Denon 2900

Face

buymesome wrote: »

Hey ben could you post a pic of the faceplate?

http://lmgtfy.com/?q=Denon+2900+faceplate

ben62670

buymesome wrote: »

Hey ben could you post a pic of the faceplate?

I didn't mod the faceplate:D

Face

You need these:

ben62670

I may do it:)

Face

If you want a little more highs and great transparency, go for MR's. For something a little more neutral, a little less transparent, and a lot cheaper, ESA's.

ben62670

$77 each for the MR's:eek: ESA's $18 much more in my budget.

ben62670

Face wrote: »

Time for some boutique caps.

Let's see some more pics.

like this? Circa 1990?

ben62670

GV#27 wrote: »

Give the offset levels a check with your DMM but I suspect it has a differential DAC chip(PCM1791/92?) and with the low offset of the 2134 should allow you to remove the output coupling caps altogether.You may also want to bypass those muting transistors at the output.(Atleast that what they appear to be for in the pic.)

Burr-Brown 24-bit, 192-kHz DSD-1790 Audio DACs that decode PCM and DSD signals discretely with no down-conversion of DSD
I need to get my read on. I am hoping they are not voltage outs.

Edit: The DAC chips are under the drive. This is a PIA I want to steal the analog right off the chips v out.

comfortablycurt

Face wrote: »

http://lmgtfy.com/?q=Denon+2900+faceplate

So...I clicked on that link, and where does it lead me? The google search was performed, and the very first hit was this VERY thread...Crazy.

ben62670

One of the best things I like so far is the imaging is very pronounced at low volume levels sounding very full and airy. Never before have I had this at this low of a volume setting. Very pleased so far.

Edit: BTW even with the caps not burned in yet the sound stage is better with them than without

Systems

ben62670 wrote: »

Burr-Brown 24-bit, 192-kHz DSD-1790 Audio DACs .... I am hoping they are not voltage outs.

They don't appear to be a regular BB product so are likely a custom version of the V-out DSD/PCM1791 or I-out 1792.You should be able to determine if it's a V or I out by the number of op amp stages following the DAC.Even with the integral I/V convertor the DSD/PCM 1791 is a VERY good chip.

ben62670

I couldn't find any data on the chip either. I wanted to steal the signal straight off the chip, and tube it from there. From what I have read the filter stages are more for presenting good numbers and you can omit them without harming anything.

Systems

ben62670 wrote: »

From what I have read the filter stages are more for presenting good numbers and you can omit them without harming anything.

For the most part thats true there is a lot of hi frequency noise involved with the noise shaping process of delta sigma DAC's.Combatting this noise is the purpose of the LPF.Assuming a V out you could run your tube directly from it but keep in mind the tube itself will add gob's of noise and distortion:eek::D j/k.

If the DAC has a I out you might be able to use a simple resistor for I/V conversion before the tube stager.

ben62670

GV#27 wrote: »

...
If the DAC has a I out you might be able to use a simple resistor for I/V conversion before the tube stager.

This is where I was looking. A 100r is suposed to be sufficient for the tube into. The only thing that I need to figure out is the fact that the DAC is balanced out. Not sure if I am supposed to use just the vcc+ or sum both after the tube stage? I have been doing a lot of reading.

Systems

ben62670 wrote: »

This is where I was looking. A 100r is suposed to be sufficient for the tube into. The only thing that I need to figure out is the fact that the DAC is balanced out.

Yes it will have balanced (differential)outputs.

Not sure if I am supposed to use just the vcc+ or sum both after the tube stage?

Sorry can't help on that one.

ben62670

I'll figure it out and share:)
Thanks again.
Ben

ben62670

Well I have about $30 in parts in this thing so far, and all I can say is WOW. The sound stage is better than ever. Room filling with some depth. The upper mids are not exactly to my taste. A little hot. I am going to hunt down a better OpAmp solution, and change the output caps. The biggest disappointment is I can't figure out why manufactures don't use ever so slightly better components in the final stages When I first received this player I was pretty disappointed. It did not sound much better than my 400 disc Sony DVD/SACD/CDP. I now know why this player is very high up on the list of players to mod. I hesitate to write this, but I never thought I would bother to upgrade a player instead of using a separate DAC. I still like the idea of a separate DAC with multi digital sources. I may be seeking another 2900 for a second system in the future.

Edit: Listening to YES 90125. Awesome on SDA's

ben62670

Well I have been looking into an OPA627 solution. Also the voltage is +9/0/-9. I wish it were a little higher, but it does make for safer biasing into class A. I am very happy with the 2134 sound, but everyone likes the 627 much more. It figures because it cost 10 times as much. Also some 4-4.7uf AuraCaps are going to be used. Like I said I can't complain about anything, but I am a freak, and I must mess with it. Well maybe the vocal mids are slightly dark, but they were previously too hot and forward.

