F5 power amplifier

Yes your statement might also be true too.But you know that it is not a good think to use capacitor at the end point for life factors etc.And the distortion of capacitor increases by this way.
But you are using a very high quality sounded F5 Class A amplifier.This is a push pull class A amplifier.
So why not give some more ten bucks and use higher capacitance?When i add more capacitor i can easily see that bass and treble performance improves.
Some diyers/buyers give hundreds and thousands dollars for speaker cables/line filters but they do not know that increasing capacity(only some ten dollars) improves amplifiers performance more than they do
This is your philosphy.You can use whatever you use.We are both true.
 
Anyone? I got more boards to stuff!

russellc

Russellc,
PM Diyaudio member Blues, he has well matched JFets for F5 available.
He has a thread for it, but I can't seem to find it. Him and tech-diy offer excellent service.

Thanks for the alley-oop slam dunk T-Bag!

Russellc, please check out my signature below for the wormhole to the thread...
 
I am asking myself:

as I build a stereo amp and the voltage from the tranny is a little bit to high:

Does it make sense to add per channel separated RC filters?

I have enough of this 22000uF caps and space is also available in the enclosure.

Or is it better not to use electrolytics for this additional RC filters? Some MKP's with 10uF?

Franz
 
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I am asking myself:

as I build a stereo amp and the voltage from the tranny is a little bit to high:

Franz

Your tranny does not look very big. Is it a 300VA tranny (20V AC x 2)? I agree with Juma that the DC output may be just 25V-26V when idle current is biased to the specified level after amp has been fully burned in and warmed up.

The toroid tranny I used was 400VA (18V AC x 2). Without load it was a little over 25V DC each rail. With load it was 23V DC each rail.

I personally would increase the filter resistors' resistance a little rather than adding another RC filter, if the voltage is really over just a little. In my opinion, another RC filter will make the amp sound dry and dull.
 
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So why not give some more ten bucks and use higher capacitance?When i add more capacitor i can easily see that bass and treble performance improves.
.

Umut
The main reason is that I do not like capacitors. However, I cannot do without it. I think it is my problem. By the way, I like the Turkish movie "Pandora's Box", which is a very good movie.
 
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Your tranny does not look very big. Is it a 300VA tranny (20V AC x 2)? I agree with Juma that the DC output may be just 25V-26V when idle current is biased to the specified level after amp has been fully burned in and warmed up.

Yes, it seems to be a 300VA tranny, guessed from the size. It is out of my parts box.

I will try to arrange the parts in a way, that I can replace it later by a 500VA version, when I think I need it.

In my opinion, another RC filter will make the amp sound dry and dull.

I will stick with the original psu design, CRC filtering.

Franz
 
I finished my (first) F5 amp.

It was a really great diy experience! The result: probably the best amp I've ever built.

All my questions I had are already answered in the 18 pages manual. RTFM...

The only answer I never got: how much is PSRR of the amplifier circuit.

Let's give me the answer by myself: Enough :)

Great work, Nelson!

It was a great pleasure to do the initial adjustement using two DVM's at the resistors and one old analogue mili-voltmeter at the output.

The voltages with my tranny are now at 24.6V per rail.

I made this amp for a friend who is driving this speakers with it:

An externally hosted image should be here but it was not working when we last tested it.


This coaxial two way speakers are built in a Mini Onken enclosure with a very special design:

An externally hosted image should be here but it was not working when we last tested it.


Before the F5, my friend used a tube buffered LM3886 gainclone or a TK2050 t-amp.

The gainclone was not satisfying in the bass area and the TK2050 produced listening fatigue.

The F5 beats them both, no question. In every aspect.

It is a awesome sounding amp without any hassles. Absolutely dead silent at idle, no power up or power down pops, nothing.

It was one of this famous euphoric moments when we listened the first time to the F5 today, after having it adjusted and measured during two hours in the workshop.

I think, after my vacation I have to build for myself three stereo F5's to drive my active setup.

And to think about airconditioning in my flat...

Just for fun, here a picture I made some years ago, when I made this mini onkens. First bass test with my little daughter (she had a cold at this time and a strong cough).

An externally hosted image should be here but it was not working when we last tested it.


Nelson: thanks for this nice amplifier!
Franz