Questions about building new power amp

IPG Event

2011-01-29 5:46 pm
Hello! I'm going to build a new power amp to my new purchased speakers, I've been looking for good schematics on the net but I need a lot of watts, so the only thing I've found is this: :cop: Link removed as this project is lethal.
but the only people sheer is that it is "dangerous" to build but I want someone to see if it really works, I have built many smaller amps and have repaired all sorts of electronics whole life so I'm no amateur in the subject.
I also know that it is illegal to build in some countries. and that it is un-insulated against AC-net in some parts, so the only thing I want is a professional judgment if it really works :)
Or if anyone knows any others simmlar schematics that works

Sorry for bad english

/ / Kim :)
Last edited by a moderator:
I did not much look at the schematic, but 5 kW at 230 V AC line level is about 21.5 A. 75% efficiency, at best brings, that to 28.5 A. Enough power for a stadium that seats 20,000 spectators. I think, I would look for more efficient speakers first to allow me to reduce power requirments! E
You could IF you used the proper rated input transformer, connect the grounding correctly and insure that the speaker is always insulated. If the speakers can't guarantee insulation then you have to use an insulated output transformer. The whole issue is that if parts of the circuit are not isolated from mains then electrocution between the circuit and earth GND can be quite easily acomplished. :RIP: One solution is a properly rated SMPS. It seems to me that for this much power, you either have a large heater or you would go with a class D type circuit or a switching rail follower power supply.

IPG Event

2011-01-29 5:46 pm
Okay thanks for the quick response!

Is there anyone else who has reached similar schematics that works then or they are difficult to get hold of? they are expensive and difficult to build is not important only that they work well, I've found schematics that put out around 1.500 watts / CH that seems to work, and would do if I did not get something else

or is there anyone who knows any other site there i can look?

/ / Kim


Paid Member
2007-09-15 8:14 am
You're being MUCH too nice. That contraption is a death waiting to happen. The irony is that the transformer is an autotransformer which is already pretty big. How much bigger would it be with a properly isolated secondary?

:cop: Indeed !

Which is why I've taken the very unusual step of editing a post. The link in the first post has been removed.

As long as the discussion keeps to normal amplifiers (safe isolated transformer powered) then the thread will stay open.

What do need 5000 watts for anyway :D
Unless you have access to extremely cheap surplus parts, it's generally cheaper to buy a used power amp. They can be worth buying just for the parts alone, since big heatsinks, transformers, filter caps, and cases cost a lot if you're buying them in small quantities.

The Behringer digital amp is worth a look. Also those digital amp modules from places like Digital amplifier modules from CAD AUDIO DK
They can be worth buying just for the parts alone, since big heatsinks, transformers, filter caps, and cases cost a lot if you're buying them in small quantities.

The case is worth a bit too. Having to hack out mains sockets etc on a new chassis is a real pain.

I sometimes use PC cases for amplifiers. It has a mains input socket and holes for fans.

Take care when buying second hand smoothing capacitors as it is likely they are approaching the end of their life.