Kooka, that LED SK8 will only light up when it locks onto your transport. It is not a power indicator. When you push play on your transport with CD in tray, the LED must emit light or else you have a problem.
You can test whether you have the traffos hooked up by measuring the voltage by placing your multimeter leads on the screw heads of the wire terminals (on the pcb) to which your traffo leads attach. If you are a beginner like me, be careful
You can test whether you have the traffos hooked up by measuring the voltage by placing your multimeter leads on the screw heads of the wire terminals (on the pcb) to which your traffo leads attach. If you are a beginner like me, be careful
riotubes said:
That's great, and it is what I was thinking. My big problem is that I do not have any kind of instructions about this dac beside this great thread, and only one status led made me doubt it was a power led... Thanks.
Thanks Ronald and Quan Tran for prompt and helfpul feedback. Yes, the Tjoeb is an entirely different animal; with the 1541 I wanted to try NOS. I do appreciate Quan's characterization of the 1541's presentation. And I think it is a fair point that the signal should be reclocked on the dac board. I have delayed this, as I always intended to install usb>i2s from the beginning. I am still awaiting the usb>i2s board (with Tent clock) from Doede. Hopefully by 3rd wek in Jan I will have it running. Based on the previous positive feedback from Shane, I look forward to an improvement.
I will replace the decoupling caps. I am not sure what is available in the US but I read some prior posts by Thorsten suggesting that .1uF foil/film work well except for the msb pins where he suggested Os Cons of 3.3uF value to improve bass (post is quite dated...2001).
This brings me to one more Q. Quan, have you tried a single, double crown 1541? Obviously, this would mean less decoupling caps. It would also mean lower voltage for me
not good for use with passive pre unless I go with a higher mu tube which presents problems in itself. At slightly above 2V with the present 6dj8 stage, I feel like I could benefit from slightly more headroom.
I will replace the decoupling caps. I am not sure what is available in the US but I read some prior posts by Thorsten suggesting that .1uF foil/film work well except for the msb pins where he suggested Os Cons of 3.3uF value to improve bass (post is quite dated...2001).
This brings me to one more Q. Quan, have you tried a single, double crown 1541? Obviously, this would mean less decoupling caps. It would also mean lower voltage for me
not good for use with passive pre unless I go with a higher mu tube which presents problems in itself. At slightly above 2V with the present 6dj8 stage, I feel like I could benefit from slightly more headroom.Kooka,
I have step-by-step instructions, please pm me and I'll send them to you. They are not detailed, but do encompass all of the steps to get it running. Mind you, I installed the tube buffer....not the op amp board.
I have step-by-step instructions, please pm me and I'll send them to you. They are not detailed, but do encompass all of the steps to get it running. Mind you, I installed the tube buffer....not the op amp board.
Mike
I probably made you confused about the caps. The ERO decoupling caps next to the tda1541a are quite good actually. Of course they could also be changed for something even more exotic but I think you should change all the power supply bypass caps first. They are the brown colour ones. The caps in the filter circuit of cs8414 should also be changed. Any decent polypropylene caps like WIMA or RIFA will be good. Foil caps may be slightly better than metallised one but they are very big so are difficult to install.
I also replaced the cap in series with the input transformer with a piece of wire. If your transport also has an output transformer, this cap is useless and only degrade performance.
All the 1nf caps across the diodes were also replaced with polystyrene foil caps I have on hand.
I am using a normal pair of tda1541a only (date code HSH8910). I think there is some think else to do with the lack of dynamic you mentioned because I use my DAC to drive a SS power amp with input impedance of about 20K directly. I do not feel that it lack any dynamic.
Cheers
I probably made you confused about the caps. The ERO decoupling caps next to the tda1541a are quite good actually. Of course they could also be changed for something even more exotic but I think you should change all the power supply bypass caps first. They are the brown colour ones. The caps in the filter circuit of cs8414 should also be changed. Any decent polypropylene caps like WIMA or RIFA will be good. Foil caps may be slightly better than metallised one but they are very big so are difficult to install.
I also replaced the cap in series with the input transformer with a piece of wire. If your transport also has an output transformer, this cap is useless and only degrade performance.
