Linear Power Supplies

[m1abrams]

The switching power supply is creating HF noise.
This noise has not only negative effect on the Touch, but on all other hifi components in the system.
When for somebody switched ps is enough, than it is finally not my problem

And a rather large power transformer creates a good bit of EMF noise. Place that transformer anywhere near a line level signal and you will induce a nice 60hz hum.

FYI you really do not need a 120VA transformer to power a device that at most needs 15Ws. A 25-50VA transformer should be plenty and would produce less EMF.

[toby10]

Pat was measuring the older (original - pretty bad) style switcher not the current one. Also, he was measuring the analogue output...

So.... I guess it's back to theory and ears.

[earwaxer9]

Anyone used a battery supply for the Touch? - Just curious.

[praganj]

And a rather large power transformer creates a good bit of EMF noise. Place that transformer anywhere near a line level signal and you will induce a nice 60hz hum.

FYI you really do not need a 120VA transformer to power a device that at most needs 15Ws. A 25-50VA transformer should be plenty and would produce less EMF.

I know that 120VA is overkill, but look at Naim Audio and their power supplies for preamps. Why they are doing it ? Are they so stupid ?

Big transformator has lower impedance, than the small one. Good power suplly should have the lowest possible impedance.

Thats the reason why i took one 120VA

[Phil Leigh]

I know that 120VA is overkill, but look at Naim Audio and their power supplies for preamps. Why they are doing it ? Are they so stupid ?

Big transformator has lower impedance, than the small one. Good power suplly should have the lowest possible impedance.

Thats the reason why i took one 120VA

1) They are not stupid. They know that nobody is going to pay £300+ for the 20VA that is required...
2) The SB will never see the "impedance" of the transformer. It will see the regulation circuitry...

[praganj]

Hi Phil,

Power supply is just one electric circuit build from few elements.

The impedance of the power supply in our case is composed of the impedance of the reg + main caps + rectifier + transformator. This is very simple rule of physics (or electric if you like).

Some companies trying to lower the impedance are using rectifier with two diodes instead of four and the transformator has to be made of thicker, harder wire, than it has lower impedance.

[Phil Leigh]

Hi Phil,

Power supply is just one electric circuit build from few elements.

The impedance of the power supply in our case is composed of the impedance of the reg + main caps + rectifier + transformator. This is very simple rule of physics (or electric if you like).

Some companies trying to lower the impedance are using rectifier with two diodes instead of four and the transformator has to be made of thicker, harder wire, than it has lower impedance.

Hi
I know how to build power supplies, which is I why I also know that you don't need over-sized transformers on line level circuits and why you won't get full-wave rectification from just 2 diodes...unless you use an (expensive) centre-tap transformer.

The performance of the PSU is predominantly determined by the smoothing caps and the voltage regulator. Using an oversize transformer to support a mere 3 amps at 5v is just a waste of money. There's also transformer ringing to consider...

[ralphpnj]

Hi
I know how to build power supplies, which is I why I also know that you don't need over-sized transformers on line level circuits and why you won't get full-wave rectification from just 2 diodes...unless you use an (expensive) centre-tap transformer.

The performance of the PSU is predominantly determined by the smoothing caps and the voltage regulator. Using an oversize transformer to support a mere 3 amps at 5v is just a waste of money. There's also transformer ringing to consider...

"But it sounds better!"

The standard audiophile response whenever they are presented with clear scientific facts regarding the latest, greatest and very expensive after market upgrade. See also high priced USB and Cat 5 cables.

Still to come: air purification systems which will claim to improve the signal transmission of one's home wi-fi system resulting in much better sound and sharper video for all streaming devices. And of course the first ever truly high end router complete with gold plated connections and a fully regulated linear power supply, all for a mere $2,500 excluding Cat 5 cables.

Hey Phil perhaps we can become partners in the first "audiophile air" company!

[mooblie]

And of course the first ever truly high end router complete with gold plated connections and a fully regulated linear power supply, all for a mere $2,500 excluding Cat 5 cables.

Well, those Cat 5 cables are already here for the suckers. Directional, too! Don't the idiots EVER feel maybe, just maybe, they're being taken for a ride?

[ralphpnj]

Well, those Cat 5 cables are already here for the suckers. Directional, too! Don't the idiots EVER feel maybe, just maybe, they're being taken for a ride?

I know about these outrageously priced cables but as of yet there are no "audiophile" routers on the market nor is there an air purification system for improving wi-fi signals available. So there still remains several good money making opportunities available