F5 power amplifier

[wahab]

Wahab,
I suggest you P2P hook one F5 up, so that you know what you are talking about.
It is so simple and you are experienced: it would not be too much time consuminng.

thank you juma, i already downloded all Pass articles, as he s
knowledgeable engineer...

yes bobo, i will try one, i m curious about the thing..
and thank you all for the (positive) nfeedback...

regards,

wahab

 

[gaborbela]

All I can write the Profet is the best amp I ever built ![/I]So far I built at the last 20 years or so several great amps. Just to name some Aleph X the 100W , Aleph30 , Hiraga Class A , M Hiraga , Symasym , SEWA and so on .....
For the F5 I just got the parts I can not (I will not at least not now !) comment the sound since I never heard one !!
I can suggest some of you guys instead arguing over which amp sound better build both of them and you can experience it ..
Because I love the sound of the Profet so much "that is the main reason "I decided to give a try to the F5 but I want the X-ed version .
Remember Mr Pass wrote different wine different taste !!! For some people the Gain clone is the best , to another Aleph3 so on these really matter of the taste! Do not forget you always listening a stereo system not just a amplifier . The best to test both amp in the same system .
The Grand Mos and the Profet two different amp be careful with those ! Same company , same designer etc .
The Profet is 15W in Class A
The Grand Mos 100w but only a few Watt in Class A since the bias just 400mA/channel .

Greets

 

[Zen Mod]

Gabo - we are not arguing about taste ; we just arguing about tech differences and chicken - egg issues ;

 

[jacco vermeulen]

Like comparing F5X with this ? => http://www.selectronic.fr/upload/produit/fichetechnique/profet/7480_banc_test_rds.pdf

 

[osscar]

F5 one channel negative side bias problems

Hello ,

2 days amplifier sounded great in test mode , then I thought adjust bias (before real life sound tests during weekend) - and then something "mysterious" happened .

I can not settle bias for one channel negative side . Please find attached schematic with voltages on negative side. Positive side seem working. On scope screen appears distorted curve... Power supply voltage on the amplifier PCB also OK. DC offset about 1V.
Board and soldering seems ok, also output transistors looks fine. No overheating or burned parts. Which transistor should I change ? Currently, I have only ZTX speare - others i will have to order.
maybe I touched and shorted the PCB holding screw with multimeter clamp with R12 ,,,

Thanks for the hints in advance.

 

[Sangram]

What is the voltage at the R2/R6/R8 junction vis-a-vis the upper half?

 

[osscar]

I am not ready to respond immediately ( I took a small break), ill measure little later, and then write (I also think maybe the SJ is dead by static electricity or burned). Thanks.

 

[Blues]

It's always the transistors that go first so please re-check Q2, 4, and 6 especially Q6. Also check trim pot...

 

[osscar]

Thank you, it will be done - i will check them. Trim pot i measured - seems ok.

 

[cviller]

I would say that four things could give you a voltage of 0.01V over R4. A broken pot, Q6, Q2 or a random short. Maybe check if you have turned Q6 correctly.

 

[osscar]

Thanks Cviller, i will check and then post results. Before it works fine. not short-circuit, checked several times.No one component was removed, everything is as it was before when it sounded.

 

[cviller]

Well, turned around transistors may "work" for a while and then give up - I learned the hard way.

 

[Brian Kingsbury]

I can suggest some of you guys instead arguing over which amp sound better build both of them and you can experience it ..

You should take your own advice! You've been trying to redesign the F5 you've never heard for months now. It shouldn't take you more than a day or two to put an original F5 together so you could have something to listen to while you work on your redesigned version.

 

[osscar]

Thank you, everything ended well - negative rail missing was due to a very small gap on the trace where minus wire soldered - probably bad etching.
Now its working fine.

 

[Zen Mod]

Well, turned around transistors may "work" for a while and then give up - I learned the hard way.

lucky Bstrddanske ......

I still didn't learned that ......

 

[Melon Head]

You should take your own advice! You've been trying to redesign the F5 you've never heard for months now. It shouldn't take you more than a day or two to put an original F5 together so you could have something to listen to while you work on your redesigned version.

Gaborbela doesn't need to prove anything. So he can take as long as he wants.

 

[tinitus]

Balanced X-schematic is a built and proven schematic

Hopefully he will return with a good working amp

 

[gaborbela]

Balanced X-schematic is a built and proven schematic

Hopefully he will return with a good working amp

Thanks guys
Also I hope the F5X it will be a improvement when I com pair the Profet (bridged or X-ed amplifier , I'm busy with that right now) and the F5X amplifiers .
I spent to much on the F5X parts , I hope not in vain all.
What I mean I already has a Aleph X.
Yes tinitus fingers crossed !
Greets

 

[Nelson Pass]

Thank you, everything ended well - negative rail missing was due to a very small gap on the trace where minus wire soldered - probably bad etching.

It's always something.

 

[jackinnj]

It's always something.

Thank you Nana Rosana Danna (SNL)