I have some experience with the Tripath parts and can offer some advice to those interested in modding theTeac amp. I don't own one the amps myself, so I'm going based on the digital photos I've seen.
Each 2-channel amp is implemented in a two-package product - the TP2000 (the visible part) is the "controller" for the H-bridge power die, the TP2050 (mounted on the "back" of the PCB (under the large aluminum heatsink). There are two 2-channel amps in the Teac, one on each board. On the L/R amp board, the outputs are connected to the L/R speaker connectors. For the center channel board it APPEARS that they have left unconnected one of the outputs, driving the center channel with one channel of a stereo pair. This seems very strange, as there are output inductors for both channels on each board, and if you are not driving one channel you do not need these parts. I've never known CE manufacturers to give away free parts, so I'd have to assume that the "center" channel is actually a paralleled output. The way to tell would be to look at the top of the main board and see if there's traces present on the center channel's 7-pin output connector that parallel the outputs.
IF the center channel output is a paralleled stereo pair, then you have a higher output current capability on the center channel. You could drive (for instance) a 4 Ohm load to 90W (at .5% THD), assuming you had enough mojo in the power supply.
If you are only going to use this as a 2-channel design, then you might want to consider paralleling the L/R channels as well. Driving 4 Ohm loads, this will give you a 2x70W amp (.005% THD) if the power supply can provide 7 Amps at 30V (210W). Looking at the photos of the Teac supply, my guess is that it's closer to 120W than 210W, so maybe it's only good for 2x40W. Who knows? After all, it's only spec'ed for 6 Ohm loads.
Anyway, there's nothing to paralleling the L/R channels. Just run a heavy wire from the left red post to the right red, and another from left black to right black. Connect the load to either output. On the input side MAKE SURE that you have the same mono source connected to BOTH channels, and NEVER run in a stereo source into the L/R inputs. If the L/R outputs are paralleled and the L/R inputs are not the same, bad things will happen.
If you're driving 8 Ohm loads, there's really no point in paralleling the outputs. You won't get any increased power output, as the voltage swing is the same either way, and at 8 Ohms you're not going to current limit the device. Paralleling on the TP2050 is really only useful for 4 Ohm loads.
If you have a 4 Ohm sub and 8 Ohm satellites that you like, this amp is set up really well as it is.
If I were hot rodding it, I'd first check the power supply. The TP2050's sweet spot is in the 28-30V range. If you can find a nice quiet supply that provides 30V (regulated) at 7A, you are set. Switching supplies are not a disaster with a switching amp like this, so you can get away cheap if you need to. If you do change the power supply, remember that the TP2000 requires +5V as well (it looks like there's a 7805 on the main board). And if you change the supply voltage, you'll need to adjust the output offset. Fortuntely, they have the pots for this (VR80 and 81).
Second thing I would do would be to bulk up the local storage cap. There's not a lot of room, unfortunately. Probably have to lay it across the top of the chip. Bypass it with a high quality film.
With the increased current capability I'd look at the four output inductors L309-L311. These may be perfectly capable for higher current outputs, but there's no harm in replacing them with bigger cores. Maybe swap them in one channel only and compare them with an unmodified board to see if you like the change. I'd stay with the default filter value of 15uH.
I'm slowly talking myself into going out and buying one of these things. It looks like a nice design for the money, with lots of room for mods. If I do, I'll post here and let you know what works for me.
regards,
Sluggo
