Nelson Pass F5 Part Deux

qboneus · Aug 14, 2009

Inspired by Jeff's F5 thread I had to start my own project.
Rather than crap his thread i am posting a different build of the same amplifier using some different components.
I started with MMmetals heatsinks 6.5"x12.25"x2.3"
(SurfaceArea sq"/1") 96.972

www.mmmetals.com/extrusions/drawings/MK62430.JPG

Par-metals EMI/RF shielded enclosure.
http://www.par-metal.com/14series.htm

Acme/Amveco 400Va 18Vx2 audio grade power transformer.
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&KeyWords=TE60403-ND&x=17&y=11

WBT Binding posts
http://www.wbtusa.com/pages/0765m.html

and RCA's
http://www.wbtusa.com/pages/0201t.html
I sourced the Semiconductors at
http://www.tech-diy.com/Store/CloneKits.htm
power entry module.
http://search.digikey.com/scripts/D..._link=hp_go_button&KeyWords=Q305-ND&x=25&y=13
24V 19mm indicator.
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=679-1745-ND
High performance entry power filter.
http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&KeyWords=603-1147-ND
enough of the starting details here's a few build pictures!
Here I am tapping the heatsinks out to a 10-24 N.C threading.

i had to cut out the side panels and build stand-offs to place the heatsinks away from the top edge of the sides so that the top can be placed on.

then I mounted the heatsinks to the side of the enclosure utilizing 8 10-24 1/2" fasteners per heatsink.

i cut the openings a little over on the edges of the hs on the sides to try and improve circulation and mounted the heatsinks to the enclosure

I am going to need to cut some ventilation into the top as well.
Next I cut in the Binding posts, RCA's and power entry module

followed by my 19mm indicator light.

I have everything else needed and a few upgrades :yes:already standing by, but I am awaiting my PCB's to be able to proceed any further..

hopefully they should arrive here from Canada on monday..
Resistors are IRC .1% precision resistors with exception of a few 'select' positions that I decided to upgrade to better resistors yet..
more to follow shortly.
tal

qboneus · Aug 14, 2009

Reserved for future build steps.

specialidiot · Aug 14, 2009

Nice Tal... cool that I can watch this over again. I love my F5 and have been listening to it every night for the past month while my MC225 is being rebuilt.

It's going to be weird going back, I think.

vinyldavid · Aug 15, 2009

That's beautiful!

I can't wait to see part tres!

dokblues · Aug 15, 2009

Nice build tal! Can`t wait to see and hear your thoughts after completion.

1MOR · Aug 15, 2009

Thanks for posting this!! :banana:

qboneus · Aug 17, 2009

Wired in the Transformer, Filters, and Bridge recti-fires

\

close up of the BR wiring.

Wide shot of enclosure and power components

being the brave overconfident sort, I skipped the variac and went directly to testing the filter, transformer, and rectifiers.

Guess I did something right!

Now if canada post can get me the damn boards!!
Not sure what more I can do until the boards get here:tears:
thanks for your comments.
cheers
Tal

specialidiot · Aug 17, 2009

beauty... I hate waiting for parts.

Are you going to tap the heatsinks in place or pull it apart again?

qboneus · Aug 18, 2009

I will pull it to tap.
Boards arrived today and I am rapidly populating them.

next, on to the semi's!!
cheers,
tal

qboneus · Aug 19, 2009

Powersupply in and wired..
for the picture is worth a thousand words people here is the wiring between bridges and PSU

Red is + off of both BR's and Black is -

.
More to follow.
tal

1MOR · Aug 19, 2009

The caps match the board nicely. I got a stiff neck trying to read the manufacturer of the caps. I can see that they are made in the USA, CD perhaps?

qboneus · Aug 19, 2009

Sorry, yes they are CD caps.
mocked up both driver boards and getting ready for placement.

I will include more partslists shortly..
happy listening,
tal

specialidiot · Aug 19, 2009

Tal, make sure you solder the outputs LAST, don't flex those pads at all.

My boards just hang from the outputs..... nice work!

qboneus · Aug 19, 2009

specialidiot said:
Tal, make sure you solder the outputs LAST, don't flex those pads at all.

My boards just hang from the outputs..... nice work!

qboneus · Aug 20, 2009

'Rounding the home stretch

Just need to finish thermistors and input wiring and then it's on to adjustment and clean-up!!
cheers,
tal

qboneus · Aug 22, 2009

Finished with assembly, testing, and adjustment

all put together and ready to test.

after initial adjustments..

And after 6 hours run-in re-tested

My heatsinks are more than adequate, after 6 hours I can hold my hand on the HS indefinitely.
Tomorrow i will do some more clean up, run in and testing followed by some critical listening.
It really is a great sounding amplifier:thmbsp:
cheers,
tal

specialidiot · Aug 22, 2009

very nice build Tal. I've grown very fond of my F5.

What are the overall dimensions of the case including heatsinks?

qboneus · Aug 22, 2009

specialidiot said:
very nice build Tal. I've grown very fond of my F5.

What are the overall dimensions of the case including heatsinks?

22"x17"x7", it certainly isn't little :no:

but it is really sweet sounding:yes:
I did away with the testing speakers this morning and hooked her up to one of my a past DIY projects.

http://www.audiokarma.org/forums/showthread.php?t=197508

And am listening to the combo right now; it is surely excellent!!!:thmbsp::thmbsp:
once i have time to clean her up i'll post some final pictures; but right now it's time for some listening :music:

thanks for the compliments.
cheers,
tal

qboneus · Aug 23, 2009

Checked Dc offset after 48 hours continuous run and Left was at 1.3Mv Right was at 1.1Mv!
Good enough for a graduation from the DIY morel speakers to the klipsch Cornwall III.
My thoughts?

WOW!! just Stellar!
This amp is well worth the work.
I can see why it has the following it does:thmbsp:
cheers,
tal

specialidiot · Aug 23, 2009

Yep, my F5 has been admirably filling in for my MC225 whilst away at summer camp. I just got word that it will be back soon and the F5 will go back to driving the Cornwalls. Its a very sweet combination.

I can't recommend the F5 enough. If you can't build one, find someone to do it for you or buy a commercial version. Even at the higher prices it is a bargain.

Nelson Pass F5 Part Deux

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