Russ

[G.Michael]

I feel bad that you popped for the transformers on my recommendation only to not use them.  One alternative use is as a splitter to send separate preamp outputs to a main amp and to a sub (or subs). 

No problem, Russ.  It's part of playing in this league.

Earlier you wrote

I've used this pair of transformers in three different players in the past four years

How'd you use the transformers?  Any use for these in my tube DAC, I wonder.

Gary

[Russtafarian]

Where the transformers really worked well was with the differential voltage output DACs that were in the Pioneer and Sony players that I had (may they rest in peace).  The transformers galvanically isolated and kept the differential (balanced) +/- analog output from the DAC separate from the chassis ground so that no coupling capacitors were necessary to block DC.  Very clean sound.

The Oppo's DAC is single-ended so the signal ground and chassis ground are combined, so a coupling cap is necessary to block DC.

Russ

[fajimr]

The 970 plays SACDs.  Don't know what DAC the 971 uses.

thanks...
jim

[edit- deleted a reference to a thread that didn't exist  ]

[Monolith]

Picked this up off the AVS forum to answer my own question:

"non-audio-grade op-amps (some Chinese version of RC4558), the Oppo's engineers did a great job in implementing the so-so quality parts for its excellent audio performance.

BTW, I'm planning on changing its three op-amp chips to BB audio-grade ones (OPA2134)"

[dragonknightTTTT]

BTW, I'm planning on changing its three op-amp chips to BB audio-grade ones (OPA2134)"

I have done the job.But the Oppo  sounds less clean.I think the reason is that the bandwidth is too wide( 8MHZ) and the voltage noise density is too high (8nV/√Hz）。If the oppo use better DAC and more clean power supply. I think the OPA2134 will work better.I think the best op-amp for DV-970 maybe is NE5532(Philips).

[kbuzz3]

Not to hijack this tread but:

I have a bolder modded Oppo DV-971H. At turn on the player always defaults its eq setting to rock.  Anyone know how to change the default setting at turn on to my preffered listening eq-also called OFF

[dragonknightTTTT]

Not to hijack this tread but:

I have a bolder modded Oppo DV-971H. At turn on the player always defaults its eq setting to rock.  Anyone know how to change the default setting at turn on to my preffered listening eq-also called OFF

Maybe you have made your DVD to remember the setup.Then you can try to  initialize your DVD or update the  original software.