F5 power amplifier

[udailey]

FAA
225VA is way to low. Minimum 300VA, better 400VA for original Papa version.
Uriah

[bobodioulasso]

Dependind on your speakers afficiency and impedance, 225 va could be ok if you slightly underbias -say about 1
amp-
It will leave class a bit sooner but will work quite as well.

[juma]

Originally Posted by gaborbela

... with Lateral mosfet F5 does not working !!

Please, don't write about things you know didley squat about. That tends to discourage people who are willing to learn something new.
You may present your own experience, like: "I didn't have success with lateral mosfets in F5"
Laterals have different pinout, different Vgs, different transconductance, tempco, etc... But when you are aware of those differences and adapt the circuit/PCB properly, laterals work very nice in F5.

[gaborbela]

Dear Juma
If you read my post after after that I did corrected myself .
I knew only someone tried with out success right at the beginning .
But after I was informed there are some amplifier built with Laterals . So I said if is OK please go on and build it .
Sorry I was misinformed . But after I got the right information I did corrected myself .
So please forgive me , I would delete the post but I can't .
I did my best I wrote if is working please go on and build it .Actually I like the sound of (a good lateral better )
Greetings

[tinitus]

I dont see why 7A pr device would be a problem when we use 3 or 4 outputs pair
I think the major reason we want the laterals are fore easier drive of multiple outputs with the single Jfet, and cascode
I suppose its the doing of low Vgs
Mine have 0.5-0.8 NPN,PNP respectively
Is that what also makes it heat faster
And maybe thats also what makes it slightly more "nervous" at higher bias
And all this would mean that generous heatsinks are important
With multiple poutput and optimal heat transfer, case temperature will be closer to heatsink temperature
To me its not about which sounds better
I expect better sound to come from better function

btw, I got a better price on 1meter heatsink with possible 0.2k/W , which I expect will keep it perfectly cool, and base will be milled planed fore optimised cooling, and I have the keratherm isolators

[gaborbela]

What I wanted to write with out modify the circuit it does not work.
Actually you right .
Sorry one more time .
I know these can cause some confuse , it happaned with me also .
Lineup wrote in another post the Toshiba 2SK1529 /2SJ200 Lateral mosfet .I purchased for a couple hundred Dollars (15 pair -$17 each) and after people inform me that is not lateral mosfet .
Now I know even with lateral mosfet will work with the right mod...

[jackies]

Thanks for pointing that out, bobodioulasso!
I guess I'll stick with the plan B, wire the transformer for 220v and plug it in 110, and have a center tapped 33v secondary, albeit at half the power rating. The transformer is specced at 800VA I think, so it's still plenty. Thanks again!

[tinitus]

Originally Posted by gaborbela

What I wanted to write with out modify the circuit it does not work.

I suspected that
But sounds to me like your mistaken again
Its exactly without mods it actually should work
With that I mean to use the thermistors and current limiter curcuit as pr original

The reports about issues have all been with modified curcuit
Which means raised bias, and maybe slightly higher voltage
And also without thermistors and current limiter

In manual Nelson specify heatsinks with 0.6 K/W which isnt that much
But frrom experience he also suggest about 6" x 8", TWO pr channel
And a power supply capeable of continious 6amp, and more than 10amp peak pr channel
Thats fore an optimal or maybe conservative build
Its been stated and proven that less will work perfectly fine
But only fore original with no changes
With the changes we have been talking about, raised bias etc., I think it would be wise not to go cheap on these matters
I could suspect that may have been the case fore some of those who have experienced heating problems
Or maybe unknown issues with heat transfer

[gaborbela]

Originally Posted by juma

Please, don't write about things you know didley squat about. That tends to discourage people who are willing to learn something new.
You may present your own experience, like: "I didn't have success with lateral mosfets in F5"
Laterals have different pinout, different Vgs, different transconductance, tempco, etc... But when you are aware of those differences and adapt the circuit/PCB properly, laterals work very nice in F5.

These is JUMA statement on the laterals !

All I can say I agree with these statement .
One more time if I knew F5 works with laterals I have 10 pair orig Hitachi I'd rather use them than the Toshiba verticals .
Please feel free if you have the right information and use laterals .
It was proven it can be done .Please go for it !
The reason I was touch with these problem when I was mislead by someone , I spent over $600 on Toshiba mosfet . I purchased as they laterals and after I get the right info those are vertical mosfet(s)
I could not return to the store , thank God I can use them in these project !
Greets

[juma]

Originally Posted by gaborbela

... I was mislead by someone ...

You allowed to be misled because you were too lazy to learn how to read datasheets, right ?