Edit:

If Wile E. Coyote had enough money to buy all that ACME $hit, why didn't he just buy dinner?

ben62670

GV#27 wrote: »

They don't appear to be a regular BB product so are likely a custom version of the V-out DSD/PCM1791 or I-out 1792.You should be able to determine if it's a V or I out by the number of op amp stages following the DAC.Even with the integral I/V convertor the DSD/PCM 1791 is a VERY good chip.

Quote from SACDmods
This player is among the best that I have to offer. With the modifications listed below, the Denon DVD-2900 reaches a level of performance that pretty much equals my modified Sony SCD-C555ES, a feat that I thought could not be repeated. The 2900 features balanced current output DACs like the 555ES, and it is therefore a perfect candidate for the ZapFilter analog output stage. The player features Texas Instruments/Burr Brown's latest DSD DAC, the PCM1790. The 1790 features a wider dynamic range than my favorite, the PCM1738

Systems

So it's a current output device.It must be a custom for Denon variant of the 1792 as used in your eval board because it appears there are no data sheets available from TI/BB for it.

As for the OPA627 it being a single you will need an adaptor to get two of them into the 8 pin DIP footprint.Aswell I understand the DIP versions are hard to source.Going SMD with the apropriate dual SMD-DIP adaptor might be your only option if you want to use them.I'd avoid the cheap 627's on epay as they are likely counterfits.

Why the coupling caps if your offset is low enough to eliminate them?

ben62670

Yep yep and yep. I have two R+L jacks on the outs. I usually prefer no caps, but adding the caps makes some music sound a little better. The 627's are as you know surface mounts, and require the adapter. Thanks for the heads up on the flea pray chips. I can get some from digikey. I may make a custom board to take the signal after the IV conversion, and do a power supply on that board for a more acceptable +12/0/-12 instead of 9v+-. Also the PS in Denon's is SMPS and It would be easy to drop a toroid in there:) Thanks again for that eval board it is a great learning device for this project:)

Systems

ben62670 wrote: »

but adding the caps makes some music sound a little better

So the colourations they add are of the ear pleasing variety.:D

Also the PS in Denon's is SMPS and It would be easy to drop a toroid in there:)

It looks like you have enough room to add a Talema toroid and filter caps in front of the SMPS like I did with one of my Pio's.See pics in post #31 in this link. http://www.polkaudio.com/forums/showthread.php?t=55733&highlight=pioneer+dv563&page=2

Thanks again for that eval board it is a great learning device for this project:)

Your welcome.Basically you will have the same circuit to work with in your Denon as in the eval board but the added advantage of not having to use the SPDIF connection so potentially less jitter.

ben62670

I have a 15-0-15 avel for it. I need to get off my butt and get some boards made that are fairly universal. I only have 2x3"s for the boards to work with so it makes it tough to get everything on there I want, and it is $65 for 3 boards... I am toying with the idea of the LM4562

ben62670

Looking at the PS I am thinking of totally removing it. From what I see it is all +9/0/-9 and 5vdc. A couple toroids and I think I would be on the way to even more improvement. Again the very least a +12/0/-12 PS for the anolog section.
Ant thoughts?

Systems

ben62670 wrote: »

Looking at the PS I am thinking of totally removing it.

I would leave it in there.The display,transport, transport logic controls etc. are powered by it. IMO your best bet is to have a fully isolated supply to power everything in the analog stage after the DAC chip.(I-V,LPF / output buffer). You could place the the raw supply externally in a bud box if there is not enough room to fit it into your chassis.

ben62670

Well I picked up a second player seeing I was having major read issues with mine. I received the second one and it read everything. I put it in my system, and had issues reading disks. Well come to find out my little 30vdc tube buffer was making the players have problems. Now I have two good players that have been modded. It's a good thing really because I want to setup a system in my bedroom. Live and learn.
Ben

billbillw

Two 2900s is not a bad thing. Great little unit there. I kinda wish I still had mine. Glad you figured it out.

ben62670

Thanks Bill. I hope this helps anyone else who gets stuck in a similar situation. BTW it is sounding so good.

ben62670

I have my OPA627's in for a customers upgrade, and I am going to do mine also. The customers 2900 is getting the Clarity ESA 10uf caps I can't wait to here those.

Outfitter03

ben62670 wrote: »

I have my OPA627's in for a customers upgrade, and I am going to do mine also. The customers 2900 is getting the Clarity ESA 10uf caps I can't wait to here those.

I am patiently waiting too Ben. Hope this crisis in your life will soon pass. Sent several emails over the last 2 months just to touch base. Not pushing, just wanted to touch base and make sure this is still on the back burner.