Tripath TAA4100 Users - Hiss

[speaker]

I'd like to hear from other users of this chip. I have a Tripath demo board, EB-TAA4100 and there is a good deal of hiss that is noticeable from 2' feet away.

I am curious if this is an artifact of the early Tripath demo board design, a potentially bad chip, or an innate chararacteristic of the chip itself? As there are a few designs out now using it, what has your experience been in this regard as to hiss?

[Bearman]

I am using Jan's AMP9 and there is no hiss at all. In fact, it's very quite.

What type of power are you using?

[speaker]

Originally posted by Bearman
I am using Jan's AMP9 and there is no hiss at all. In fact, it's very quite.

What type of power are you using?

AC - bridge - capacitor bank - amp

[Bearman]

Is it in a case? How about isolated from chassis with shielded inputs?

I don't know about the Ref board but Jan's have a .01uf speaker output to ground, to cut down on EMI. How about the ref board?

It sounds like a grounding or EMI problem somewhere?

[speaker]

Originally posted by Bearman
Is it in a case? How about isolated from chassis with shielded inputs?

I don't know about the Ref board but Jan's have a .01uf speaker output to ground, to cut down on EMI. How about the ref board?

It sounds like a grounding or EMI problem somewhere?

It has hiss both in & out of a metal case that is grounded. Currently it is out of the case as it did not make a difference when it was in. The noise is a constant "ssssssssssssssssssssssssssss". It is reasonably masked when music is playing but clearly audible on quiet passages.

The eval board appears to be a close implementation of the reference design shown on the device data sheet.

There is a .01uF across the speaker output as the last stage in the output filter. There is no .01uF cap to ground. That is easy to implement & I will try that & see if there is improvement.

What is good to know is that this seems unusual to those familar with the TAA4100 chip. That gives me hope that the "problem" here is unique to this demo board and not the Tripath reference design.

[Bearman]

Make sure that all flux has been removed also.

[speaker]

Originally posted by Bearman
Make sure that all flux has been removed also.

Nothing I can see at least.

Put a .01uF to ground from each speaker positive, no difference.

Shorted inputs, no difference.

Increased supply capacitance from 22KuF to 69KuF, no difference.

[BWRX]

Check the solder joints on the biascap pin of the chip. Also check the solder joints of the cap connected to that pin. Reflow those and see if that helps.

[speaker]

Originally posted by BWRX
Check the solder joints on the biascap pin of the chip. Also check the solder joints of the cap connected to that pin. Reflow those and see if that helps.

Will do!

And to everyone who has been offering suggestions as to what might cause this, thank you!

I appreciate it very much.

[v-bro]

What voltage are you driving it?

It is exactly what happened in one channel of a SI T-amp I owned before it broke down (chip was damaged).

Unfortunately the chip just went up in price...