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 in message

Anton Gÿsen wrote:

The power input on the DAC requires 1.5 amps AC.

Forgot to mention, it's 12 volts.

Designing power supplies is a cookbook process.

The transformer you linked to is vast overkill, but also inadequate. You
don't need a 6 amp transformer for a DAC. Even 1.0 amp might be overkill.

If you want to build a power supply that puts out 12 volts, you will
probably need a power transformer that puts out more than 12 volts. The
extra voltage will be taken up by losses, particularly in the regulator.

Also, you want some allowance for situations where the power line's voltage
is lower than spec.

It is common to build regulated power supplies for 120 volts that work well
when the power line is 90 or 100 volts. For example a power transformer for
a power supply that puts out 12 volts might be based on a 16 or 18 volt
transformer. The voltage regulator will take up the slack most of the
time.

Arny Krueger wrote:

It is common to build regulated power supplies for 120 volts that work well
when the power line is 90 or 100 volts. For example a power transformer for
a power supply that puts out 12 volts might be based on a 16 or 18 volt
transformer. The voltage regulator will take up the slack most of the
time.


When modders get in and change the internal circuitry about, say trying
upgraded opamps, then the power supply is the next natural target for
the upgrade.

The following document, for my dac-in-the-box is one approach of said
improvements (I've not tried this - I'm happy as the item is) where the
proposer has also had to upgrade the voltage regulators and then find a
better PSU. And suffer more regulator heat dissipation.

http://www.audioasylum.com/images/DITBMOD.pdf

--
Adrian C

Adrian C wrote:

Arny Krueger wrote:

It is common to build regulated power supplies for 120 volts that work well
when the power line is 90 or 100 volts. For example a power transformer for
a power supply that puts out 12 volts might be based on a 16 or 18 volt
transformer. The voltage regulator will take up the slack most of the
time.

When modders get in and change the internal circuitry about, say trying
upgraded opamps, then the power supply is the next natural target for
the upgrade.

You mean downgrade of course !


The following document, for my dac-in-the-box is one approach of said
improvements (I've not tried this - I'm happy as the item is) where the
proposer has also had to upgrade the voltage regulators and then find a
better PSU. And suffer more regulator heat dissipation.

http://www.audioasylum.com/images/DITBMOD.pdf

They don't call it AUDIOASYLUM for nothing. I hope your straitjacket is a good
fit.

MORON !

Graham

"Arny Krueger" wrote in message
...
"Anton Gÿsen" wrote in message

Anton Gÿsen wrote:

The power input on the DAC requires 1.5 amps AC.

Forgot to mention, it's 12 volts.

Designing power supplies is a cookbook process.

The transformer you linked to is vast overkill, but also inadequate. You
don't need a 6 amp transformer for a DAC. Even 1.0 amp might be overkill.

If you want to build a power supply that puts out 12 volts, you will
probably need a power transformer that puts out more than 12 volts. The
extra voltage will be taken up by losses, particularly in the regulator.

You must have missed the "AC" in the OPs post.

David.

David Looser wrote:

You must have missed the "AC" in the OPs post.

Very dangerous to mis the 'AC' in the OPs post. The society misfit who
posts in his underwear and socks will be knocking the rum bottle back to
start screaming again.

--
Adrian C

"David Looser" wrote in
message
"Arny Krueger" wrote in message
...
"Anton Gÿsen" wrote in message

Anton Gÿsen wrote:

The power input on the DAC requires 1.5 amps AC.

Forgot to mention, it's 12 volts.

Designing power supplies is a cookbook process.

The transformer you linked to is vast overkill, but also
inadequate. You don't need a 6 amp transformer for a
DAC. Even 1.0 amp might be overkill. If you want to build a power supply
that puts out 12
volts, you will probably need a power transformer that
puts out more than 12 volts. The extra voltage will be
taken up by losses, particularly in the regulator.
You must have missed the "AC" in the OPs post.


No.

The good news is that a full-wave rectifier will turn 12 VAC into about 17
volts DC, but the bad news is that the voltage drop across the regulator
plus a reasonable allowance for low line voltages will pretty well eat up
the 5 volt advantage.

"Arny Krueger" wrote in message
...
"David Looser" wrote in
message
"Arny Krueger" wrote in message
...
"Anton Gÿsen" wrote in message

Anton Gÿsen wrote:

The power input on the DAC requires 1.5 amps AC.

Forgot to mention, it's 12 volts.

Designing power supplies is a cookbook process.

The transformer you linked to is vast overkill, but also
inadequate. You don't need a 6 amp transformer for a
DAC. Even 1.0 amp might be overkill. If you want to build a power
supply that puts out 12
volts, you will probably need a power transformer that
puts out more than 12 volts. The extra voltage will be
taken up by losses, particularly in the regulator.
You must have missed the "AC" in the OPs post.


No.

The good news is that a full-wave rectifier will turn 12 VAC into about 17
volts DC, but the bad news is that the voltage drop across the regulator
plus a reasonable allowance for low line voltages will pretty well eat up
the 5 volt advantage.

What on earth are you on about? the DAC is specified for 12 V *AC* input.
Nobody ever said anything about needing 12V DC.

David.

Arny Krueger wrote:

The good news is that a full-wave rectifier will turn 12 VAC into about 17
volts DC, but the bad news is that the voltage drop across the regulator
plus a reasonable allowance for low line voltages will pretty well eat up
the 5 volt advantage.

Perfectly true and don't forget ripple voltage (min value of) too.

Graham