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OLD THREAD DAC End by Andrea Ciuffoli

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#384
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#389
General Question

The boards look great !!!!.

When there is a discrepancy between schematic and BOM which should be followed?

for example I/V power supply schematic calls for 2.2 ohm/3W resistors whereas BOM says 0.2 ohm/ 3W. Please don't take this as criticism.

For the I/V stage are C1,C7, R30,R31,R32,R33 needed for this project?
It seems that the resistors are taken care of by the 200 ohm resistors on DAC board.

Thanks

Bob
 
#393
HV power supply for the Tube stage

Hi Andrea, Quanghao and all members,

I would like to know in your experience if it would be any improvement with using a tube rectifier instead of the solid state diodes in the HV power supply for the E182CC. I can see in the schematic there are caps in parallel to the diodes of the bridge rectifier to suppress switching noise of the diodes. I know the tube rectifier is more gentle with switching the half waves. Please tell me your experience.

Also what would be the result of using tube regulators in place of the 47+47uF capacitor next to the loading resistor of the E182CC.
What is your experience of capacitor vs tube regulator? Is there any rule of thumb about it?

Thanks
 
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#397
apelizzo,
In a my recent experience with the my 845 two stage amplifier I have created a comparison test between the vacumm tubes and the solid stage rectifiers.
A full bridge of 6D22 Svetlana has been compared with a series of 1N5408 diodes (see http://www.audiodesignguide.com/Claudio845/GM70_ps1.gif for detailts).
No difference in the final sound has been detected from my friends.
Only using lower performences vacuum diodes like 5R4 and GM70 connected as diode you can detect a more softened sound but many many details are lost.
So, my idea is that in many cases the vacuum diodes may worsen the sound and it is very difficult that these improve it.
In any case you can make your experince and design a simple vaccum tube for this dac using a 5Y3, a 47+47uF Jensen cap. and a LL1636 20H 100mA choke.
 
#398
Glow Tubes voltage regulator or Cathode Gas Diode

audiodesign said:
apelizzo,
In a my recent experience with the my 845 two stage amplifier I have created a comparison test between the vacumm tubes and the solid stage rectifiers.
A full bridge of 6D22 Svetlana has been compared with a series of 1N5408 diodes (see http://www.audiodesignguide.com/Claudio845/GM70_ps1.gif for detailts).
No difference in the final sound has been detected from my friends.
Only using lower performences vacuum diodes like 5R4 and GM70 connected as diode you can detect a more softened sound but many many details are lost.
So, my idea is that in many cases the vacuum diodes may worsen the sound and it is very difficult that these improve it.
In any case you can make your experince and design a simple vaccum tube for this dac using a 5Y3, a 47+47uF Jensen cap. and a LL1636 20H 100mA choke.
Click to expand...

Andrea,
Thanks for sharing your experience. I really appreciate.
I would like to know also about your experience with Gas tube regulator used as shunt on the plate resistor. They should act as "large capacitor". But what is your experience with these glow tubes instead of electrolytic capacitors for example in a E182cc tube stage like the DAC1865?

Best Regards
 
#399
audiodesign said:
apelizzo,
In a my recent experience with the my 845 two stage amplifier I have created a comparison test between the vacumm tubes and the solid stage rectifiers.
A full bridge of 6D22 Svetlana has been compared with a series of 1N5408 diodes (see http://www.audiodesignguide.com/Claudio845/GM70_ps1.gif for detailts).
No difference in the final sound has been detected from my friends.
Only using lower performences vacuum diodes like 5R4 and GM70 connected as diode you can detect a more softened sound but many many details are lost.
So, my idea is that in many cases the vacuum diodes may worsen the sound and it is very difficult that these improve it.
In any case you can make your experince and design a simple vaccum tube for this dac using a 5Y3, a 47+47uF Jensen cap. and a LL1636 20H 100mA choke.
Click to expand...

My experiences in my 4xTDA1541 DAC projekt are quite contrary to yours,

after changing to the 6X4 rectifier with the Tent Lab E-Choke.

An externally hosted image should be here but it was not working when we last tested it.
 
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