This coverage (lack of big nulls) looks just as good as a the mono sub sims posted earlier.
And multiple individual sources = more control than lumping all drivers in one throat.
I wonder: if one was to construct 8 horn throats in a line (as discussed around post 133-140, and as pictured by tb46), with a large, wide shared mouth (~10'x25'), would that mean:
-there would be no benefit to making the sub mono?
-most of the drivers could be run as pure subs (below 60Hz or 80Hz or wherever), with one pair run relatively high (~200Hz), allowing the use of relatively petite HF boxes in front of* that pair?
LLLLRRRR
*or just inside
Yep, and having experienced sensurround it makes more sense to me than a huge, low XO'd mono horn from any POV other than its sheer size, but then ~burying it in the ground ~negates this, plus this mono sub system [100-120 Hz XO?] was keyed to the center [dialog only] channel, so for the relatively few recordings with stereo bass it seems to me that the sub should be stereo also since this is an outdoor system Vs an acoustically small room where mono bass makes sense, not to mention that the horizontal dims are so wide that even an 80 Hz XO is stretching it for side mounted mid-bass, so making a concrete expo for just a couple of octaves seems such a waste when the pioneers built wooden ones down to 30 Hz to XO @ 500 Hz.
Well, to get the 'kick' factor would require more than a pair, so from the get-go I was thinking more in terms of 2/5 for left, right and the middle 1/5 for 'fill' same in concept as many concerts I've been to in case he changed his mind. Regardless, I can't recall any that had a center stage only mono sub except way back when the concerts were essentially mono in that each speaker [or array] was for a specific instrument and even then they sometimes had drum/guitar bass fills out at the edges.
Anyway, too OT, so back to lurking.
GM
So this recommendation is 8 drivers with 8 throats sharing a single horn flare so the single horn can play stereo (only 4 drivers active at a time if the signal is panned hard one way) and at higher frequencies only two drivers are active?
I'd suggest simulating a horn situation like that where 8 drivers are active some of the time, 4 drivers are active some of the time and two drivers are active some of the time. It's going to change every aspect of the horn, the frequency response is going to be different. You want to talk about tone and pitch changing with frequency, this is that situation.
And when a higher frequency stereo signal is played and panned hard to one direction only one of the drivers will be active feeding a horn designed for 8 drivers.
The only way this could possibly work well is if all 8 drivers that were attached to horns that were completely modular and separated from throat to mouth, which of course is what I recommended in the first place.
As I understood it, exactly this was hollowboys suggestion. In this "multicell" case OP would have to consider the upper cutoff frequency he wants to achieve with the horn. Because with adjacent discrete horns you have to again consider summing effects (aka comb filtering) when the individual horn's width (and thus acoustical center spacing of the array) approaches half wavelength.
If the horn width is kept to 1m, this would give a comfortable margin in case a crossover higher than 80 Hz is desired later. This would be roughly consistent with my simulation of 10 DBH218 next to each other
sloppy terminology use here. Musical pitch (or it's perception) would not be affected in any way.
The timbre of the music MIGHT change, if the frequency response of the horn changes momentarily.
Interesting proposition and compromise - it would keep more options open for OP how to run his system later.
JAG,
the way I see it there are two issues being discussed:
1) comb filtering at bass frequencies in stereo (two subs with big spacing) VS mono bass, and to a lesser degree lobing at the subwoofer/lowmid crossover point
2) how high can the subwoofer/lowmid crossover point be set without ill effects to stereo imaging
you seem to be only concerned with issue # 1 and ignoring the discussion about #2
#1 has been solved already, see OP's statement:
Entropy455 said:
the point of the Geddes quote is that it refers to the same psychoacoustic mechanism (albeit in a different context) I was talking about when arguing in favor of playing the whole bass range thorugh the big horn in mono.
but it seems with have a new issue #3 now, namely:
3) should OP build one single big horn, or an array of 8 - 10 discrete horns next to each other
this new (or old?) proposition would open more options, such as applying delay to the discrete horns to manipulate the sound radiation of the horn(s)
OP's head must be spinning now......
