In this post, I'm going to talk about the latest integrated circuit that satisfies both Audiophiles and the budget conscious that can wave a soldering iron.
20 years ago we had the Tripath chips that dominated the market, and are well reviewed in TA2020 amps such the Lepai. A $20 headphone amp that musters maybe 5wrms per channel, though it's sold as 25w rms with no consideration for distortion.
More recently, the Texas Instruments tpa3100 range has taken the crown, and as of a few years back, 50w per channel amps that can bridge have been released. It's this tpa3116 that has my interest.
A quick search will reveal 1000 page long threads on this topic, hosted on DIY HiFi forums. This chip is satisfying. As is the £10 price tag on boards that deliver 100wrms X 2 with the right power source: http://www.ebay.com/...r-/281712272349
Like most, they want between 9v and 24v. With 12v we would see just a quarter of that power, but just £10 buys a 12v to 24v convertor. So hey presto, 100wrms X 2 for £20 http://www.ebay.co.u...=STRK:MEBIDX:IT
This would be quite rough. Like a midi system, not a hifi. That 100rms is 70rms if we are realistic about distortion. The input caps want swapping for metal film and two stages of simple capacitor based filtering is missing compared to the TI supplied diagrams. Some supply decoupling caps right by the chip are missing and It's hard to say if they configured the two amps as master and slave or as other Chinese boards, forgot and introduced noise. All this can be fixed though.
I'm listening to one of these right now: http://www.ebay.co.u...=STRK:MEBIDX:IT
That is just a single chip, but just one stage of filtering is missing and the decoupling caps. All of which is in the post at £4. Running off a 12v 12w psu from an old router it's doing a fair job. A big warm sound with a midrange reminiscent of a valve amp, due to the fairly low damping factor of integrated amps. Unfortunately it gets muddled if I try and play lots of tracks all at the same time. The missing filtering lives between the chips output and the chokes, which will give the chokes less to do and is said to give much better separation. I don't see this amp ever competing with a £500 HiFi amp, but $500 headphone amps exist that revolve around the tpa3100 which was the first one made and rather low powered.
I think anyone capable and interested could put together something rather special. The endless help online, and many youtube video's using serious test equipment should back this up as a viable project.
There are many tpa3116 based boards and boxes out there. Some with bluetooth. Others with tone controls. Many 2.1 50+50+100 designs. One or two can just be bought and used, but most need attention if your really serious about your sound.
The £20 starting point of this thread presumes the 24v convertor doesn't require work to cure noise. A smoothing cap perhaps. It's a simple solution for pushing some small subs about though. Accept it's £10 and run it off the 12v system to get maybe 25wrms per channel, which could feed these: http://www.richersou...0/pion-s-slw500
They're 12x43x36 so might hide behind a seat. It's a £20 project. An amp and two subs. Add the £10 12-24v convertor if it works, to release 4 times the power. The pio's claim they will take it. That 12cm is including the feet so they are fairly narrow.
While I'm having a waffle... The Mission cube subwoofer. Pair of 8s sharing under a cubic foot. Sealed. I paid £25 though people ask that per driver. It would make a small sub of well reviewed quality. It's a bit deep though for a real shallow box. I could measure if anyone wanted to know.