Comparison of Denon DVD-2900 Mods

[rtate]

Chas, did you have any problems removing the opamps for the I/V and filter stages???

Mine seem to be glued down under the body of the chip...

 

[clm811]

Once I desoldered them, I kept applying heat and used a small jewellers screwdriver to pry them up- Not an elegant solution, but it worked for me. Just be careful not to lift the pads/traces.
-Chas

 

[rtate]

I got the opamps changed and all is good!!!

Now I would like to install new rca connectors.

However I am not sure how or where to connect them to the audio board

Any suggestions???

 

[clm811]

Changing RCA jacks

I didn't change mine.

If I did, I'd feel compelled to change the jacks on my preamp and power amp too (not to mention upgrading interconnects!)...

I've heard that some guys reported good results direct-soldering their right and left channel interconnects directly to the PCB, and used rubber grommets/strain relief through the panel. This eliminates the jacks and another set of contacts(the plugs)!

Sounds like a hassle, but I can see where it would sound better.

Attached pic shows the main R/L jacks, which can be de-soldered then seperated from the multichannel outs(which I'd leave stock).

Cheers

-Chas.

 

[rtate]

Thanks again Chas for all your patience and help!!!

Do I have to de-solder all of the jacks to seperate the L/R? or can I leave the others alone and just de-solder the ones I want to remove...

 

[clm811]

Do I have to de-solder all of the jacks to seperate the L/R?

I never attempted this and it's been a year since I had it apart so I can't remember exactly (and my photos weren't taken from the right angle to see this).

Take a close look at the pcb.
The jacks either seperate pcb jack modules or one big multiple unit, from which you'll have to desolder the leads and then cut off the L/R pair from the rest (at which point-if you're really OCD- you could replace all with "audiophile" quality jacks silver-wired to the pcb). Depending upon the quality of your interconnects (and other components), you may decide to "go all the way".

The big improvements, sonically, seem (to me) to be from the improved I/V stage, Class-A biased outputs and power supply upgrades. My friends and I have favorably compared the modded player(with the stock jacks) to a few very high end CD players.

YMMV

-Chas

 

[clm811]

The big improvements, sonically, seem (to me) to be from the improved I/V stage, Class-A biased outputs and power supply upgrades.

Oops! I should have re-read that before I posted (up way too late the night before when I wrote that)!

I meant to say that (IMHO) the biggest improvements I could hear came from (in order of the improvement each made):

1) Replacing the output(electrolytic) coupling caps with film caps.

2) Replacing output Opamps with improved, Class-A biased units (e.g. AD 826, AD827, OPA627's on browngdog adapter).

3) Power supply upgrades (especially the large caps on the PS board and the use of Black Gates on the audio board).

Next in line would be: improving I/V stage and then replacing the clock with the Dexa "D-Clock"unit. The last two involve greater difficulty and cost (respectively) for the amount of improvement realized.

Hope this clarifies things.

-Chas

 

[rtate]

Thanks Chas, I have just a couple more questions...

regarding the opamp decoupling capacitors.

Did you remove the smt chip capacitors c343,344,345 and 346 before adding the .1uf blackgates?

Also I noticed that you decoupled across V+ and V- as well as
V+ to gnd and V- to gnd.
Thr data sheets I read suggested one or the other.
Why did you choose to implement both methods??

 

[clm811]

Did you remove the smt chip capacitors c343,344,345 and 346 before adding the .1uf blackgates?

Yes. Removal and replacement of the chip ceramics with good film types, around the opamps, improves sound quality IMHO (The ceramics are retained as bypasses in the digital section, due to their low ESR at very high frequencies).

Also I noticed that you decoupled across V+ and V- as well as V+ to gnd and V- to gnd.

Yes, The use of both together was recommended by others in the threads on op amp bypassing.

"...one [small] film cap from + to - on the opamps supply pins is also used. [The]key is to use all three caps as close to the pins as possible for optimal results."

"The purpose of the bypass capacitors is to produce a low impedance ground return for high frequency garbage which makes its ways on the power supply rails."

As I mentioned earler, I used whatever small value polystyrenes I had on hand(330pf-10nf).

Try to avoid "analysis paralysis" (a mistake I've made), when it comes to the mods. Remember that any of the changes listed should make an improvement, and in most cases they're additive!

Disclaimer: YMMV

Enjoy listening to your newly improved player!

-Chas

P.S. Credit for the mods must go to the many others, more knowledgeable than I, who've posted here on the forums (I was a virtual "newbie" before I joined DIYaudio and began modifying my gear)! I'm just using this forum to compare and share my results.

 

[rtate]

I do believe that I suffer from "analysis paralysis" and it drives me crazy .

I too am a noob when it comes to modding gear althouh I have built several amplifiers and speakers from scratch...

Now my worst nightmare seems to be coming true...

I seem to have an intermittent problem on the right channel only.

It was working perfectly and I removed the audio board to look at something and when I put it back in the music from that channed was horribly distorted!!
I removed the audio board again, looked at a few things but did nothing,and when i put it back in the player it worked!!
I thought the problem was gone however the same senerio has happened again!!!

Any suggestions on where to look Chas???

 

[clm811]

Progressing with fitting LCaudio clock & Zapfilter so will post back with comment on completion
Richard

Richard, Can you post an update on how your DVD2900 is going(how does it sound)?

Mine is still doing a terrific job (although the disc drawer sticks closed periodically).

-Chas

 

[cetoole]

I modified a Denon 2900 a few months ago, and it is working well. Removed the stock I/V and buffer stages for both phases of the L/R channels and replaced them with a discrete common base stage, and added XLR jacks for balanced output. Fairly long wires from the current outputs, but I couldnt come up with a great way to get around that and still be able to mount the video boards.

An externally hosted image should be here but it was not working when we last tested it.

 

[ben62670]

May I ask where you bought those boards? I am very interested.
Thanks
Ben

 

[cetoole]

They are my boards, had them made by PCBCart, as I dont have the patience to etch them myself.

 

[ben62670]

I hear ya. I would rather pay for someone to make the boards for me. Again very nice.
Ben

 

[SoNic_real_one]

Did anyone compare the 2900 vs 2930ci? Are those similar?
Is anybody willing to share the SM?

 

[SoNic_real_one]

I did find the SM.
Now... NJM 2068 used in the I/V stage are very popular OpAmps in many consumer devices. I am planning to swap them with something else. Options are:
OPA 1612 1.1nV/sqrtHz, 27V/uS, 40MHz, low power.
OPA 1632 1.3 nV/sqrtHz, 50V/uS, 180MHz, high power (termal pad).
Any opinions?

 

[eurodezign]

opamp upgrade options

I amp wanting to upgrade the opamps for the front two channels on my dvd 2900,
Ive read conflicting accounts for the amount of opamps that need to be replaced (3 per channel vs 2)

I've read quite a bit about different options that people have used. I want to try the BURSON-71484
(I guess i would need two dual kits if there are 2 per channel)


does any one have the final verdict on this?

Or would I be better off just throwing in some 627s and be done with it?
http://www.partsconnexion.com/burson_71484.html