F5 power amplifier - Page 406

bobodioulasso · 15th June 2009, 05:11 PM

Quote:

Originally posted by AndrewT
that question was regarding a transformer for a ClassAB amp with a bias ~70mA (see National datasheet), not a ClassA amplifier with a bias of 1300mA as being discussed in the last few posts of this F5 thread.

No this question was about F5 post #3952.

labjr · 15th June 2009, 05:27 PM

Quote:

Originally posted by bobodioulasso

Is your trafo running hot after many hours ?

Mine runs at room temperature because it's still in the box waiting to be built.

However, when we auditioned Tea-Bag's F5, I remember the transformer running a little warm. No big deal.

Babowana · 15th June 2009, 09:07 PM

If I read the F5 owner's manual, it says that the power supply of +/-24 volts, 6 amps "continuous" duty and "more" than 10 amps peak per channel for the "tested" amplifier.

And, spec mentions "Output power stereo 8 ohms: 25 watts@1%THD, 1kHz" only. (pure class A)
And, fuse size 1.25 Amp for 240VAC main.
And, actually, F5 has the 300VA transformer.

For the big transformers, what are your AC main fuse sizes?

Bill Fuss · 15th June 2009, 09:34 PM

See what you guys started! Take over Andrew, I quit.

Melon Head · 15th June 2009, 10:04 PM

I can't believe we are still talking about transformers.

nigelwright7557 · 15th June 2009, 10:12 PM

Quote:

Originally posted by AndrewT
so which is it that you use?
a 100W+100W amplifier powered by a 1kVA transformer
or
a 200W+200W amplifier powered by a 1kVA transformer
or
a 400W+400W amplifier powered by a 1kVA transformer.

I will answer "advice" by private Email, it's too far off topic to expand here.

If I remember correctly 60% of power is dissipated in the load and 40% in the output transistors.
This means you need a transformer that can supply around 1.66 times the power into the speaker.

So a 100watt RMS amp requires 160VA transformer.

Babowana · 15th June 2009, 10:15 PM

Quote:

Originally posted by Bill Fuss

... some people complaining about their trafo buzzing and that is what you get when you use more caps than the trafo can handle because of the peak charging current.

Are you talking about the turn-on inrush current?
Otherwise, I don't believe so . . .

Babowana · 15th June 2009, 10:32 PM

Quote:

Originally posted by AndrewT

the first Watt F5 specifies 6Aac (216VA) for the transformer.

It says, "6 amps continuous duty" . . . for the "tested" amplifiers . . . (not for the market products) . . .

I don't understanf where you get the 6Aac . . . ???

Bill Fuss · 15th June 2009, 10:40 PM

You can believe anything you want.

Babowana · 15th June 2009, 10:47 PM

I believe that the amount of charging and discharging current in the filtering caps is depending on the load current . . . My point is that it doesn't depend on the cap-size vs trafo-size . . .

Probably, I didn't understand correctly what you were talking about?

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15th June 2009, 09:07 PM	#4053
Babowana Formerly "jh6you". R.I.P. Join Date: Jul 2006	If I read the F5 owner's manual, it says that the power supply of +/-24 volts, 6 amps "continuous" duty and "more" than 10 amps peak per channel for the "tested" amplifier. And, spec mentions "Output power stereo 8 ohms: 25 watts@1%THD, 1kHz" only. (pure class A) And, fuse size 1.25 Amp for 240VAC main. And, actually, F5 has the 300VA transformer. For the big transformers, what are your AC main fuse sizes?

15th June 2009, 09:34 PM	#4054
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	See what you guys started! Take over Andrew, I quit.

15th June 2009, 10:04 PM	#4055
Melon Head Formerly Thanh1973 Join Date: Nov 2006	I can't believe we are still talking about transformers.

15th June 2009, 10:40 PM	#4059
Bill Fuss RIP Join Date: Oct 2005 Location: Central Florida	You can believe anything you want.

15th June 2009, 10:47 PM	#4060
Babowana Formerly "jh6you". R.I.P. Join Date: Jul 2006	I believe that the amount of charging and discharging current in the filtering caps is depending on the load current . . . My point is that it doesn't depend on the cap-size vs trafo-size . . . Probably, I didn't understand correctly what you were talking about?

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