F5 power amplifier

[wensan]

You can easily build a balanced F5 with dual diff pairs.

Who wants the glory of posting the schematic?

Like this?

 

[Zen Mod]

Like this?

nope ;

this way is more functional ;

 

[Nelson Pass]

That's one. I can think of a couple others...

 

[Zen Mod]

That's one. I can think of a couple others...

seems that there is more than few ways to skin a ... UGS .....

 

[Zen Mod]

 

[wensan]

That's one. I can think of a couple others...

I wonder this one will be better or not ?

 

[umut1001]

Hi umut1001,

Using 15R instead of 10R will reduce the Idss (see fig 4B, page 28 of Borbelly Part 1) of the jFET.

hi..I matched my jfets and there are high IDSS ones.12ma.Maybe i can use them.
Also i am waiting for a good bridged circuit

 

[Blues]

hi..I matched my jfets and there are high IDSS ones.12ma.Maybe i can use them.
Also i am waiting for a good bridged circuit

Save your high Idss jfets for a long tail differential inputs (Aleph J) and use 6 or 7mA BL jfets or even highish GR rated ones. The F5 jfets are set for about 4mA or less.

 

[Zen Mod]

I wonder this one will be better or not ?

interesting ; I admire lateral thinking

but - I'm not sure in amount of benefit

 

[bobodioulasso]

Wensan,
why not to keep the 2 ways NFB?
I have been thinking since the beginning that was an interesting particularity of the F5.

 

[Zen Mod]

Wensan,
why not to keep the 2 ways NFB?
I have been thinking since the beginning that was an interesting particularity of the F5.

in this case - you can't , because of need to implement inverting topology .

that's SUSY bridged F5

 

[bobodioulasso]

I am the champion for asking stupid questions.

May be another one:
Is the schematic ( post 6620) for a symetrical input only, working or not?

 

[ejfud]

Has anyone completed monoblock F5's yet?

If so, what changes did you make?

Thanks

 

[Sangram]

Dual mono, not monoblock - twin 440VA transformers, 80,000uF per channel, nothing else changed from references.

Shared power cord, no chassis.

 

[wensan]

Wensan,
why not to keep the 2 ways NFB?
I have been thinking since the beginning that was an interesting particularity of the F5.

The 2 ways NFB will interfere with the differential structure.

 

[wensan]

I am not certain.

The input signals counteract each other.
No signal will be amplified.
I don't think it will work.

 

[bobodioulasso]

Thx for your answers.

 

[wensan]

The input signals counteract each other.
No signal will be amplified.
I don't think it will work.

Oh! I am wrong.
Most of signal will be amplified without feedback control.

 

[bear]

like with every other known gain stage .

besides - even plain vanilla F5 have diff pair at input

not a diff pair... a diff pair is also known as a "long tail pair"... that means a common resistor shared between the emitters or in this case the sources. the input of the F5 does not have this featue.

_-_-bear

 

[umut1001]

Save your high Idss jfets for a long tail differential inputs (Aleph J) and use 6 or 7mA BL jfets or even highish GR rated ones. The F5 jfets are set for about 4mA or less.

I do not have low idss jfet.All of them are above 8ma.Does not them work well ?