Thoughts on using this supply on chip amp?

[joeytvr]

Got this power supply a while back for $10. I want to build a chip amp soon and was thinking about using it.
What's everyone's opinion?

 

[rayma]

You could (with a single supply circuit), but the maximum power would be around 8W into 8R.

 

[multisync]

you could use it to power some 3116 chip amps. 20 watts at 8 ohms. The problem of course is what happens to the power supply when current demands exceed 3 amps. With 2 8 ohm speakers in pararell you will have an equivelent 4 ohm load and if you drive the amp to clipping you will exceed the 3 amps rated output. A large capacitor reservoir might help, but some switching powersupplies dont like starting up with a large capacitor bank as a load. If the output of the power supply has an adjustment you could try lowering the output to 18-20 volts.

 

[jjasniew]

Interesting a switching supply with a fuse for load protection. They expect the fuse to blow (time delay type) to protect the electronics, so the power supply must be capable of doing so - at least 4+ amps for the second or so it takes to blow the fuse.

Thermally, with the case enclosed and in the long term, it can provide 3.125A continuous. Transient or short term it can probably do better. Since music is transient (unless very compressed stuff) you could probably occasionally hit 4A w/o issue.

FWIW,

 

[PRR]

...With 2 8 ohm speakers in pararell you will have an equivelent 4 ohm load....

The DC equivalent load for a totem-pole amplifier delivering just-clipped Sine audio into 8 Ohms is about 50 Ohms. (The full math has a Pi, but you also allow for device losses; "50" works.)

So he actually could drive 6 channels at 8W 8r. (Total 48W sine audio, which is a fair share of the nominal 75W DC power.)

Or three channels at 16W 4r. (2* 16W 4r is a non-trivial "stereo hi-fi".)

Or one channel bridged across two amplifiers for 32W 8r. (Killer little guitar club amp.) Maybe even 48W in 6r.

 

[joeytvr]

Just want to do a 2 or 3 channel. Have one of these I might use and get a 100w mono for sub

 

[joeytvr]

TPA3116 D2 120W+120W dual-channel stereo digital audio power amplifier 12V-26V | Wish

 

[Mark Tillotson]

Got this power supply a while back for $10. I want to build a chip amp soon and was thinking about using it.
What's everyone's opinion?

Its switch mode so there is significant switching noise on the rail. Whether this affects audio will depend on a lot of factors. It might be necessary to further filter the output to reduce noise, be aware of that. Switching supplies have a maximum load capacitance to further complicate things.