Last week I made the first steps to modify my Denon DVD2900. I have started at the output stage. The first thing I did was carefully removing the mute transistors from the front channels. The improvement was very clear. A transistor between the signal path and ground seems to cover the smallest details on the recordings. The player now makes a few small pops when turning on the power or changing records. But it’s not very annoying really.
The second thing I did was replacing the coupling caps with polypropylenes. There capacitance is now only 6,6uF compared to the original >220uF. If the cap is too small it will affect bass levels but I have calculated that with a 10k load the –3db point is 2Hz with the new caps, so I think I can live with that. Also this time the improvement was clear. The high frequencies sound cleaner.
Next I will continue working on the output stage. Have a look at TR231 in the pic below. Depending on the state of the transistor the IC215 amplification will be roughly 1 or 2. The wire that changes the state is marked “PCM/DSD”. My guess is that the stage amplification is changed depending on weather the record being played is a CD or SACD/DVDA. As the TR231 could have a similar effect on the sound as the mute transistors I would like to remove it. My logic says that removing TR231 will make the sound level change depending on what format is being played. I can live with that if the sound is improved. Has anyone made similar mods? Any thoughts?
The DVD2900 has two pairs of front channel outputs. I will connect one pair of outputs past the coupling caps directly trough a resistor to the op-amp. This should work as long as the preamp has coupling caps on the inputs. Anyone tried this?
Also more ideas about easy improvements are appreciated!
-thomas
The second thing I did was replacing the coupling caps with polypropylenes. There capacitance is now only 6,6uF compared to the original >220uF. If the cap is too small it will affect bass levels but I have calculated that with a 10k load the –3db point is 2Hz with the new caps, so I think I can live with that. Also this time the improvement was clear. The high frequencies sound cleaner.
Next I will continue working on the output stage. Have a look at TR231 in the pic below. Depending on the state of the transistor the IC215 amplification will be roughly 1 or 2. The wire that changes the state is marked “PCM/DSD”. My guess is that the stage amplification is changed depending on weather the record being played is a CD or SACD/DVDA. As the TR231 could have a similar effect on the sound as the mute transistors I would like to remove it. My logic says that removing TR231 will make the sound level change depending on what format is being played. I can live with that if the sound is improved. Has anyone made similar mods? Any thoughts?
The DVD2900 has two pairs of front channel outputs. I will connect one pair of outputs past the coupling caps directly trough a resistor to the op-amp. This should work as long as the preamp has coupling caps on the inputs. Anyone tried this?
Also more ideas about easy improvements are appreciated!
-thomas
Attachments
Hi Tomas,
Thx for the information.
I also replaced the output capacitors by 10 uf mkp audyn capacitors. Sounds better indeed!
muting transistors is a good suggestion. did not see them yet. I have no scheme...:-( how they look like?
Got the idea on this dutch site:
http://www.soundevolution.nl/article_Denon_DVD_2900_SE.html
Also a new clock is placed inside and better op-amps.
A new clock which can be obtained here:
http://www.tentlabs.com/Products/DACUpgrade/DACUpgrade.html
I did not do the clock my self yet. But I expect a huge difference. Because i have the same clock in my CEC transport. And the was WOW!!
Hope to hear from you.
Rene
Thx for the information.
I also replaced the output capacitors by 10 uf mkp audyn capacitors. Sounds better indeed!
muting transistors is a good suggestion. did not see them yet. I have no scheme...:-( how they look like?
Got the idea on this dutch site:
http://www.soundevolution.nl/article_Denon_DVD_2900_SE.html
Also a new clock is placed inside and better op-amps.
A new clock which can be obtained here:
http://www.tentlabs.com/Products/DACUpgrade/DACUpgrade.html
I did not do the clock my self yet. But I expect a huge difference. Because i have the same clock in my CEC transport. And the was WOW!!
Hope to hear from you.
Rene
Clock upgrade....
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
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
Hello again,
I did remove the transistors I referred to in my first message. I also removed the muting transistors for all the other channels as well. So totally I have now removed 26 (!) transistors from the player.
The denon has two pairs of outputs for the front channels. I have the coupling caps bypassed for one of the output pairs. This is possible because the preamp has coupling caps on the input.
q1: The mute transistors are surface-mounted and very small. It took a while to desolder them carefully, but I'm really happy about the result.
So far removing the muting transistors had the biggest impact on the sound quality. Also upgrading the coupling caps was a clear improvement. Bypassing the improved coupling caps didn't change much, only a slight increase in the bass level. That effect could certainly be imaginary.
