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Opinion on Non-oversampling mod for TDA1541 based player?

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Posted on February 17, 2016 at 06:04:30
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010
Hello fellow members,

I acquired a ReVox B226 cD player a few weeks ago.
It's a 25 or 30 years old player in need of a refresh (altough it sounds surprisingly good as it is now).

I've decided on a global recap (all the electrolytics and probably also the output coupling caps) + replacement of the output stage NE5532 opamps with Sparkos Labs SS3602 dual discrete opamps.

while I'm at it, as the board will be out and all, it seems to make sense to upgrade the clock as well - as such a thing might be a great leap forward in sound quality, according to internet sources (haven't heard what a proper clock can do).

Looking for an affordable clock module I keep bumping on all-in-one, low-jitter reclock and NOS modules that solder in place of the SAA7220 chip found in TDA1541 based players. Those modules are supposed to be "plug and play" and require no further modification of the board, wich sounds appealing.

So here are my questions:

1) does it make sense to NOS an existing player designed for 8 times oversampling and sounding quite good that way?

2) is a NOS dac configuration compatible with a tripath-based power amplifier (knowing I'm using a conventional SS preamplifier between the CD player and the power amp), or is there a risk of instability or other problems due to spurious very high frequencies "garbage" that will be left unfiltered at the player output?

3) does NOS modification bring any real upgrade in SQ (in general and on this particular ReVox B226 player) or is it more like a change in flavour and a matter of taste?

4) If I would decide to keep the oversampling, and keep the SAA7220 chip active, wich clock module would you recommend knowing that I need something not too expensive and easy to implement, and if possible reversible (no destruction of board tracks)?

Thanks a million!

 

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RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 17, 2016 at 15:07:52
tube524
Audiophile

Posts: 254
Joined: August 1, 2009
Keep the over-sampling as is, just get a Guido Tent 11.2896 MHz, clock from Tent Labs which is soldered on pin 13 of SAA7220 if I recall correctly plus a ground. You need to know exactly they type of capacitors used around the NE5532 i.e de-coupling or coupling caps. I suggest you keep clock cost at minimum because you need to replace all capacitors on the board. I did the same on my PHILIPS and I'm happy with it. Just don't expect it to have the clarity of current production players.

t.



 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 17, 2016 at 23:30:36
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010
Thanks for your answer.

when you say "get a clock from tent labs" are you talking about the full xO2 module or just a crystal? Can I get just a crystal and expect any improvement at all?

What about the reclock modules offerings often seen on ebay? at around 40 or 50US$, are they any good?

I guess I will only change the electrolytic caps, not the other ones, Revox uses premium parts and Im mainly concerned about aging. Well, I can always have a look but...

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 17, 2016 at 23:40:15
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
Hi,

Service manual here:

ftp://ftp.studer.ch/public/Products/Revox/Revox_B226_B126/Revox_B226_Serv.pdf

First, the SAA7220 is a first class noise generator. If you keep it, make sure to block off the power supplies seriously to avoid it contaminating everything else. Note that in the B226 all IC's (including DAC) share a common +5V supply!

It is probably worthwhile to give the TDA1541 it's own +5V regulator and perhaps something a trifle better than the 317/337 Studer designed in. Same story for the +12V/-6V/-15V lines.

Second, if you put in a socket for SAA7220 and a clock, you can very easily try out Non-OS, simply jumper the signals across the Digital filter.

If trying Non-OS you need to be aware that the SAA7220 B version in the Revox includes a Treble boost to compensate for the analogue lowpass, so you need to reconfigure that part to get reasonable HF output, especially if you account for Non-OS already dropping the treble by around 3dB @ 20kHz.

The fixed outputs of the B226 have only two Op-Amp's in the signal, I might be tempted to skip the second one and just do a simple LC Output filter, with some peaking build in to compensate the treble rolloff of Non-OS... But I guess you can live with the filter as is, I refurbished (and modded) a fair few TDA1541 players and I never did a halfway house mod, I either left the analogue filter or threw all Op-Amp's out.

For the I/U conversion Op-Amp use something fast. Personally I had the best success with AD811/LM6181/LM6182 current feedback op-amp's, these are rated at > 1000V/uS. I also rather liked the AD844 in "open-loop" mode as suggested by Pedja Rogic and an OPA637A (135V/uS) with a 10nF cap from inverting input to ground.

For the Filter section I tried all sorts and liked the BUF03 Buffer best, BUF634 second, AD811/LM6181/LM6182 with a 1K resistor in the feedback loop also did ok. Sadly all my preferred devices seem deleted and I have not really kept up with what may be good replacements.

But AD811/BUF03 was quite magical, followed by OPA637/BUF634 was not much short of this. All the above did way better than NE5532/5534.

Properly sorted the old TDA1541 Players and DAC's have a magic little else (IMNSHO nothing else) touches.

Hope this helps.

PS, I prefer Non-OS with compensation for the drooping treble and tube output stages with TDA1541, but that's just me.

As they say on cooking programs - "Here is one I prepared earlier..."

http://www.enjoythemusic.com/diy/0310/marantz_cd_mod.htm

This machine was also modified for Non-OS (not visible), but the SAA7220 was retained for clock distribution.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 18, 2016 at 00:26:50
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010
Damn... I've been reading few times already, with great interest, the article about your modded CD80...

