The Sonoran tube preamp is inspired by the preamp section of the classic 400+ tube amplifier. Utilizing a 12AX7 at high voltage, this pedal packs a ton of features and tone in a tight package.
 
Following the 400+ topology, the Sonoran begins with a tube gain stage, followed by the gain control feeding the tube's second gain stage. This allows you to dial in the amount of tube saturation for your bass or guitar. The 12AX7 tube has good clean headroom and can be clear and powerful, but can also be pushed into sweet tube harmonic overdrive. Use the bright switch in the up position to add extra treble content at this stage.
 
The tube's second gain stage drives the EQ section of the pedal. The three band EQ is an expanded Fender tone stack, with added bass and treble shift switches. With all switches in the down position, you get the classic passive tone stack with a scoop at 500 Hz. The bass control gives a 20 dB range at the deepest frequencies, becoming less affected in the mids. The middle control gives a 10 dB range at about 500 Hz. The treble control gives a 24 dB range above 2 kHz.
 
With the treble shift switch in the up position, the mid scoop is nullified, and the mid knob will have minimal effect. (It slightly increases the overall volume by a few dB as you turn it up). 
 
With the bass shift switch in the up position, the EQ gain stage low frequency response is shifted deeper into the subsonic region. This will be mostly noticeable with drop tuned or 5+ string bass guitars. 
 
Finally, the output signal is buffered to isolate the EQ section from outside loading and to provide a low impedance and low noise output.  Use the master volume control to set your output signal to the desired level for other pedals or preamps. 
 
The Sonoran uses a unique power supply that converts your pedal power to a clean, low noise high voltage for the tube to use. The pedal requires a 12V DC power supply for maximum performance. The pedal can be powered by a 9V supply, but the gain and headroom will be decreased. Do not use a supply greater than 12V or less than 9V. The supply must be capable of providing at least 300 mA, and must be regulated. The supply must use a 2.1mm barrel with center negative polarity.
 
The Sonoran has a true bypass switch.
 
Dimensions: 4.8" wide x 4" long