Sonic Impact T-Amp Switching Power Supply

VintageNut

Super Member
I have been using a switching power supply with my T-Amp. I got it for 8.00 at my favorite local electronics surplus store owned by a techie type. He advised that at the frequency the power supply switched at, I would not hear any noise out of the T-Amp. And I don't, it sounds good to me. My question is, has anyone had problems using switching power supplies in audio applications? Or is it one of those deals where only my dog could hear it, and she ain't complaining either.

Quote from another audio board:

"Linear" supplies are "traditional", they are largely inefficient but supply
a nice clean supply. "Switching" supplies were invented as a means to more
efficiently generate large currents, but their switching puts high frequency
noise into the supply. Things like computers don't care about this, and so
use high power high efficiency switching PSUs... while of course Audio is
more sensitive to such things, and so people generally stear clear of
switching supplies (at the price of power efficiency!).
 
I just did some interesting reading on the web, looks like they use switching power supplies in some car audio.
 
i use the recommended 12v adapter from partsexpress. sounds good to me, no "noise" just great sound.
 
The best upgrade to your SI is to use a battery powered jump starter found at any Wal Mart or Lowe's, etc. Using straight battery power deepens the soundstage and makes the amp dead silent. I've played mine 8 hours without having to recharge. It really does make a difference.
 
I honestly don't think it makes much difference. I had my modded SI hooked up to a computer power supply for awhile. I couldn't make out any difference in sound quality.
 
I've been using two SI's simultaneously and it makes a big difference between dc power supply and battery power. Very, very noticeable. Better dynamics, deeper field, more refined highs, overall better imaging. I also found the thickness of the power cabling has an effect on the sound.
 
I have one SI for the left, the other for the right. I'm using a preamp that has two sets of pre-out rca's. I run a set of IC (terminated with the mini-plug) from both left pre-outs to the left channel SI. I take 4 conductor speaker wire and connect both the SI L/R power outs to my 2-way bi wireable speakers. So, each driver has its own, independent 6 watt amplifier. For power, I just got normal banana plugs and attached both positives to one and negs to the other. That means my battery power supplies two SI's at once.

Essentially, this makes my SI's monoblocks with each channel feeding its own dedicated driver.
 
I bought a Sonic Impact Amp, ditched the case and that rotten 50K volume pot. Put in a larger power supply cap.

Then put in decent RCA jacks and inputted them directly to the board.
Skipped the volume control, and used a 100K stepped attenuator before the amp.

I tried Alkaline batteries at first, nuthin' special there.
Tried a run of the mill car battery. Yuk.....talk about dirty power.
Never tried the little SLA batteries, may try that someday when I'm more flush.

The best(or cleanest) power source that I've had luck with is a 12 volt regulated wall-wart at about 1300 ma. It has a 12+, 12-, and a ground rail.
But the current is kinda low, and it runs out of steam.

I would think a good regulated 12 volt supply at about 2000 mils would help the grunt factor, I dunno......

With batteries and the wal-wart, the little amp would hiss through the tweeters. Granted you have to be right up on them, but all my tube amps don't hiss through the tweeters. That kinda bugged me for some reason.

I guess I'd rather listen to a wee bit of filament/heater hum that more or less cancels out once you get a foot or so from the speaker.
Maybe I'm just partial to AC heated single-ended amps........

I ain't done with that little digi-amp however. (Class T, D or whatever the hell it is.)
 
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