I say this from experience, and I do not claim to be a golden-eared audiophile as many well know. All else being equal, a speaker system with a response of 20Hz-20kHz (or even wider response) will be a more accurate (and usually better sounding) reproducer of music than one with a response of 40Hz-14kHz or 30Hz-17kHz. I know what he is saying is true for sound reinforcement systems (I run a 30Hz LC on my QSC amps), but as I argued with a sound reinforcement friend of mine who made a similar case, hi-fi is a different game. Indeed it is an informative post, though I would argue, respectfully, about the audibility and/or other effects that high and low frequency extension have on the sound and performance of the speakers. There are no downsides to subsonic filters. The more powerful the amp, the more important it is to have subsonic filtering. Yes, not running a subsonic filter can be the cause of burning up tweeters. Subsonic noise draws a LOT of power, causing the amp to clip. They advised using a high pass (low cut) filter with these designs. The same design was known variously as the JBL 4530, Eminence Scoop, Fane Scoop, and others. JBL also had some rear horn loaded speakers (4520, 4530) best known as "scoops". When running such a speaker, not only EQ, but subsonic filtering is vital for protecting the speaker. And amps don't have to be hung from the ceilings of auditoriums. This takes more amp power, but you can move around amps easier than speakers. BUT with the proper EQ, a 6 db boost down low, the smaller box would give the same response as a much larger box with no EQ. If you can make a 5 cubic foot speaker or a 12 cubic foot speaker both perform the same, which would you rather move around?ĮV came up with box sizes and port tunings that would have some rolloff on the bottom end, if run with no eq. With commercial "pro audio" gear you actually have to load this stuff on and off trucks, move it around. Some speakers, such as EV's commercial "step down mode" designs use a ported speaker that is smaller than you would normally use for those woofers. A USABLE subsonic filter will usually be around 30 hz with a very steep rolloff. But such a filter may only be a rolloff to zero at 3 hz-5 hz. My old Onkyo "super servo" amp had an active filter (op amp) that did the same. This is in the form of a capacitor tied to ground in the feedback loop. Many amps have subsonic filtering built in whether they say so or not. A warped record can actually damage a woofer, pushing the cone out or bottoming going in. High power pro audio gear depends on subsonic filtering to prevent speaker damage. Similar with a horn.īelow that range the horn or port is no longer loading the woofer, and cone excursion greatly increases. For example, a ported speaker tuned to 35 hz, in the region from about 30 hz on up the speaker cone movement will actually be less than at other frequencies, and most of the bass will come from the port. Many speakers, especially ported speakers, the resonance of the port and box loses control of the speaker cone movement below the port resonance. And if it does 30 hz - 17 khz +/- a few db, it is truly impressive. If a speaker is truly flat from 40 hz - 14 khz, it is a pretty good speaker. To think that speakers that don't reach 20 hz are no good is silly. There is some pipe organ music that goes lower, down to about 30 hz or so.īTW, even though human hearing is said to be 20 hz - 20 khz, many adults can't hear over 14 khz or so. Generally, you can filter out anything below 30 hz without it being audible. And not heard.įiltering out subsonic signals will not hurt the music. Subsonic signals may be something as simple as a record warp, dropping the needle on the record, or as obscure as a bass player running a subharmonic sythesizer.
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