Anyone use an offline switcher PS for GC?

[speaker]

There are a few companies that offer ~$90 switching supplies for telco/computer apps with dual +/- DC outputs w/ sufficient wattage. Has anyone gone this route rather than using an XMR supply?

speaker

[adx]

I've used them, but they're still not as convenient as linear:

1) Most SMPS have an overload trip - as soon as you exceed the maximum current they trip out. Because they're voltage regulated no amount of caps on the output can help (the caps are effectively out of circuit once (if) they're charged). What you want is current limiting, or better still power limiting, or a vastly over rated supply - this seriously reduces your options.
2) They are often not earthed, this puts approx half the wall supply voltage onto the ground of the system (at a very low current), that can cause buzzes and small shocks unless you earth the system somehow.

Never had a problem with sonic performance though.

[speaker]

Originally posted by adx
I've used them, but they're still not as convenient as linear:

1) Most SMPS have an overload trip - as soon as you exceed the maximum current they trip out. Because they're voltage regulated no amount of caps on the output can help (the caps are effectively out of circuit once (if) they're charged). What you want is current limiting, or better still power limiting, or a vastly over rated supply - this seriously reduces your options.
2) They are often not earthed, this puts approx half the wall supply voltage onto the ground of the system (at a very low current), that can cause buzzes and small shocks unless you earth the system somehow.

Never had a problem with sonic performance though.

Thanks for the feedback adx. I've seen a couple of home subwoofer designs with switchers that isolate the audio input by transformer coupling. I would gather that is to eliminate buzzes & shocks? I've got a couple of these supplies as well as wideband 600:600 audio tranformers from UTC & Hammond so I may try this approach. Can't imagine I'd run it out of steam though in the application I have in mnd.

speaker

[adx]

Originally posted by speaker
...isolate the audio input by transformer coupling. I would gather that is to eliminate buzzes & shocks?

Possibly is, although it's not necessarily a characteristic of all switchers, if they're earthed they should be fine (although that can then cause ground loops in audio, which is more likely be the reason for the transformer). This is different from an amp where the internals are deliberately live (rectifying the mains directly), these need to have a safety approved input transformer which is a whole different story.

Also the power thing may be worse than you're thinking - because a regulated supply effectively has no output capacitors, it needs to supply all the instantaneous speaker current without tripping out. This means the SMPS may need to handle about 4 times what an equivalent linear supply would usually be rated for.

Only one way to find out!

[speaker]

Originally posted by adx
Only one way to find out!

"Cover me, I'm going in!"



speaker