zxi hifonices

[Hexhclass]

Two channes on this amp plays low and distorted.One of the output transistor is geting
hot when i connect a speaker to the channel even with no singal applied.

I had that same problem with a crunch amplifier and to get the amp wprking.I had to
decreasing the value of the resistor connecting between the base and collector of the bias transistor.
I also tried bridging the emmiter and collector of the bias transistor but no change. Any ideas?


output transistor

1:0.788
2:23.07
3:0.390

bias transistor
1:0.974
2:1.079
3:1.019

 

[Perry Babin]

Are you sure that only 1 output transistor is getting hot?

If the bias is a problem, it's generally going to cause both transistors (high and low side) getting hot unless one is shorted.

 

[Hexhclass]

One would get hot fast so I didn't live it on long enough to check the other one.
I change both output and bias transistor but no change.

 

[Perry Babin]

Does the transistor get hot with no load connected?

 

[Hexhclass]

no,only with load

 

[Perry Babin]

That would indicate that you have excessive DC offset (doesn't appear to be the problem with the voltages you posted) or the amp is oscillating.

Does setting the crossover to low pass make a difference?