Trim the aluminium and MDF, then drill out required holes.
Finish the aluminium and MDF as required. The top plate is sanded by hand and sprayed with lacquer.
Assemble the chassis and begin construction of the circuit.
first working breadboard of the feed forward high voltage shunt regulator.
the second version with the 4 x 10M45S on a single heatsink.
2nd resistor changed to 3k9, lowering B+ to 130v, 22.2ma per tube, 11.1ma per section.
preamp in action, green LED bias the tube at 4v.
~295.8vdc of B+ before the first 10M45S
0.009vac of ripple at B+ before the first 10M45S
245.8vdc between the two 10M45S
~0.008vac of ripple between the two 10M45S
~125.1vdc after the 2nd 10M45S
~0.002vac of ripple after the 2nd 10M45S
the DACT CT1 50k, 24 stepped attenuator
in place of the 100k Alps Blue
the shaft of the CT1 is a little longer than my selector, so it is protruding slightly. this is especially evident when viewed from the side.
Raytheon 5687 tubes, green light from led biasing can be seen near the foreground tube. The blue lights at the background is the top of the RCA83 rectifier.
Closer look of the 5687 tube.
The PS2 Solo (John Broskie's design), the 10M45S are the ICs on the top and the LT1085 are the ones on the bottom.
The underside of the board with the components. The ground plane is the same solid wire used in the Feedforward Shunt Regulator.
Mounted to the heatsink and wired to the ICs. Here is a closeup of the RIFA 1uF capacitor, BI 7276 50K 10 turn potentiometer, Wima capacitors used as bypass, Mundorf 47+47uF capacitor, Motorola MUR110 diodes, Dale and Kiwame resistors. All top notch parts. ;)
Works like a charm. Adjusted to 100vdc on the plate of each 5687. Strangely, they put out around 35mA - 40mA instead of approximately 50mA as indicated in the tube datasheet. Maybe my tubes were mildly used ones when I purchased them from eBay. The voltage will drift a little, up to around 1v odd when turned on in the day vs the night. Otherwise, in the same session, it will vary by up to around 0.3v. Could be due to supply AC variations.
PS-2 shunt regulator mounted in the preamp.
Power supply rebuild. The aluminium for 3 chassis. Only one required for the power supply, the other pair is for another project.
E-nuts, counter sunk screws and covers.
Mark out the 3/4" MDF and aluminium plates.
The e-nuts on the MDF.
Drilling the 35mm hole. Some WD40 to lubricate before starting.
The hole saw is not deep enough to cut 3mm, so need to flip it over and drill the other side
Good to drill the aluminium slightly larger. I used 5mm drill for the holes on the aluminium. This gives me some room to even out the sides.
Marking out retaining holes on the UX4 tube socket. I had the tube on the other side. This makes it easier to mark out the 2 holes. I used a 5mm drill. 1mm larger than required.
This auto dot punch is great! It has a spring mechanism inside. Just push down and it will punch very accurately onto the work piece.
The 4mm front panel after sanding. I rounded the edges to make it look nicer.
After spraying with Tamiya paint. I wanted to make it the same look as my preamp.
Here's the assembled power supply. The screws and screw covers are used on the top. I have not done the sides yet.
Closer look of the screw covers with the RCA83 rectifier.
Another view. The top panel was lacquered with super gloss lacquer spray.
Side view of the power supply.
The rear with the IEC inlet, switch and Neutrik Speakon outlet.
Testing the power supply with my preamp as load. Look at all the hook up wires... What a mess.
Completed the wiring. The regulator was redone also, with a LT1085 regulator mounted with a medium sized heatsink instead. The output had a 100uF 20V Os-Con. I have a bag of these.
Closer view of the TO-3P package 1085CT regulator and the heatsink.
56uF GE oil capacitor and 47uF+47uF Mundorf capacitor.
Applying glue for the face plate.
Adjusting the face plate and letting it to dry.
Marking the aluminium plates with a pen knife.
Makita jig saw and safety googles.
Clamping the work piece.
Getting ready to sand the work piece with a Makita finishing sander.
Attaching the e-nut onto the side of the chassis.
A closer view of the M5 allen key screwing the e-nut into the MDF.
Taking some readings just to be sure.
With the side panels up. There is some gaps though, cos I took off 1mm more than I should with the jig saw.
Another angle.
With the elder sibling, the 5687 preamp. The power supply is the slightly plumber brother.
Another view.
Packing for transport to a preamp shootout.
