F5 power amplifier

[bobodioulasso]

What size of two channel amplifier is your 1kVA transformer driving?

I do not understand the question.
I told 2x100w/8ohms, 2 ohms capable.

[tinitus]

How about a couple of 2kva trafos

[bobodioulasso]

[tinitus]

Never mind
Anyway, this is all too confusing to those who seek advice, and not relevant to builders of F5


Nelson states 6A continious is needed, and 10A peak
2x 18Vac trafos with minimum 10A
360watt trafos pr channel is absolute minimum

500watt pr channel should work fine

Here we can get Amplimo 300, 500, 625, 800VA, with 2x 18Vac

I dont know, but I have always known 500watt toroids to be the upper limit without using softstart

[bobodioulasso]

How about a couple of 2kva trafos

At first glance, i have been thinking you were joking.

But finally i think you are not far from the truth.

100w/8ohms give peaks of 200w corresponding to 5A pk
then, 10Amp pk@4 ohms and 20amp pk@2ohms.

Which correspond to a 2x35v transformer 1400va/ channel.
And not less than350va@8ohm and 700va@4ohms.

The problem is, when you read about this on the web or in books, opinions differ.

[tinitus]

Ok, measured voltage is actually 2x 38Vac, 25-30A(?)

Specced by pros doing a balanced 500watt classA, 2000watt AB
I think two of those were used each channel
Water cooling, PC control, motor vario powerup

They did build working proto amps
Aimed at recording studios etc
Not sure they sold any

Well, they are from before anyone thought about classD

These trafos are leftovers
Fun to look at, but have become more of a burden now
Today, I tend to believe that smaller sound better

I have 50watt AB monos with 500watt trafos
With singel pair BJTs they play in 2ohm easily, and still sound nice

I suppose classA is best done BIG, not to have all sorts of heat issues
ClassA is no cheap affair

I have really no interest in classA as such
But I do have interest in F5
And I really like the size, and its elegant "simplicity"
But had it been bigger I wouldnt be here

[tinitus]

forgot to say that I had a Hiraga clone some 30years ago

And since then been waiting for this to happen

[Babowana]

Impressive . . .

And, all including me are making readers entirely confused . . .
in the transformer sizing . . .

God bless us . . . please . . .

[tinitus]

I sure hope this one was correct
Noone argued, so I suppose it is

Originally posted by tinitus


Nelson states 6A continious is needed, and 10A peak
2x 18Vac trafos with minimum 10A
360watt trafos pr channel is absolute minimum

500watt pr channel should work fine

Here we can get Amplimo 300, 500, 625, 800VA, with 2x 18Vac

I dont know, but I have always known 500watt toroids to be the upper limit without using softstart

Originally posted by Babowana
Impressive . . .

And, all including me are making readers entirely confused . . .
in the transformer sizing . . .

God bless us . . . please . . .

[labjr]

Originally posted by tinitus
I sure hope this one was correct
Noone argued, so I suppose it is

I got lost way back in this discussuion. I can't even figure out what it is you're asking? Are you building the textbook F5 or something else?