So what's next? Tampering with the clock is too challenging for me, so I'm thinking about a new psu for the audio circuits.
-thomas
I did remove the transistors I referred to in my first message. I also removed the muting transistors for all the other channels as well. So totally I have now removed 26 (!) transistors from the player.
The denon has two pairs of outputs for the front channels. I have the coupling caps bypassed for one of the output pairs. This is possible because the preamp has coupling caps on the input.
q1: The mute transistors are surface-mounted and very small. It took a while to desolder them carefully, but I'm really happy about the result.
So far removing the muting transistors had the biggest impact on the sound quality. Also upgrading the coupling caps was a clear improvement. Bypassing the improved coupling caps didn't change much, only a slight increase in the bass level. That effect could certainly be imaginary.
So what's next? Tampering with the clock is too challenging for me, so I'm thinking about a new psu for the audio circuits.
-thomas
As you know, I achieved the biggest change for better by changing the op amplifiers from output.
I can easily send OPA627+adapter to you for testing (I can send also AD8065 if you like but then I have to listen to old NJM4580 while you're testing
) . All you need to do is desolder the old opa and change it to dip8 socket. This enables you to change opa rapidly without any risk of harming the PCB. If you like (I'm sure you won't!) you can install the old opa by just sticking it to the socket. In my opinion, AD8065 is more technical sounding opa and OPA627 is more musical (or should I say emotional). Concidering your equipment, I think you would prefer the latter. I have 5 (!) DIP8 single-to-dual OPA adapters because of the Browndog incidence so I can sell you one of them for a niominal price. You can get OPA626 from RS. I also have 5 AMD single-to-dual which are suitable for AD8065 (however I recommend buying an assembled module from LCAudio).
Any thoughts about this?
btw. The easiest way to desolder SMD components is using two soldering irons and heating all pins at the same time. I used that tecnique the second time I removed muting transistors and it was about 100 times easier and safer than using only one soldering iron.
I can easily send OPA627+adapter to you for testing (I can send also AD8065 if you like but then I have to listen to old NJM4580 while you're testing
) . All you need to do is desolder the old opa and change it to dip8 socket. This enables you to change opa rapidly without any risk of harming the PCB. If you like (I'm sure you won't!) you can install the old opa by just sticking it to the socket. In my opinion, AD8065 is more technical sounding opa and OPA627 is more musical (or should I say emotional). Concidering your equipment, I think you would prefer the latter. I have 5 (!) DIP8 single-to-dual OPA adapters because of the Browndog incidence so I can sell you one of them for a niominal price. You can get OPA626 from RS. I also have 5 AMD single-to-dual which are suitable for AD8065 (however I recommend buying an assembled module from LCAudio). Any thoughts about this?
btw. The easiest way to desolder SMD components is using two soldering irons and heating all pins at the same time. I used that tecnique the second time I removed muting transistors and it was about 100 times easier and safer than using only one soldering iron.
No problem It would be interesting to hear your thoughts about the OPA's so if you change your mind and wan't to test before purchasing, send me an email.
Have you considered Jung superregulator to power supply. In some applications Jung superregulator should be the best there is but I've also heard that it isn't a fool proof regulator. You can buy PCB's for low price from here:
http://www.aoselectronics.com/jungsrpcb.html
I'd like to get one of those but I don't know how to adjust the voltage and where to use it
It would be interesting to hear your thoughts about the OPA's so if you change your mind and wan't to test before purchasing, send me an email.Have you considered Jung superregulator to power supply. In some applications Jung superregulator should be the best there is but I've also heard that it isn't a fool proof regulator. You can buy PCB's for low price from here:
http://www.aoselectronics.com/jungsrpcb.html
I'd like to get one of those but I don't know how to adjust the voltage and where to use it
thomsva said:
Hi Thomas,
I think removing TR231 seems a good idea.
How about removing everything that follows the OPA275?
DOES ANYONE KNOW whether the output of the OPA275 needs any of the resistors in series or parallel that follow in this scheme? (See picture in first post of this thread)
The 100k resisors on ground together with the 470 pF caps are probably there to prevent oscillation, but are they really necessary? CAN ANYONE COMMENT?
You do need of course one output cap in series to prevent DC ruining you amps (unless you are sure your preamp filters thsi out). 6.8 uF is surely large enough, and in case of using large prolypropyleen (speaker) caps it is wise to try smaller ones. However if you would use Blackgates you could also try 47 to 220 uF. The larger blackgate the more dark and bass-pronounced the sound gets with some lack of fine detail in the treble.
Regards,
Lucas
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
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
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.
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.
Re: Clock upgrade....
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
A 8 said:
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
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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