I removed the fan from the Suhr, because I didn't like the idea of it adding a weird load into the mix. If you want to add a fan to this project, I recommend including a small power supply to run it. I added the shield to the transformer with copper tape. The High/Low level switch gives a boost to the level for when you're using low powered amps.
- 6.5mH ferrite core inductor: https://www.parts-express.com/6.5mH-20- ... quantity=1
- 650uH air core inductor: https://www.parts-express.com/Jantzen-1 ... quantity=1
- 250uF 100v Non-Polar electrolytic capacitor: https://www.parts-express.com/250uF-100 ... quantity=1
- 62 Ohm 10w resistor - I used an Ohmite from Mouser, couldn't find this value anywhere else I was buying from.
- 4 Ohm 50w resistor x4 - I used Arcol style aluminum body, found cheaply at All Electronics. They're sold out there now. Mouser is easiest choice, but can get a bit pricey there. But various power resistors are usually easy to find cheap at surplus outlets.
- 10K:10K 1/4w audio transformer Edcor PC10K/10K I modified this by adding a shield with copper foil tape.
- 10K audio taper potentiometer - I used a Tocos RV24 type from Amplified Parts, they're really nice.
- 22nF 400v film capacitor x2 - I used CDE 716P "orange drop" style from Amplified Parts
- 10K 1/2w resistor - I used an RN65 from Mouser
- 47K 1/2w resistor - I used an RN60
- 33K 1/2w resistor - I used an old carbon comp I had laying around. You can play with this value; make it smaller if you need more level boost.
- SPST switch for impedance select - you can omit this if you only need one impedance. Make sure the switch is high current. Look for 10A minimum just to be safe.
- SPST switch for High/Low level select - I actually used a SPDT in my bulid, doesn't really matter. This switch doesn't need to be high current.
- XLR Male Jack - I like to use Neutrik, though the mounting hole is a pain to cut, because you have to file out an odd shape to fit the keying. I used one I had on-hand. I don't remember where I had gotten it, but most likely Mouser.
- 1/4" Mono jack for input - Must use an insulated jack. I used a Cliff brand jack from Amplified Parts.
- 1/4" Stereo jack for line out - Should also be an insulated jack. I used Cliff as above.
- 30cal M19A1 steel Ammo Can - From Harbor Freight https://www.harborfreight.com/metal-030 ... q=ammo+box . I like that the lid comes off easily on this one - makes it much easier to work in. Don't use a plastic ammo can, it will melt!
- Knob for volume control - I used a "Fester" knob from Amplified Parts.
- Solder lug for chassis ground. This is attached to an XLR jack mounting bolt.
- Enough 4-40 bolts and nuts to mount all hardware that needs it. I also used nylon washers on the two transformer bolts.
- 4-40 standoffs x4
- Nylon zip ties to secure components to the circuit board.
- Large hole perf board, 3.5" x 5", for mounting reactive components: https://www.parts-express.com/White-Per ... quantity=1 (sold in pairs)
- Various Wire - I recommend teflon insulated wire so they don't melt from the heat. I used 16AWG for the main speaker level wiring to the load, and 22AWG for the line level. I used some fancy Cardas wire for wiring up the transformer and output jacks, because I had a some on-hand that I had never gotten around to trying. I also used some 20AWG uninsulated bus wire in a few spots, like on the power resistors.
- Piece of cork - I used this between the transformer and the case to give it some cushion
