This is my take on the ultimate Tweed “5F1” type of amplifier. I have always enjoyed playing around with smaller amplifiers to see how far they can be taken. As far as I’m concerned, a 1X8, single ended 6V6 beam tetrode operating in Class A1 can do literally “everything” we as guitarists can desire. It’s true they don’t move a ton of air but they do generate the very finest and most diverse range of guitar tones conceivable. Contrary to what I’ve heard over the years, they can excel at every style and genre and are not relegated to simply being a practice/student amplifier. They certainly are great for practice and noodling about at times but are capable of infinitely high performance-such as critical recording and live performance. I’d like to enlighten the guitar-playing-public-at-large of this fact-that small amps are often the very best amps one could choose to use.
This is a very special amplifier with a few design improvements which elevate the performance significantly compared to originals. I built two [2] of these as an experimental limited run. Each features NOS Tubes, Heyboer Iron, an Armadillo Amp Works Cabinet, and Warehouse WGS AlniCo 8″ speaker. Both amplifiers have several tricks under the hood including an improved custom circuit board/layout, moved the fuse block to the bottom of the chassis and added a true mains power switch, isolated input and output jacks, a modified star grounding scheme, treating the first power filter stage as a “tank” circuit-thus adding an additional B+ filter node stage before the 6V6 plate, tweaked circuit values, non-polar caps used in the bypass, 2 watt Ohmite carbon film signal resistors, adding screen grid resistors, plus a CTS switchable pot with a silver mica bright cap across the volume for standard or brighter-louder performance. In addition, the true power switch is especially cool because removing it from the pot and adding the brite cap with the switch allows more of the volume pot’s resistance to be used-giving finer control of the gain/volume. Slick.
Performing these improvements allow this small amp to fill a room in such a way and provide a soundstage a much larger amplifier would-on a scaled down level. In otherwords, this amplifier [as well as the Vibe] fills the space like sound like a scaled down wall of sound where you feel and hear everything the same way a large amplifier would-just not at ear bleeding sound pressure levels.
This design takes effects exceptionally well, has less noise/hiss/hum than most other single ended amplifiers, has more headroom and cleaner useable power to the point of clipping, breathes incredibly well, sounds crisp and clear, and does get harmonically dense & nasty when fully cranked. This idea is to be able to have a super high performance small amplifier for home studio/practice, small gigs, and not having to lug a larger, heavier amplifier around town when jamming with your pals.
Jason C. Arthur
