My 1024W RMS CLASS A+ amplifier.

[Juergen Knoop]

but the hum-voltage after the rectifier would be less with a 3phasic-bridge?

[myhrrhleine]

Originally posted by juergenk
but the hum-voltage after the rectifier would be less with a 3phasic-bridge?

3 pulses at 50 hz=150 pulses
or
3 pulses at 60 hz=180 pulses
or double for full wave bridging.

1 pulse for single phase 1/2 wave or 2 pulses for full wave rectification= 60 or 120 hz.

Not counting induced currents.

[Juergen Knoop]

more pulses, but less intense I guess
because the one big charge pulse at the capacitor is divided up into three smaller ones
I have build 3-phasic heating supplies, but no experience with 3-phasic rectification.
So I am curious.

[myhrrhleine]

Originally posted by juergenk
more pulses, but less intense I guess
because the one big charge pulse at the capacitor is divided up into three smaller ones
I have build 3-phasic heating supplies, but no experience with 3-phasic rectification.
So I am eager to learn.

'hum' is repetative pulses.
The cap recharges on every pulse

[Christer]

Som Mark Levinson amps convert the incoming mains to 3-phase 440 V to make it easier to smooth out the ripple. Since it is aircraft standard, they can also make use of certain technologies from that field. I don't think they say how they make the conversion and if it is really worth the price compared to using the same amount of $$$ on big caps an chokes instead.



Glen,

clever with the floating supplies. I assume they are just separate windings on the transformer with ordinary rectification and caps. However, the crossover artifacts from the class AB stage will bleed through to the supply of the class A stage, I suppose? Of course, that is much better than having them directly at the output.

[Nelson Pass]

Originally posted by Hartono
If you build it, probably you will be on world's class A hall of fame. 1000 watt class A

Sorry, I just strapped 5 XA200.5's in parallel and got that.

[Christer]

Originally posted by Nelson Pass


Sorry, I just strapped 5 XA200.5's in parallel and got that.

Isn't it summer in California? Sounds more like a winter experient, I think.

[Nelson Pass]

They were on the burn-in rack anyway.

[JRKO]

With all the variations on amp design is there really a benifit of having a 1000w amplifier rather than the 20-30w or even 3w designs out there?

What sort of speakers are you driving/how big is your listening room?

I have some fairly effecient speakers and have given them 100 class A watts, 5/6 class A watts and 10 digital watts. My favourites are the smaller amps, especially the little class A one. I get the control of class A over AB for example but cant see the benefit of 1000w in any residential setting.


Just so you know these are genuine questions and not meant to start an argument

[PB2]

Originally posted by G.Kleinschmidt



All up it will be a lot more than that. I've ordered four 200VA EI (split bobbin - better primary-secondary isolation than a toroid) transformers to provide the floating supplies for the class-A stages. These weigh 2.8kg each.

A pair of 2kV toroidal transformers supply the class B stages. I don’t know what these will weigh.
There are also various little transformers for ancillary stuff.
Incidentally, whilst finalising the transformer order and looking into available electrolytic capacitors, I have revised the amplifiers rated power/load impedance again

The amplifier is now going to be built to deliver 1000W rms per channel (continuous sinewave) into 2 ohms, not 4 ohms. This is much more sensible, as a pair of 4 ohms speakers (or even a quad of 8 ohm speakers) can be paralleled to make a 2 ohm load. Ever seen a 4 ohm 1kW speaker in a HiFi shop ) ??

The 2 ohm rating also means that the class-B supply voltages can be kept well below +/-100V (1kW rms into 2ohms = 63.2V peak). Electrolytic filter capacitors for supply voltages below 100V are much cheaper and easier to obtain.

Phew. I’ll get back to the (final? ) version schematics and PCB layouts now.

Cheers,
Glen

Nice work I must say, I like crazy all out designs.

As I read this is it going to be a single amplifier chassis?

I very strongly suggest that you go to mono blocks, after having lived with a few amplifiers that were too difficult to move. You also get twice the line power.
Cutting those heat sinks in half would make a lot of sense.
On the other hand that huge tower would certainly make a visual statement. You'll certainly have the tallest audio amplifier ever made!

Pete B.