Build A Baking Pan Tube Amplifier
By James Grahame
Gio Militano points out this brilliant hack, "I love using baking pans because they are so cheap. Quite often a professional chassis costs more than everything else in a project."
Australian Mark Houston built this particular project in a $7 baking pan. He cautions, "Drilling thin metal can be more problematic than drilling a heavy chassis, so be patient with drilling. I mounted the power and OTs on rubber grommets that were sliced in half. This was done to reduce the potential for transformer vibrations reaching the tubes which can be microphonic. The thin chassis is mounted on thick lacquered pine and silicon feet to also help absorb vibration.
An Alps blue velvet 50k stereo potentiometer with an audio taper was used for signal attenuation. The front of the amp was finished off with a 4 oz solid brass knob. The brass knob and attenuator are expensive but what I saved on the chassis allows me to spend in other areas and still make this an inexpensive amp to build."
The amp is built around a $16 printed circuit board from Spare Time Gizmos and features a pair of General Electric 6T9 compactron tubes that incorporate a triode and pentode in a single envelope. Surprisingly, these tubes are still easy to find and cost only $7 each. Houston estimates you should be able to put together a similar amp for about $250 in the USA.
DIY 6T9 Tube Single-Ended Amplifier [diyaudioprojects.com]