F4 power amplifier

[slr 5000]

ok Zm
hit me !!!!! leme see

Sheafer

 

[Zen Mod]

look in F6 thread

if you can't find it , then buzz

 

[slr 5000]

cheers Zen

 

[slr 5000]

hi Zen
checked it out ,looks nice but I was hoping to do something without a transformer
I,m thinking ba3 front into f4 using 2 pair 2sk82/ssj28 per side
I read somewhere nelson said "they make great followers"
and I already have 2x fully populated f4 boards to try
any advice , on whats involved dropping these in

Sheafer

 

[Zen Mod]

it deserves dedicated thread ......... biasing ( depletion mode parts ) is what's most complicated

however , when made properly , you'll not hear so easily difference between boutique parts and plain vanilla mosfets based follower stage

so , if name of the game is fun - why not ....... but if you expect some miracle , it's just throwing money and time through window

 

[6L6]

Sheafer -

I agree with ZM; using unobtanium rare parts in a follower is gilding the lily. One of the (many) reasons to use a follower stage is that the devices themselves impart very little of their sonic character on the signal. You will get as good results with more commonly available parts.

You want an amp where the signal makes it through the output - an F6-style would be fantastic in this regard, and be a good place for your parts.

If you have the F4 PCB, build a 'normal' F4... It's a fantastic amp in it's own regard.

 

[slr 5000]

ok guys
get the message ,my problem is I,ve stuffed up one of my f6 boards (lifted traces) from trying to repair a mistake I made and would have to buy new boards to make it work

I spose I will just concentrate on the f4 for now and put the sony parts off for another day
I have

cheers Sheafer

 

[slr 5000]

ok cant help myself
I keep looking at these parts and the schematics on the amplimos site
I may start a thread and try to get some boards made
I have contacted the designer and asked his permission

Sheafer

 

[generg]

Yes would interesting!

 

[slr 5000]

hi how are you Gerd
I have received some advice from Francesco regarding a few of his designs so all should be good
I asked if he would mind if we had some boards made and await his response with crossed fingers

Sheafer

 

[generg]

Fine....!

Francesco was already active here as mos57, Look here

http://www.diyaudio.com/forums/pass-labs/216616-f6-amplifier-500.html#post3567209

So I think he will not mind making boards for the circuits he posted here at diyaudio.

 

[slr 5000]

any preference on these Gerd?
I,m thinking version b of the post you linked to

Sheafer

 

[buzzforb]

If it were me, I would try the F6 variation.

 

[generg]

Yes, version B of the complementary version looks interesting .....

The SE version is more or less the same what Mike did, only with changed type polarity...

 

[slr 5000]

hi guys
we have approval from Francesco
I will start a dedicated thread in solid state ,all welcome

hi Buzz
I may still try the f6 variant but I am hoping to try something without a transformer front end to start with as I just want to hear the sony parts "sound " first with out other flavours added

regards Sheafer

 

[lhquam]

Is there any consensus about the choice of MOSFETs in the F4? I have the following to choose between:

FQA28N15/FQA36P15
IRFP240/IRFP9240
FQP19N20C/FQP12P20
FQP16N25/FQP17P10

I suppose I could give them all a try, but I was hoping for some comment on experiences others have had.

 

[6L6]

I used the Fairchild 19N and 12P from Buzzforb and am very happy.

 

[valvesound]

I see the Fairchild 19N and 12P parts are much cheaper a 1/3 of the price of the IRFP parts.
As I have not bought yet.....what should I buy? Why did you use the Fairchild parts 6L6?

 

[generg]

I see the Fairchild 19N and 12P parts are much cheaper a 1/3 of the price of the IRFP parts.
As I have not bought yet.....what should I buy? Why did you use the Fairchild parts 6L6?

So you have good luck... they are unobtainable normally...

the 19N and 12P haver a brighter and more detailed sound, but of course less relaxed than the IRF, matter of taste....and speakers and room .... and CD-player.....and .... and ....

 

[buzzforb]

I think he was referring to FQP versions in TO-220. I think there are differences, but they are nuanced. Discover if you like the topology first, then tweak...if you feel it necessary.