The controller is not the problem. It's the communication with the dac that I don't like. I don't want to count on a mass produced cd-rom chip producing a digital out when I think there is better. Wouldn't it be worth finding the best possible I2S cd-rom and build a controller around it?
I don't know I want I2S. I don't think the Plexor has it. This tda1541A chip can take it. So why not use it? Maybe it's not as good as I think it is?
If there was a cd-rom controller that extracted digital data from many types of cd-rom drives (for playing around), connected it to this ver.3 dac, and other dacs, and sounding realy good, then yes.
This is where I am at. I can't find sound comparisons of cd-roms anywhere. Probably because it would be very difficult. I think I'm ready to listen to music for a while. The cd rom digital, sounds worse then my Eastsound E5's digital. It probably could be tweeked, but I want to plug and play. Literally, with many I2S dives.
I don't know I want I2S. I don't think the Plexor has it. This tda1541A chip can take it. So why not use it? Maybe it's not as good as I think it is?
If there was a cd-rom controller that extracted digital data from many types of cd-rom drives (for playing around), connected it to this ver.3 dac, and other dacs, and sounding realy good, then yes.
This is where I am at. I can't find sound comparisons of cd-roms anywhere. Probably because it would be very difficult. I think I'm ready to listen to music for a while. The cd rom digital, sounds worse then my Eastsound E5's digital. It probably could be tweeked, but I want to plug and play. Literally, with many I2S dives.
The dac is where I want to focus. I think improvments on this dac can benifit me too. I purchased the 8412-is chip and some Philips opamps. I also spent $80.00 on the S2. I would like to modify the power supply and output, but I'm not an engineer. I can read a schematic. I am hoping to pick up some tips from this forum.
Hello Jean-Charles
thanks for your reply #20.
The Jfet I/V stage ( there is one on this forum) or the original Passlabs , do cascode the output of the 1541A .
Both have a output buffer with a low enough output impedance .
On the main board You can isolate the resistor I/V stage ( 50 ohm load ) and the OP amp output stage by removing the JP6 shorts on it .
Then connect 3 wires of the external I/V stage directly to the DAC output, L R and groud .
Pretty simple and there is no need to modyfy anything on the DAC Ver3 board .
But -yes- the DAC Ver3 has a groud loop . Connecting external I/V stage and run the RCA pins *from* there , it shows far less effects . But on board it is quite noticiable .
I 'll try to isolate some grounds from the Power Supply and report later if I can get rid of the loop.
thanks for your reply #20.
The Jfet I/V stage ( there is one on this forum) or the original Passlabs , do cascode the output of the 1541A .
Both have a output buffer with a low enough output impedance .
On the main board You can isolate the resistor I/V stage ( 50 ohm load ) and the OP amp output stage by removing the JP6 shorts on it .
Then connect 3 wires of the external I/V stage directly to the DAC output, L R and groud .
Pretty simple and there is no need to modyfy anything on the DAC Ver3 board .
But -yes- the DAC Ver3 has a groud loop . Connecting external I/V stage and run the RCA pins *from* there , it shows far less effects . But on board it is quite noticiable .
I 'll try to isolate some grounds from the Power Supply and report later if I can get rid of the loop.
Kip :
since there are I P issues and it is not possible to link to the service manuals anymore if you want I can PM to you a copy of the Pass Labs I/V stage .
since there are I P issues and it is not possible to link to the service manuals anymore if you want I can PM to you a copy of the Pass Labs I/V stage .
Hi Stefanobilliani,
I'm also interested in the Jfet Pass output stage.
Can you mail it also to me?
Thanks,
Peter.
I'm also interested in the Jfet Pass output stage.
Can you mail it also to me?
Thanks,
Peter.
Stevox said:
Well if you send to me a PM I can attach back the file .
Or show your address here .
By the way , the original Pass I/V is with Mosfets IRF610 .
I builded a very similar version with Jfet Lovoltech LU1014D, and one design from a member here is with 2SK170 .
Hi Stefanobilliani,
What do you mean with ''On the main board You can isolate the resistor I/V stage ( 50 ohm load ) '' ?
peter.
What do you mean with ''On the main board You can isolate the resistor I/V stage ( 50 ohm load ) '' ?
peter.
I mean that via JP6 ( 3 jumpers) TDA1541A is connected to: the I/V stage (R56-R57 left channell , R59 R60 right channell ) ; the OP amplifier ( via R58 left and R61 right ) . So by removing the jumpers the TDA1541A analog current outputs are completely isolated and ready to be connected at a different I/V stage .
For the ground loop issue I suggest to disconnect the grounds from PS to MAIN board relative to + 12 V and - 12 Volt ( JV7 - JV8 ) .
