A1421B – K&K — Bassmaster Pro – (Combo) Bass Max & Double Twin 4 pots


The Bass Master Pro is a pickup combination system for the upright bass, consisting of a Double Big Twin bridge transducer, a Bass Max wing transducer, and a specially designed two-channel preamp. The combination of pickups delivers the most complete transmission range for the versatile upright bass player. The Double Big Twin transmits very high and very low frequencies, which makes it especially suitable for jazz bass. The high frequency translation ensures a clean amplification of the finger attack with the picked bass. The low frequency translation refers to a desired very bassy sound picture. The Bass Max wing mount transducer transmits more midrange, which adds power and definition to the sound. When playing arco, we recommend using only the wing transducer. The preamp is a two-channel, belt clip unit that features two volume controls, a stereo input, and a line level output on the outside of the box. Inside the box, there are adjustable controls for gain, bass, and treble for each channel. The tone controls offer an incredible +/- 20 dB. This is a wider range than some big boards on the market today! To keep the box as small as possible these controls are trim pots (small potentiometers that should be adjusted with the included precision screwdriver). Once you install the pickups, you can adjust the two channels with these trim pots to your personal preference and needs. While performing, the two volume knobs on the outside allow for quick adjustments.


The Bass Master Rockabilly is the first upright bass transducer system designed specifically for Rockabilly and slap bass. It combines two transducers (the Bass Max and a fingerboard pickup) to create an integrated double bass pickup system that brings out the percussive and subtle fingerboard sounds, as well as strong and warm bass tones. Each Bass Master Rockabilly can be fine-tuned via the separate bass and treble controls within the two-channel preamp, providing an infinite range of combinations for every player and any style of play.

The first component, the popular Bass Max, is positioned in the bridge wing. To make the Bass Max, we combine two transducers into a “sandwich” in order to maximize and enhance vibrations captured from the entire bridge. Only one Bass Max is necessary to provide an even signal from all four (or five) strings. Its strong midrange signal is ideal for cutting through the mix in loud Rockabilly situations, or providing a warm and supportive line for country bluegrass.

The fingerboard transducer’s unique size and shape allows it to be precisely placed on your instrument. The preamp lets the player blend in just the right amount of slap, growl, and other fingerboard sounds to reach their audience. This allows the player to achieve the exact sound they desire.

The two-channel preamp has internal gain, bass, and treble trim pots for each pickup, allowing impressive +/- 20dB tonal adjustments. External volume controls let you balance the volumes of the bridge and fingerboard transducers on the fly. A convenient belt clip is included with this compact preamp, which weighs a mere ten ounces with the battery installed. A six foot, high quality three conductor (1/4 inch stereo) cable is included to complete the package.

Technical Specs
Wing: 22 mm diameter, 4 mm thick
Fingerboard: 12.5 x 10mm, 0.7 mm thick
Preamp: 3″ x 3.5″ x 1″ Input
Impedance: 1 MegOhm (each channel)
Output Impedance: 10K Ohms
Input: Stereo 1/4″ | Output: Mono 1/4″
Cable: 6 foot, 1/4″ stereo plugs
Power: 9 volt battery (not included)

Additional information

Weight 2 lbs