SA-15 S.M.S.I. Mini class d 12v amp, need more input sensitivity...

[ppia600]

I asked in the lepai 2020 thread but no help so far so here is my thread dedicated to this: TA2024 mini Class T Amp Mini HI-FI Stereo Amplifier #1 - eBay (item 270547118593 end time Aug-11-10 14:34:19 PDT) mini amplifier.

Very low priced for a complete amp and very compact. I plan on using it at work to power two 5.25" sony speakers and will be running it off my zen mp3 player and 12v4A power supply.

It seems to have very low input sensitivity as running it with my portable mp3 player was very disappointing so I plugged my home dvd player outputs into it and VOILA it sounds a LOT louder and is still very clean.

Could someone point me in the right direction on correctly modifying the input circuit in this amp to substantially increase sensitivity so I don't have to buy or rig some kind of preamp? I'd like to maintain the clean sound of this thing and have as few components as possible. Thanks for any help

[ppia600]

[theAnonymous1]

Originally Posted by ppia600

Could someone point me in the right direction on correctly modifying the input circuit in this amp to substantially increase sensitivity so I don't have to buy or rig some kind of preamp?

Page 7......

http://www.datasheetcatalog.org/data...h/mXyzxwwt.pdf

[ppia600]

Thanks, that's two references to the datasheet so I'll give it a shot.

[ppia600]

Well the closest thing I could find to RI was the one I took out and replaced with 200ohms (two series 100ohm). It was originally 20k ohm. Seems to work fine but now of course I have hiss with the amp volume knob all the way down or at anything past 3/4. I put it at a little less that 3/4 and the gain is perfect so I can control it with the mp3 player. It should work well enough in our noisey shop. I'm also replacing the four .22uf caps on the output side with .47uf as per the circuit diagram and changing the two 1/4watt 10ohm on the outputs with 1/2 watt versions. Hopefully it will still sound nice. I'm also thinking of installing a thick silicone conductor pad on the bottom to transfer some heat through the sink.

Resistors I soldered in:


Area that will be getting slightly different values:


Thanks for the help guys, now let's see if this little beast can stay alive for a while.

[ppia600]

Replaced the .22's with .47's and upped the two resistors to 1/2w per datasheet. Now I'm wondering if the bias needs to be tampered with. Still sounds very nice, now I have to get the ported boxes made for the 5.25" sony coaxes.