Hi/Lo Voltage Mod
new Mod-10 Hi/Low voltage switch
The Hammond 290AX has two secondary high voltage options: 325V and 275V.
In Episode 13 of Truth about Vintage Amps podcast, Skip mentions that the 275V option is useful for making an amp sound like an older Champ.
Back Panel Contents
With the amp in normal position, looking at the back, from left to right:- Fuse
- Power outlet
- 325V / 275V switch
- Tube / Solid-state rectifier switch
- Impedance switch 1
- Impedance switch 2
- Speaker jack 1
- Speaker jack 2
Back Panel Switch note: All of the back panel switches should only be changed while the amp is off
First I drew a horizontal centre line along the back.
- Voltage Hi/Lo
- Rectifier Tube/Solid Stae
- Impedance selection
First I drew a horizontal centre line along the back.
Since I moved the Power Transformer close the back edge for support (see link), everything else had to scoot right.
The Output Transformer is not that close to the back edge so we still have lots of room for the speaker jacks.
The power outlet is another rectangle. This one was tricky to cut with the fret saw because it's close to the top of the chassis.
Here's the start of the layout:
Here is a test fit of the components so far:
