TDA7293 IC

[UltimateX86]

Why not using transistor like LINN CHARKA ?
https://static.qobuz.com/info/IMG/jpg/Amplificateurs.jpg

GB2405275A - A discrete transistor boost amplifier for an audio driver IC, wherein the boost amplifier is automatically activated at high output levels
- Google Patents

linn abandoned the parallel to use transistors

 

[UltimateX86]

HD photo : Mao Audiophile Modifications: A Linn Klimax Chakra 500 Twin rescued from the last flood

 

[danielwritesbac]

Daniel, is it possible to combine the »modular« approach with the »economic« approach in the TDA7293 datasheet? That means paralleling the output stages of two or more chips and arrange them in a class g/h (whatever it may be...) environment? Best regards!

I didn't find out. See the arrangement with 1000uF connected near small signal portion of the amp? Large signal support on a board that ought to be treated like small signal, says that it is a subwoofer amplifier... and I lost interest directly. Today, we use Class D for subwoofers, especially NXP's Class D (after you put on a real input circuit including 470R series to each input to lower crosstalk).

However, it was interesting to see the possibility of TDA7293 chips in slave mode working at up to +-50vdc (32+32vac transformer). So, a parallel output tube hybrid looks promising. Or, if you happen to have a driver chip handy. I haven't tested at that voltage, but TDA7293 in slave mode looks like bargain priced audio output fets.

 

[santitrucco]

Friennnddsssss !!!!
I have a new module with TDA7293.

I have a little hum 60hz, in ONE channel..
Only little and only in one channel.
Whyyyyy ?

And i have 0.014 ac in these channel.

 

[santitrucco]

Is not in one chassis , only in a wooden board.

could be this ?

would it serve a cable from ground on pcb to chassis or main transformer ?

 

[santitrucco]

.

 

[santitrucco]

Please

 

[PRR]

> only in a wooden board. could be this ?

Yes.

 

[santitrucco]

I will Try

 

[santitrucco]

the 60hz are still in one channel

 

[danielwritesbac]

Friends i build a tda7293 module estereo , and i have 60hz hum in one channel.
0.014v ac ,is not a lot of ac noise, but why ?

First, make ALL wires for right channel Exactly the same length and size/gauge as left channel (especially, identical left/right, input wires and dc power wires--NO left/right difference).
Second, use a battery powered source (because it can't ground loop if it isn't plugged in).
SO,
The above steps will help to find the layout fault; because, if it wasn't the wiring, then the fault is in the board layout.
For that, you'll need to post photos, using the attachment feature.

 

[santitrucco]

The noise is still in a channel.

I'm sending some pictures.

 

[Mark Whitney]

Very likely that the cause of the hum is related to your layout. The input+ runs across the board without its ground and/or mixing power and input currents along the same (ground) trace.

 

[danielwritesbac]

There's a power supply squatting in an area with small signal amplification. That will sound like consequences.

 

[santitrucco]

I will try.

I will tell you the result.

But there is 8 cms between +input , and AC rail , too mach near.

 

[Mark Whitney]

It's the DC and DC ground that are the problem.

 

[santitrucco]

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

 

[santitrucco]

 

[santitrucco]

It would be a problem of dc and dc ground .

Is it a input line level problem ?

 

[Mark Whitney]

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.