Hi folks!
I'm currently using - and very much have a ball listening to - my Shanling CD-T80 with Peter Daniel's amazing NOS DAC.
Obviously as I am not using the analogue outputs in the CD-T80 any longer the output valves are just being wasted.
Is it OK/safe to take the valves out, and just have the unit running as-is and using the digital out, or will I damage anything by running it without valves?
Cheers,
- John
I'm currently using - and very much have a ball listening to - my Shanling CD-T80 with Peter Daniel's amazing NOS DAC.
Obviously as I am not using the analogue outputs in the CD-T80 any longer the output valves are just being wasted.
Is it OK/safe to take the valves out, and just have the unit running as-is and using the digital out, or will I damage anything by running it without valves?
Cheers,
- John
Unless you have a schematic and service information I would just leave them in place, it is possible although not likely that removing them will result in higher than intended HV supply voltages which could result in overstressing caps in the supply and the output coupling caps. It is probably not an issue, but if you are concerned about wasting good tubes just stick a known good cheap pair of the same type in the player.
Thanks for your reply Kevin - no circuit diagram alas and can't seem to find one, so best leave everything in place I guess.
Cheers 🙂
Cheers 🙂
I have got Shanling CD-T80 for tweaking. It has very good DAC, Burr-Brown PCM1738 onboard. It is current output chip. There is standard opamps based I/V and gainstage. After that there is poorly designed tube buffer also. The buffer makes nothing good to the sound:
I've got rid off all the opamped stage. I reworked tube stage totally also. The new gainstage looks like that:
I made passive I/V conversion with four 120 ohm resistors. The signal for tube gainstage is derived from 26 (left) and 16 (right) legs of the PCM1798 chip. 17 and 25 legs are loaded with 120 ohms resistors and unused.
The tubes and signal capacitors were replaced too. I used 5670 General Electric tubes and vintage ITT oil caps.
The benefits in sound quality are obvious. There is more details, more precision, more space and more air, but the sound is not too bright or harsh. It is rather sonorous and silky.
More pictures:
I've got rid off all the opamped stage. I reworked tube stage totally also. The new gainstage looks like that:
I made passive I/V conversion with four 120 ohm resistors. The signal for tube gainstage is derived from 26 (left) and 16 (right) legs of the PCM1798 chip. 17 and 25 legs are loaded with 120 ohms resistors and unused.
The tubes and signal capacitors were replaced too. I used 5670 General Electric tubes and vintage ITT oil caps.
The benefits in sound quality are obvious. There is more details, more precision, more space and more air, but the sound is not too bright or harsh. It is rather sonorous and silky.
More pictures:
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One more photo of CD-T80 showing how its design matches to my handmade tube output DAC and tube preamplifier:
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