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Old 23rd November 2004, 01:27 AM   #11
BerntR is offline BerntR  Norway
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Join Date: Nov 2004
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Default Power supply modifications

This was a very interesting thread as I am currently in the middle of a modification process of a DVD 2900. I bought it because I wanted a multiformat player and because it is a very promising modding object. I searched the net and companies like Underwood and Modwright describe their modifications very precise. So I took those as guidlines.

In my setup the DVD 2900 replaced an older Denon CD S-10 modded with clock and analog buffer from LCAudio. I am still happy with the sound from this old horse - but now it is on a new assignment.

Right from the shop - and after some hours of burn-in the DVD 2900 were miles behind the older brother on CD playback. In my ears it sounded ... "dirty" and I frequently turned the volume down after short listening sessions. The comparing was done through the digital output. Regarding sound quality 2 channel digital output is my main priority. But almost any digital improvement will also improve the analog outputs.

As I also have a Tact RCS preamp with digital room correction I am an eager member of the TACT forums over at Yahoo. And one major subject of discussion there has been power supply. Some build separate linear PS and other modify the inboard SMPS The DVD and the RCS both has switch mode PS.

So I started out with component replacement in the power supply. Basically, I used Auricaps on the power input for Hf filtering. Then I replaced the diodes with high speed soft recovery types. Then I replaced every electrolyte on the board with Black Gates. On the input side, I used one PKW type. On the output rails I installed bipolar black gates in super e-configurations where appropriate. (super e: face-to face in order to cancel inductance. This is said to increase bandwith very significantly). For the rest, I basically used standard BG's.

These capacitors require quite a few hours of "idling" before they reach their potential, but the improvement was huge right away. Now it was on par with much more expensive players. Black Gates are quite costly when you replace the lot, but it is cheaper than buying a clock kit and the resulting improvement is worth every cent.

After the SMPS modification I installed an LClock XO3. The improvement was marginal compared to the Black Gates - probably because I'd already cleaned up the power feeding the clock. Or maybe because this clock is feeding another clock generator.

The improvement from similar mod of the Tact unit's smps was at least as huge as in the DVD player and the combination was a taste of magic. I am still running SPDIF outputs here.

I then replaced virtually every electrolyte on the DVD audio board with BG's (N, Nx and Nx Hi-Q types - and the film caps (the blue ones) with a better type. I've not touched the muting transistors nor the output coupling electrolytes as I plan to deal with those later (perhaps a bias adjustment on the output and DC coupling right through the speakers). So I still play through those brown caps - but guess what?

The analog output (which is converted back to digital in the Tact unit - and then back again to analog) is ...ng close to the SPDIF line (which eliminates DA+AD conversion in my setup). Analog has slightly less resolution but the highest frequencies are smoother and more powerful passages are represented in a more relaxed (as in less distorted) manner. Analog and digital outputs are anyway now so close that an A/B comparison is required to sort them out.

This means that the digital signal feeding the audio board must be quite OK by my standards - and that the BG's have improved the sound quality from the DACs and the op-amps by a mile.

So yesterday, I went for the SPDIF output. That had to be the reason digital out wasn't best in all disciplines. I found some alternative circuitry on diyAudio.com - and had a buffer stage available in the house. So I bypassed the circuitry after the 74HC04 with: same value as originial series caps of BG super e combo, R10k/R1k attenuation, BUF 04G with unity gain, a Bybee Purifier and a BNC connector. And now - the digital ouput (which in my setup eliminates two conversions) is finally better than the analog. I haven't compared with good old S-10 after the last steps but I guess that the new dog now performs better than the old horse.

I nearly forgot - I've also damped the cabinet with some damping sheet - and today i replaced the feet with a set of very soft rubber-like consistensy. I don't know how this affects the sound, but I guess it all adds upp.

I am really thrilled by the impact of BG's - and I almost panicked when I realised that they are going out of business next year so I've placed a new BG order. (but no need to panick - there are large stocks "everywhere - or so I'm told)

I don't know if there are any more quantum leaps left in the DVD 2900. I've already reached my satisfaction platau. But due to the very good results so far I am going to replace all the electrolytes on the digital board beneath the transport mechanism. In fact I am going to replace all the electrolytes through the two channel audio chain exept the large 160.000uF bank in the power amp that feeds current to the speakers.

I've spent a few hours on the internet during the process. Black Gates have S/N ratios in the range 140-180 dB if my memory is correct. Some other "high end" electrolytes are also said to perform very well.

Anyway, it seems that mainstreem hifi electrolytes often has signal/noise of 60db - 100 dB which is very poor compared to most of the other components you can find in this player. They don't do their job very well. Due to limited band with they do not smooth the DC power in an smps very well - and their smaller brethren do a poor job on the audio board. Noisy *******s!

Those on the digital and video board may be struggling hard to keep up with all the digital components in this player. But they seem to be a different - and probably better - kind. I will find out soon.

Has anyone done any serious work on the digital board?

Regards,

Bernt
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Old 23rd November 2004, 07:41 AM   #12
A 8 is offline A 8  Sweden
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I can recommend doing the main board, for me the difference was significant. My 2900 now beats a heavily modded Pioneer cdp as transport for cd's which was not the case before. It really cleaned up the hights, became more 3 dimensional and with more lowfreq punch.
I changed all decoupling caps to oscons svp's 120uF to 470uF from the drive unit to the audio dsp. I also used the additional filteroption availible on the board for the laser unit.

When you get to the main board it seems there is a lot of space to add stuff but be aware that the discassembly moves down when you eject the disc.