All the 1nf caps across the diodes were also replaced with polystyrene foil caps I have on hand.
I am using a normal pair of tda1541a only (date code HSH8910). I think there is some think else to do with the lack of dynamic you mentioned because I use my DAC to drive a SS power amp with input impedance of about 20K directly. I do not feel that it lack any dynamic.
Cheers
Thanks Quan Tran for the clarification. You said bypass caps and I mistakenly thought "decoupling". I guess the topic of decoupling caps was fresh on my mind. I understand. Yes, I was also thinking those film polyprop caps look too big!
Regarding the input cap on the digital line, this is good to know because my transport does have a digital transformer. I'll try these mods.
Regarding the input cap on the digital line, this is good to know because my transport does have a digital transformer. I'll try these mods.
The Tjoeb is non-oversampling as well 😀 But I guess the main difference is in the I/V conversion which is done by an opamp in the Tjoeb and by resistors in this DAC.riotubes said:
I also replaced the power supply diodes for much faster schottky types.
I did not listen (yet) if this makes any audible difference but it should be better.
I did not listen (yet) if this makes any audible difference but it should be better.
SCHEMATICS
Does anyone have schematics for Thomas’s dac ver.2 (tube buffer, op amp stage, main board, clock boards etc.)
I purchased one and did not receive the schematics.
Thanks
Tony
Does anyone have schematics for Thomas’s dac ver.2 (tube buffer, op amp stage, main board, clock boards etc.)
I purchased one and did not receive the schematics.
Thanks
Tony
CDM9 gear
Hi Thomas,
As I am a new member to diy I can't email you directly yet. I wanted to know if you still had any of the drawer drive gear for my Theta Data Basic or CDM9 transport? If so you can email me at dkloepping AT bellsouth DOT net Or leave info on how to get them on this thread. TY
David
Hi Thomas,
As I am a new member to diy I can't email you directly yet. I wanted to know if you still had any of the drawer drive gear for my Theta Data Basic or CDM9 transport? If so you can email me at dkloepping AT bellsouth DOT net Or leave info on how to get them on this thread. TY
David
Re: SCHEMATICS
Yes, can someone please email me all the documentation for assembling the Ver.2 DAC as well?
Also, if anyone has the Ver.1 DAC instructions, I'll take those too.
My email address is ftjandra (AT) mindspring (DOT) com
Thanks!
dod996 said:
Yes, can someone please email me all the documentation for assembling the Ver.2 DAC as well?
Also, if anyone has the Ver.1 DAC instructions, I'll take those too.
My email address is ftjandra (AT) mindspring (DOT) com
Thanks!
hi all.
long long long time no see. My health was bad & I left for my work post approx 8 months pass year. During this period I funish some project& now hope to share .
Take a full look of the dac, all transformers nort include, 5687 cathode follower not include.
This is full balance 1541a DAC, total had 11~12pcs PCB.
USE three isolate power transformers.
nano-amorphous pulse transformers input.
USB input.
pre-amp output stage.
5687 cathode follower output stage.
IV transformers.
thx
thomas
long long long time no see. My health was bad & I left for my work post approx 8 months pass year. During this period I funish some project& now hope to share .
Take a full look of the dac, all transformers nort include, 5687 cathode follower not include.
This is full balance 1541a DAC, total had 11~12pcs PCB.
USE three isolate power transformers.
nano-amorphous pulse transformers input.
USB input.
pre-amp output stage.
5687 cathode follower output stage.
IV transformers.
thx
thomas
Attachments
Hi Thomas,
As I am a new member to diy I can't email you directly yet. I wanted to know if you still had any of the drawer drive gear for my Theta Data Basic or CDM9 transport? If so you can email me at dkloepping AT bellsouth DOT net Or leave info on how to get them on this thread. TY
David
As I am a new member to diy I can't email you directly yet. I wanted to know if you still had any of the drawer drive gear for my Theta Data Basic or CDM9 transport? If so you can email me at dkloepping AT bellsouth DOT net Or leave info on how to get them on this thread. TY
David
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