Khan Talks (Sort of a Blog…)

Obeid has been hard at work, his latest creation being the Reason Reato. The Reato is the first single channel amplifier from Reason. It is truly a unique amplifier that uses the 6AQ5 power pentode, the same tube used in the 8 watt Bambino. Obeid has pushed these miniature bottles in a fixed bias A/B configuration to 20 watts! The Reato includes a new 20 watts fixed bias A/B setting, and the original 8 watt/2watt cathode biased class A settings of the Bambino. This gives the Reato a reach into the club range of power, where the Bambino at 8 watts might have been a little spry.

One of the other cool new features of the Reato is the vibrato circuit. It is essentially the Fender “white” bandmaster phase shifting harmonic tremolo with a few twists added in. The signal drive and clip characteristics left much to be desired with the original circuit, in other words it lacked headroom in it’s original placement. Obeid developed the preamp with a different approach, with the vibrato stages earlier in the amp’s gain structure and came up with truly a unique sound. The Reato now pushes clean to clip wonderfully and maintains high headroom for all the pedal boosts in front of it. Tone controls are unique as well with a bass filter 6 position rotary switch to trim the bass for the guitar/volume/sound you want, and a treble control that can cover warm jazz, smooth glassy blues clean sounds, and has a midrange boost at the very end of it’s range that pushes the amp into rock territory.

The Magnatone brand is being resurrected by Ted Kornblum of St. Louis Music with design by an engineering team that includes Obeid Khan as one of the main design engineers. Ted relied on Obeid’s expertise in guitar amps and tube technology to design the new product line.

Magnatone and Vibrato are two words that go hand in hand. Magnatone was the first company to include true “pitch shifting” vibrato into their amplifiers, this was in 1958! Most other companies at the time, like Fender and Gibson, were doing tremolo which is amplitude modulation. Don Bonham, the Magnatone design engineer, had developed a true vibrato circuit using varistors. Varistors are devices that change their impedance with voltage applied, they are commonly used in the power industry as surge supressors. Bonham had developed a unique circuit that changed the phase relationship of a signal with impedance. The varistors were used as the impedance varying device, driven from an LFO (low frequency oscillator) and phase shifting was realized. Note I said phase shifting, the human ear detects a changing phase as a change in pitch (doppler effect) and thus we percieve it as a pitch change. See the original patents here.

Ken Mathews of Mathews Technical Services and Greg Geerling of Analog Devices were instrumental in detailing the circuit and unlocking the mystery of the Magnatone Silicon Carbide Varistor. Once the parts had been V/I mapped, Ken began the search process and found 2 vendors in Europe that made SiCa Varistors for the power industry that closely matched the curves. Obeid then built a prototype chassis that was based heavily upon a Tweed Pro amplifier. This proved to be the test bed for the new Varistors. Many test were conducted on this “mule” including trips back and forth to Larry Cragg, Neil Young’s guitar and amp tech. Larry was also instrumental in maintaining the amplifier’s tonal response with the vibrato and reverb added in. Obeid kept at the design, going back and forth and trying out different versions of the circuit to find out what worked best with the new parts. Soon the “mule” had served it’s purpose and the design was finalized. A new chassis was built and thus the SingleV was born.

With normal and bright channels, treble, bass and presence controls, the SingleV is right in line with Obeid’s philosophy on amps, SIMPLE. Easy to operate and wide tonal response with familiar controls and layout, the addition of reverb and varistor vibrato set it apart from anything else out there in the market. A pair of 6L6 tubes provide 30 watts for a much bigger sounding amplifier than the old Magnatone 280. This amplifer is destined to be a classic and will find it’s way into the hands of many touring professionals through Ted’s artist network. Check out a sneak peek as Obeid takes us for a quick tour. The word is out on Magnatone!