Input caps picking rfi??

[rayma]

Oh you think input caps are extra
Yeah it still works..

Is there a DC voltage at the input now? If so, don't connect it to any other source
unless that source has a blocking capacitor at its output.

My bet is still for oscillation.

 

[scottjoplin]

Not exactly, I was trying to rule it out as the source of the noise, but in a single supply amp the input is biased halfway between the power rails so you can't simply short it

 

[slmnklyc]

Is there a DC voltage at the input now? If so, don't connect it to any other source.

Thanks rayma.
I just 2-3 seconds shorted the input cap.I think it is still ok..

 

[slmnklyc]

Maybe these can help..

 

[rayma]

Maybe these can help..

Do you have a schematic diagram?

Also, Is this a new, unproven board and circuit, or has it been successfully built before?

 

[scottjoplin]

Have you a multimeter to check it you have DC at the inputs. I think each of those chips is stereo, so do we have two bridged amps?

 

[slmnklyc]

TA8210 bridged 2-ch amp chip.
I used 2 of them one for L-ch and other chip for R-chip.
I used exact same channel inside the chip for each channel.
I used two supply cap and they are connected to one single power input connector.

 

[slmnklyc]

Do you have a schematic diagram?

Also, Is this a new, unproven board and circuit, or has it been successfully built before?

No,I made it with diptrace..
You can see the image just I used R-ch of the diagram.
2 bypass caps(*2) for each ripple filter cap and main filter cap.
I connect the stb pin to directly to main voltage.
That's it.
If it helps, I can draw the schematic..

 

[scottjoplin]

You've used one channel in each chip? Why?

 

[slmnklyc]

You've used one channel in each chip? Why?

I want it to be stereo without btl.
I think it maybe helps crosstalk and I can also use it with headphone-power amp adapters..

 

[scottjoplin]

I see. It's probably ok to leave one amp disconnected, I'm not sure, maybe someone else would know if this might be an issue

 

[slmnklyc]

I see. It's probably ok to leave one amp disconnected, I'm not sure, maybe someone else would know if this might be an issue

I also short the unused channels to gnd.
But it didn't make any difference..

 

[slmnklyc]

I also short the alp blue velvet volume pot case to the gnd.
Same result..

 

[scottjoplin]

How does the noise level compared with the pot set around mid way?

 

[slmnklyc]

How does the noise level compared with the pot set around mid way?

It is like half noise maybe ?

 

[scottjoplin]

Haha, less than with it right down and right up?

 

[slmnklyc]

Less than volume fully open..

 

[scottjoplin]

I think you should start by using proper coax cable to connect to your source and see if that's any better, of course, we don't know how loud this noise is you're hearing, you say you have to put your ear right up by the speaker?

 

[slmnklyc]

Please don't say a little noise quite normal or something like that..
I don't know and I am asking because of that:
If you think it can make difference, I can cut the wires goes to pcb??

 

[MAAC0]

The Million Dollar question here is What kind / Type of noise are You hearing ?