Bottlehead Crack

Here's my Crack build. Pictures start with the basic build with basic upgrades, and then progressively show more upgrades/mods.

• Pot upgraded to a stepped attenuator

• All the wire in the signal path to upgraded to pure silver

• Speedball

• Choke

• Diode rectifier mod 

Note: the Red crack below is my second crack. I have a short time lapse of making my first crack. I wanted to use a stepped attenuator, but it wasn't working properly, so I switched mid video. 

Oh, my tubes:

• Telefunken ECC82 12AU7 ($47.95)

  • Halo getter

  • Diamond Etch on Bottom of Tube

  • Ribbed Plate Design

  • Made in W Germany

• Siemens Silver Plates 12AU7 ($62.99)

  • Sometimes called "chrome plate"

  • Shiny plates

• NOS Tung-Sol 7236 ($55) 

  • ruggedized 5998

  • Dual D Getters

Above is a video I made when I put together a prior crack a few years before. I had an issue with the pot I was going to upgrade to, so I revert int he meddle in the video to the stock pot.

Choke installed! I still need to ground it, but it works. On suggestion was to use metal standoff for the choke. That would ground the choke to the chassis, thus removing the need for the choke to chassis ground wire. Less clutter.  

And finally, I added the Speedball! I think it makes the sound tighter, but there is no way to A/B test with the speedball.

Folks on the Bottlehead board and the SBAF board discussed a minor upgrade to the rectifier. 

• 4 cree "Schottky" diodes (Parts Connexion # DIODES-68247, Mouser # 941-CSD01060A) $1.50/ea

• 1 small board (Parts Connexion # PCB-77727) $1.95

Wires run to the board should be tightly twisted (I think). I will mount mine with a 1" nylon spacer and super glue.

And here is my final build. Note, it's sitting in a crappy box while I lacquer the main box.