Bradley SE-5
I started building this amp because I wanted a small, easy to tote amp that had good tone with enough power for jamming with my cousins. I started by buying a power transformer for a Fender Champ from New Sensor. I had an output transformer from an old console stereo that had two 35C5's in it. I used a 5Y3 to keep the voltage down to about 405V on the 6V6 power tube. The power transformer puts out 350-0-350V at 125mA. The preamp tube is a 6SL7. I used a blackface Fender style tone stack, which gives me both treble and bass controls. Here is the schematic. The skirted knobs I used are from Mouser Electronics, and are numbered from 1 to 10. The layout of the amp from left to right is input jack, treble control, bass control, volume, pilot light, stand-by switch, and the power switch. I plan on mounting a 1967 Jensen C10Q speaker that I have. Here are a few pictures!
This is the wiring, showing the large resistor I used to lower the plate voltage.
Here is a picture of the front of the amp. The amp is upside down in the picture, so the controls are reversed. Sorry about the fuzzy pictures!
UPDATE!
I've started on a cabinet for this amp now. I'm going to house the Jensen C10Q and the amp in an open back combo style cabinet. It's going to be a TV style cabinet, with a single round hole in the middle of the face of the cabinet. The baffle is actually going to be the front of the cab. All of the corners are going to have a 1/2" radius, and the controls are going to be on the top, like on tweed era Fenders. I'm using 3/4" pine plywood and I'll probably stain the cabinet blue and put a coat of polyurethane on it!
UPDATE:
I'm finished! I didn't stain the cabinet, the green stain I bought just didn't look right. I did put three coats of polyurethane on it, and made a back plate for the cabinet with a nice sized hole, so that the tubes could cool. The corners are rabbet jointed and held together with dowels. I think it looks good for my first amp!
Here's the front view:
And here's the back:
UPDATE:
I now have a Sovtek 6SL7 in the preamp. When I replaced the 6SN7 with the 6SL7 the gain increased so much that I had problems with oscillations, so I rewired it to 5F1 specs, except for the beefed up power supply and high plate voltage. With the new 6SL7, this thing can rattle the windows! Getting an overdriven tone now is no problem, and the amp starts to distort at around 40% on the volume dial.
UPDATE:
Here's a few sound samples of the champ in it's new cabinet with the C10Q. The preamp tube is a 6SL7. These *.wav files were recorded with a Shure 588SB microphone into my Fostex X-14 four track, then converted to *.mp3. The guitar was my blue Korean Strat. The clean sample was recorded at about 20% on the volume knob, and the dirty sample was at 1/2 volume.
