Hi,
a line array with little speakers, say 3", seems to be able to reproduce low frequencies.
An array of 16 speakers will go lower than 1 of those speaker.
Right or wrong ?
How does it come ?
Do you some links of theorie for computing or simulating that ?
Thanks !
a line array with little speakers, say 3", seems to be able to reproduce low frequencies.
An array of 16 speakers will go lower than 1 of those speaker.
Right or wrong ?
How does it come ?
Do you some links of theorie for computing or simulating that ?
Thanks !
You can do it but there are issues
The IDS-25 uses 25 full ranges and it drops down to 30Hz and below without any major issues but 20 Hz is a stretch.
Not a major theory, just 25 longer than average stroke (Xmax) Vifas in a sealed box that uses a lot of EQ to get it smooth. The downside is distortion at sub bass frequencies at higher output levels. One of the interesting things about arrays is very low distortion so the idea of driving them hard with huge EQ bass boost is taking away one of their advantages.
Have my third revision of line arrays under construction in the garage. 12 five inch woofers in a sealed box can be EQ'd to 20Hz--it does work but not worth risking blowing the little guys. Throwing a subwoofer into the mix gives a cleaner sound and less of a chance of having a dozen cones to garnish fruit drinks with. 😱
If you want a little line array theory--here is a good link to get an overview of line array types, issues and various solutions the pro sound world has devised.
Live Sound International | Tech Talk: Understanding Line Array Systems
The IDS-25 uses 25 full ranges and it drops down to 30Hz and below without any major issues but 20 Hz is a stretch.
Not a major theory, just 25 longer than average stroke (Xmax) Vifas in a sealed box that uses a lot of EQ to get it smooth. The downside is distortion at sub bass frequencies at higher output levels. One of the interesting things about arrays is very low distortion so the idea of driving them hard with huge EQ bass boost is taking away one of their advantages.
Have my third revision of line arrays under construction in the garage. 12 five inch woofers in a sealed box can be EQ'd to 20Hz--it does work but not worth risking blowing the little guys. Throwing a subwoofer into the mix gives a cleaner sound and less of a chance of having a dozen cones to garnish fruit drinks with. 😱
If you want a little line array theory--here is a good link to get an overview of line array types, issues and various solutions the pro sound world has devised.
Live Sound International | Tech Talk: Understanding Line Array Systems
Hi 18Hurts
thanks for your answer.
On this paper,
http://www.linearx.com/files/pdf/EncShopApp_02.pdf
SPL response p153 (one box) and p 159 '5 box array) show " a remarkable increase in the low frequency amplitude", as written.
How explain this ?
Is it a way to compute it ? (without LEAP😀)
Cheers.
thanks for your answer.
On this paper,
http://www.linearx.com/files/pdf/EncShopApp_02.pdf
SPL response p153 (one box) and p 159 '5 box array) show " a remarkable increase in the low frequency amplitude", as written.
How explain this ?
Is it a way to compute it ? (without LEAP😀)
Cheers.
Whether you have an engine with four cylinders and long strokes or 10 cylinders with shorter strokes you can get the same output. An array of tightly coupled small speakers can be every bit as effective at producing deep bass as one or two much larger speakers. However you have to keep in mind the following;
Small speakers generally have a much lower Xmax than larger speakers so even if the surface area of the cones is comparable the amount of air they can move may be less. Therefore you may need several times as many as you'd think.
Small speakers generally have a much higher Fs than larger drivers so you have to consider enclosure design and possibly the use of equalization carefully.
Small speakers generally don't have the power handling capacity of larger speakers so this argues for a larger number of them.
A sealed acoustic suspension design IMO is always the best choice for a low frequency loudspeaker despite what others say. The Thiel Small parameters are a cookbook way to apply Newton's second law of motion for forced oscillation that governs the behavior of all speakers.
