DAC for Studer d730 or d731

OneyedK

Member
2007-10-02 9:57 pm
mrtakib said:
The internal DAC on the Studer d 730 and d 731 gives a great sound on these machines. I was wondering if anyone had found or used an external more modern DAC that can further improve the sound?

Yups, I did.
Problem with those machines is that the AES-output has a lot of jitter.
(measurements done on several D731's)
Think improving the clocks would benefit them more than using an external DAC.
(D730's have to be wordclocked or they really run out of spec)
 

OneyedK

Member
2007-10-02 9:57 pm
There are several options:

1) simply feed a wordclock signal to the wordclock input. (easy, if you have a wordclock at hand)
2) remove C720, C721, R729 and X701. Connect a decent clock (kwak, tent, ...) to pin 2 of IC707. btw, fequency of that clock is 11.2896MHz

These two options leave every function of the D731 intact.
It's a good idea to change the most important alectrolytic caps while you have the device open.
Best to change D701 (BB212), part of the VCO, they age quickly...

Now the other option is to replace the system clock completely.
Remove IC705 and feed the output of a decent clock to where pin 3 of that chip used to be.
This option certainly the best sounding, but there's no way to use the varispeed again. (wordclocking will also be impossible)

The DAC of the D731 consists of a format converter from Philips transport to Sony format (basically a 16-bit shift register), 8x oversampling filter (SM5803_APT), 3rd order noise shaper (SAA_7350) and finally the TDA1547.

Now after the TDA1547, Studer moves directly to single ended.
By means of NE5532AN (room for improvement there, IC402 and IC452). After those, the industrial part of the D731 begins, nothing you want to see in a high end player, simply do not use it.
L = pin 7 of IC402
R = pin 7 of IC452

When you want to use an external DAC with the D731, you should clean up the digital output portion of the mainboard, not exactly easy to do. (and still have to improve the clock)
 

mrtakib

Member
2008-01-07 9:49 am
Thanks, I will see if I can find a decent clock and see what I can do with it.

On the other hand the D731 does sound pretty amazing just the way it is, so I wonder if it is even worth doing now.

I was thinking of connecting it to a DAC because I want to connect my computer to my hi fi system and if I do get a DAC for that, I want it t least to be an improvement for the D731 while I'm at it.

In the end did you keep your Studer "as is" ?
 

OneyedK

Member
2007-10-02 9:57 pm
mrtakib said:

On the other hand the D731 does sound pretty amazing just the way it is, so I wonder if it is even worth doing now.

I was thinking of connecting it to a DAC because I want to connect my computer to my hi fi system and if I do get a DAC for that, I want it t least to be an improvement for the D731 while I'm at it.

In the end did you keep your Studer "as is" ?

If you like the sound, don't change anything!

But changing the NE5532's (IC402, IC403, IC452, IC453) won't hurt and is easy to do.
There are also 2 100µF coupling capacitors in the audio path, chage them to 47µF high quality types. (C411 and C461)
Remove the resistors R416 and R466.
Remove Q401, Q402, Q451 and Q452 (BC817, mute transistors)

All thes things are easy to do and have a very audible and positive effect.

I don't own a D731 or D730, but we're using loads of them at work (100+) since they are the only players with a simple serial protocol to read de display info into other systems.
We do have to service them, after all, they are old...
 

mrtakib

Member
2008-01-07 9:49 am
OneyedK said:


If you like the sound, don't change anything!
...

Well, some CD's sound much better then others that could sound a lot better.

But changing the NE5532's (IC402, IC403, IC452, IC453) won't hurt and is easy to do.
There are also 2 100µF coupling capacitors in the audio path, chage them to 47µF high quality types. (C411 and C461)
... [/B]
Thanks for that.
Remove the resistors R416 and R466.
Remove Q401, Q402, Q451 and Q452 (BC817, mute transistors)
... [/B]
Remove and don't replace ??


Thanks a lot for all the information, it's hard to get and not many people know about these.
What did you think of the DAC in them by the way ?


oh and I'm I correct in thinking that the jitter problem is only using the AES-output and not in normal balanced or unbalanced output ?

Again, thanks.
 

OneyedK

Member
2007-10-02 9:57 pm
mrtakib said:

Remove and don't replace ??

