Bottlehead Crack - Coppermine Edition

H

HF9

New member
Just finished up a very special Bottlehead Crack build I lovingly call the Coppermine Crack. This guy took quite a bit of work: I mitered and routed the wood base, then copper leafed it, which is a fun experience if you haven't tried it. The plate of the amp is a 12" x 12" x 0.1" copper plate, punched and drilled. Some fun little changes from the stock unit are the 6SN7 signal tube, the excessive use of film caps for power and coupling, and a pair of bulky chokes. Hope you enjoy the pics.

Finished-Internals.jpg



Completed-Crack-Coppermine.jpg



Completed-Crack-Top.jpg



For a very detailed rundown of the build and more pics, visit:
http://www.diyaudioblog.com/2013/05/bottlehead-crack-coppermine-edition.html

A special thanks to Shappers for his beautiful and inspirational Crack build. I happened to have a pair of oil obbligatos sitting on the shelf and thought I'd put them in an octal Crack too :)
 
Wow, nice job!  I am really elated to see somebody take the design to the 12" x 12" form factor, it really opens up room for larger parts!

-PB
 
Really impressive build well done. I too had one of those cheap volume pot's (valab) too. I changed it for a seiden/Takman metal film 24 step pot and for me at least it was a worthwhile upgrade. I was only just thinking about tinkering with my crack the other day!! and along comes the MAINLINE. Decisions decisions, i wonder how it would compare to your Turbo-charged Crack?
 
Wow!

Double wow - you drilled, punched, cajoled all those holes by hand. At first look I thought you must have sent out out somewhere for machining.
 
I like the nice neat wiring as much as the top! There is something really beautiful about a nice symmetry of wires and parts.
 
Thanks for the kind words gents. I do enjoy a nice symmetrical design in and out. I had planned the layout on this one pretty carefully before I started punching / drilling / hole-sawing away :)  It's actually my first time trying the Valab stepper, it seemed a little nicer than the garden variety overseas stepped attenuators and the price was right, so I gave it a shot and am pretty pleased with it. The DACT / Goldpoint / Elma steppers are a little better of course, but I didn't want this build to get too pricey too quickly ;) Where did you source the Seiden / Takman stepper Viking?
 
2wo said:
Very nice, tell me more about this "copper leafing"...John
Click to expand...
Metal leafing is a very old process (Wikipedia says 5,000+ years old) where extremely thin sheets of metal "leafs" are adhered to a surface. You purchase metal leafs in books of 20-25 sheets for various prices, depending on how precious the metal is. There's copper, gold, silver, brass, palladium, imitation gold, imitation silver, etc. These are so incredibly thin that smaller pieces will float in the air during the process. You paint the surface you wish to color with adhesive sizing, then lay the sheets of metal down and burnish using a brush and cheesecloth. There's a little more detail in this link:

http://www.diyaudioblog.com/2013/05/bottlehead-crack-coppermine-edition.html
 
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