Output Transistors/Ultimate Power Amp?

[alanandlexie]

Hi everybody, I'm planning on building a combo amp based on 3 of the following circuits:http://sound.westhost.com/project27.htm#bass

One will be a Bass channel, the other 2 will be guitars.

Now my question is probably dumb but I just can't find the answer. I want to add more output transistors to share the power in the power amp, but I haven't a clue how to modify the circuit. It's going to be used pretty aggressively and I don't fancy having just two output transitors for each 'channel' as it were.

Woudl there eb a better design of power amp I could try? Would I be able to put all 3 pre amps into a single large 3 channel power amp?

I'm pretty good withelectronics but not had any real involvement with amps, only fairly simple circuits involving model railways.

[EchoWars]

Try here: http://www.sound.westhost.com/phpBB2/index.php

[nigelwright7557]

You would be better going for a more powerful design.

The driver stage needs to be powerful enough to drive the extra transistor pairs.

I designed my own 900watt amp with 3 pairs of MOSFET's on the output and it is very loud. I use it for disco and guitar use.

[AndrewT]

Hi,
for PA duty, you have to decide what power output you need.
Borrow some amps and experiment to find your requirements. Listen to feedback from your audience. Do you have a soundman/roadie you can rely on?

Is 100W into 8ohm sufficient for your needs?

If you decide on a power output make sure your PA can adequately drive 4ohm speakers if you ever decide to connect them up or double up the cabinets you use.

That gets you to a minimum requirement of 180W into 4ohms.
Even that is low for PA duty with 94/96dB/W/m PA speakers.

If you need reliability, then use ONsemi mj15003/4 or mj21192/3
These are both 250W 200degC devices on big fan cooled heatsinks.
With lots of protection features built in to keep the amps working all night.