I only buy the fully stuffed pcb without casing. the build quality is adequate and paid less than US 20 with shipping to malaysia.
when i first tested it on arrival the sound is rather poor with scratchy volume pot and the ground pin for the rca input broke . there is a constant hissing sound. i decided to play with the board by repairing/ replacing the broken parts . i change the input caps from cheap polar electrolytic 10 uF to film smd caps retrived from a broken harddisk. it is soldered on the underside of the pcb. the TPA application notes mentioned about low esr bypass caps near to the tpa 3123 chip. i tried ceramic disc soldered on the underside of the 1uf films caps next to the power supply electrolytic caps. I build a linear regulated power supply with LM 338 regulator adjusted to 18 V dc. all this mods transformed the amp powering the markaudio 12 p fullranger.
The sound is fantastic with great dynamic swings, extended high, tube like mid and well controlled bass. multiple layers of orchestral music is discernible. It truly sounds like a hi fi --rather good one !!! this is the cheapest amp that i have used in my set up and surprised me everytime i listen to music.
what a discovery !!!
i try to add an attachment at 550Kb but the forum says i have exceeded the limit !!!
TPA 3123 is a class T amplifier chip manufactured by Texas Instruments. It is designed to work in Television audio. The chip is about the size of the postage stamp and is partially hidden between the blue caps in the picture. There is no heatsink . There is extensive discussion in the diyaudio forum on the TPA 3116 board at less than US 20 . I also owned the same board but the TPA 3123 seems more transparent in my set up.
Thanks for posting about your tpa amp, it reminded me that I had a Sure TPA3110-based pcb sitting idle.
I connected it up earlier this week, power from a random 19V laptop brick and music from a Sansa Clip. It was a little tizzy sound-wise initially, but settled down nicely once the caps had formed. It sounds very nice, with a surprisingly well formed sound stage.
The main reason that I'm surprised is that this little 8W stereo amp cost less than £9 delivered! It's perfect for use in a desktop system, which is where I'll be using it. Connected to a Raspberry Pi/PK Dac, it'll do music/radio duties just fine.
If you've got the money spare, it's worth buying, and dead simple to get running - it's more Lego than DIY!
BTW, if you want more than 8W, look at an amp based on the TPA3116 or TPA3123.