Considering your setup you might want try another mod I've done, get a DIT and tap the digital frontchannel streams just after the Analog devices DSP, this way you get the dsp funktions (if you want to, good for DD and DTS and multichannel tracks) and dvd audio 24/96 through a spdif feed.
Running cd's with this output sounds better then the built-in spdif on my unit.
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Old 23rd November 2004, 09:02 AM   #13
BerntR is offline BerntR  Norway
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Quote:
Originally posted by A 8
I can recommend doing the main board, for me the difference was significant. My 2900 now beats a heavily modded Pioneer cdp as transport for cd's which was not the case before. It really cleaned up the hights, became more 3 dimensional and with more lowfreq punch.
I changed all decoupling caps to oscons svp's 120uF to 470uF from the drive unit to the audio dsp. I also used the additional filteroption availible on the board for the laser unit.

When you get to the main board it seems there is a lot of space to add stuff but be aware that the discassembly moves down when you eject the disc.

Considering your setup you might want try another mod I've done, get a DIT and tap the digital frontchannel streams just after the Analog devices DSP, this way you get the dsp funktions (if you want to, good for DD and DTS and multichannel tracks) and dvd audio 24/96 through a spdif feed.
Running cd's with this output sounds better then the built-in spdif on my unit.
Thanks,

This sounds very promising.

What is a DIT? Could you explain the last paragraph in more detail? I'm in new territory here.
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Old 23rd November 2004, 09:13 AM   #14
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Default Re: Clock upgrade....

Quote:
Originally posted by A 8
I am not sure it will be worth the effort changing the clock in these players. The clock that controls the timing is derived from 27MHz (for video) crystal and then uses Clock IC to create the master clocks for audio.
The clock then passes several IC's and many centimeters before it reaches the actual da chips.

Putting a nice clock in and let it pass all that crap seems a waste to me. In my world a good clock needs to be clean close to where it matters.

Perhaps a better approach would be to start by making sure that the existing clock circuit gets the best possible working conditions, then take it from there depending on the results.

I've just dismantled my 2900 for the next level of mods and will start to change decoupling caps for Oscon SVP's on the main board. There are also several existing options to filter ps noise on the pcb that's not being used.

/Michael

Hi

You are right abouth the subsequent PLL IC, however, what you don't throw in, doesn't come out....

Especially the LF jitter will improve, when feeding that IC from a better clock

Also cleaning up the PLL IC supply will help, especially at the LF side of the spectrum

(hint: Adding capacitors won't work)

best regards
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Old 23rd November 2004, 11:12 AM   #15
A 8 is offline A 8  Sweden
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Quote:
Thanks,

This sounds very promising.

What is a DIT? Could you explain the last paragraph in more detail? I'm in new territory here.

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Regards,

Bernt
A DIT is a Digitalaudio Interface Transmitter like the CS8405 or 06 from Cirrus logic . CS8405

/Michael
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Old 23rd November 2004, 11:53 AM   #16
A 8 is offline A 8  Sweden
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Quote:
Hi

You are right abouth the subsequent PLL IC, however, what you don't throw in, doesn't come out....

Especially the LF jitter will improve, when feeding that IC from a better clock

Also cleaning up the PLL IC supply will help, especially at the LF side of the spectrum

(hint: Adding capacitors won't work)

best regards

__________________
Guido Tent
Hi Guido,

I agree fully on cleaning up the PLL supply which was why I suggested improving the existing clockcircuits conditions.
It is however not only the PLL IC that needs attention, you have additional logic in the clock path that even share other streams, supply and local decoupling with additional logic so even if you have a nice clock feeding the PLL you'll never get close to the clocks potential without fixing the subsekvent signal path. Even then it is still somewhat polluted by shared signalprocessing, supplies and logic.

In Sweden we have a saying that goes something like "throwing pearls at the pigs..... "

I am sure it will be different though and some might think that is an improvement.

Cheers.
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Old 24th November 2004, 03:42 AM   #17
BerntR is offline BerntR  Norway
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Join Date: Nov 2004
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Default Re: Re: Clock upgrade....

Quote:
Originally posted by Guido Tent

Also cleaning up the PLL IC supply will help, especially at the LF side of the spectrum

(hint: Adding capacitors won't work)

best regards
Guido,


I would appreciate more than hints on this subject. What will work??

best regards,

Bernt
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Old 24th November 2004, 03:42 AM   #18
BerntR is offline BerntR  Norway
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Join Date: Nov 2004
Location: Norway
Quote:
Originally posted by A 8


In Sweden we have a saying that goes something like "throwing pearls at the pigs..... "

Cheers.
Pigs are underrated. Physically, they are perhaps the animal that's most similar to homo sapiens audiophilis.....


I WANT MORE PEARLS!!

Nff.
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Old 24th November 2004, 08:54 AM   #19
A 8 is offline A 8  Sweden
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Quote:
Pigs are underrated. Physically, they are perhaps the animal that's most similar to homo sapiens audiophilis.....
Bernt,

I just realized how this could be interpreted, Sorry it was really not referenced to you or any other tweaker I was mearly refering to the existing clock circuit as the pig and exotic clocks as the pearls.

Again, I am sorry for the confusion.

/Michael
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Old 24th November 2004, 10:35 AM   #20
BerntR is offline BerntR  Norway
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Join Date: Nov 2004
Location: Norway
Quote:
Originally posted by A 8


Bernt,

I just realized how this could be interpreted, Sorry it was really not referenced to you or any other tweaker I was mearly refering to the existing clock circuit as the pig and exotic clocks as the pearls.

Again, I am sorry for the confusion.

/Michael

Michael,

Don't be. I understood you the first time. I was just trying to make a joke out of it. Not with great success I must admit.

I didn't realise that I could be interprated as identifying with the pig until now. I guess the next laugh is on me.
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