Original Bose 901 and series II was an array of small acoustic suspension drivers tightly coupled. Bose deliberately made the enclosure small enough to push F3 up above 180 hz where he said phase shift associated with resonance became inaudible. He relied on the known linear falloff of an AS design below resonance of 12 db per octave but only provided 6db per octave boost. This resulted in inadequate low bass output unless there is additional boost. But this made power requirements enormous, not the 60 to 250 wpc he said but more like 600 to 1000 wpc. But each enclosure could only handle 250 so multiple enclosures, say 3 or 4 per channel are required. Nevertheless both experience and measurements show that within its power handling capacity this array will achieve about 23 hz with 10% THD. You can do better with somewhat larger higher capacity drivers, say 5" or 6" and a larger and lower F3 tuned enclosure.
Small speakers generally have a much lower Xmax than larger speakers so even if the surface area of the cones is comparable the amount of air they can move may be less. Therefore you may need several times as many as you'd think.
Small speakers generally have a much higher Fs than larger drivers so you have to consider enclosure design and possibly the use of equalization carefully.
Small speakers generally don't have the power handling capacity of larger speakers so this argues for a larger number of them.
A sealed acoustic suspension design IMO is always the best choice for a low frequency loudspeaker despite what others say. The Thiel Small parameters are a cookbook way to apply Newton's second law of motion for forced oscillation that governs the behavior of all speakers.
Original Bose 901 and series II was an array of small acoustic suspension drivers tightly coupled. Bose deliberately made the enclosure small enough to push F3 up above 180 hz where he said phase shift associated with resonance became inaudible. He relied on the known linear falloff of an AS design below resonance of 12 db per octave but only provided 6db per octave boost. This resulted in inadequate low bass output unless there is additional boost. But this made power requirements enormous, not the 60 to 250 wpc he said but more like 600 to 1000 wpc. But each enclosure could only handle 250 so multiple enclosures, say 3 or 4 per channel are required. Nevertheless both experience and measurements show that within its power handling capacity this array will achieve about 23 hz with 10% THD. You can do better with somewhat larger higher capacity drivers, say 5" or 6" and a larger and lower F3 tuned enclosure.
What LEAP is showing is simply the in-phase gain of an array of woofers. This assumes they are relatively close together vs. the wavelength.
Easy to calculate, it is:
20 * log👎 where n is the number of woofers.
So 5 woofers = +14dB relative to one.
This is a general bass level gain but not really an extension in cuttoff. Still, with some EQ you could probably turn it into a relative extension.
David S.
Easy to calculate, it is:
20 * log👎 where n is the number of woofers.
So 5 woofers = +14dB relative to one.
This is a general bass level gain but not really an extension in cuttoff. Still, with some EQ you could probably turn it into a relative extension.
David S.
The original Bose 901 had 18dB of LF gain, max at about 30Hz. That is in the max boost position of the EQ box they provided. They also boosted the highs.
What Speaker Dave says I agree with. But you get some improvement over a single driver in a single small box due to the relative length of the array, and IF the array is flush to the floor you get the benefit of the "image" on the floor, and IF the array is to the ceiling, you again get the "image" up there making the vertical dimension look larger. In general a larger baffle helps one get better bass response, and helps to make the in-band response flatter.
But EQ is generally applied to small drivers in an array to make them go lower... but then you also need a subsonic HP to prevent excessive excursion, or else you have to build the filter like a somewhat moderate Q peaking (reverse of a notch) filter to not have excess subsonic excursion.
Generally an array is only as good as the sound of a single driver, just able to play louder and probably with higher sensitivity if wired in series-parallel...
_-_-bear
What Speaker Dave says I agree with. But you get some improvement over a single driver in a single small box due to the relative length of the array, and IF the array is flush to the floor you get the benefit of the "image" on the floor, and IF the array is to the ceiling, you again get the "image" up there making the vertical dimension look larger. In general a larger baffle helps one get better bass response, and helps to make the in-band response flatter.
But EQ is generally applied to small drivers in an array to make them go lower... but then you also need a subsonic HP to prevent excessive excursion, or else you have to build the filter like a somewhat moderate Q peaking (reverse of a notch) filter to not have excess subsonic excursion.
Generally an array is only as good as the sound of a single driver, just able to play louder and probably with higher sensitivity if wired in series-parallel...
_-_-bear
It looks to me like the differences in LF response are due to directivity of the array being tested.
They also discuss the anechoic vs. IB response.
This stuff does not apply much to home applications.
Also the room boost at LF that we see at home doesn't occur outside in a stadium or in an arena.
