Sunn Model T Preamp Clone Build

[hoi]

Hey!

Recently found the Coda Effects Sunn Model T project and decided to build one of my own. It was my first amp in a pedal type project. I'd like to make a Fender Bassman and the Marshall Silver Jubilee in a box but need more time! I made a few modifications to the Coda Effects project. Instead of having a LPB in the boost section mine has a Jack Orman Mini Booster. Also, the booster is engaged using a 2PDT switch on the right of the pedal. I should have put the switch right under the red knob instead. I also added two outputs so that I can plug into both channels of my amplifier. Tried plugging into two separate amps but got some hum. Can anyone shed some light on this?

The artwork was engraved onto the painted enclosure using a Bantam Tools desktop CNC machine. Took about 3 or 4 hours using a 60 degree engraving bit. Also made the circuit board on the machine. I wasn't too happy with my pcb layout because the wires were not all on the edges but mainly wanted to get this build done before spending time on details like that. Typically, I do not like labeling my pedal enclosures but something with this many knobs kind of needs labels. Maybe icons that fit into whatever design is being used.

The controls are as follows:

• The red knob is the volume for the Jack Orman booster that I put ahead of the preamp. The right 2PDT turns it on/off. I should have put the switch on the left.
• The toggle switch allows you to select either the normal or bright channel.
• The left 3pdt turns the effect off/on.
• The black knobs from left to right / top to bottom are as follows: volume, normal channel gain, bright channel gain, treble, mids, bass.

[mth5044]

Looks really great! Love the artwork.

This may help you on your de-hum quest:

http://www.geofex.com/FX_images/TransformerSplitter.pdf

[hoi]

Thank you!

[rankot]

Enclosure's really nice, but having so much wires inside can be the reason for hum. You could make bigger and better organized PCB to avoid such a mess.

[anotherjim]

This is a bit late, but driving 2 amps from a common "box" usually will result in hum. The "secondary" output jack ground can have a "hum-break" inserted in series with its ground contact lug. The hum-break is only a low-value resistor with a non-polarized capacitor across it. Something like 100R¦¦100nF. This will have little impact on audio signal but discourage AC power hum from passing that way. Of course, this is only going to work if the output jack is electrically isolated from the pedal chassis ground.