CUSTOM
BUILT AMPLIFIERS
I build between ten and twelve amps a year with most of these being Tweed
Cabineted.
My amps are individually designed for each commission, hand built and
hand wired.
Output power ranges between 5 and 40 watts with the majority being 10
to 20 watts. Very seldom I will build two amps the same.
Two or three of these amps are not commissioned but are prototypes that
I build to test concepts, components and performance. At the end of the
testing these are sold as one of a kind.
Chassis are custom fabricated from heavy gauge aluminum
and hand punched.
Output stages are cathode biased class A or A2. I like the sound of this
biasing and it gives the musician freedom from the tech when selecting
output tube combinations.
Circuit layout is done on a ground plane using terminal strips and isolated
from the chassis. Although this is more labor intensive than other methods,
it is the best system for controlling hum.
Tube sockets are ceramic, hookup wire is aircraft grade Teflon insulated silver plated copper.
Resistors are selected to the player’s taste, I use a mixture of metal film, metal oxide, carbon film, carbon comp and wire wound.
Critical capacitor types and values are selected when I tune the amp with the musician.
Tubes are current production and hand selected.
I am a firm believer of not cluttering up the signal chain, if it’s not needed, don’t put it in. The simpler the design, the more responsive the amp becomes. Component selection is very important in this style of an amp and allows me to tune the amp to the player’s style.
The transformers of choice are Mercury Magnetics, I have used transformers from just about every manufacturer and Mercury Magnetics gets it right.
London Power power scaling is available for most amps. This is the premier system for power reduction and is completely transparent.