<P> The smallest subwoofers are typically those designed for desktop multimedia systems . The largest common subwoofer enclosures are those used for concert sound reinforcement systems or dance club sound systems . An example of a large concert subwoofer enclosure is the 1980s - era ElectroVoice MT - 4 "Bass Cube" system, which used four 18 - inch (45 cm) drivers . An example of a subwoofer that uses a bass horn is the Bassmaxx B - Two, which loads an 18 - inch (45 cm) driver onto an 11 - foot (3.4 m) long folded horn . Folded horn - type subwoofers can typically produce a deeper range with greater efficiency than the same driver in an enclosure that lacks a horn . However, folded horn cabinets are typically larger and heavier than front - firing enclosures, so folded horns are less commonly used . Some experimental fixed - installation subwoofer horns have been constructed using brick and concrete to produce a very long horn that allows a very deep sub-bass extension . </P> <P> Subwoofer output level can be increased by increasing cone surface area or by increasing cone excursion . Since large drivers require undesirably large cabinets, most subwoofer drivers have large excursions . Unfortunately, high excursion, at high power levels, tends to produce more distortion from inherent mechanical and magnetic effects in electro - dynamic drivers (the most common sort). The conflict between assorted goals can never be fully resolved; subwoofer designs necessarily involve tradeoffs and compromises . Hofmann's Iron Law (the efficiency of a woofer system is directly proportional to its cabinet volume (as in size) and to the cube of its cutoff frequency, that is how low in pitch it will go) applies to subwoofers just as to all loudspeakers . Thus a subwoofer enclosure designer aiming at the deepest - pitched bass will probably have to consider using a large enclosure size; a subwoofer enclosure designer instructed to create the smallest possible cabinet (to make transportation easier) will need to compromise how low in pitch their cabinet will produce . </P> <P> The frequency response specification of a speaker describes the range of frequencies or musical tones a speaker can reproduce, measured in hertz (Hz). The typical frequency range for a subwoofer is between 20--200 Hz . Professional concert sound system subwoofers typically operate below 100 Hz, and THX - approved systems operate below 80 Hz . Subwoofers vary in terms of the range of pitches that they can reproduce, depending on a number of factors such as the size of the cabinet and the construction and design of the enclosure and driver (s). Specifications of frequency response depend wholly for relevance on an accompanying amplitude value--measurements taken with a wider amplitude tolerance will give any loudspeaker a wider frequency response . For example, the JBL 4688 TCB Subwoofer System, a now - discontinued system which was designed for movie theaters, had a frequency response of 23--350 Hz when measured within a 10 - decibel boundary (0 dB to - 10 dB) and a narrower frequency response of 28--120 Hz when measured within a six - decibel boundary (± 3 dB). </P> <P> Subwoofers also vary in regard to the sound pressure levels achievable and the distortion levels they can produce over their range . Some subwoofers, such as "The Abyss" by MartinLogan for example can reproduce pitches down to around 18 Hz (which is about the pitch of the lowest rumbling notes on a huge pipe organ with 32 - foot (9.8 m) - 16 Hz - bass pipes) to 120 Hz (± 3 dB). Nevertheless, even though the Abyss subwoofer can go down to 18 Hz, its lowest frequency and maximum SPL with a limit of 10% distortion is 35.5 Hz and 79.8 dB at 2 meters . This means that a person choosing a subwoofer needs to consider more than just the lowest pitch that the sub can reproduce . </P>

What does frequency response on a subwoofer mean