Pass F6 amp build completed

[anilva]

Finished this vacation, the long awaited Pass design F6 amp build. The extinct Semisouth JFets were bought by me before they shut shop.

This design has a high quality signal transformer from Jensen as a part of the design.

Did some listening yesterday and my first impression is that this the best Pass Amp I have built. Superb clarity, dynamics and sweetness of sound. Tested with my Fostex's. Simply amazing level of reproduction. This is a definite keep.

Few pictures attached.

Cheers

 

[bibin3210]

Great job Anil....:clapping::clapping:.....Waiting to see more WIP pictures...

Thanks,
Bibin

 

[spirovious]

Nice work Anil,Some more pictures will be a breeze.

 

[GeorgeO]

So this is how the holiday is spent, eh? No objections from the spouse? Lucky guy!

 

[magma]

Hey anil


cool !!!

only one question
Are those sinks enough for the heat dissipation ?
or have you biased ti low ?

 

[anilva]

Sorry, I tried attaching more pictures in the original post, but they did not get uploaded. Here are few pictures which show WIP.

Cheers.

 

[anilva]

Hey anil


cool !!!

only one question
Are those sinks enough for the heat dissipation ?
or have you biased ti low ?

The chassis used was one of my earlier F5's. The heatsink requirement is slightly less than a fully biased F5. This F6 is fully biased at 1.5amps per PowerJFet and the heatsinks get hot but the touch test limit is never reached.

Cheers.

 

[omishra]

As always, inspiring build. Congratulations!

 

[ravi_d]

@anilva
Congrats on the build.
Do you think the F6 sound like a SET amp if you remember listening to one in the past?

 

[magma]

i didnt understand whats the copper like strip with 4 screws above the device PCB

 

[anilva]

i didnt understand whats the copper like strip with 4 screws above the device PCB

You have seen this before. Because each side is not one single piece of heatsink, but two pieces aligned side by side, the copper strip is meant to homogenize the heat across the two pieces. This is meant to operate both the power transistors at similar temp levels .

 

[Anil kumar]

Nice DIY Anil hope i get a chance to audition this amp.


Regards,
Anil

 

[GeorgeO]

One more great build from Anil.

 

[magma]

You have seen this before. Because each side is not one single piece of heatsink, but two pieces aligned side by side, the copper strip is meant to homogenize the heat across the two pieces. This is meant to operate both the power transistors at similar temp levels .

i had a doubt its that
but then that raised another doubt in my mind so i got unsure

why not use a slightly larger / wider piece and then screw the transistors onto the copper directly

which in turn would trnasfer to the heatsinks faster and at the same time homogenize?

sorry for asking these qusetions
BUt i just wanted to know since i plan to do that for the kanwar amp

 

[praveencshekhar]

Congrats on your new DIY

 

[anilva]

i had a doubt its that
but then that raised another doubt in my mind so i got unsure

why not use a slightly larger / wider piece and then screw the transistors onto the copper directly

which in turn would trnasfer to the heatsinks faster and at the same time homogenize?

sorry for asking these qusetions
BUt i just wanted to know since i plan to do that for the kanwar amp

You know better. I am sure your idea is a better one, but in my case I would have lost the flexibility of trying out different designs with different power transistor placements.

 

[gopib]

I would have lost the flexibility of trying out different designs with different power transistor placements.

Priceless advise for diyers!!! It is little things like these that makes sharing DIY efforts so meaningful!!

 

[captrajesh]

the copper strip is meant to homogenize the heat across the two pieces.

Quite an interesting concept but I'm not sure if a strip of copper would be sufficient to homogenise the heat across the two comparatively much bigger masses that the heat sinks are. Have you taken any measurements to see that it actually does?

why not use a slightly larger / wider piece and then screw the transistors onto the copper directly

which in turn would transfer to the heat sinks faster and at the same time homogenize?

Since you would be using a one piece heat sink, mounting the trannies directly onto the heat sink would enable better heat transfer IMO.

 

[t.antony]

Another great build from the most prolific pass amp diy'er in India.

 

[captrajesh]

Hmm Anilva appears to have gotten so immersed in the music from the F6 through the Fostex that he has forgotten to update this thread :licklips::clapping:

Awaiting a review, albeit a brief one.