T3 stereo 300W amplifer board

[hifimediy]

Hi all.
I got the PCB yesterday and it took me 2 hours to finish to solder work. Now here it is.

[Saarmichel]

Give gas, I want to buy ;o))

When have the boards in your shop.

Greeting

Michael

[hifimediy]

I made only 1 pcs by now

[trevmar]

Looks like a nice, clean, board

I see a 680nF output cap, and two 100nF Zobel caps. Are they enough to critically damp the output inductor?
.

[hifimediy]

Originally Posted by trevmar

Looks like a nice, clean, board

I see a 680nF output cap, and two 100nF Zobel caps. Are they enough to critically damp the output inductor?
.

yes, we have some SMT parts for filter very close to the chip.

[kc7wdg]

+1

[Saturnus]

Looks great hifimediy.

One comment though. I still don't understand why you (and other designers) place the output chip, and thereby the heatsink, on the component side of the PCB instead of the more natural bottom side so that it would be much easier to bolt onto a heatsink.

[hifimediy]

Originally Posted by Saturnus

Looks great hifimediy.

One comment though. I still don't understand why you (and other designers) place the output chip, and thereby the heatsink, on the component side of the PCB instead of the more natural bottom side so that it would be much easier to bolt onto a heatsink.

On the T3 mono version, we put output chip on the bottom side of pcb. That just depend on design.

[alkasar]

Hello,
so here it is excellent news.

tell us more
- i see 3 power terminals. Do I understand correctly that this board can be powered by AC dual voltage transformer or DC single voltage ?
- does it have external on/off control same as you have on T4 (PWR down connector) ?
- did you use the tripath output filter topology (like on T2) or the ST topology (like T3) ?
- have you already measured the board THD / IMD. How does it sound ? what is the gain setting on this board ?

Thanks

[trevmar]

Originally Posted by hifimediy

yes, we have some SMT parts for filter very close to the chip.

When testing the new SURE TDA7498 board, I found their SMT ceramic caps for the output filter were the cause of excessive harmonic distortion, which cleared up when I replaced them with poly film. I know that it is customary to use ceramic SMT for the less critical components in the filter network, but is this really a good idea in an audiophile-quality product? Have you checked the harmonic distortion in the 1-20KHz region using both SMT and film capacitors?
.