_-_-bear
In principle you can tune any driver/enclosure combination to any frequency you want and it will respond within its limits of power handling and excursion. In practice there are limits for poor choices. There is no practical amount of power that can overcome a 4"midwoofer's" intertial mass to where it will produce much energy in the top octave. And there is no amount of surface area that will turn an electrostatic speaker into anything but a stinker of a woofer since its Xmax is next to nil (speakers in your laptop have far more.) But small dynamic drivers designed as woofers or midwoofers in sufficient quantity, in suitably designed enclosures, and properly equalized can produce enormous bass down to very low frequencies, with little distortion and with enough of them they will do it at whatever loudness you need even though most LF subwoofers are not designed that way.
Within its excursion and power handling limits original Bose 901 will equal Teledyne AR9 but the electrical power required and number of enclosures to do it at the same loudness is far greater. I know, I own both.
Within its excursion and power handling limits original Bose 901 will equal Teledyne AR9 but the electrical power required and number of enclosures to do it at the same loudness is far greater. I know, I own both.
The only advantages I can think of for multiple small woofers for bass is that you tend to accumulate a lot of woofer magnet from the multiplicity of units, and can also pick up a fair amount of thermal capacity. As Soundminded points out the Xmax for a small woofer will be less than for a large one, so equal area for large woofers vs. multiple small woofers will typically not give equal volume displacement.
David S.
David S.
Using multiple small drivers offers many advantages over a single large woofer. The most obvious is that you have far greater flexibility in enclosure design, especially if you used a sealed enclosure. Because of their shallow depth you can design relatively flat enclosures just a few inches deep. When used as midwoofers you have the option of all kinds of directional arrays, not just a line array but surface arrays, dipole line and dipole surface arrays, multidirectional arrays. You can power them not just as a single group but individually or in small groups with multiple T-amps. A large surface array would likely provide all of the advantages of flat panel speakers with none of the drawbacks. IMO the special characteristics of flat panel speakers comes from their spatial propagation characteristics, not from reduced non linear distortion. Dynamic loudspeakers of good quality have inherently low non linear distortion especially when each one is driven to only a small fraction of its output capabilities. This keeps the voice coils in the most linear region of the magnetic fields.
One concern about arrays, especially tweeter arrays is comb filtering. This occurs when drivers are spaced apart at the same order of magnitude or greater compared to the wavelengths they reproduce. This is especially a concern with tweeters. However, with large numbers of drivers because of comb filtering between every pair and their filter frequencies being different, as the number increases the number of frequencies in the filter becomes so many and so closely spaced that for all practical intents and purposes it doesn't exist. A flat panel large surface array comprising many midwoofers and inexpensive tweeters could likely produce a very fine speaker. However, such an array could cost as much or more than a conventional single driver per frequency band system. Some of the most expensive systems such as Infinity IRS and IRS Beta designed by Arnie Nudell for example use multi-driver line arrays but on a very large scale. I think many floor to ceiling ribbon speakers also are line arrays.
One concern about arrays, especially tweeter arrays is comb filtering. This occurs when drivers are spaced apart at the same order of magnitude or greater compared to the wavelengths they reproduce. This is especially a concern with tweeters. However, with large numbers of drivers because of comb filtering between every pair and their filter frequencies being different, as the number increases the number of frequencies in the filter becomes so many and so closely spaced that for all practical intents and purposes it doesn't exist. A flat panel large surface array comprising many midwoofers and inexpensive tweeters could likely produce a very fine speaker. However, such an array could cost as much or more than a conventional single driver per frequency band system. Some of the most expensive systems such as Infinity IRS and IRS Beta designed by Arnie Nudell for example use multi-driver line arrays but on a very large scale. I think many floor to ceiling ribbon speakers also are line arrays.
Hi,
Its not "remarkable" is the normal meaning of the word, very bad English
(for a technical document), its noteworthy in an alternate sense of the word.
It is going to happen going from a single 2x15 to stacked set of five 2x15's.
It very much depends on the measuring distance what you "see".
With 3" drivers your talking effects that will occur 5 times higher in frequency,
You certainly won't get the sort of bass balance change shown in the pdf.
rgds, sreten.
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