TDA7293 IC

[santitrucco]

Hi Mark..

Here is an example of a 5pin IC.

See how the input runs through the capacitor1, under the resistor1 to pin1,
then back through the resistor1,
under the capacitor1 and back to the input ground.

Here i see a 22k resistor from input to ground .

 

[Mark Whitney]

Here you can see the current paths of the input (red) and the feedback (yellow). See how small the loop area of the input is and the length of the trace between the resistor and pin1.

 

[santitrucco]

shorten all the traces I could, taking care where the line in go.

I do not know what else to do

 

[danielwritesbac]

...what else to do

Personally, I'd buy the smallest amplifier boards possible, and use a separate power board.

 

[nigelwright7557]

The 60hz It keeps being here.
I bypass connect signal input , direct to input cap !!
But nothing change.

Does it still hum with input shorted ?

Your pcb isn't star grounded.
The input signal ground should go to power supply gnd on the pcb connector.

 

[santitrucco]

nigelwright7557

The input signal ground go to power supply gnd on the pcb connector

 

[santitrucco]

I gave up, use the source of this module estreo, and buy two boards mono without a source, following their advice.

 

[santitrucco]

Does it still hum with input shorted ?

Your pcb isn't star grounded.
The input signal ground should go to power supply gnd on the pcb connector.

The HUM is only with left input..

 

[santitrucco]

is good to use .66uf input cap, NFB Resist 22k , shunt resistor 890R ( 24.7x ) and 220uf Nfb cap, and 100uf Bootstrap ?
I prefer sound quality to Watts.

Santiago

 

[santitrucco]

The transformer is +- 30vdc.

 

[JMFahey]

The 60hz It keeps being here.
I bypass connect signal input , direct to input cap !!
But nothing change.

60 Hz?????
Santi, estás en Argentina !!!!!!

 

[Mark Whitney]

Only a correctly designed board is going to fix your problem. Messing around with resistors and capacitors will have no impact at all.

 

[santitrucco]

I have a new board..

Is good to use .66uf input cap, NFB Resist 85k , shunt resistor 3.3k ( 25x ) and 220uf Nfb cap, and 100uf Bootstrap ?
I prefer sound quality to Watts.

Santiago

 

[Mark Whitney]

Why are you keeping it a secret? Post your new build and perhaps we can help.