Noise Killer, whats this? ATX

[iUSERTLO72p]

Hi all, been running my sub from a car amp using an old ATX PSU. Damn thing smoked, I needed to hide the hideous box and proceded in extending the wires and somehow got a short. So out came my other spare. It says its got a Noise Killer, is it something to do with a Choke(?) mounted on the case, and how does it work, please? Will it perform well?


Cheers

iUSERTLO72p

[m-tech]

It's a passive PFC.

[iUSERTLO72p]

So, Does Power Factor Correction have nothing to do with making it quiet as in noisy fan? On my previous supply, I had a noisy fan, I tried to reduce the voltage, 7 volt mod etc, but when my sub hit low, the fan stalled and made a noise when it recovered. I had to switch it off, then on again. Running the fan properly worked fine, but on silent passages, became annoying, hence why I wanted to move the hideous looking thing. Not only is the case ugly, but its noisy too. Maybe a Scotch/Scouring pad might damp the noise????

Cheers

iUSERTLO72p

[error401]

Originally posted by iUSERTLO72p
So, Does Power Factor Correction have nothing to do with making it quiet as in noisy fan? On my previous supply, I had a noisy fan, I tried to reduce the voltage, 7 volt mod etc, but when my sub hit low, the fan stalled and made a noise when it recovered. I had to switch it off, then on again. Running the fan properly worked fine, but on silent passages, became annoying, hence why I wanted to move the hideous looking thing. Not only is the case ugly, but its noisy too. Maybe a Scotch/Scouring pad might damp the noise????

Cheers

iUSERTLO72p

Nope, nothing at all. Switching power supplies are a difficult load on the AC mains, and the large PFC choke suppresses some of the undesirable effects from making it back onto the AC mains. It's mostly a consideration for energy efficiency and the health of the power grid. As a consumer it doesn't really make any difference.

I would suggest that if you want a silent supply for your sub amp that you just shell out for a purpose-built one. An ATX supply that's designed with a fan will surely overheat driving such a load without any cooling. Sure Electronics on eBay sells a decent 12V 145W switcher with no fan for about $25. That's about the same amount of current you'd be able to get off a single +12V rail from an ATX supply.

Your other options are either to buy a good quality supply with a quiet fan (see silentpcreview.com for suggestions/reviews), or replace the fan in your existing supply with a better quality one.

[AndrewT]

Hi,
your other option is to build up a conventional transformer/rectifier/smoothing cap PSU.

[iUSERTLO72p]

I'm upset now. Can't get the new supply to fire up. Fan rotates for a moment then stops. I need to buy a big transformer to make a linear supply. I could put up with this car amp permanantley, for a while anyway. Got to buy a new car this year, and pay for a new addition to our family. I think I should stroll over to the Car Forum, see if the chaps there, can't help me bypass the amp's switcher and power it directly.

Cheers everyone anyway.

iUSERTLO72p

[poynton]

Originally posted by iUSERTLO72p
I'm upset now. Can't get the new supply to fire up. Fan rotates for a moment then stops..........

If you are sure the power supply works, this usually means that the 'load sensor' is on the +5v line not the +12v line.

The psu requires a minimum load to run.

Andy

[error401]

Originally posted by poynton



If you are sure the power supply works, this usually means that the 'load sensor' is on the +5v line not the +12v line.

The psu requires a minmum load to run.

Andy

IOW you need a power resistor on the 5V line.

[iUSERTLO72p]

Hi,
I got a 2.2ohm 25watt power resistor bolted to the case and tied onto the +5v to Gnd.



iUSERTLO72p

[star882]

Try another load on the 3.3v line.