Crack with some cosmetic mods

Bourney · 3573

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Offline Bourney

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on: December 09, 2022, 04:09:06 PM
Crack is my fourth Bottlehead build and completes my set of headphone amps. In order I built the S.E.X. (standard with C4S), Mainline (with some big caps), Crackatwoa (with a few cosmetic mods) then Crack, a somewhat random journey.

With this build I wanted to continue the theme I started with the Crackatwoa. https://forum.bottlehead.com/index.php?topic=14324.0

My goal was to have zero visible fasteners. Crack has few fasteners to begin with, but swapping in the 4PIN XLR and recessed RCAs adds another 6.

Thanks to a suggestion from forum member Karl5150 I opted for stud inserts to eliminate the through holes. The plate/studs were obtained from Front Panel Express.

I've just test fit the hardware for these photos and will complete the wiring soon. Don't worry Doc, I'll build it standard first then add the Speedball!

Some tips/notes on the studs:
  • Do not have them installed by the manufacturer. Have the locations machined and the studs supplied uninstalled. The manufacturer uses epoxy in addition to the threads. The epoxy creates significant resistance to ground and the studs will not serve as good ground points. Install the studs yourself without glue, using threadlocker if you wish, and you will achieve less than 1 ohm resistance to ground. My plate has about 1/2 ohm resistance between any two studs. My plate is powdercoated. The manufacturer machined all elements of the design, except the stud placement, then powdercoated, then machined the stud locations, leaving a nice path to ground for each stud.
  • I specified load bearing studs in all locations. These are rated to support a load, such as a transformer. Using these means your plate will need to be a minimum of 3mm thick. Non load bearing studs are also available and these have a smaller footprint and lesser requirement regarding plate thickness.
  • Load bearing studs require more space between them and the nearest edge of the plate or nearest through hole. With the benefit of hindsight I could have used load studs for the tube sockets (firm pressure is often required to seat the tubes) and regular studs for everywhere else.




Offline Paul Birkeland

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Reply #1 on: December 10, 2022, 05:18:48 AM
That looks very well thought out!

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline larcenasb

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Reply #2 on: December 11, 2022, 06:13:10 AM
Wow, sooooo clean! Not flashy, just tastefully elegant. Enjoy the rest of the build :)

Lowell B.


Offline Karl5150

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Reply #3 on: December 11, 2022, 12:41:08 PM
Great job, and good tips on the inserts. I sanded the powder coating around the inserts to ensure a sufficient ground, but your method is way more attractive. As Paul said, well thought out.
I'm guessing you attached the PT with bolts up from the bottom into the custom top cover this time. Or?
Karl

Karl
Downstairs: Planar3>PH-16>Stereomour II>OB Betsy+
Upstairs: RP1>Eros/CD5004>Seductor (2x Monoblocks)>FH3
Office: Modi Uber 2/Sirius>SEX2.1.1>µFonken FF85WK + DC160 subs
BR: FiiO M6>SEX3.0.1>ScanSpeak 10F + TangBand W6 (Mono)/DT770Pro
Garage: X12 streamer>Quicksand>Minimus 77


Offline Bourney

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Reply #4 on: December 11, 2022, 01:03:21 PM
Wow, sooooo clean! Not flashy, just tastefully elegant. Enjoy the rest of the build :)

Thanks, should be a quick wire up, will need to number the terminals carefully as I have rotated the main board 90 degrees.

I'm guessing you attached the PT with bolts up from the bottom into the custom top cover this time. Or?
Karl

Correct. Instead of the through holes with recess used on my Crackatwoa this time I used blind holes threaded for the bolts. It's more fiddly to assemble and I had to cut the bolts to length, but I'm happy with the final look. I'll add a drop of threadlocker to support the lock washers.