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Joined 2005
K-amps said:
It is a high bias class-AB amp. I need it to be 2 ohm capable. 37 v at 37 amps > 1kW.
Click to expand...


Such high currents circuits are very tricky to build
- practically

Because at those levels rails that normally have 'no resistance and inductance'
will start to behave as resistors and inductors

PCB layout and wiring plays very important role!
Instead of making one very thick rail/wire,
you may need to parallel several tracks at PCB.

---------------



It was interesting to read the building instructions
to an Elektor Amplifier project, for use with 1-2 ohms loudspeakers.
They are called Ribbon speakers, or something like that.

http://en.wikipedia.org/wiki/Loudspeaker#Ribbon_speaker
Ribbons have a very low resistance that most amplifiers cannot drive directly.
Click to expand...

The Amp Power supply was only +-15 Volt. But the currents were THE BIGGER.
And very special considerations for construction and wiring had to be used,
to keep performance quality at high level ... and avoid disasters ...


I think some other members may also recall and have this article.
I have it somewhere in my Elektor magazines collection.
This power amplifier was tested with data at 0.5, 1.0 and 2 ohms loads, if I remember.


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Zen Mod

Zen Mod

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K-amps said:
It is a high bias class-AB amp. I need it to be 2 ohm capable. 37 v at 37 amps > 1kW.
Click to expand...


I'll give you tomorrow exact data for my "5A" chokes;
they are used in ancient movie projector machines in tone bulb circuit; if memory serves me well-they are pretty cold with 5A DC on them.......


you can make 4 of them if your route is two monoblocks
or even just 2 of them -as I do- for common PS
but-if you insist on higher current....that's easy-bigger pack of iron and thicker wire
 
Zen Mod

Zen Mod

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K-amps said:
Granted this is an absolute worst case scenario. Under normal running I'd say 600 watts max. or 15-20 amps.
Click to expand...

take EI84 lams ,at least 40mm package height,fill entire bobin with 1.5 to 1.6 mm dia enamell wire,make 0,4 to 0,6 mm air gap.......
and you are there

two chokes ,common PSU for both channels....?

just one thing (just now I read again first post) : how Aleph 2 can be AB amp?
 
Zen Mod

Zen Mod

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Stuart Easson

Stuart Easson

Member
Joined 2002
saturation...

IIRC the saturation current of the erse parts is documented on their website...to calculate the number needs a bunch of parameters associated with the core material that are probably not known...

I've mentioned this before, but it bears repeating: At the point in the current curve where the inductor saturates, it then behaves like a resistor as far as increasing current goes, in other words, you have a CRC power supply. Still not a bad solution and for lower currents you get the much improved smoothing of the inductor...

Another thing, I haven't tried cross coupled inductors, where the windings are bifilar woudn so the AC ripple from each rail attempts to cancel the induced voltage from the other...I would think for a class A type amp where the upper and lower rail current demands are largish and mostly equal the extra reactance would be of benefit...I've seen it used on SMPS, but I have no direct knowledge or experience of this in a 'normal' PSU, too lazy to wind my own inductors...

Stuart
 
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