Replacement transformer
 

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

Replacement transformer
 

Anton Gÿsen wrote:

The power input on the DAC requires 1.5 amps AC.

Forgot to mention, it's 12 volts.

Replacement transformer
 

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

Replacement transformer
 

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.

Replacement transformer
 

"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.

Replacement transformer
 

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.

Replacement transformer
 

"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.

Replacement transformer
 

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.

Replacement transformer
 

"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

Replacement transformer
 

"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.

Replacement transformer
 

Serge Auckland wrote:

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.

The on/off switch is my main complaint, but I can't help feeling like
the power supply was done by Cambridge Audio on the cheap. For instance,
sometimes the sound drops out for a fraction of a second when I switch
my CRT TV on. I refuse to believe that the design of this PSU cannot be
improved upon.

I am now thinking of moving the transformer part into something like an
old computer power supply which conveniently already has a physical
on/off rocker switch. There must be some modification I can make to at
least improve the sound a bit. Adding capacitors?

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

I seem to subconciously choose the hard way in life!

Replacement transformer
 

David Looser wrote:
"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.

The best I can find is 30VA.

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.

Point taken! Makes sense now.

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.

Yes I'll take your word for it. I know what you mean because I've seen
the heatsinks they use on voltage regs.

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

It will, it's not a problem.

It's inefficient!

Replacement transformer
 

"Anton Gÿsen" wrote in message
...
Serge Auckland wrote:


The on/off switch is my main complaint, but I can't help feeling like
the power supply was done by Cambridge Audio on the cheap. For instance,
sometimes the sound drops out for a fraction of a second when I switch
my CRT TV on.

Not necessarily due to mains wiring coupling, even if it is changing to the
transformer will *not* help with that. Try an external mains filter (with a
switch!).

David.

Replacement transformer
 

"Anton Gÿsen" wrote in message
...

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

It will, it's not a problem.

It's inefficient!

Even toroidal transformers get warm in use! If you are that bothered by
"efficiency" just leave the DAC permanently unplugged, then it will never
get warm :-)

David.

Replacement transformer
 

David Looser wrote:
"Anton Gÿsen" wrote in message
...
The
"wall wart" PSU gets warm although it is encased in plastic.
It will, it's not a problem.
It's inefficient!

Even toroidal transformers get warm in use! If you are that bothered by
"efficiency" just leave the DAC permanently unplugged, then it will never
get warm :-)

Truth!

Replacement transformer
 

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


The on/off switch is my main complaint, but I can't help feeling like
the power supply was done by Cambridge Audio on the cheap. For instance,
sometimes the sound drops out for a fraction of a second when I switch
my CRT TV on.

Not necessarily due to mains wiring coupling, even if it is changing to the
transformer will *not* help with that. Try an external mains filter (with a
switch!).

I'd like one but can't afford one at the moment.

I'm still convinced that this PSU can be improved in some way, shape or
form.

Replacement transformer
 

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


The on/off switch is my main complaint, but I can't help feeling like
the power supply was done by Cambridge Audio on the cheap. For instance,
sometimes the sound drops out for a fraction of a second when I switch
my CRT TV on.

Not necessarily due to mains wiring coupling, even if it is changing to
the
transformer will *not* help with that. Try an external mains filter (with
a
switch!).

I'd like one but can't afford one at the moment.

I'm still convinced that this PSU can be improved in some way, shape or
form.

A mains filter will cost a few pounds/euros. You're not thinking of an
audiophile one are you? That's a £€5 part in a £€ 50 box with a £€ 1000
price tag.

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

Replacement transformer
 

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


The on/off switch is my main complaint, but I can't help feeling like
the power supply was done by Cambridge Audio on the cheap. For instance,
sometimes the sound drops out for a fraction of a second when I switch
my CRT TV on.

Not necessarily due to mains wiring coupling, even if it is changing to
the
transformer will *not* help with that. Try an external mains filter (with
a
switch!).

I'd like one but can't afford one at the moment.

If you can afford a new transformer, you can afford a filter!


I'm still convinced that this PSU can be improved in some way, shape or
form.

As a rule equipment is designed to a constant level of build quality &
performance. If one part is cheap and shoddy then so is the whole thing.
Bearing in mind what you said about audio drop-out when you switch on your
TV, I suggest that the DAC is no better than it's transformer.

David.

Replacement transformer
 

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


The on/off switch is my main complaint, but I can't help feeling like
the power supply was done by Cambridge Audio on the cheap. For instance,
sometimes the sound drops out for a fraction of a second when I switch
my CRT TV on.
Not necessarily due to mains wiring coupling, even if it is changing to
the
transformer will *not* help with that. Try an external mains filter (with
a
switch!).
I'd like one but can't afford one at the moment.

If you can afford a new transformer, you can afford a filter!

Apparently so.

