All tube push-pull circuit
2X6BM8EH Pentode-Triode Tubes + 1 NOS made-in-Holland Amperex ECC88/6DJ8 dual triode 'Totem Pole' preamp. (6DJ8s are in current production).
Bootstrapped cathodyne phase inverter for exceptional drive tone.
Internal 6" speaker, jack for 16-ohm external load.
One volume control -- that's it! No extra stuff to suck tone.
Twice the power of a Tweed Champ in smaller package.
Circuit breaker -- no searching for fuses.
This hand-wired amp is an original design -- nothing else quite like it out there.
The current-production 6BM8 tubes from Electro Harmonix each contain a power pentode (essentially an EL82), and a triode with similar characteristics to a 5751 This permits construction of an entire amp with a single tube, or, as in this case, a higher-power push-pull power section, including phase inverter, with just one pair. The cascode 'totem-pole' configuration twin triodes deliver much of the tonal complexity and touch sensitivity of a small-signal pentode without the attendant tendency toward microphonics (a concern in so small an enclosure).
Output transformer is a high-quality USA-made units from Edcor, while the Antek torroidal power transformer was selected for compact size and low noise. Speaker is a 15W, paper-coned 6" unit selected specifically for this application.
Despite the small enclosed cabinet, no issues with heat (after several 60-minute sessions the guard is just warm to the touch.)
The enclosure for this prototype is from a solid-state practice amp I had on hand. Production versions will use a standard Tweed Champ cabinet and chassis, with a variety of high-quality 8" speakers, depending on configuration and output power.
I'll be offering the production versions in configurations from the current 10W circuit, up to a 45W version using two 6L6s (or EL34s) and a high-power Fane 8" speaker, with a 20W pure class-A version in between.
Production versions will start at $1495.
More Pics (Click to Enlarge)
(Using only internal 6" speaker)