This is Steve Bench's series-regulated power supply as shown at members.aol.com/sbench/reg3.html. The triode section of the 6BM8 isn't in use yet, but the components for the additional regulation from members.aol.com/sbench/reg4.html have been mounted in the chassis. I built this supply using mostly parts I had on hand, including most of an existing ham radio power supply that I bought at the ham fest, a 6LX6 pass tube (in lieu of the spec'd EL509/6KG6), and some cool red surplus Raytheon knobs. Unfortunately it hasn't passed the smoke test yet - I spent a lot of time on it a couple months ago and have not come back yet to debug it. Soon... I've included a link to my Brook 12A clone notes here; they include my thoughts during construction.
Center, the back of the power supply. The B+ and filament transformers are at the left and right, and the gray box in the background holds most of the capacitors for the supply. The 6LX6 pass tube (with top cap) is in the foreground, and the Cinch-Jones connector for the umbilical on the right. There's a cage for this beast too (part of the ham radio supply) but it needs to be modified slightly to clear the umbilical connector and the two utility outlets (left side, not shown).
Right, the power supply from below, with the cover removed. Most of the passive components (capacitors, resistors) are mounted on FR4 glass fiber boards with turrets. You can also see the 110V isolation transformer (near upper right) used for the floating pass tube screen supply as described in Steve's pages. Lead dress has not been completed, except for the mains wiring.
Three views of an RIAA phono stage for my Dynaco PAS-2. The circuit is from Steve Bench, RIAA-5 with one 12AY7/6072 and one 6DJ8 per channel. Construction is on 0.125" FR4 glass fiber board with eyelets used to secure the sockets and components to the board. Copper tape on the underside forms a handy and effective ground buss. Wiring is solid copper #24 with teflon sleeving where needed. This construction method is quick and easy, but requires careful planning or else there will be a mess of jumper wires. Limited space in the PAS-2 chassis also constrained the placement and size of the components in this implementation.
Another RIAA phono stage for my Dynaco PAS-2. This circuit is from the RCA tube manuals, originally with one 7025 tube per channel. Here I've built it using 6AV6s - the electrical equivalents of 12AX7/7025 except for the 7 pin package and one triode section per device. Construction technique is the same as above.
Another board for my Dynaco PAS-2, but this is the line stage. Using some Freed matching transformers bought surplus by Joe Roberts, and inspired by the "Soul Sister" line stage as shown in V5.4 of VALVE, I've made a parafeed line stage using a single 6085 twin triode and the C4S current source boards. Although the Freed transformers are no longer available, the same circuit could be built with Magnequest transformers, or there are many surplus line matching transformers that could be used. Schematic coming soon.
Tim Reese