I'm still convinced that this PSU can be improved in some way, shape or
form.

As a rule equipment is designed to a constant level of build quality &
performance. If one part is cheap and shoddy then so is the whole thing.
Bearing in mind what you said about audio drop-out when you switch on your
TV, I suggest that the DAC is no better than it's transformer.

The DAC sounds great for £200. I'm happy with it (transformer aside).

Replacement transformer
 

Serge Auckland wrote:

A mains filter will cost a few pounds/euros. You're not thinking of an
audiophile one are you? That's a £€5 part in a £€ 50 box with a £€ 1000
price tag.

I can only find the audiophile ones. Would you kindly show me where I
can get one a lot cheaper than that?

I get drop-out from the DAC when flicking the mains switch on my Cyrus
tuner, and it's plugged into a different gang plug from the DAC!

Replacement transformer
 

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

The DAC sounds great for £200. I'm happy with it

But you said you get audio drop-outs when other things are swiched on or
off, are you happy about that?

(transformer aside).

I still don't understand what's supposed to be wrong with it. OK, so it gets
warm in use, that's entirely normal for transformers!

David.

Replacement transformer
 

"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

Why is it inefficient? What tests have you done and what have you compared
it to?

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


I think that says it all, don't fix it unless it is broken. You will not
improve the
audio unless you redesign the amplifier or use different speakers. Changing
power
supplies (unless broken) and using big fat leads does absolutely nothing !
It's one massive con. The market for such products only exists because of
daft
people who believe all the crap adverts they see.

For a power supply you will need a case, fuse/holder, mains switch,
transformer,
bridge rectifier, capacitors, voltage regulator, surge and over voltage
protection etc.
You will also require some ferric chloride to etch a circuit board, a 1mm
drill bit,
solder and soldering iron. You could always try a switching mode type which
will
be more efficient but would require some seriously clever designing to stop
any
noise, buzzing, humming etc.

Replacement transformer
 

"Anton Gÿsen"

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.


** You cannot legally build your own AC "plug pack" - such items require
specially design transformers and must be made and ** agency approved **
to meet the Class 2 safety standard.


So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer,


** Worst possible choice.


Would something like this do?

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


** No - a standard toroidal like that cannot possibly meet Class 2 safety
requirements.


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?


** Yep.



...... Phil

Replacement transformer
 

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

The DAC sounds great for £200. I'm happy with it

But you said you get audio drop-outs when other things are swiched on or
off, are you happy about that?

I can live with it because it only happens for a fraction of a second
when I switch something on. I'm happy because I think the DAC is good
value for money. It's not perfect, but nothing is.

(transformer aside).

I still don't understand what's supposed to be wrong with it. OK, so it gets
warm in use, that's entirely normal for transformers!

Yes but it consumes electricity when it is doing nothing useful
whatsoever. That, in my mind, is extremely poor design. Why couldn't
they have integrated it into the DAC itself so the power switch on the
DAC actually cuts all power to it? It's not rocket science. This poor
design is ****ing the planet up.

Replacement transformer
 

Tim 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

Why is it inefficient? What tests have you done and what have you compared
it to?

It's inefficient because it draws 2.4 watts when it's just sitting there
doing nothing. I don't think this is good.

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


I think that says it all, don't fix it unless it is broken.

That seems like the consensus.

For a power supply you will need a case, fuse/holder, mains switch,
transformer,
bridge rectifier, capacitors, voltage regulator, surge and over voltage
protection etc.
You will also require some ferric chloride to etch a circuit board, a 1mm
drill bit,
solder and soldering iron. You could always try a switching mode type which
will
be more efficient but would require some seriously clever designing to stop
any
noise, buzzing, humming etc.

Yeah, it's a drag!

Replacement transformer
 

Phil Allison wrote:
"Anton Gÿsen"

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.


** You cannot legally build your own AC "plug pack" - such items require
specially design transformers and must be made and ** agency approved **
to meet the Class 2 safety standard.

Balls to health and safety.

So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer,


** Worst possible choice.

Why?

Would something like this do?

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


** No - a standard toroidal like that cannot possibly meet Class 2 safety
requirements.

See above.

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?


** Yep.

OK, but I'm still not happy :(

Replacement transformer
 

"Anton Gÿsen"

Yes but it consumes electricity when it is doing nothing useful
whatsoever. That, in my mind, is extremely poor design. Why couldn't
they have integrated it into the DAC itself so the power switch on the
DAC actually cuts all power to it? It's not rocket science. This poor
design is ****ing the planet up.


** Oh dear - we have yet another rabid, Green Nazi ****wit.

That tiny AC adaptor is warming up the WHOLE planet !!!

Wanna bet he drives a real petrol guzzler.

ROTFLMAO !!!



