Thx.
offtopic, but could u suggest smth with similar performance, that would have less footprint?
I have a DIY 6 channel amp, made with tda7293 small kit pcb's.
It does not necesserily require boucherot/ inductor, so pcb's are really small.
The problem is, it is not very reliable at +-42 supply..
So I think of discrete solution with power transistors.
One of the channels (sub 4 ohms) - to be with parallel transistors, as the respective tda7293 channel had two chips in parallel.
3 out of 6 channels are burned currently
.
Otherwise I am content in terms of sound quality and output power for what I am using it.
offtopic, but could u suggest smth with similar performance, that would have less footprint?
I have a DIY 6 channel amp, made with tda7293 small kit pcb's.
It does not necesserily require boucherot/ inductor, so pcb's are really small.
The problem is, it is not very reliable at +-42 supply..
So I think of discrete solution with power transistors.
One of the channels (sub 4 ohms) - to be with parallel transistors, as the respective tda7293 channel had two chips in parallel.
3 out of 6 channels are burned currently
.Otherwise I am content in terms of sound quality and output power for what I am using it.
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Have a look at-
Zobel networks
Notice the different values for different models of loudspeaker by the same manufacturer.
Its always a compromise but it works the British GPO/BT used Zobel networks for their external lines , I worked for them .
While not the same in this age of fibre the principle hasn't disappeared or been made redundant its a scientific Principle.
Yes you can have an amplifier with no zobel network but it must be a good design and stable without it and you can have a design without the series/parallel resistor /inductor JLH had only a series resistance in some of his designs as the WW resistor had enough inductance built in.
Zobel networks
Notice the different values for different models of loudspeaker by the same manufacturer.
Its always a compromise but it works the British GPO/BT used Zobel networks for their external lines , I worked for them .
While not the same in this age of fibre the principle hasn't disappeared or been made redundant its a scientific Principle.
Yes you can have an amplifier with no zobel network but it must be a good design and stable without it and you can have a design without the series/parallel resistor /inductor JLH had only a series resistance in some of his designs as the WW resistor had enough inductance built in.
If an amp oscilates then it doesn't care about if there is a tweeter or a woofer connected.
The inductor is there to prevent to amp-output from RF-frequencies catched by the speaker cable. The resistor in parallel "preloads" the amplifier in this area. Keep it as close to the summed outputsignal as possible, as far from components that are open to influence for disturbence as possible, too.
The inductor is there to prevent to amp-output from RF-frequencies catched by the speaker cable. The resistor in parallel "preloads" the amplifier in this area. Keep it as close to the summed outputsignal as possible, as far from components that are open to influence for disturbence as possible, too.
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The above article (#7) only addresses a speaker application. That's too little, too late in the audio chain to be effective. The better place for the Zobel network ( the function is to squish HF instability artefacts) is right at the junction of the output and emitter resistors of a typical emitter follower output stage amp.
The coil and parallel resistor network is there to damp ringing, i.e. reflected pulses of oscillation that happen with the inevitable mismatches of amp:speaker impedance. It can be located in any position from the Zobel up to the output terminal. However, if an output relay is included in the design, it makes sense to fit it before that.
RF damping is usually achieved with a small value shunt cap., often right at the output terminal.
The coil and parallel resistor network is there to damp ringing, i.e. reflected pulses of oscillation that happen with the inevitable mismatches of amp:speaker impedance. It can be located in any position from the Zobel up to the output terminal. However, if an output relay is included in the design, it makes sense to fit it before that.
RF damping is usually achieved with a small value shunt cap., often right at the output terminal.
Re: discrete STK4241 build
Unfortunately, an equivalent circuit without component values won't help to recreate anything, let alone a specific hybrid amplifier module. You would need to disassemble the module, trace the real circuit interconnections and measure the components individually to make a practical schematic and check that it works correctly with reliable SPICE simulation. Then the thermal integration of the hybrid module has to be taken into account. It won't be there with a discrete build so what to do about it?
You may be able to measure and estimate what type of semis are used but overall, thats a job even an engineer would avoid. It will be a long, hard road doing this. I would simply substitute a chip amp using a suitable, small PCB for its support components. That will be much better in most practical ways than trying to recreate a hybrid with any particular sound quality it might have, and perhaps you would like to reproduce.
Unfortunately, an equivalent circuit without component values won't help to recreate anything, let alone a specific hybrid amplifier module. You would need to disassemble the module, trace the real circuit interconnections and measure the components individually to make a practical schematic and check that it works correctly with reliable SPICE simulation. Then the thermal integration of the hybrid module has to be taken into account. It won't be there with a discrete build so what to do about it?
You may be able to measure and estimate what type of semis are used but overall, thats a job even an engineer would avoid. It will be a long, hard road doing this. I would simply substitute a chip amp using a suitable, small PCB for its support components. That will be much better in most practical ways than trying to recreate a hybrid with any particular sound quality it might have, and perhaps you would like to reproduce.
Not only this. Even better, this may just be regarded as a side effect. The primary purpose is to isolate the amplifier from highly capacitive loads which may affect it's stability.
Best regards!
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