Most pro drivers do not have appropriate T/S for sub work and as has been noted, generally are not used for the bottom octave. 41Hz is low E on a bass guitar and that is usually sufficient and a reasonable tradeoff considering spectrum, size, weight and efficiency.MaVo said:454Casull, please elaborate. Why could a driver not be appropriate for a certain frequency range, given that it has fitting ts paramters?
iand, thanks
They can be made to work in unusual alignments such as EBS and URP.
The question of:
"Who makes the lowest distortion pro-sound subwoofers?"
- is more than a little confusing.
If we accept limiting our search to a single driver in use in either a an IB or a LT system (rather than a commercial system), we then have to ask:
1. linear and/or non-linear distortion?;
2. at what freq.?;
3. at what level for that freq.?
For instance there are a LOT of drivers out their claiming to have incredibly low non-linear distortion - and sometimes in fact do, but typically only above 50+ Hz.
For most domestic settings a *subwoofer* is a system that goes to at ***least*** 20 Hz. What good is a driver that has great non-linear distortion above 50 Hz when its predominant passband is below 50 Hz?
"Who makes the lowest distortion pro-sound subwoofers?"
- is more than a little confusing.
If we accept limiting our search to a single driver in use in either a an IB or a LT system (rather than a commercial system), we then have to ask:
1. linear and/or non-linear distortion?;
2. at what freq.?;
3. at what level for that freq.?
For instance there are a LOT of drivers out their claiming to have incredibly low non-linear distortion - and sometimes in fact do, but typically only above 50+ Hz.
For most domestic settings a *subwoofer* is a system that goes to at ***least*** 20 Hz. What good is a driver that has great non-linear distortion above 50 Hz when its predominant passband is below 50 Hz?
Siegfried Linkwitz once came up with the idea to transform a speaker's transfer function into another (desired) one by employing an electric cancellation of the original speaker resonance in order to then impose a more preferred one onto it.
Depending on how far down you want to tune the enclosure, the (amplifier) power and the cone excursion requirements can raise rapidly with the amount of EQing applied.
This puts some prerequisites on the possible driver. It needs to have a strong motor, high power capability, stiff and stable cone and a resonance frequency not too high and not too low...
Turns out most PA speakers don't fulfill these requirements very well. Most of them have the efficient motor with a high power capability, but the cone is either too weak or too heavy.
The best compromise for sub duty comes out as being a strong 10" speaker with a stiff cone and a 4" voice coil. A 12" speaker would still be okay if the cone is really stable, but the surface area is rather large for the small coil pushing it, you likely won't find a 12" speaker with a 5" voice coil. And if the coil is too small, the cone just flexes (and eventually breaks) at larger power levels, instead of creating higher sound pressure.
Cheers,
Sebastian.
PS: I've tried it with an 18" speaker and know a little something about what I'm talking about.
Depending on how far down you want to tune the enclosure, the (amplifier) power and the cone excursion requirements can raise rapidly with the amount of EQing applied.
This puts some prerequisites on the possible driver. It needs to have a strong motor, high power capability, stiff and stable cone and a resonance frequency not too high and not too low...
Turns out most PA speakers don't fulfill these requirements very well. Most of them have the efficient motor with a high power capability, but the cone is either too weak or too heavy.
The best compromise for sub duty comes out as being a strong 10" speaker with a stiff cone and a 4" voice coil. A 12" speaker would still be okay if the cone is really stable, but the surface area is rather large for the small coil pushing it, you likely won't find a 12" speaker with a 5" voice coil. And if the coil is too small, the cone just flexes (and eventually breaks) at larger power levels, instead of creating higher sound pressure.
Cheers,
Sebastian.
PS: I've tried it with an 18" speaker and know a little something about what I'm talking about.
Hi Scott,
The good thing about pro speakers is their efficiency, which makes them capable of very high SPL in their intended passband. But take a look at the slope of the acoustical low frequency rolloff (high pass function) in, i.e., a closed or vented box.
The acoustic slope can be expected to come out somewhere between 6dB/oct. and 12dB/oct., depending on construction and tuning.
So for a speaker putting out, say, 130dB(spl) at 50Hz with an input of, say, 1000W, this would mean between 124dB(spl) and 118dB(spl) at 25Hz. Now I admit, 130dB(spl) at 1000W is quite optimistic for a single transducer, but two good 15" drivers can easily accomplish this.
In that sense, a profesional speaker, while not overly efficient below it's passband, is still capable of high SPL levels in the hifi subwoofer range compared to many dedicated hifi "subwoofer" speakers.
