Acoustic Image Double Bass Amp – Flex S4 System


Acoustic Image Flex S4 System combines purity, power, and portability in a package that sets a new standard in high fidelity amplification. FREE SHIPPING



The Acoustic Image Flex S4 System is a break though in double bass amplification technology. This system separates the control function from the speaker cabinet and puts it at the player’s fingertips providing ultimate convenience and control over the sound. The system consists of a tri-amped 2×10 plus tweeter speaker cabinet and a remotely connected preamp that can be mounted on a music stand or mic stand within reach of the performer. The Flex System is the smallest and lightest 2×10 combo system on the market today. Upton Bass offers FREE DOMESTIC SHIPPING on the Flex.

The Acoustic Image Flex is available in three options: Two Channel Flex System (S4 System, $2128), Preamp Only ($599), and Cabinet only ($1399). Also available for the AI Flex Preamp is a padded carrying case ($35), and an AC Adaptor ($20).

Flex System Features:

  • Remote preamp feature offers ultimate in control flexibility
  • Preamp mounts magnetically to cabinet when remote feature is not used
  • Flex Pre and Flex Cab can be used as standalone units

Flex Preamp Features:

  • Extended frequency range, high fidelity sound
  • Light weight (2.5 lbs.), small size
  • Unique, slanted front chassis
  • Mounts anywhere for player’s convenience
  • Separate XLR and 1/4 inch inputs in each channel can be used simultaneously
  • 48V phantom power and 10 dB gain select for mic input
  • Input level control per channel
  • Four band EQ per channel
  • Selectable phase reverse and sweepable low cut filter per channel (phase reverse can be converted to low pass speaker emulation filter with internal jumper option)
  • Effects loop per channel
  • Selectable reverb and delay effects with level and rate controls and pseudo stereo output
  • Direct out with selectable 10 dB pad, pre/post switch and ground lift
  • Headphone output
  • Switchable limiter
  • Mute switch
  • Mono or stereo output from the preamp section
  • Selectable internal jumper options for gain and stereo operation
  • High fidelity, low noise operation: 110 dB SNR at direct out
  • Powered by Flex Cab via Cat5 cable or using supplied DC power supply for stand alone operation

Flex Cabinet Features:

  • Two 10 inch woofers each driven by a 300W class D power amp
  • 2.5 inch tweeter with 50W class D power amp
  • Standard detachable ac power cord
  • Operation over 100V to 240V range with automatic voltage switching
  • Tweeter level control
  • Downfiring woofer controls (low cut and level)
  • Through connection for daisy chaining other cabs
  • Power/signal interface for preamp (RJ45/Cat5)
  • Lightweight structural foam cabinet with spring loaded tilt mechanism

All AI amps are ordered when you order and typically have a 1 to 2 week lead time.  AI assembles all amps by hand and we’ve found that ordering them as we need them makes sure the most current product ships out to you!

Upton Bass String Instrument Co. specializes in building award-winning custom double basses and offers accessories for the double bass. Upton Bass also services all instruments and bows of the violin family with world class restoration and repair, to view our online restoration portfolio visit

Upton Bass is ready to offer advice and answer any questions regarding double basses or related bass topics. Please contact UB at or call the shop at +1 (860) 535-9399. Hours of operation Tuesday through Saturday 10am – 6pm. The Workshop (The Barn) and showroom are located in Mystic, Connecticut conveniently between Boston and NYC.


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