Yups, you could change the resistors from 10k to 100k, just to fill the empty holes ;-)

mrtakib said:

What did you think of the DAC in them by the way ?

I think it's one of the best implementations of the TDA1547.
Sounds very natural and neutral.
(It's a matter of taste)

mrtakib said:

oh and I'm I correct in thinking that the jitter problem is only using the AES-output and not in normal balanced or unbalanced output ?

Partially correct, it depends on the age and the condition of the caps around the clock and in the power supply. The BB212 should be replaced, depending on how many hours the divice has been switched on.

If you can, borrow a DAC from somebody, if it sounds worse connected to the D731 than when connected to another decent player, you'll know your D731 needs to be taken care of.
 

mrtakib

Member
2008-01-07 9:49 am
OneyedK said:



Partially correct, it depends on the age and the condition of the caps around the clock and in the power supply. The BB212 should be replaced, depending on how many hours the divice has been switched on.

If you can, borrow a DAC from somebody, if it sounds worse connected to the D731 than when connected to another decent player, you'll know your D731 needs to be taken care of.

That is a good idea ! I will see what I can find. btw, where is BB212, I don't seem to find that?


earlier you mentioned...
2) remove C720, C721, R729 and X701. Connect a decent clock (kwak, tent, ...) to pin 2 of IC707

If I did go this route what happens to C720, C721, R729 and X701 after I connect a new clock, do they go back on ?


How is it you know this machine so well !

Thanks again for all your valuable information. I do like this player and hope to keep it up as best as possible. As for the future I think I will give a hard drive as a transport for non compressed music a go. There are also a bunch of ipod transports on the way that will bypass the internal dac and offer digital out.
 

OneyedK

Member
2007-10-02 9:57 pm
mrtakib said:
btw, where is BB212, I don't seem to find that?

It's close to IC704 and looks like a transistor.

mrtakib said:

If I did go this route what happens to C720, C721, R729 and X701 after I connect a new clock, do they go back on ?

The parts mentioned there are all part of the original oscillator,
they have to be removed or the new clock will not work properly.

mrtakib said:

How is it you know this machine so well !

We use a lot (100+) of these machines at work...
They all are end of life (transport nog longer replaceable or serviceable) but we want to keep them as long as possible.

mrtakib said:
I do like this player and hope to keep it up as best as possible. As for the future I think I will give a hard drive as a transport for non compressed music a go. There are also a bunch of ipod transports on the way that will bypass the internal dac and offer digital out.

It's a great player, but if the transport dies, it's finished :bawling:
@home, I use Denon CD-players, not the best, but a lot of room for audible improvement. Measurements of my unmodified DCD-1550AR don't differ much from those of a great unmodified sample of the D731. Still working on the DCD-1550AR.
If that's finished, I'll start on a quiet Linuxbox to play uncompressed audiofiles.
I still like the CD as a media format best, not from a audiophile point of view, but I like to have a disc in my hands ;-)

Good luck with the modifications!
 

mrtakib

Member
2008-01-07 9:49 am
OneyedK said:
It's a great player, but if the transport dies, it's finished :bawling:

I have seen Philips CDM3 's often on ebay, either from Hong Kong or in Germany.

OneyedK said:
[If that's finished, I'll start on a quiet Linuxbox to play uncompressed audiofiles.
I still like the CD as a media format best, not from a audiophile point of view, but I like to have a disc in my hands ;-)
[/B]

I feel the same, I will do the best I can with the Studer and slowly rip my disks to HD. However I remember doing that with films and when my HD with the films died I was more then a little pissed off at the time wasted.

I was thinking of a Tent XO2/5 clock with an xo supply, the other I looked at was a Superclock 4 from Audiocom, but it's a lot more expensive.

I should ask you this on another thread, but did you try your Opus dac after the Studer ?
I'm thinking to build something like that as a DAC1 or DA10 are a bit expensive . First I was thinking of it for the Studer, but now just for HD playback when I get around to that.

Another piece I need to build from a kit or buy cheap, is a phono stage. Ever do that, any recomendations?
Good luck with the modifications!

Thanks, I'll need it. and thanks again for all your help.
 

OneyedK

Member
2007-10-02 9:57 pm
mrtakib said:
I have seen Philips CDM3 's often on ebay, either from Hong Kong or in Germany.

