| Groove Tubes SFX Stereo Reproduction System. List: $1,300 (complete)
by Brett Ratner
January 23, 2001
Back in 1997, Groove Tubes founder Aspen Pittman and a musician buddy of his developed a technology for a 300 degree stereo sound field, derived from a single speaker cabinet.
In a nutshell, the guitar is split into a stereo signal, but instead of “left” and “right,” it becomes “front” and “side.” The “front” part is self explanatory. The side signal, meanwhile, preferably receives a slapback delay and/or reverb. It is then “encoded” and sent to a side-mounted speaker. The side-mounted speaker is wired out of phase with the front-mounted speaker.
The result is quite dramatic: the front signal is in your face while the side signal adds an amazing amount of depth and “size” to the sound. “Stereo separation doesn’t do any good unless you’re sitting in the middle,” Pittman said. “With this system, every stereo effect takes on a different characteristic.”
Fender quickly recognized the potential of Pittman’s invention, licensed the technology and incorporated it into select models of its Acoustisonic line of acoustic instrument amplifiers.
But lets say you want your Les Paul or Strat to sound huge. Groove tubes now offers a system allowing electric guitarists (and also keyboard and organ players) to enjoy SFX technology.
The system consists of two primary components: the SFX Encoder and the SFX decoder guitar cab.
The decoder cabinet houses a front-mounted 12” “Classic Clone UK” speaker and two 12” “Classic Clone USA” speakers. The side mounted speakers are aimed right at at each other, but are separated by a wooden baffle. All three speakers, Pittman said, are wired out of phase with each other.
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SFX Encoder front and rear panels
(Click for a close-up) |
To make the system work, you plug your guitar into your amp. You send a mono signal out of your amp’s effects loop into a stereo signal processor of your choice. You send the processed stereo signal into the encoder, which does something wacky with the phasing and such. You send the stereo, SFX-encoded signal into two separate power amps... one could be the effects return on your main amp and the other could be the effects return on a second amp. You also could send the signals to a stereo power amp. The point is you will need two amps.
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| SFX Decoder Cab |
Once two amps are procured and activated, the two amplified signals are sent to the SFX Decoder cabinet to be heard in all their three-dimensional glory.
Pittman said if you use stereo pedals and vintage amps, you could send the pedal signal directly to the encoder and then directly to the front of your vintage amps. The caveat here is that you would need some sort of device to transform the Encoder’s “line level” signals back down to “instrument level” signals.
Would the SFX system noticeably improve your sound? Absolutely. Is it worth $1,300 plus the hassle of shlepping a huge cab, two amps and a small rack to every gig? Hard to say, but it’s definitely worth a listen. For more information, visit www.groovetubes.com. | 
