Hi all,

I am wishing to build a replacement transformer for my Cambridge Audio
DacMagic DAC (the new one that's just come out). I am unhappy with the
original PSU because it is inefficient and doesn't have a physical
on/off switch so it's constantly drawing a current unless you unplug it,
and I like to save evergy where I can.

So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer, in the hope that it will reduce
power consumption and, if I'm lucky, make the DAC sound better.

Would something like this do?

http://preview.tinyurl.com/6q5ceu (eBay item # 270286161572)?

The power input on the DAC requires 1.5 amps AC.

What else would I need, other than a circuit board, a rocker switch and
some kind of housing? Or should I just give up on the idea and stop
wasting my time?

Any advice is appreciated, my electronics knowledge is GCSE standard
(i.e. not very good).

Thanks in advance,

Anton

Anton Gÿsen wrote:

The power input on the DAC requires 1.5 amps AC.

Forgot to mention, it's 12 volts.

Anton Gÿsen wrote:
Hi all,

I am wishing to build a replacement transformer for my Cambridge Audio
DacMagic DAC (the new one that's just come out). I am unhappy with the
original PSU because it is inefficient and doesn't have a physical
on/off switch so it's constantly drawing a current unless you unplug it,
and I like to save evergy where I can.


Use a PC switchmode power supply? or just disconnect the whole thing and
run from the original audio outputs of the CD player.

/me looks, ducks and runs for cover ...

Seriously, the replacement "enthusiast" power supply market for digital
addons is getting a bit OTT. I've got an Audio Alchemy dac-in-the-box
(use it for PC audio from S/PDIF) and lots of folks are brewing
alternative power supplies for that. Same goes for the
Slimdevices/Logitech Squeezebox.

--
Adrian C

Adrian C wrote:

Use a PC switchmode power supply? or just disconnect the whole thing and
run from the original audio outputs of the CD player.

/me looks, ducks and runs for cover ...

Nice try

Seriously, the replacement "enthusiast" power supply market for digital
addons is getting a bit OTT. I've got an Audio Alchemy dac-in-the-box
(use it for PC audio from S/PDIF) and lots of folks are brewing
alternative power supplies for that. Same goes for the
Slimdevices/Logitech Squeezebox.

Glad I'm in the right ballpark and my idea is not ridiculous. I love the
DAC but they really scrimped on the cheapo Chinese PSU.

"Anton Gÿsen" wrote in message
...
Hi all,

I am wishing to build a replacement transformer for my Cambridge Audio
DacMagic DAC (the new one that's just come out). I am unhappy with the
original PSU because it is inefficient and doesn't have a physical
on/off switch so it's constantly drawing a current unless you unplug it,
and I like to save evergy where I can.

So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer, in the hope that it will reduce
power consumption and, if I'm lucky, make the DAC sound better.

Would something like this do?

http://preview.tinyurl.com/6q5ceu (eBay item # 270286161572)?

That is a 75VA transformer, far too large for what you want.

And what makes you think it would be any more efficient that what you
already have?

David.

David Looser wrote:
"Anton Gÿsen" wrote in message
...
Hi all,

I am wishing to build a replacement transformer for my Cambridge Audio
DacMagic DAC (the new one that's just come out). I am unhappy with the
original PSU because it is inefficient and doesn't have a physical
on/off switch so it's constantly drawing a current unless you unplug it,
and I like to save evergy where I can.

So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer, in the hope that it will reduce
power consumption and, if I'm lucky, make the DAC sound better.

Would something like this do?

http://preview.tinyurl.com/6q5ceu (eBay item # 270286161572)?

That is a 75VA transformer, far too large for what you want.

Will the DAC not just draw what current it needs? Is there danger of
damaging my DAC with that transformer?

And what makes you think it would be any more efficient that what you
already have?

Wikipedia reckons they're more efficient than the standard type of cheap
transformers (the name of which escapes me). They seem to be the
audiophile transformer of choice.

"Anton Gÿsen" wrote in message
...
David Looser wrote:
"Anton Gÿsen" wrote in message
...
Hi all,

I am wishing to build a replacement transformer for my Cambridge Audio
DacMagic DAC (the new one that's just come out). I am unhappy with the
original PSU because it is inefficient and doesn't have a physical
on/off switch so it's constantly drawing a current unless you unplug it,
and I like to save evergy where I can.

So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer, in the hope that it will reduce
power consumption and, if I'm lucky, make the DAC sound better.

Would something like this do?

http://preview.tinyurl.com/6q5ceu (eBay item # 270286161572)?

That is a 75VA transformer, far too large for what you want.

Will the DAC not just draw what current it needs? Is there danger of
damaging my DAC with that transformer?

Transformers are designed to produce the nominal output voltage at full
current draw, when under-loaded the output voltage is higher, typically
10-15% higher. This may not damage your DAC, but it will increase the heat
dissipation within the DAC and increase the stress on the internal
components. In addition an over large transformer is, well, over large;
bigger, heavier and more expensive than you need. Oh, and it will be less
efficient than one of the correct size.


And what makes you think it would be any more efficient that what you
already have?

Wikipedia reckons they're more efficient than the standard type of cheap
transformers (the name of which escapes me). They seem to be the
audiophile transformer of choice.

They are *slightly* more efficient (if correctly rated). But most of the
total inefficiency is due to the rectifier/regulator part of the PSU, which
is inside the DAC. Toroidal transformers also have a lower external magnetic
field, but if the transformer is external to the DAC that isn't important.

Changing the transformer will make negligible difference to the efficiency
of your DAC, and no difference whatsoever to the sound.

David.

