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.
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 .
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.
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 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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