QUASI Amplifier for Beginners

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#641
There is a limit to the voltage, so adding more outputs will only give more power into a lower impedance.

At some point the driver transistors will not be up to the task. At that point I would probably go to a triple (pre-driver, driver, outputs). I found six pair of outputs into a low impedance gave a circular 'bite' out of a sine-wave in the second and fourth quadrant (classic sign of not enough drive current). Crown uses the triple in most of their amplifiers.
 
#642
Ok...i think the output power it depend to the,input voltage? Then if you,add,more transistor i think to prevent over heating? Because the output transistor is in parallel,connection so that the power input divided, on how many output transistor have? Am I right?
 
#643
"Ok...i think the output power it depend to the,input voltage?"

The ± supply voltage.

"Then if you,add,more transistor i think to prevent over heating? Because the output transistor is in parallel,connection so that the power input divided, on how many output transistor have? Am I right? "

Basically, yes.

With good heat sinks you will be able to get roughly 100W per pair of outputs. A Crown DC300A doesn't have real big sinks, so they use four pair of outputs to do 300W/4Ω. They later offered a heat sink up-grade, or you could add fans.

See here for up to 10,000W with the 2N3773.

http://www.diyaudio.com/forums/solid-state/211635-simple-100w-power-amp-3.html
 
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#648
A single pair for 100W of maximum output power is a bit ambitious, especially if the devices chosen have poor SOAR.
I prefer to use device power rating as a guide to maximum output power.

Pmax ~ {total device power rating} divided by 5 to 6 for BJTs. I use divide by 4 for FETs
A two pair 1943/5200 has a total device rating of 600W. That would indicate a safe and reliable 100W to 120W of maximum power output.
For an 8ohms amplifier that would require a +-50Vdc to +-54Vdc PSU.
For a 4ohms amplifier that would require a +-38Vdc to +-42Vdc PSU.
For a 2ohms amplifier that would require so much output current, that I would not bother entertaining such a nonsensical target.
 
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#649
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#653
"When i put 80+- it is ok and add more output transistor? "

Only if you can hand-select the outputs to be sure of a higher voltage than what the part is rated for. For instance, Crown hand-selects all the 160 outputs used in the MA10K to run at 163V (rail-to-rail), plus a safety margin for high line-voltage.
 
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