WRT distortion, a lot of research has been done on low frequency distortion perception of the human auditory system. The results essentially show that the ear has a very low sensitivity to harmonic distortion in the lowest registers.
On top of that, hifi or HT woofers don't neccessarily offer lower THD in their passband, see the well regarded Peerless (X)XLS series as an example. The XLS10 is capable of delivering 115dB(spl) above 25Hz with a nominal 250W, exactly fitting into this analogy.
Cheers,
Sebastian.
ScottG said:For most domestic settings a *subwoofer* is a system that goes to at ***least*** 20 Hz. What good is a driver that has great non-linear distortion above 50 Hz when its predominant passband is below 50 Hz?
The good thing about pro speakers is their efficiency, which makes them capable of very high SPL in their intended passband. But take a look at the slope of the acoustical low frequency rolloff (high pass function) in, i.e., a closed or vented box.
The acoustic slope can be expected to come out somewhere between 6dB/oct. and 12dB/oct., depending on construction and tuning.
So for a speaker putting out, say, 130dB(spl) at 50Hz with an input of, say, 1000W, this would mean between 124dB(spl) and 118dB(spl) at 25Hz. Now I admit, 130dB(spl) at 1000W is quite optimistic for a single transducer, but two good 15" drivers can easily accomplish this.
In that sense, a profesional speaker, while not overly efficient below it's passband, is still capable of high SPL levels in the hifi subwoofer range compared to many dedicated hifi "subwoofer" speakers.
WRT distortion, a lot of research has been done on low frequency distortion perception of the human auditory system. The results essentially show that the ear has a very low sensitivity to harmonic distortion in the lowest registers.
On top of that, hifi or HT woofers don't neccessarily offer lower THD in their passband, see the well regarded Peerless (X)XLS series as an example. The XLS10 is capable of delivering 115dB(spl) above 25Hz with a nominal 250W, exactly fitting into this analogy.
Cheers,
Sebastian.
Hi sek!
I'm not down on pro drivers.. mostly the opposite actually.
But I would argue the perception of distortion, particularly at very low freq.s.. I do however think that conscious perception of low freq. non-linear distortion is largely a learned trait.
In fact in normal use I find higher distortion more audible with harmonics than in the fundamental passband.
(..in the fundamental it tends to "attach" to auditory cues/"imaging".. where as in the harmonic region its more of a pervasive overlay across the "sound stage" that obscures detail.)
I'm not down on pro drivers.. mostly the opposite actually.
But I would argue the perception of distortion, particularly at very low freq.s.. I do however think that conscious perception of low freq. non-linear distortion is largely a learned trait.
In fact in normal use I find higher distortion more audible with harmonics than in the fundamental passband.
(..in the fundamental it tends to "attach" to auditory cues/"imaging".. where as in the harmonic region its more of a pervasive overlay across the "sound stage" that obscures detail.)
Well, I had my time with the good and not so good hifi drivers from RFT, Seas, Peerless and some more. Now I'm into something more dynamic, or so they say.
It's very interresting to see that those in the pro audio scene who have a reputation for making very good sounding PA systems are usually always following the exact same approaches and goals as good hifi developers: quality components, low distortion, consequent measuring, phase and time considerations, well thought out crossovers, proper off-axis dispersion, etc.
My take on pro audio speakers clearly is not high SPL in the living room, but quality sound with unrivaled dynamics over the full audible bandwith. In that sense (and as of my experience) a high quality PA cabinet (or sub/top system) easily beats an average hifi box!
Well, as we're talking subwoofer use, the influence of distortion would be more of a revealed box localization rather than overly bad sound coloration. Up to a point.
I mean we're of course not talking about gross distortion levels here...And I think a distinction between harmonic and disharmonic distortion is in order, just to make clear what is being said. The harmonic distortion actually adds to the sound. We could already call this colouration, but it's usually still of the acceptable kind.
(Watch out, anecdotal proof
: I've once experienced what had to be damaged bass speakers in a theater. But it could also have been tape compression from the recording played back, or a recording intentionally enriched with harmonics. Anyways, after getting used to it after a couple of seconds, I was amazed at what characteristic signature this obvious distortion gave to the actors' performance! Finally I came to the impression that I would have missed this sound signature in case they had turned off the distortion. In fact, it's the distortion richness that makes me remember this awesome sound impression as if I was sitting in front of this theatre stage right now.)The dis- (or non-) harmonic distortion, otoh, really screws the sound perception, as it doesn't relate to the original sound's spectrum. As of my experience, this is far more evident with harmonic input signals than with complex music. But as I am deeply into electronic music, these two points easily go together and thus I agree that low frequency distorion can be problematic for some of us.
