Big Honkin' Amp Design - Help Me! (Nelson?)

I have two transformers for 12V 40A power supplies, and they're just sitting there.

Here's my thought - hook them back-to-back for an amp with ~120v rails (120V-12V-12V-120V). But, this is quite a bit higher than anything I've ever worked with.

Now, the questions:
- I really like the Zen designs, but which would be best for something like this?
- Which output FET's would be be best (and how many)?
- What would the power output be (and rail voltage, so that power supply caps can be chosen)?
- What other precautions would there be, when working with these large voltages?
- What kind of mechanical design? (The xfrmrs are 25lbs each)

Now I'm not an advocate of that but to each his own. Looking at his diagram (120-12 -12 -120) just struck me as the obvious. I thought it was kind of funny, and I don't say that to be poking fun at anyone. Maybe he was going for some Isolation with that. I don't know. Is Kilowatt still alive? If he is I bet he's running really cool round about now.:D


2001-02-04 4:23 am
"NEVER I repeat NEVER use a audio circuit directly connected to the walloutlet. This is asking for disaster!!!
Your power amplfier will be lethal! " I tried telling that to JasonL and the others at 'Switching amplifier', but they all seem bent on earning the Darwin Award with that Popular Electronics death wish. I hope their life insurance policy is paid up.
You don't have to worry about me though you should do a search on Kilowatt and check out what he is doing to build KW amplifiers. Be forewarned though, what he is doing has been discussed and thought out and warned against so he is well beyond all that, save your breath. I understand high voltages, I work with them everyday. Believe me, you must NEVER lose your respect for what they can do. I have seen people walk away from 7600 volts to ground through their body yet more people die from 120 volts because anyone can gain access to it. The most important thing in your equipment is a good ground connection that goes all the way back TO THE PANEL. It's no good if you have older wiring in your house with no ground. This ground allows fault current a return so it can overload the circuit breaker. Without this ground the breaker has no way to pick up a fault. It will however still trip on overload, but we're more concerned with a LIVE chassis than an overload. We must think of everything in the circuit as a whole from the panel to the speaker.:cool:
Transformerless direct connection to the mains

Hi Skippy,
If want to build kliowatt amplifiers you will need kilowatt transformers unless you build a switching powersupply that uses a much smaller ferrite cored transformer.
I thought I was clear enough but I would not let my life depend on a groundfault switch.
Remember a diaster is always a chain of bad events: f.a. space shuttle Challenger, Tsernobyl, etc.
<B><I>You will never forgive yourself if one of your beloved ones, wife, children gets electrocuted as you wanted to overule this important safety code.!</B></I>

Hey guys, I'm still alive!:D Passfan, I too understand and respect high voltages. Though lots of people have said I'm nuts, some have said that it's ok to do what I'm doing (on the US power system), as long as you know what your doing and have the amp totally decked out with safety devices and circuits.

I guess I'd be a hypocrit if I warned against line powered amps, but this isn't about line powered amps.

My amp will have +/-160V rails, but I'll be using a double barrelled OPS, much like the Leach Superamp, but with MOSFETS.
Heat loss?


Are you sure that such heat production will occur... it's simply transfering potential between the two transformer, with such an heave secondary connected together I don't see any problem...
Never tryed that on such big scale but i don't think it's impossible

well if anyone can proove me wrong pls do so!


What output device will you use in your amp?how many? (just curious)

IRF240/IRF9240. 2 in series, 5 in parallel for each N-channel and each p-channel bank, 20 in all per channel. 8 channels all delivering 900W into 12 ohms. 7200W, 160 devices in all. I'll be running 240VCT from the outlet, but with inductive filtering to reduce noise, and several 100,000uF filtering. It will mostly be running from it's own private power source (generator), so not so much interference from switching on the line. I figure the whole thing will draw maybe 12KW from the outlet at the very most.

I´m not the right one to explain it theoretocally, but what i can say from experiments with lots of old transformers, sold out of old radios with tubes etc. we put in series to make the voltages we needed to play with, it was always the more transformers in series, the less power out of all, much less than out of one of the elements on the powerline as they where designed for. It was very easy to get 2 KV, but no Ampere. Also experiments with transformers for 50Hz driven with 100Hz or more gave no power at the secundaer winding, but lots of heat.