Power Output Transistor

[marvz]

hello,

I am building a power amplifier rated at 500 watt with +/- 80 volts supply. using sanken 2922 and sanken 1216 as power output transistor. how many power output devices are needed for each supply rail?

 

[audioguru]

An amplifier that uses +/- 80V power supply has a max output of about 152V p-p. Then its power at clipping into 8 ohms is "only" 361W RMS.
It might produce 578W RMS at clipping into 4 ohms.

An ordinary 500W class-AB amplifier is about 55% efficient. So for an output of 500W the transistors dissipate about 410W. Each transistor can dissipate about 70W if the heatsink is huge and maybe 100W if the heatsink is big and there is a high velocity fan. 6 output transistors are needed if the heatsink is huge and there is no fan. 4 transistors are needed if the heatsink is big and there is a high velocity fan.

But most people don't play music at full blast all the time.

 

[marvz]

thanks..

you mean 4-6 transistor for each supply rail with the total of 8 to 12 all in all?

 

[audioguru]

thanks..

you mean 4-6 transistor for each supply rail with the total of 8 to 12 all in all?

Never mind how many supply rails.
Use 4 transistors or 6 transistors so that 4 can dissipate 100W each with a fan or 6 can dissipate 70W each without a fan.

 

[marvz]

ah ok..
4 transistor this will be a double output stage, and triple output stage for 6 transistor, is it advisable to put a coil in the output? what is the purpose of it?

 

[redeye]

Never mind how many supply rails.
Use 4 transistors or 6 transistors so that 4 can dissipate 100W each with a fan or 6 can dissipate 70W each without a fan.

there are only two supply rail for +/- 80 volts supply. 4 output transistor means 2 transistor in each supply rail 2 transistor for the positive with respect to ground and 2 transistor for the negative with respect to ground. not including you driver transistor.

am I right?

 

[Nigel Goodwin]

ah ok..
4 transistor this will be a double output stage, and triple output stage for 6 transistor, is it advisable to put a coil in the output? what is the purpose of it?

Yes it is, it's purpose is to improve stability feeding capacitive loads. A zobel network is needed as well.

However, do you consider it's a viable project? - you can buy far higher power amps for much less money than the cost of the parts.

You also have a pretty high chance of the amp self-destructing, maybe more than once, during development.

 

[marvz]

Yes it is, it's purpose is to improve stability feeding capacitive loads. A zobel network is needed as well.

However, do you consider it's a viable project? - you can buy far higher power amps for much less money than the cost of the parts.

You also have a pretty high chance of the amp self-destructing, maybe more than once, during development.[/Q

Sometimes hand made amplifiers have a better performance and it is easier to troubleshoot when it fail to function than the company made

what is the advisable inductance of coi in the output for a 500 watt amp.?
in my circuit diagram it uses 5.7uH.

 

[marvz]

Never mind how many supply rails.
Use 4 transistors or 6 transistors so that 4 can dissipate 100W each with a fan or 6 can dissipate 70W each without a fan.

the PCB foil pattern is based on 1.5kw schematic diagram with +/-130 volts supply.

lowering the supply voltage to +/- 80 volts supply and removing the 12 transistor for 500watt power.

originally from 18 power output transistor minus 12 equal 6 transistor 3 for each supply rail.

Is there any modification need for resistance of resistor in series with the supply for pre driver transistors like R8 or R7?

 

[bokbaard]

Holy moly, I am clearly a noob.
This is probably the scariest of output stages I have seen in a while.

 

[Nigel Goodwin]

Sometimes hand made amplifiers have a better performance and it is easier to troubleshoot when it fail to function than the company made

Sometimes - but very rarely

Heres a highly respected PA amplifier, well known for it's reliability and performance, it offers 700W per channel to 2 ohms, and 480W per channel to 4 ohms, and can be bridged if required to give 1400W to 4 ohms.

Only £225 - bargain!.

 

[audioguru]

The Australian 1500W amplifier was drawn as a joke and was never built.
It will probably blow up until it is tweaked properly.
If it works then your 500W stripped version should also work.

 

[marvz]

Holy moly, I am clearly a noob.
This is probably the scariest of output stages I have seen in a while.

yes! it is, the scariest number of power output transistor in rail like this.

 

[redeye]

The Australian 1500W amplifier was drawn as a joke and was never built.
It will probably blow up until it is tweaked properly.
If it works then your 500W stripped version should also work.

it was never built by the author himself, because the article is provided as an information only.

It will probably blow up if the constructor is not a well experience in a high voltage circuits.

but! there's nothing wrong about the circuit. if it is build properly it will work fine for a +/- 80 volts supply.

_____________________

May I borrow my design? the author says when time come that his design amplifier is in commercial used.

No One believes at all if an author wrote an article for a purpose of a joke.


some of the posted projects are high school problems. and some can answer directly to their questions... but high power circuits are not.

for me it is better not to answer question if my answer does satisfy the people who give a question that expects a concrete and right answer.

 

[audioguru]

Please post a video of the amplifier or your speaker blowing up!

 

[marvz]

**broken link removed**