F5 power amplifier

[thanh1973]

I could be totally wrong but I think there should be another reference to ground around the feed back loop like there is on the Aleph JX.
For some reason I don't feel comfortable with this circuit design.
Hopefully some one else here can look at it more critically than myself (I know nothing).
I will try and present another version that works for people to have a look at.

[gaborbela]

Patrick he built the first F5X I think more than a year a go . It is around at 120th page .
He use 16V rail power supp. Works fine .
I want to build a bit higher power .
I have some experience with the Aleph X , I built one .
One think is sure every step have to be made careful . Also not to be afraid .
I plan at first use lower V transformer to power it up jut to get some experience with the bias .I didn't built any regular F5 . So some experience would help to be more confident .
Greets

[thanh1973]

Yes I know Patrick built it, and it worked, but he didn't seem too impressed with it.
Which suggests to me that something is not quite right.
Peter Daniel has built the standard version and he absolutely loves it.
So if implemented correctly the F5 X should be an improvement over the standard version not worse.
Hopefully Patrick, Peter and others might like to revisit this design to see if it cannot be improved further, or at least discuss why they feel it did not perform as expected.

[gaborbela]

I just posted that schematic because the schematic originally posted there is no ground at all .
Please take a look at smyslow picture posted from his working amp and the PC board next . Even Patrick used that as a reference when he built his F5X .
I also interested any new advise , the truth is after my knowledge only two F5X was built .
Surly that will not stop me to give a try .
Greets

[thanh1973]

Yes you should go with this design.
I just want to make sure you get the best possible info and advice on this one.
One thing I dont like about it, is 4 trim pots to adjust bias and dc offset. This could be a nightmare trying to adjust.
If the Jfets are matched, I think you should be able to get away with two trim pots.
Anyway it would be nice to discuss this design a bit before you get into trouble with it.

[bobodioulasso]

I remember of a Nelson's post about the subject in the early pages (farther than page 50). A search for it could be usefull. I have no time now but i will try later.

[gaborbela]

Please read Smyslow comment on both amp .
He built at first the regular F5 and after couple month he completed his X verizon .
To him the X sound better than the regular F5, it is improvement .
Also Patrick use protection 4PC BJT and extra 12PC resistor each channel.
I would like to to build mine exactly after the Smyslow amp .
To be honest not always easy to take people comment on the sound of the amp as a fact , I read someone built his amp after P Daniel's F5 and he wrote , he is not happy at all it has week bass etc .
Many time the result depend on the components we use , transformer size (Wattage) wires etc .
I think you know all these .
Please read Smyslow comment on his X-ed F5 . Just go back some 5 page or so .
Greets

[gaborbela]

Hello thanh
You probably right about the 4 trim pots but I think it will give you more possibility fine for adjustment , fine tuning .
After there is a possibility to replace them if we get the same value at each trim pot .Probably a lot depend on the well matched JETs mosfet(s)?
If you think only two people made the X verizon , so not much information out there .
But that not mean we can not get help from some expert guy .

[jacco vermeulen]

Originally Posted by osscar

irfp9240 from Vishay and 240 from International Rectifier (IR).

Read this : VISHAY FORMERLY INTERNATIONAL RECTIFIER|IRFP240|MOSFET, N TO-247 | Farnell United Kingdom
Vishay bought the power semiconductor branch from IR in 2007.
(the two companies have been fighting over it in court ever since, reached an agreement with some alterations of the initial contract just a couple of months ago)

So: different label, but exact same deal.

[flg]

Originally Posted by jacco vermeulen

...Vishay bought the power semiconductor branch from IR in 2007.
(the two companies have been fighting over it in court ever since, reached an agreement with some alterations of the initial contract just a couple of months ago)
So: different label, but exact same deal.

IR sold portions of their older, lower profit margin, MOSFET bis to Vishay. Not their "power semiconductor branch". If you noticed, Vishay instantly raised the price on all of those products by a buck or two
But, your right "different label, but exact same deal"