The Spectrum is a culmination of all my years tweaking the old classic tube preamp circuit. I learned a lot in the early years of our Revelation Preamp, tweaking the voicing of the EQ, capacitor choices, etc. with the wonderful help and ears of Randy Beavers, Buddy Emmons, John Hughey and others. Much of that related to the shaping and range of control of the midrange, the midrange dip, the frequency range. Also influenced by a bit of inspiration from Dan Healy of the Grateful Dead, his mods and tweaks to Buddy Cage's steel amp and Jerry Garcia's guitar preamp, and his shared thoughts on a variety of aspects. All these inspirations and influences mixed with a bunch of my own basically amount to subtle tweaks and mojo and capacitor choices, resistor choices, etc that all add up to something new and unique. And this great forum was no shortage of brilliant minds and great ears and invaluably helpful insights too that helped feed my design work.
For the Spectrum Tube Preamp, these are some of the aspects I included:
- Hand assembled turret board
- USA stranded/tinned cloth (vintage style) hand-wired throughout.
- 100% tube (12AX7, 12AT7 reverb driver, 12AX7)
- Add a "Dwell" (reverb send level) control to the spring reverb to control the range from smooth to surfy
- Tubes accessible on the back, no need to open or remove the preamp from the rack
- 2 RU chassis, heavy steel faceplate, aluminum chassis
- Real Spring Reverb tank, external, connected by a cord (like a Fender Amp does it)
- VERY high voltages for the most depth and dimension you can milk from a 12AX7
- Extremely well filtered power supply, very clean DC, very 3D dimensional sounding
- Every single cap and resistor thoughtfully and consciously chosen for its character
- Simple controls: Gain, Bright switch, Treble, Mid, Bass, Dwell, Reverb mix, Master out
- BIG central ground bus bar across the circuit for great noise control
- Ships with a modern Accutronics 3-spring, medium decay tank
- Tweaked and refined reverb send and recovery circuit to expand the depth and richness of the reverb effect itself.
The Spectrum really stunned me. I knew what to expect, I thought. But the synergy and culmination of all the factors, the layout, the components, the voltage, it just does the classic tube preamp thing better than I could have dreamed. It's lush, sweet, responsive. I hand build each one myself here in my little garage/shop/factory with a lot of love and a LOT of hours.
And here's a very incomplete list of more great minds that have inspired and influenced me in this work.
Obeid Khan
Keith Hilton
Ken Fox
Derrell Stephens
Jim Evans
Jim Webb
Tim Marcus
TC Furlong
Randy Beavers
Mike Scaggs
Pat Quilter
Hartley Peavey
Craig Baker
Goodrich
Dave Beaty
Kenneth Cain