Geddes fits theory to align with the topology of his speakers but this is oh so wrong. As much else in the quote you posted.
I think using multiple subs with a mono signal the bass would still be classed as 'in mono' due to there being no source signal differences between the multiple subwoofers.
granted the argument has been painted with a very broad brush, and could be misconstrued as stating there is no localization info <700Hz whatsoever (which is definitely wrong!). But the essence is the same as stated in my post: if ILD and ITD cues are conflicting (low coherence), the brain will prefer the ILD cues.
true. GM neglected to specify if he was suggesting one or multiple subs. i interpreted his statement as the former.
I'm not ignoring it, I already gave my opinion several times. 80 hz crossover with as high as slope as required (pending testing).
As far as I'm concerned if people are still suggesting dual horn subs it's not solved. OP should take all the provided info into consideration and do his own tests in his own backyard.
Weltersys seem to be arguing that OP's goal of a small audience area is dumb, so he seems to want to set it up for a much larger area using dual subs like a concert venue that needs to serve a huge audience area with even spl, which is somewhat at odds with even coverage and lobing considerations.
Nothing is solved until OP drags his subs out and actually tests dual subs spaced at 60 feet center to center.
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I didn't post the Geddes quote. And as far as I'm concerned none of it has anything to do with what we are discussing anyway. He's very specifically talking about imaging, which is usually referred to as what happens over 1khz. We are talking about stereo separation (which is not usually what we refer to as imaging) and localization which happens much lower, down around 80 - 120 hz.
Hi all,
A single sub setup with an 'empty space' between L&R and the sub more than 1/4WL of the crossover frequency you have 3 point sources at the crossover.
Regards,
Djim
A single sub setup with an 'empty space' between L&R and the sub more than 1/4WL of the crossover frequency you have 3 point sources at the crossover.
Regards,
Djim
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Guys, I have Brian C.J. More, introduction to the psychology of hearing, in front of me, page 242-243, from the printed information era. Buy the book, reading it will be time much better spent than bitching about.
But actually, this is a good case where 'think for yourself' will do the trick. 'We localize on sounds >700 Hz'. Umphhh. You wouldn't be able to localize crying kid.
Entropy, homework. Download a free sine generator or the free version of TrueRTA and listen to a 200 Hz tone. That is not a low tone at all. Then go to 100 Hz. That doesn't even come close to a bass tone also. Don't forget that at 200 Hz you are already at 1/3rd of the audible frequency range, and at half of the frequency range of fundamentals of musical instruments.
I would not use the horn beyond 3 octaves, giving 160 Hz as an absolute maximum, but lower would even be better.
But actually, this is a good case where 'think for yourself' will do the trick. 'We localize on sounds >700 Hz'. Umphhh. You wouldn't be able to localize crying kid.
Entropy, homework. Download a free sine generator or the free version of TrueRTA and listen to a 200 Hz tone. That is not a low tone at all. Then go to 100 Hz. That doesn't even come close to a bass tone also. Don't forget that at 200 Hz you are already at 1/3rd of the audible frequency range, and at half of the frequency range of fundamentals of musical instruments.
I would not use the horn beyond 3 octaves, giving 160 Hz as an absolute maximum, but lower would even be better.
that's not what I said. read again.
if ILD and ITD cues are conflicting (low coherence), the brain will prefer the ILD cues.
sorry, but localization is based on the two psychoacoustical mechanisms which I have now repeatedly mentioned. I don't know on what you base your understanding of these terms, but localization definitely happens based on cues in the whole auditory spectrum of human hearing, not just around 80 -120 Hz.
Maybe you should read up about ILD and ITD, and check the research paper which I linked to in detail to understand this.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3003727/
please read post 641 carefully. It's all there
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3003727/