Hi Stefanobilliani,
Is this the correct D1 I/V Stage you are using www.diyaudio.com/forums/showthread.php?postid=616248#post616248 ?
Or is there an update on ?
Another question if I would replace the clock on the main board by another one from Tentslab.
Which do you recommend XO or VCXO.
Thanks,
Peter.
Is this the correct D1 I/V Stage you are using www.diyaudio.com/forums/showthread.php?postid=616248#post616248 ?
Or is there an update on ?
Another question if I would replace the clock on the main board by another one from Tentslab.
Which do you recommend XO or VCXO.
Thanks,
Peter.
stefanobilliani said:
Hi stefano,
Thanks for mail. Are the above modifications complementary to the others you wrote previous?
Marc
Hello Peter (stevox) ,
no I am using one with Lovoltech J fets .
The schematic linked probably has an error if you are using a TDA1541A .Depending on the Vgs of the paralleled Jfets it may be possible that R13 and R14 needs to be at -30V and not at +30 .
Note the polarity of C1 and C2 accordingly .
By my point of view the Xo is pretty good . It needs to drive 2 input gates each one with its own 47ohm series resistor . I also added a ferrite bead and a 100n cap close to it .
It remains an open question for the VCXO since I do not have experience with it .
no I am using one with Lovoltech J fets .
The schematic linked probably has an error if you are using a TDA1541A .Depending on the Vgs of the paralleled Jfets it may be possible that R13 and R14 needs to be at -30V and not at +30 .
Note the polarity of C1 and C2 accordingly .
By my point of view the Xo is pretty good . It needs to drive 2 input gates each one with its own 47ohm series resistor . I also added a ferrite bead and a 100n cap close to it .
It remains an open question for the VCXO since I do not have experience with it .
Hi Stefanobilliani,
Can you tell me, how you exactly connected the ferrite bead and a 100n cap.
Thanks,
Peter.
Can you tell me, how you exactly connected the ferrite bead and a 100n cap.
Thanks,
Peter.
HI Stevox,
On the back of the little clock board I cutted the trace that goes from +Vcc to the Xo . Replaced the trace with the ( double )ferrite bead .Then from there to the ground pin of the Xo placed the capacitor .
On the back of the little clock board I cutted the trace that goes from +Vcc to the Xo . Replaced the trace with the ( double )ferrite bead .Then from there to the ground pin of the Xo placed the capacitor .
Hi Stefanobilliani,
Okay I understand what you are meaning whit this.
The ferrite bead are there different types in, and what did you used.
Thanks,
Peter.
Okay I understand what you are meaning whit this.
The ferrite bead are there different types in, and what did you used.
Thanks,
Peter.
well that's a good question. The answer is : the one that was supplied with the Xo by Mr. G. Tent .
hi stefanobilliani,
can U tell me the different between the tebt XO or VCXO, since I was waiting for NSK.com.cn to call back the VCXO if the VCXO was 5PPM & low jitter, will same as 4 picos or not I don't know now but the price will really expensive.
But the way, can U advise that any point of the dac still need improve???
I was funishing the ultimate dac, I fix the ground loop already with re-layout the power supply area & use two step regulator. But stiill use op-amp but will use transformers output stage.
pass lab IV was good. I had email to nelson already that may be i will reference his IV & wil use into Dac, but looks nelson not like it. so I give up for this. Secondly I was test in LS844,2SK170 & 2sk389. But looks 2sk389 was the best. finally I was choose jan 2n930 with BC109 for the IV of the full balance. any comment of this??
Hi Kip,
I will choose one brand such as plextor or pioneer CD-rom with model no. Hope diyers will easy to know how to modify the clock of the cd-rom with the external clock & how to get the I2S output from the chips.
thx
thomas
can U tell me the different between the tebt XO or VCXO, since I was waiting for NSK.com.cn to call back the VCXO if the VCXO was 5PPM & low jitter, will same as 4 picos or not I don't know now but the price will really expensive.
But the way, can U advise that any point of the dac still need improve???
I was funishing the ultimate dac, I fix the ground loop already with re-layout the power supply area & use two step regulator. But stiill use op-amp but will use transformers output stage.
pass lab IV was good. I had email to nelson already that may be i will reference his IV & wil use into Dac, but looks nelson not like it. so I give up for this. Secondly I was test in LS844,2SK170 & 2sk389. But looks 2sk389 was the best. finally I was choose jan 2n930 with BC109 for the IV of the full balance. any comment of this??
Hi Kip,
I will choose one brand such as plextor or pioneer CD-rom with model no. Hope diyers will easy to know how to modify the clock of the cd-rom with the external clock & how to get the I2S output from the chips.
thx
thomas
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