LC Audio Low noise regulator PSU

[zanash]

Has Anyone used this unit to build a psu for a SB3...

I've initally set up a tranny and the reg board ....hooked up to the sb3 ...

sound went from standard dull and lifeless [with the wall wart] to dynamic fast and open. Down side is the psu is dumping heat ...too hot to touch. This suggest the low noise reg is meant to run at much higher voltages [?].

I'm thinking of fitting the board into a ali case with big case mounted heatsink or do you think a fan might be better ?

[tonyptony]

Do you have a link for this?

[mudlark]

I've tried to use a fan in a power supply and I was unable to make it work satisfactorily. The thing ran cool, but with the size of case i used the fan was too noisy. I ran a quiet 50mm fan with 5Volts on flexible mounts and fixed solid all to no avail.

I subsequently drilled holes in the box underneath and small ones on the side of the box close to the top edge. This has been the best compromise.

My box is made of lightweight aluminium and is a really good device to pick up vibration and re-radiate this as sound.

If you want to try a fan then the enclosure should have stiff sides so re-radiation doesn't occur.

m.

[zanash]

here's a link

http://www.lcaudio.com/index.php?page=69

[Patrick Dixon]

The heat dissipated will depend on the voltage you are dropping through the regulator - I don't know what head room the LC regs require, but you need to feed it an input voltage as close to the minimum as you can.

Since the SB3 draws about 1A, every extra volt dropped will result in an extra watt's worth of heat.

[zanash]

yes thought that was likely the reason ....I've currently fitted the board and tranny in an metal case with a full length heat sink ...as a temporary home ...but to find a tranny of 100va with a 5 volt secondary is going to be hard work.. the current tranny is 15v secondaries.

[mudlark]

I am no electronics engineer, but the secondary has to be well over 5v because the regulation isn't 100% efficient. The voltage also drops when loaded. I would guess 9v might be ok, but you need good advice on this.

M.

[zanash]

you right ...though so diodes give you 1.4 x the input voltage or is it drop ? Anyway a 10v secondary should not be too hard to find ...I'll experiment and find the best compromise.

I've also got a standard linear variable psu that I shall build into a second psu....but more of that when the unit is assembled.

So far the lc audio based psu has given a great lift to the performance ...It no longer sound flat and lifeless ...so it must be doing some things right !

[Patrick Dixon]

I'd go for a 6V or 9V (at most) secondary.

For 6V, the smoothing caps will give you 6 x sqrt2 = 8.5V (less the diode drop), as an input to the regulator. What do LC recommend as the minimum headroom? Every extra volt you drop requires an extra watt of heat dissipation, so you need to drop the absolute minimum you can get away with.

[zanash]

I'm waiting on lcaudio's comments ...

thanks for the advice ....I'll try and pick up a suitable 9v tranny and see what effects this will have....hopefully it will just reduce the excess heat and not effect the sound !

[AndyC_772]

Also don't forget: most transformer manufacturers quote the RMS output voltage, but a simple linear power supply actually delivers an output which is slightly below the PEAK voltage that comes from the transformer. So, if you build a linear supply around a "9V" transformer, you'll actually get about 12V...

[zanash]

I've order a 50va 2x 9v tranny and I'll see if this helps control the temp ....

[zanash]

lc audio have got back to me and and confirm the route suggested ..which is nice. Thanks to all those who offered the advice.

[zanash]

Ok...this is odd

The simple linear out performs the low noise by a wide margin ...

the simple linear is a 25va 230v ac to 2 x 9v ...using one 9v secondary feeding a reg module from RSWWW. part number 494-9072. Wired using 1mm silver in ptfe from tranny to reg board and to the sb3. The standard cap was replaced with a 2200uf 50v pannasonic fc , but other than that its stock.

sound is big fast dynamic live, using the quad 99 dac . In comparison the supplied psu make the unit sound thin, shut in and constricted.

oh yes and it runs stone cold !

[S-Man]

Ok...this is odd

The simple linear out performs the low noise by a wide margin ...



At last somebody who listens instead of looking at specs!

Your findings do not surprise me in the least.

http://forums.slimdevices.com/showthread.php?t=36626&page=5

BTW the LC audio is a primitive sort of super-reg.

[zanash]

Cheers.....

I gave up on specs ...as the best specs were often either complete fabrications or the gear sounded dire. exactly how is the man in the street ever going to ratify the many claims and specs made about items ?

I've long gone over to the simple expedient of listening ..if I like the sound of one thing over another then its got to be better for me !