A NOS 192/24 DAC with the PCM1794 (and WaveIO USB input)

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rfthon

Member
Joined 2013
G600 said:
Doede, what do you think for the power supply upgrade : replace the 2 blue trafos with one big toroidal maybe 250VA with two secondaries : 15V and 8V (1A on each ?), and wire them to 2 of your power suply boards ?
Or maybe it's a better idea to buy a big one just for 12V, no improvement for 5V ?

One thing I don't understand with regulator upgrades : we just have to replace the existing ones and voilà, or is there a voltage increase to do for the "voltage drop" ?
Click to expand...

Doede uses 2 (rectifier) diodes instead of a rectifier bridge (4 diodes).
This is possible because the blue transformers have 2 secondaries, so 2x 9V or 2x 15V.
See also the schematic drawings of his power supplies.

If you want to use another transformer with lets say 1x 15V you need to exchange the 2 diodes with a diode bridge of 4 diodes.
 
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ErikdeBest

Member
Joined 2003
Thinking along the lines of G600 about using a big customized transformer.

I remember a post by Nelson Pass where he describes that for extreme low noise he uses overdimensioned toroidal transformers with 240V primaries connected to the american 120V net. As G600 is able to have a big toroidal made to order, it could be interesting to put request a 380V primary on a 250VA core, with secondaries at 25V (or 50V with CT) and 15V (or 30V with CT). Connecting the 380V primary to the 230V European mains would result in the right (15V and 9V) on the secondary. The VA rating would decrease from the 250VA, but still be enough to feed the DAC circuit.
 
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rfthon

Member
Joined 2013
G600 said:
Thank you for helping rfthon.

As i'm thinking of having a toroidal made to order, I can ask for custom secondaries.
So with your help I can keep Doede's PS boards and use a big transformer.

I assume this upgrade is useful only for 12V ?
Click to expand...

I didn't try it for myself, but I think for the 5V it could also be useful.
The proof of the pudding is in the eating.:)
Had some good experience in changing the power supply of my Mac Mini.
Maybe somebody on this forum has allready a good experience with a heavier power supply for the usb board.
Remind you that Doede uses 9V secundair on the transformer for the 5V PS.
 
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rfthon

Member
Joined 2013
ErikdeBest said:
Thinking along the lines of G600 about using a big customized transformer.

I remember a post by Nelson Pass where he describes that for extreme low noise he uses overdimensioned toroidal transformers with 240V primaries connected to the american 120V net. As G600 is able to have a big toroidal made to order, it could be interesting to put request a 380V primary on a 250VA core, with secondaries at 25V (or 50V with CT) and 15V (or 30V with CT). Connecting the 380V primary to the 230V European mains would result in the right (15V and 9V) on the secondary. The VA rating would decrease from the 250VA, but still be enough to feed the DAC circuit.
Click to expand...

Interesting experiment
 
R

rfthon

Member
Joined 2013
ErikdeBest said:
Thinking along the lines of G600 about using a big customized transformer.

I remember a post by Nelson Pass where he describes that for extreme low noise he uses overdimensioned toroidal transformers with 240V primaries connected to the american 120V net. As G600 is able to have a big toroidal made to order, it could be interesting to put request a 380V primary on a 250VA core, with secondaries at 25V (or 50V with CT) and 15V (or 30V with CT). Connecting the 380V primary to the 230V European mains would result in the right (15V and 9V) on the secondary. The VA rating would decrease from the 250VA, but still be enough to feed the DAC circuit.
Click to expand...
 
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rhlauranna

Member
Joined 2005
5 Volt and 12 Volt controlled/regulated power supplies

there are some questions regarding the implementation of external ( n o t via USB) controlled power supplies for both the DDDAC1543 and DDDAC1794 for 5 Volt and 12 Volt...

so, for those who might be interested in our fantastic ameliorations in sound reproduction with these, please have a look here:

#1072
http://www.diyaudio.com/forums/digi...-192-24-dac-pcm1794-waveio-usb-input-108.html

TWOGOODEARS - ??????????: Reinhard's new essay about ISO, USB and Doede Douma's DDDACs - digital ripping and reproducing done right

TWOGOODEARS - ??????????: A Reinhard Huttenburg's essay - "Is it possible to combine futuristic music sources with a 100 year old loudspeaker system?"
 
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