TDA7293 single, bridge, parallel

[abraxalito]

I can't think of a way to modify the buffer as its integrated into the chip. But if we employ it bridged then the overall gain won't change since there will always be one M1 and one M2 FET in the circuit. At least to a first order anyway.

 

[Kindhornman]

I guess I was thinking of a discrete buffer stage that wasn't part of the following op amps. A simple 5532 or something like that.

 

[panson_hk]

As far as I can see from image, at the moment you are using one PSU with dual bridge rectification. If that is correct you should use power ground formed by local decoupling caps near TDA7293 power supply pins as your reference for signal and speaker ground reference.

I'am little suprised to see crossover distortion from TDA's even at low power level...they (invertors) claimed there will be no distortion😱

Output power of 10 W is not a low level. Unless TDA7293 output stage has high bias level to get Class A operation for more >= 10 W. You will see crossover distortion. This is seen for 1 W. TDA7293 is definitely not such an over-biased chip.

 

[panson_hk]

I am curious how much of the XO distortion is even harmonics? Any chance to see how the distortion residual looks in bridged mode?

Sounds like an interesting topic for my next step.

 

[jcx]

I've biased paralleled op amp outputs against each other up to Class A bais - no reason you couldn't do the same with power chip amps

as pointed out above, opamps cannot be pin-to-pin paralleled

they have to have separate feedback loops and output current sharing resistors due to their differing open loop gains and input offset V, even op amps on the same die in a dual/quad don't match well enough

I have paralleld tpa6120, and biased them into push=pull Class A:

What are your opinions on headphile stands?

posts 13,19 shows the heatsinking, 16 a simplified simulation of the otuput paralleling/Class A bias

 

[tiefbassuebertr]

Hi Charlie,

I think +/- 40 V rails is fine for paralleling the chips. For single, it would be too high. Yes, a big heatsink is needed.

I think improvement for 4 Ohms will be more or less stop when paralleling up to four chips as LM3886.

I am also thinking to use a configuration "opamp + TDA7293 (slave)". We may have an amp with better performance where output stage in a single package with protection.

Panson

ae there commercial amp devices, where this approach is realized?