..... Phil

Green Nazi on the LOOSE
 

"Anton Gÿsen"
Phil Allison

** You cannot legally build your own AC "plug pack" - such items
require
specially design transformers and must be made and ** agency approved **
to meet the Class 2 safety standard.

Balls to health and safety.


** No - a standard toroidal like that cannot possibly meet Class 2
safety
requirements.

See above.


** Oh **** - we REALLY have another rabid, Green Nazi ****WIT.

That tiny AC adaptor is warming up the WHOLE planet !!!

And this ****ing lunatic would rather KILL someone with a dangerous POS he
built himself.

Pray to god it kills him.




..... Phil

Replacement transformer
 

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.

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.

And how exactly would it make the DAC sound better ? Details please ?

Do you think you know more about high-end audio electronics design than
Cambridge Audio ?

If you don't like it, sell it and buy something else FFS !

Graham (pro-audio design engineer for 37 years)

Replacement transformer
 

Adrian C wrote:

Use a PC switchmode power supply?

To make it sound REALLY crappy ?

MORON

Replacement transformer
 

Anton Gÿsen wrote:

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.

Inside the DAC there will be a 'regulator chip'. Or possibly it's inside the
PSU itself.

It will make **** all difference other than deal with your entirely misplaced
preconceptions. Some of the best quality electronics comes out of China now. I
know. I've been there and seen the factories and worked with them.

Graham

Replacement transformer
 

"Adrian C"


Use a PC switchmode power supply?


** It's a 12 volt AC output adaptor !!!!!!

Do learn to read things before you SNIP and ignore them !!!




....... Phil

Replacement transformer
 

Anton Gÿsen wrote:

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.

Toroids are great when mounted INSIDE equipment since the stray radiated
magnetic field is low helping to lead to low induced hum levels. Better than
toroids are R-core designs and the very best are O-core designs. In the long
past C-core designs were also well considered but are humungously expensive to
make and I haven't seen one in decades.

For an EXTERNAL power supply located say a metre or two from the DAC it's
doesn't make a tinker's cuss of difference.


Graham

Replacement transformer
 

David Looser wrote:

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

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.

Well said that man. Give him a cigar.

Graham

Replacement transformer
 

Anton Gÿsen wrote:

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?

No, the magnetising current (and field) stays largely constant regardless of load.
Basic Physics.

You are fretting over nothing.

If you don't like this DAC buy another one - don't fiddle with it.

Graham

Replacement transformer
 

Serge Auckland wrote:

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

I think 'torpedo' switches are now illegal but you can get switched power
blocks.

Graham

Replacement transformer
 

"David Looser"

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.

** True only for small transformers - say under 80VA.

Above that, regulation steadily improves to around 4% at rated VA.


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.


** Ignoring core magnetising losses, transformer efficiency IMPROVES when
the load VA is made less than the rated VA.

Percent efficiency = 100 minus the ACTUAL percentage regulation - so a
transformer rated at 75VA and 15 % regulation will have 3.6 % regulation at
20 VA.

The above transformer is 85% efficient at full load and 96.4 % at the
reduced load.

BTW

A 75 VA toroidal will dissipate about 1 watt due to magnetising losses.


...... Phil

Replacement transformer
 

Phil Allison wrote:

"Anton Gÿsen"

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.

** You cannot legally build your own AC "plug pack" - such items require
specially design transformers and must be made and ** agency approved **
to meet the Class 2 safety standard.

So I was wondering whether I could build a new transformer for it based
around a toroidal core transformer,

** Worst possible choice.

Would something like this do?

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

** No - a standard toroidal like that cannot possibly meet Class 2 safety
requirements.

Onlt specially made toroids can meet Class 2 and the leakage field goes UP as a
result.


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?

** Yep.

..... Phil

Succinct and true.

Graham

Replacement transformer
 

Phil Allison wrote:

"Anton Gÿsen"

Yes but it consumes electricity when it is doing nothing useful
whatsoever. That, in my mind, is extremely poor design. Why couldn't
they have integrated it into the DAC itself so the power switch on the
DAC actually cuts all power to it? It's not rocket science. This poor
design is ****ing the planet up.

** Oh dear - we have yet another rabid, Green Nazi ****wit.

That tiny AC adaptor is warming up the WHOLE planet !!!

Right now over here it could do with some warming !

Already 60% of the British public think 'global warming' is ****witted. At
the end of this winter expect that to be more like 90%.

Get out the guillotines for the 'greens'. And for the politicians like Al
Bore who fell for (or wanted to make money out of) it. He has a 'carbon
credits' company. Nice way to line your pockets at everyone else's expense.

Graham

Replacement transformer
 

Anton Gÿsen wrote:

David Looser wrote:
"Anton Gÿsen" wrote in message
The
"wall wart" PSU gets warm although it is encased in plastic.

It will, it's not a problem.

It's inefficient!

Oh GROW UP !

Graham