TPA3116 troubleshooting help wanted

Svindel

Member
2016-02-14 2:31 pm
I have recently bought Sure Electronics' webstore 2 x 50 Watt 4 Ohm Class D Audio Amplifier Board - TPA3116 and I have a rather significant problem with it.
When both channels (left/right) are plugged in, and fed from the same source, there is no bass ie. sounds below ca 300Hz is not played correctly.
I have tested multiple sources an speakers - to no avail, and as I am now banging my head at a wall in frustration, I humbly ask for help.
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
Only two thoughts come to mind. Firstly, are the speakers phased correctly ? Just swap the wires over to one of them at the amp (the speaker - and +) and see if it improves.

Secondly a floating ground on the inputs can do odd things. Worth checking ground continuity from the input sockets back to your source (preamp etc).

And I suppose it could always be a faulty amp.
 

Svindel

Member
2016-02-14 2:31 pm
The speakers are correctly phased, as to the floating ground I'm uncertain. I have tried 3,5mm to 2xRCA from several sources, aswell as 2xRCA from a compact stereo 2xRCA output, the problem remained.
If only one of the input cables is connected - left or right, the problem dissapears.
 

Mooly

Administrator
Paid Member
2007-09-15 8:14 am
That does sound a bit strange and without examining the unit its hard to guess what may be wrong.

If you look at the RCA sockets on the board (the soldered underside), and were to link the two input pins (one on each socket) together with a piece of wire, and then connect just one RCA lead then you should get perfect mono. If it failed on that then I would say there was a problem with the amp.
 

Sangram

Moderator
Paid Member
2002-09-25 11:01 am
India
The outputs are sometimes connected out of phase to prevent bus pumping in Class D amplifiers, and/or to make bridging the amp easy by grounding one input and using the other to provide the signal. I know of many amplifier boards made by East Asian companies to use this technique (it is also recommended on some product datasheets, though not all).

Without looking at their schematic, though, you would not know for sure, and depend only on your listening abilities.