The FEA Dual Band Distortion pedal ($245) was designed to provide an extremely flexible multi-band distortion/overdrive for bass and guitar. Basically it is comprised of a variable crossover, two distortions, an overdrive and a final mixer incorporated into a single pedal.
A variable cross-over divides the incoming bass or guitar signal into two bands of frequencies. The frequency bands are then routed to distortion and overdrive circuits that are specifically tailored for their respective qualities.
The low frequency band is sent to an octave-up distortion circuit. Then both the octave-up distortion and the clean low band signal feed a hard clipping distortion circuit. The octave control functions as a cross-fader between the two signals. This allows the signals to be blended together in any amount desired. The drive control sets the amplification gain of the signal sent to the hard diode clippers. The hard clipping distortion circuit utilizes germanium diodes in a unique asymmetrical configuration which adds even order harmonics to the tone. The tone control operates as a passive high frequency cut filter following the hard clipping stage. Then the level control adjusts the amount of signal from this distortion stage that it is sent to the final mixer circuit.
The high frequency band connects to an overdrive distortion circuit. The overdrive circuit utilizes two audiophile quality discrete FET (field effect transistor) amplifiers employing a global diode feedback loop. This design approach is very different from most designs that have a single amplifier for the overdrive distortion circuit. It is also well known that discrete high gain FET amplifiers add a very pleasant musical quality to the tone. The drive control sets the global gain for the FET overdrive pair. The mid and high tone controls are an active boost/cut type circuit that allows you to precisely dial in on your desired tone. Then finally the level control from this stage adjusts the amount of signal to the output mixer circuit.
The dry level control mixes in various amounts of clean low-band signal along with the two bands of distortion. This is helpful for bass players to restore the low frequencies that become masked or overly compressed during the distortion process.
The distortion bypass footswitch allows either the low or high band distortion to be disabled. This lets the clean signal from the selected frequency band to pass undistorted at unity gain, while the other frequency band continues to provide distortion or overdrive. This feature provides the player with unique tone capabilities that were previously only available to the studio engineer.
The dual rail power supply in the Dual Band Distortion is built on an isolated circuit board. The power supply is over filtered two times to assure exceptionally clean power for the signal circuitry. This power supply generates 18 volts from a 9 volt battery or external power adapter. The 18 volt audio circuit provides plenty of headroom for the signal.
The case is a standard Hammond aluminum enclosure. After the Hammond case is machined and sanded it is then color powder coated. Then the aluminum faceplate is applied and then the entire case is clear epoxy powder coated for protection.
For the full story on the development of the Dual Band Distortion, click here.
• Small footprint design: 4.5” by 3.5”
• Activation footswitch (stomp switch) with direct bypass when the pedal is not active
• Dual band configuration with drive and level controls on each
• Three blend-able distortion types (hard clipping, octave, & overdrive)
• Adjustable crossover frequency control
• Passive tone on the low distortion & active two band EQ on the high overdrive
• Dry signal level blend on the low band
• Distortion bypass band selection switch
• Distortion bypass band activation footswitch (stomp switch)
• 18 volt circuitry powered by a 9 volt battery or standard 9 volt DC adapter
• LOW BAND Distortion: Asymmetrical germanium
• LOW BAND Octave: Full-wave rectification
• HIGH BAND Overdrive: Discrete FET with diode feedback
• Maximum Input: 14.5dBu
• Maximum Output: 12.5dBu
• Crossover: Variable 100 Hz to 1KHz
• Input Impedance: 1M ohm
• Output Impedance: 22K ohm
• Power adapter?noise rejection: 40dBu @ 60Hz?>90dBu @ 2KHz
• Current consumption: approx. 30mA
• Battery life: approx. 15 hours of continuous use
• Power adapter (not included): 9VDC 2.1mm Barrel Connector with negative center pin