David Looser wrote:
"Anton Gÿsen" wrote in message
...
David Looser wrote:
"Anton Gÿsen" wrote in message
...
Hi all,

I am wishing to build a replacement transformer for my Cambridge Audio
DacMagic DAC (the new one that's just come out). I am unhappy with the
original PSU because it is inefficient and doesn't have a physical
on/off switch so it's constantly drawing a current unless you unplug it,
and I like to save evergy where I can.

So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer, in the hope that it will reduce
power consumption and, if I'm lucky, make the DAC sound better.

Would something like this do?

http://preview.tinyurl.com/6q5ceu (eBay item # 270286161572)?
That is a 75VA transformer, far too large for what you want.
Will the DAC not just draw what current it needs? Is there danger of
damaging my DAC with that transformer?

Transformers are designed to produce the nominal output voltage at full
current draw, when under-loaded the output voltage is higher, typically
10-15% higher. This may not damage your DAC, but it will increase the heat
dissipation within the DAC and increase the stress on the internal
components. In addition an over large transformer is, well, over large;
bigger, heavier and more expensive than you need. Oh, and it will be less
efficient than one of the correct size.

OK so a lower rated transformer would be more appropriate?
So... when my amplifier for example (which has a toroidal core
transformer) is operating at low volume and therefore drawing a low
current it is stressing the components in the way that you describe?

And what makes you think it would be any more efficient that what you
already have?
Wikipedia reckons they're more efficient than the standard type of cheap
transformers (the name of which escapes me). They seem to be the
audiophile transformer of choice.

They are *slightly* more efficient (if correctly rated). But most of the
total inefficiency is due to the rectifier/regulator part of the PSU, which
is inside the DAC. Toroidal transformers also have a lower external magnetic
field, but if the transformer is external to the DAC that isn't important.

The DAC does get rather warm but I thought that was the DAC ICs. The
"wall wart" PSU gets warm although it is encased in plastic.

Changing the transformer will make negligible difference to the efficiency
of your DAC, and no difference whatsoever to the sound.

Thanks David, your information is useful.

"Anton Gÿsen" wrote in message
...
David Looser wrote:
"Anton Gÿsen" wrote in message
...
David Looser wrote:
"Anton Gÿsen" wrote in message
...
Hi all,

I am wishing to build a replacement transformer for my Cambridge Audio
DacMagic DAC (the new one that's just come out). I am unhappy with the
original PSU because it is inefficient and doesn't have a physical
on/off switch so it's constantly drawing a current unless you unplug
it,
and I like to save evergy where I can.

So I was wondering whether I could build a new transformer for it
based
around a toroidal core transformer, in the hope that it will reduce
power consumption and, if I'm lucky, make the DAC sound better.

Would something like this do?

http://preview.tinyurl.com/6q5ceu (eBay item # 270286161572)?
That is a 75VA transformer, far too large for what you want.
Will the DAC not just draw what current it needs? Is there danger of
damaging my DAC with that transformer?

Transformers are designed to produce the nominal output voltage at full
current draw, when under-loaded the output voltage is higher, typically
10-15% higher. This may not damage your DAC, but it will increase the
heat
dissipation within the DAC and increase the stress on the internal
components. In addition an over large transformer is, well, over large;
bigger, heavier and more expensive than you need. Oh, and it will be less
efficient than one of the correct size.

OK so a lower rated transformer would be more appropriate?
So... when my amplifier for example (which has a toroidal core
transformer) is operating at low volume and therefore drawing a low
current it is stressing the components in the way that you describe?


I don't understand what you hope to achieve by changing the transformer.
Apart from the inconvenience of the on-off switch, what is it about the
present arrangement that is inadequate? If you want to add an on-off switch,
then why not make a small mains extension, and put a torpedo switch near the
socket, and position it where you can conveniently reach it and switch it
off when not in use? A new transformer won't be significantly more efficient
than what you have. A bigger one will be less efficient at lower draws, and
as mentioned above, will have an increased voltage and stress the DAC
components more. If you're concerned about the total carbon footprint of
each item, then throwing away something existing and buying something new
will increase the total carbon footprint, and you won't recover this unless
the new one is a lot more efficient than the old, which is unlikely.

Seems you're making this much more difficult than it needs to be.

S.
--
http://audiopages.googlepages.com

"Anton Gÿsen" wrote in message
...
David Looser wrote:

Transformers are designed to produce the nominal output voltage at full
current draw, when under-loaded the output voltage is higher, typically
10-15% higher. This may not damage your DAC, but it will increase the
heat
dissipation within the DAC and increase the stress on the internal
components. In addition an over large transformer is, well, over large;
bigger, heavier and more expensive than you need. Oh, and it will be less
efficient than one of the correct size.

OK so a lower rated transformer would be more appropriate?

Yes, 20VA.

So... when my amplifier for example (which has a toroidal core
transformer) is operating at low volume and therefore drawing a low
current it is stressing the components in the way that you describe?

Indeed, and the amplifier designer will have taken that into account when
specifying components. A DAC, on the other hand, takes a more or less
constant load so the designer will not have had to allow for load current
variations in his design, or the use of an unnecessarily large transformer.

And what makes you think it would be any more efficient that what you
already have?
Wikipedia reckons they're more efficient than the standard type of cheap
transformers (the name of which escapes me). They seem to be the
audiophile transformer of choice.

They are *slightly* more efficient (if correctly rated). But most of the
total inefficiency is due to the rectifier/regulator part of the PSU,
which
is inside the DAC. Toroidal transformers also have a lower external
magnetic
field, but if the transformer is external to the DAC that isn't
important.

The DAC does get rather warm but I thought that was the DAC ICs.

Much of it will be due to the rectifier and regulator.

The
"wall wart" PSU gets warm although it is encased in plastic.

It will, it's not a problem.

David.