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Valve DAC from Linear Audio volume 13
Valve DAC from Linear Audio volume 13
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Old 11th August 2020, 01:44 AM   #561
spm is offline spm  United Kingdom
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Old 11th August 2020, 02:50 AM   #562
Dubulup is offline Dubulup  United States
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Old 11th August 2020, 05:40 AM   #563
Raj1 is offline Raj1  United Kingdom
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Quote:
Originally Posted by MarcelvdG View Post
I was seeing problems that aren't there. I just looked up the 3A5 datasheet ( http://www.r-type.org/pdfs/3a5.pdf ) and apparently the CD enhancer II circuit is designed for a 0 V input common-mode voltage. Apart from adding those 180 ohm resistors to ground, you don't need to do anything special to interface the valve DAC main board with the CD enhancer II circuit.

(For the record, using termination resistors to a positive supply at the DAC output would have been impossible anyway because of the way the mute circuit is designed.)

Ahh cool. Do I still need the reconstruction filer to precede it?
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Old 11th August 2020, 06:10 AM   #564
diyAchim is offline diyAchim
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Join Date: Dec 2012
diyAchim - 1 PCB (Germany)
Raj!1 - 1 PCB (UK)
dubulup - 2 PCB (USA)
ericoto -1 PCB
HenSch - 2 PCB (Germany)
mterbekke - 2 PCB (Netherlands)
rfbrw - 1 PCB
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pgour - 1 PCB
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spm - 1 PCB (UK)


Total = 15
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Old 11th August 2020, 06:14 AM   #565
MarcelvdG is offline MarcelvdG  Netherlands
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Raj1, you will need the two filter capacitors on the main board, but you can probably do without the rest of the reconstruction filter. That is, I understand from the website that you linked to that the CD enhancer II itself is meant to be used as a reconstruction filter for sigma-delta DACs.
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Old 11th August 2020, 06:19 AM   #566
Raj1 is offline Raj1  United Kingdom
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Yes, it creates a roll off around 22khz iirc. Iím looking forward to trying this out. Thanks to both of you for helping!
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Old 11th August 2020, 06:57 AM   #567
Raj1 is offline Raj1  United Kingdom
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I assume I need to keep C28 & C29 (and their equivalents on the other channel), and can do away with the DC blocking caps C31 & C32?
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Last edited by Raj1; 11th August 2020 at 07:01 AM.
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Old 11th August 2020, 07:37 AM   #568
MarcelvdG is offline MarcelvdG  Netherlands
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No, you will need C28, C29, C31 and C32. You might be able to do without C31 and C32 when you redesign the muting circuit and apply a negative voltage to the tail resistor of the CD enhancer II.
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Old 11th August 2020, 07:43 AM   #569
Raj1 is offline Raj1  United Kingdom
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Got it. Thanks!
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Old 11th August 2020, 03:20 PM   #570
diyAchim is offline diyAchim
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Hello Marcel - thank you for your work and your generosity!
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