It depends on the signals, the levels and the perception. To make a long story short: a professioal transducer is not neccessarily limited to a usable passband above 50Hz. And even if all of them were, you would still have enough spare SPL in the low registers to compete with a (smaller) hifi subwoofer. The controller setup (EQ) makes the difference here.
As an example and food for thought(*), consider 18Sound's 18LW1400 (fs: 31Hz, Xmax: +/-9mm, Xpeak: 50mm), RCF's LF18X400 (fs: 28Hz, Xmax: +/-9mm, Xpeak: 50mm) or even BMS's 18N860 (fs: 25Hz, Xmax: +/-19mm).
Each of these beasts can take an all-day beating with a kilowatt, exceed 125dB(spl) peaks below 40Hz and accept a linkwitz transform down to 20Hz while still maintaining about 120dB(spl) peak at full excursion. And they're not more expensive than many (let alone the more esoteric) hifi woofers, at least not considering their output. If in doubt about the output levels, double up the number of speakers just as you would do with hifi woofers...
Yet with moderate input levels, they sound like a charm in e.g. a closed box! Seriously.
My only concerns against their use would be size constraints, initial cost and power requirement (to drive a linkwitz transform alignment).
Just to get this right: Do you mean you don't believe in easy perception of low frequency distortion, or do you mean you argue my above point about the perception of distortion?
Cheers,
Sebastian.
(*) The US industry standard reference JBL 2242H also fits this scheme, but is just too pricey to serve as a good example!
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Joined 2003
I wonder if such huge Xmax is any good and a waste fore "normal" home use, maybe a 100db driver like the Beyma 18P80ND would be a much better choice ... together with a 100db 12" mid
http://www.beyma.de/fileadmin/seiten/download/pdf/Beyma_professional/18P80NdE.pdf
BMS 18N860 ... in closed box and crossed at 40-50hz with Eq it would probably be a very nice 90db+ high power sub
Maybe its time to get the design goals straight
Well, we're talking pro audio bass here. Whoever isn't satisfied with one or two 18"ers (with an excursion maximum of an inch peak to peak) will probably never get enough!
But when it comes to subsonic/infra bass and the lowest registers for electronic music and HT effects, there presumably can't be enough excursion capability.
I myself can live with a Beyma 18LX60 in a closed box (and an 18G50 in another one) for that matter. But I don't do serious theater sound at home.
Sebastian.
But when it comes to subsonic/infra bass and the lowest registers for electronic music and HT effects, there presumably can't be enough excursion capability.
I myself can live with a Beyma 18LX60 in a closed box (and an 18G50 in another one) for that matter. But I don't do serious theater sound at home.
Sebastian.
So it seems to be a matter of your (and everyone's) design goals indeed. Maybe we're just having different perceptions about bass...
To get started, how about a low cutoff at 30Hz. The attached picture shows both a vented (reflex tuned) and a bandpass (6th order) alignment of 400l (ca. 14 1/8 cubic ft.) at the speakers' excursion limit. For the sake of exaggeration, two units per enclosure are employed.
The simulation is of course preliminary, but you can always guesstimate that:
1. This is a serious oven, we're talking 4kW+ of hot air...
2. You've got headroom until 110dB SPL at 20Hz even with this 'classic' alignments...
3. There's no woofer required, you can get away with 'only' a 12" or 15" speaker in the midrange...
An alignment tuned lower could provide you with more dynamics in the 20Hz range at the expense of ridiculous box volume and reduced upper bass. A Linkwitz transform comes to mind.
Cheers,
Sebastian.
To get started, how about a low cutoff at 30Hz. The attached picture shows both a vented (reflex tuned) and a bandpass (6th order) alignment of 400l (ca. 14 1/8 cubic ft.) at the speakers' excursion limit. For the sake of exaggeration, two units per enclosure are employed.
The simulation is of course preliminary, but you can always guesstimate that:
1. This is a serious oven, we're talking 4kW+ of hot air...
2. You've got headroom until 110dB SPL at 20Hz even with this 'classic' alignments...
3. There's no woofer required, you can get away with 'only' a 12" or 15" speaker in the midrange...
An alignment tuned lower could provide you with more dynamics in the 20Hz range at the expense of ridiculous box volume and reduced upper bass. A Linkwitz transform comes to mind.
Cheers,
Sebastian.
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