Vision’s professional 5.25″ powered bookshelf speakers are purpose-built for any audio-visual presentation environments such as classrooms and meeting rooms, or bars and restaurants. They are simple to install and control. Perfect for meeting spaces or small rental applications. Serial Control RS-232 control allows this audio system to be controlled by a control system like Vision’s own Techconnect Control. Tone and volume can be adjusted,. By default it switches to Bluetooth automatically when a device is paired, but this can be disabled with RS-232. Note: this product does not have a remote control. Auto Standby Auto-standby is on by default. It can be disabled via RS-232. Bass Reflex A bass reflex port allows greater excursion of the woofer, allowing the woofer to produce lower frequencies, and the phase-delayed movement of air from behind the woofer to the front reinforces the bass even more. 5.25″ Woofer These loudspeakers use a 5.25 inch woofer – the most popular size for classroom, meeting room, and boardroom applications. They are complemented with a 0.5″ inch Mylar dome tweeter. Horizontal C bracket The adjustable brackets allow the installer to easily angle side to side, or up and down. Or leave the brackets off and use as shelf speakers. Rugged Grille Attractive and robust, the thick metal grille protects the drivers from physical interference. Memory When power is connected the SP-1900P automatically comes on and remembers the previous volume setting. Restoring power brings the loudspeakers back to life automatically. Stereo Input The 2-Phono (RCA) input makes it quick and easy to get up and running. Bluetooth Connect from your phone or tablet without missing a beat. By default the speakers auto-switch from the line-level input when Bluetooth is paired. - A button on the rear turns BT off if you don’t need it - The PIN and Bluetooth name cannot be changed The speakers have only one Bluetooth memory slot and will automatically connect to the most recent device. To unpair an unwanted device manually wait until that device is out of range then pair a new device. They can only pair to one device at a time.