FYI, a good place to put an XO is in the room's vertical eigenmode [null], so for a typical 8 ft ceiling height, ~1130/2/8 = ~70 Hz that's low enough that most folks have a hard time locating the 'sub' in room, especially since the XO's slope order combined with the null makes for an extremely steep acoustic slope order.
GM
GM
Only where the WLs are acoustically short relative to distances to the boundaries, but [a big one] is that the truncated horn be designed to account for this 'oddball' expansion between the two.
WRT how truncated a horn can be when fired into a corner, then to limit 'ripple' to an acceptable level it ideally must be long/large enough to be a full length horn down to its upper mass corner design point as opposed to an arbitrary 1/8 WL, then the corner 'fills in' the rest down to its pipe [TL] corner [Fp], not its [Fc] as it's often erroneously referred to.
This in turn makes them 'good enough' for corner BLH horns like were popular in the '50s and the ever popular PA mid-bass BLHs [AKA 'scoop bins'].
An excellent example of the concept that's obvious to the eye [and how/why I was able to figure out the basics many decades ago] is the
WE/Lansing/Altec 511, etc., sectoral mids/HF horn concept where the driver's internal short conical round horn 'throat' mates to the horn's longer round to rectangular conical horn 'throat' to make a complete tweeter horn, then abruptly transitions into a nominally 90x40 expo expansion to [pre] load it down to a usable 500 Hz.
All that said, the best true bass horn I've auditioned was a built-in that had a ripple response that blended 'close enough' with the room's eigenmodes to create an audibly seamless 'cocoon' of musically pulsed pressure like I've only experienced at the loudest concerts, a local pipe organ in a Ga. granite, marble constructed church and one moon mission launch from 3 mi away.
GM
I appreciate your input GM. I can see that to a higher frequency, the exponential part of a 511 would represent a reasonably good termination coming off the conical section. There appears to be a similarity to a conical section followed by a radius, and at least a superficial similarity to an overall higher T factor LeCleach, or a hypex centred around its 'bend', with the main difference being how much 'dragging' occurs as opposed to diffracting.
The 'oddball' transition is of course as important as it is complex. It can't be geometrically perfect but it can be practically sufficient.
The 'oddball' transition is of course as important as it is complex. It can't be geometrically perfect but it can be practically sufficient.
You mention crossing around a null. Is there any kind of pressure coupling of the pipe resonance to the listener that could help, say by creating a 'virtual' equivalent of the wanted profile expansion?
I am fortunate to have seen a Saturn V at Kennedy, so I find this awesome to imagine.
Not sure I follow.........
If you have a sufficiently powerful, wide 'enough' BW system combined with a large enough room to get some serious sustained, concussive pressure wave development, then this recording from where I was the first time played as loud as you can stand it will give you a 'hint': saturn5cd.com
The other I was at the public's 5 mi location and it was surprising how little difference I noticed; I mean when your eardrums are 'flattened' even with protective gear..........
Note that the electronics need to be extremely well damped or in another room for best results.
GM
Well, ideally we want it within a 1/4 WL and preferably a 1/4 WL of the XO's -12 dB point, so 1130/4/70 = ~2 ft at minimum and much closer if one is interested in how it affects the XO's overlapping BW in this case.
As always, I leave it to the 'gentle' reader to choose what compromises/performance trade-offs, if any, is acceptable for their intended app
GM
Do you think a down-firing horn, as TuneAudio Anima, sounds articulated?
http://www.tuneaudio.com/TA_AnimaLeaflet.pdf
Did someone around here hear it? It could be placed in the corner or a least near to one wall..
http://www.tuneaudio.com/TA_AnimaLeaflet.pdf
Did someone around here hear it? It could be placed in the corner or a least near to one wall..
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