Unfortunately, while ur article was quite understandable for a complete newbie such as me, your kind answer sounds like chinese to me.

Well, it doesn't, but I don't have the electronic knowledge to implement it.
I realise I might not be up to the task!

First, I already checked the B226 service manual and thought there was only one pair of NE5532 opamps for the fixed outputs, I thought the second pair was only for the variable ouputs; I was planning to just replace the first pair with dip8 sockets and plug in SS3602 dual discrete opamps in there and voilą!

Second, while I understand all chips share the same 5V supply, I have no idea what has to be done to "block the power supplies" or "give the TDA1541 its own regulator". I guess I could get a shunt based regulator from tent labs (for example), but where do i connect it and where do I place it on the board? the other regulators in the B226 share a metal radiator that dissipates further on the zamac drawer guides of the chassis; do I have to put the new regulator next to those? sounds like drilling holes where I shouldn't...

I wish there was a guy like you next to where I live! :)

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 18, 2016 at 09:10:37
Crazy Dave
Audiophile

Posts: 14371
Location: East Coast
Joined: October 4, 2001
Thorsten gave a very thorough answer, but you should still check out this link.

Dave

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 18, 2016 at 12:40:00
fantja
Audiophile

Posts: 15486
Location: Alabama
Joined: September 11, 2010
post pics of your project!

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 18, 2016 at 15:04:37
tube524
Audiophile

Posts: 254
Joined: August 1, 2009
Yes, the XO2 which has three connections, two as I mentioned in my previous post and a power supply lead which you connect to a filter cap on the power supply board with as much capacitance as you can find. I connected mine to a 10,000 uf, though I was advised to get a dedicated power supply for it. Modern CD Players are far superior in sound quality even if they don't have a super reliable PHILIPS CDM1 and a TDA1541 S1 Crown DAC.

t.

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 19, 2016 at 05:55:22
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010
What about this product?

(not affiliated or trying to sell anything, just posting for information duties)?

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 19, 2016 at 14:52:48
tube524
Audiophile

Posts: 254
Joined: August 1, 2009
It is your call on this, but you will not hear any difference between the XO2 and a more expensive clock on an old player.

Good luck!
t

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 19, 2016 at 18:56:46
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
Hi,

Never tried, so no comment.

I am a little concerned if I read "Femto Clock", as most (if not all) Femto Clock are optimised for low phasenoise (femtoseconds) at very high frequencies (12kHz and higher) due to the application (SONET and other comms).

But they get this by having comparably high audio band (< 12khz) Phasenoise, usually way more than a generic crystal plus inverter gate plus LM317 regulator (and you can do much better than that).

For DAC's what matters most is the < 12kHz phasenoise.

To go NOS you can just cut 3 traces and run 3 wires. That costs nothing and takes two minutes and can be reversed easily.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 20, 2016 at 07:42:45
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010
It may just be a matter of taste, and i havent heard the best modern CD players - wich is a good thing since i cannot afford them

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 20, 2016 at 07:48:46
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010
It may just be a matter of taste, and i havent heard the best modern CD players - wich is a good thing since i cannot afford them ;) but for the modest amount of cash these Revox go on the second hand market, i find them very accomplished and musical. I've had some more recent, mid-range players at hand; while they were indeed "smoother" and maybe more transparent, but most of them i found rather bland and uninspiring. But i have my own idea of what musicality is; I use an old pair of Klipsch LaScala (modded), even tho for the same price i could have last generation B&W.

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 21, 2016 at 04:00:34
KanedaK
Audiophile

Posts: 2515
Location: Brussels
Joined: April 27, 2010



Thanks Thorsten.

One more question:

I see these nice discrete shunt regulators (see link below).

Would it bring any worthwile improvement to the revox player? There's 5 regs in the player as seen on the picture above. My newbie understanding is that they would bring cleaner supply but wouldn't solve the pollution caused by SAA7220 and TDA1541 still being on the same line, am I right?

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 21, 2016 at 18:39:32
Thorsten
Manufacturer

Posts: 4209
Location: Somewhere nice on planet dirt
Joined: September 25, 1999
Hi,

There are many regulator Chip replacements, I am not in a position to comment on the specific merits.

However, just randomly replacing parts will not reliably yield a real upgrade. Please study the service manual, understand the schematic and then base your changes on that.

And seriously consider giving the TDA1541 it's own +5V supply, this means cutting traces and adding parts.

With machines like the Revox simple parts swapping might get you at best 70% of what can be done to maximise Soundquality.

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 20, 2017 at 00:33:50
Alex Peychev
Manufacturer

Posts: 1820
Location: SF Bay Area
Joined: July 15, 2003
Hi Thorsten,

Has been a long time, how are you?

Maybe you try my SAA7220 module then and let us know what you think? :-)

You are correct about the phase noise, but the clock on this module which is used to clock the CD player audio DSP and also re-clock the clock and data lines going to the TDA1541 has -100dBc/Hz noise floor even at 10Hz offset. :-)

Best wishes,
Alex Peychev

APL Hi-Fi

 

RE: Opinion on Non-oversampling mod for TDA1541 based player?, posted on February 21, 2017 at 09:37:11
Disbeliever
Audiophile

Posts: 1877
Joined: June 1, 2012
This is similar to my very old Marantz CD94 with extensive mods including new clock etc. it sounds excellent. better than Marantz SA7-S1.

 

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