Step 28. -
Black Anodized Case with Laser Etching!
Below we see the custom Beezar/ECP Audio case from Context Engineering, now black-anodized and laser-etched. This look has been so successful that all Torpedoes will be offered with the black anodized/laser-etched case from now on.
A few minor differences in construction are now due as a result of the black-anodized case. Below is a closeup view of the case front. Note that the case is now tapped for standard 4-40 screws. For the best appearance, though, black-oxide, flat-head socket screws are used.
On the backplate, note the use of black washers to maintain the great appearance of the black anodizing.
Finally, the kits sold at Beezar will include all of this hardware and a Bondhus hex wrench for the new case screws. This makes it much easier to remove the top plate if you are rolling 6J6 tubes. Note however, that in these photos the superlative E90CC tube is used. This tube is long enough that tube removal is easily possible without removing the case lid.
Some additional notes on the current (as of 7/19/2014) state of the Torpedo design, which has a revised PCB:
- D12 and D14 are now zener diodes as defined in the Zener Diode Tweak The newly revised PCB has normal pads for these now and no special "tombstoning" is required.
- The snubber capacitors for the heater power supply rectifiers (D5, D6, D7, & D8) are now 1206 SMD pad positions on the bottom of the PCB - directly underneath the rectifiers on the top. These pads are not labeled, but there is no other SMD part used in the design.
- The use of the choke is absolutely recommended instead of R2. Note that washers are typically needed under the mounting tabs of the choke to provide the best fit and avoid "torquing" the PCB.
- The safety ground is still a PITA, but absolutely needed for safety. Be sure to scrape off the black anodizing around the hole on the inside of the case bottom. The best way to attach the ground to the case is to bend the wire in such a curve that the lug lines up with the hole in the PCB. Line it up with the screw hole in the case bottom, and fish through a socket head cap screw (3/8" long) from the hole in the PCB and through the lug hole and the case bottom hole. If you hold the case sideways, the screw should stay on the end of a socket wrench while you're fishing it through. If you use 22 ga Teflon SPC for hookup wire (recommended), it's stiff enough that it holds its shape when bending. That makes things easier in terms of lining up the holes and screw.