Problem is, they have to be 100% reliable and properly calibrated.
If calibration is off, it's very, VERY difficult to correct that.
So we fix what we can, but we keep an eye on effinciëncy,
spending too many hours on one CD-player is more expensive than
ordering a new one...

mrtakib said:
I was thinking of a Tent XO2/5 clock with an xo supply, the other I looked at was a Superclock 4 from Audiocom, but it's a lot more expensive.

Tent products are really good, I'll be using Tent XO's with flea power regulators:
http://www.pinkfishmedia.net/forum/showthread.php?t=21594

mrtakib said:
I should ask you this on another thread, but did you try your Opus dac after the Studer ?
I'm thinking to build something like that as a DAC1 or DA10 are a bit expensive . First I was thinking of it for the Studer, but now just for HD playback when I get around to that.

Yes, I did, Opus is a great sounding DAC, but it reveils every problem with the transport. In case of the studer vs my denon, denon sounded a lot better. Absolute jitter from both players measures the same, but the spectrum of the jitter is very different.
--> measured with AP system two.
I'll continue working with the opus (flea powerd XO on receiver and flea powerd XO on the ASRC will improve sound even more, I hope).

mrtakib said:
Another piece I need to build from a kit or buy cheap, is a phono stage. Ever do that, any recomendations?

I did, but ended up with a Musical Fidelity A3, I really like the sound of it's phono stage. I tried different op-amps and plain simple tube stages, but in the end, the MF was the winner there.
What kind of turntable are you using? I've got one Thorens TD-160 and a Technics SL-1200mkII. Changed grounding connections on both. Ground loop problems are worse than a less than perfect phono stage.
 

mrtakib

Member
2008-01-07 9:49 am
OneyedK said:
What kind of turntable are you using? I've got one Thorens TD-160 and a Technics SL-1200mkII. Changed grounding connections on both. Ground loop problems are worse than a less than perfect phono stage.

[/B]


Normally I will receive a JF LETALLEC ALFA 1 in about 6 weeks from a friend. It has no cartridge. My pre amp is a line stage only so I will need a phone stage for sure. I'm trying to use the time I have to find something, then I'll choose a cartridge.

I'll remember the ground loop advice. What did you change then to?


I guess I better just forget about sticking a dac after the Studer !
 

OneyedK

Member
2007-10-02 9:57 pm
mrtakib said:

I'll remember the ground loop advice. What did you change then to?

The amp is the central grounding in a system.
Most turntable makers like to think the central grounding is on the turntable, so you end up with three ground connections in between.

Cartridges have two connections per channel, one hot, one cold.
The cold should be connected only to the shield of the shielded cable you use to go into your amplifier. The cold should not be connected to the ground of the turntable, nor should left cold and right cold be connected to eachother (they are connected on the amp side).
The ground wire from the amp should be connected to the turntable chassis and/or tonearm.
If there is no ground wire, create one...

This sollution works with turntables with good tonearms, good cartridges en good cabling.
If the wires inside the tonearm are of poor quality, you might have to go to a central earth point close to the bearing of the tonearm.
In that case you ommit the extra ground wire...
 

mrtakib

Member
2008-01-07 9:49 am
My friends A730 has some display problems. The battery is ok. Do you know some one that can repair ? It sounds like you would know ! He also wants to buy an unmodified D730 in case you know anyone as well.

My display some times is blank, but I just turn the machine off and on again and presto, it works.
 

OneyedK

Member
2007-10-02 9:57 pm
A730: please describe the exact display problem, there are many reasons for the display to fail in these units.

D731: check all power supply parts, when the display blanks on these machines, it's an indication of overheating or voltages out of spec.
You need to take care of the problem before another part of the player get's damaged.
If it happens when you use the player after a long switch-off time, there will be capacitors to be replaced.
If it happens when the player has been switched on for several days, you need to take care of the rectifiers too.

These are (were) professionally used CD-players, chances that you bought one that was not extensively used are very limited.
So at least the power supplies do need a cap job.
 

mrtakib

Member
2008-01-07 9:49 am
OneyedK said:
A730: please describe the exact display problem, there are many reasons for the display to fail in these units.

When the machine is turned on it does not work, he puts the disk in and gets "no disk" The machine needs to be on for a while to warm up and after that he has to keep pushng the play button many times. Like 4 or 5 mins and then the display goes on and the disk spins and plays.
I guess it's not just a display problem.