Yes, it doesn't make any sense to me either and looking up line array theory on the internet doesn't mention anything about gaining in the bass region specifically because of the line array.
Well there are some crazy examples of line array bass here on this forum:
StigErik's setup comes to mind with open baffle line arrays
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Build thread
The main difference is acting like a line source instead of a point source. That will give you the raise in efficiency. Floor and ceiling reflections will add to the line effect if it's tall enough instead of giving you problems with the floor or ceiling reflection.
StigErik's setup comes to mind with open baffle line arrays
.Build thread
The main difference is acting like a line source instead of a point source. That will give you the raise in efficiency. Floor and ceiling reflections will add to the line effect if it's tall enough instead of giving you problems with the floor or ceiling reflection.
Off the top of my head you don't per se. You do get variable (depending on wiring) efficiency / sensitivity gains up to a point where the individual sources no longer sum coherently due to the varying phase-angles resulting in an apparent drop in SPLs to more or less that of one driver. And of course, within the Fresnel zone, you only have a -3dB drop-off per doubling of distance compared to the -6dB of a nominal point-source. So, Roger Russell's IDS25 for instance has about 10dB of gain relative to a single driver up to ~1.5KHz, whereupon that excess rolls off & requires Eq to bring it back up; fair enough, not much power needed up there.
The gain in efficiency is the same as if you increased the cone area (assuming they are in close proximity) - at low frequencies the efficiency is governed by the cone area (square of to be exact), all other things equal. At high frequencies you don't get the same effect. Nothing complex here. Why you would want an array of subwoofers in a domestic environment beats me - probably useful for a rock concert!
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For reference, assuming in a region before significant output lobing takes place, then for arrays:
Efficiency gain = 10*Log (number of drivers given)
Sensitivity gain / loss = 10*Log (nominal driver impedance / nominal array impedance)
Dr. J. Griffin Design Guidelines for Practical Nearfield Arrays (Cookeville: 2003) p.17
Efficiency gain = 10*Log (number of drivers given)
Sensitivity gain / loss = 10*Log (nominal driver impedance / nominal array impedance)
Dr. J. Griffin Design Guidelines for Practical Nearfield Arrays (Cookeville: 2003) p.17
Don't those calculations relate to watts required to achieve an output, but not what the maximum output is for an infinately powerful amp?
In other words for a set cone area and x-Max, does the sub freq max output change dependant on surface area dimensions?
I.e would a rectangle floor to ceiling membrane with the 1000cm3 vd, have more Max output than a circular traditional cone membrane with the same vd given an infinately powerful amp?
In other words for a set cone area and x-Max, does the sub freq max output change dependant on surface area dimensions?
I.e would a rectangle floor to ceiling membrane with the 1000cm3 vd, have more Max output than a circular traditional cone membrane with the same vd given an infinately powerful amp?
If we talk about efficiency gain I assume we are comparing one driver to 25 drivers in a line array with the same power applied. 10*log(25) = 13.97. Assuming it sums ideal in the near field. As long as the array is long enough you are meant to be in the near field in a domestic environment at the listening distance.
Still a good question if there is a difference in output between a long rectangle being floor to ceiling and a round membrane of the same Vd. I cannot answer that one apart from the already mentioned drop per doubling of distance and the less detrimental effect of the floor and ceiling reflections.
My measurement compared to the WinISD simulation and the gain example seem to agree, keeping in mind close proximity to walls also has an effect on output. But is it the wall to the left and the wall at the back or wall to the left, wall at the back + floor and ceiling that influences these results.
Put a sub in a corner (3 walls) and it is louder, put a floor/ceiling line array in a corner and it is louder too (4 walls)
Still a good question if there is a difference in output between a long rectangle being floor to ceiling and a round membrane of the same Vd. I cannot answer that one apart from the already mentioned drop per doubling of distance and the less detrimental effect of the floor and ceiling reflections.
My measurement compared to the WinISD simulation and the gain example seem to agree, keeping in mind close proximity to walls also has an effect on output. But is it the wall to the left and the wall at the back or wall to the left, wall at the back + floor and ceiling
that influences these results.Put a sub in a corner (3 walls) and it is louder, put a floor/ceiling line array in a corner and it is louder too (4 walls)
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You see my reason for trying to drill down and get an answer to that question is because two of my sub-woofers are near field (within 1m of listening position) and two are corner placed with excellent modal behaviour, so I already have lots of placement advantages - this is one of the greatest advantages to having a multi sub set up.
But if there is a specific advantage to live arrays with some kind of special bass gain, then this is news to me and something I want to know more about.
However, if displacement is displacement and placement is placement, I have already optimised both these variables with my four subs!
But if there is a specific advantage to live arrays with some kind of special bass gain, then this is news to me and something I want to know more about.
However, if displacement is displacement and placement is placement, I have already optimised both these variables with my four subs!
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It seems like there isn't. So we're back to comparing apples with apples. My comparisons earlier on were accurate as neither were utilising any kind of room gain or boundary reinforcement, except for the fact that the simulations were done in a half space environment.
With any typical domestic line array of drivers I would want to high pass them @ around 60-80Hz and then use them with a multiple sub configuration, even just for music listening. In fact mostly for music listening as the bass improvements you get from going multiple subs are very noticeable with music.
A line array will excite room modes in a different way to that of a monopole, especially a floor to ceiling array, I guess Earl is the man to talk to that about, but it would be my guess that having some correctly integrated and optimally placed subs would do nothing but improve things, if only because it relieves the mains of stuff the subs can do better.
I can only guess but I think your current setup has advantages that one line array bass could not give you. And at low frequencies we have to have a very tall array to have all of the array advantages. Floor and ceiling mirror images help so it seems infinite long (not really though) but aren't real sources. If I had a large enough room to play with, assuming it has the same ceiling height it would be a wise lesson to see the what the output would be without the close wall boundaries.
OK thanks guys! - I thought I was missing some piece of line array physics here and was going nuts trying to work out how it could possibly work!
Sorry again to the OP to harp on about this.
To summarise then, VD is what it is all about - whether in a line array, a massive sub-woofer, or multiple subs (although they will all have different in room modal behaviours) - and therefore with a small driver line array - particularly a 2 inch line array (which will have both a lower SD and X-max therefore much lower VD) - subs will be mandatory if you want to go low and loud.
I think this was said very early on! So sorry for drawing this out!
Also to say again - wesayso - none of this was in any way relating to your particular line arrays, which have substantial VD - particularly for their footprint!
Sorry again to the OP to harp on about this.
To summarise then, VD is what it is all about - whether in a line array, a massive sub-woofer, or multiple subs (although they will all have different in room modal behaviours) - and therefore with a small driver line array - particularly a 2 inch line array (which will have both a lower SD and X-max therefore much lower VD) - subs will be mandatory if you want to go low and loud.
I think this was said very early on! So sorry for drawing this out!
Also to say again - wesayso - none of this was in any way relating to your particular line arrays, which have substantial VD - particularly for their footprint!
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I have seen distortion graphs on those Audience drivers but forgot about them. For the use in arrays they weren't clean in the midrange at higher drive levels according to distortion tests run at 85 en 96 dB. Waterfall data seemed very nice though. Source: Klang und Ton February 2010.
So even if I had the money I'd look elsewhere.
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