guitar players who use subwoofer cabinets include performers who play with extended range basses with include notes between B0 (about 31 Hz); and C#0 (17 Hz) and bassists whose style requires a very powerful sub-bass response is an important part of the sound (e.g., funk, Latin, gospel, R & B, etc.). Keyboard players who use subwoofers for on-stage monitoring include electric organ players who use bass pedal keyboards (which go down to a low "C" which is about 33 Hz) and synth bass players who play rumbling sub-bass parts that go as low as 18 Hz. Of all of the keyboard instruments that are amplified onstage, synthesizers produce some of the lowest pitches because, unlike a traditional electric piano or electric organ which have as their lowest notes a low "A" and a low "C", respectively, a synth does not have a fixed lowest octave. While performers who use concert sound subwoofers for onstage monitoring may like the powerful sub-bass sound that they obtain, sound engineers may find this problematic, interfering with the "Front of House" sub-bass sound. Cabinet design It is generally not possible to combine high efficiency (especially at low frequencies) with both compact enclosure size and adequate low frequency response. In general, to maximize low-frequency performance, a larger cabinet size is needed. Most bass speaker cabinets employ a vented bass-reflex design, which uses a port or vent cut into the cabinet and a length of carefully measured tubing or pipe to increase the low-frequency response and improve the speaker system's efficiency. Less commonly, some bass speaker cabinets use one or more passive radiator speakers, a "drone cone" lacking a voice coil, which is used in addition to a regular woofer to improve the low-frequency response of a cabinet. Passive radiator speakers help to reduce the risk of overextension. Acoustic suspension designs with sealed cabinets are relatively uncommon because they are less efficient. Some cabinets use a transmission-line design similar to bass-reflex, and in rare cases, some large cabinets use horn-loading of the woofers (e.g., the Acoustic 361 18" speaker cabinet from the late 1960s). Most bass combo amps and bass speaker cabinets are "front-firing," where the speakers and horn (if present) aim forward. However, because very-low-pitched sounds are omnidirectional, some combos and cabinets have woofers that point down or to the rear, as do many designs of home cinema subwoofer cabinets. The deep bass tone radiates from