F5 power amplifier

[bobodioulasso]

"There is no power Ground so were I connect the signal Ground ?"

To enter a symetrical amp you need a symetrical preamp output.
There is no signal ground. The outside part of the cable is a screen only. It can be connected to plus, minus or 0 volts PSU.

Anyway.. IRFP devices are not expensive. You could buy some, build 4 stock F5 modules, evrything is in the PDF, then you could easily experiment with different arrangements; bridged, parallel, Xed, or even simply four channels.
Or are your laterals even matched?

[gaborbela]

Hello
Yes my mosfets are matched ! Also have 24VDC rail power supp .
So I must use multiple power mosfet for the X verizon .
I can design the PC board lay out that is not a problem .
My question if we take a look at the original F5 schematic R10 , R1,R2 all three resistor connected to the ground .
If I look at the simplified F5X schematic there is no ground at all ? For the input it has to be some type of ground . But also it is possible to connect to the power supp ground .I'm not sure .
Are you sure none of those resistors goes to the ground ?
If these question clear I could go on and make my PC boards .
I only interested in the X topology since I have a Aleph X and I'd like it so much .
Thanks for your help
Greets

[bobodioulasso]

There is no signal ground when symetrical connexion.
There are two wires for the signal the third one is a screen only .
If ou have a symetrical PSU, connect it to 0 volts .
There is no resistor connected to ground in Patrick Euvl schematic.
I would think of some serial input resistors though in the lay out.
With 24 volts rails (did you measure this with load?) i would keep the stock F5 values.
The only ones you could have to modify are R4 R5 but these are not critical as pots parallel them.

[gaborbela]

Hello
I found many valuable information from the picture Symslow posted from his F5X .
I found the Cviller PC board and I did com pare the populated PC board and the bare board . Now I see wich components are there and wich ones aren't .
There is some signal ground because Symlow use the R10 which is 100K and goes to the ground . Even he use the R9 resistor 1K at the input .
Now all clear .
I will modify my layout .And I can go on to each the PC boards .Probably I will have to increase the 5W resistor values because I will use 3 par mosfet the rest remain the same how Patrick build it .
Thank you for your help .
Greets

[bobodioulasso]

"I found many valuable information from the picture Symslow posted from his F5X "

Could you post the link, please?

[TerribleT]

Hello,
A lot of people believe toroid core power transformers are superior to EI types in many ways, but you indicate a contrary belief. Could you share some of your experiences using EI cores transformer in your builds?
Regards,
David

Originally Posted by tinitus

Yes, indeed
You have a lot to learn about trafos too
I dont know why people persist to believe that toroids are the best
But they surely are the most available, and cheapest, and easy to fit in and mount

My friend, I have 40 years of experience, and Im still just scratching the surface of the level of knowledge in here
I feel like a complete beginner with everything
The more you learn, the more you realise how little you know

[tinitus]

Originally Posted by TerribleT

Could you share some of your experiences using EI cores transformer in your builds?

I wish I could give hard facts, but I cant
Actually I have never used EI trafos, only UI cores
UI cores are said to work like a marriage of C-core and toroid
The first contradiction about toroids happened many years ago when HAFLER entered the scene
Around here some people began to change the Hafler IE core to the new toroids, and believed it was a significant improvement
When I asked a guy about it he just said "why on earth would you wanna do that fore"
Got me thinking, but didnt do anything about it
I couldnt believe people would take such hazzle without a reason
Later on I have heard people with greater insight and knowledge claim that almost any other than toroids should be preferred

The only facts I belive to know are as follows
Toroids have huge powerup current(inrush current)
Other trafos have more "pleasant" powerup
Toroids are more sensitive to DC on the mains power, and other kinds of noise

What I do know is that you can build an amp with UI core that will pull the socks off many other amps
And probably with EI cores as well
I dont say that toroids are inferiour, not at all
Only that they arent superiour as many people believe them to be
The best toroids are probably really good stuff
Unfortunately many people go fore the cheapest ones, believing that only the price is different
Maybe its all about build quality, and nothing else
Yet again, theres always the risk of "buying tha cat in the sack"

To me, the only problem with any other trafo than toroids is that they are getting exceedingly hard to find, and expencive

[sangram]

the only problem with any other trafo than toroids is that they are getting exceedingly hard to find, and expencive

Absolutely the opposite in my country - EIs are easy to find, and get wound to custom specs and with every possible variation. Toroids are expensive to find.

Of course, R-, C- and UI-cores are impossible to find in this neck of the woods.

EIs have absolutely zero startup problems, but they have other issues, efficiency being one of them (dunno if that's so important for DIY'ers) and a high temperature rise (which is a real problem). I don't find issues with magnetic fields (plenty of distance) or with size and weight in the amps I've built, or even the DAC transformers I use.

I specify the transformers with interwinding shields and frame grounding lugs, and the manufacturer resin-dips the transformers (they smell disgusting for a few hours) to prevent any mechanical hum. Seems to work well....

[tinitus]

Originally Posted by sangram

Absolutely the opposite in my country - EIs are easy to find

and a high temperature rise (which is a real problem).

And you have those lovely old trains too

I have thought about the heating issue
Wasnt sure about it tho
According to you it is a tendency
Should be considered if its an issue with classA drive

[bobodioulasso]

What about R-core transformers?