That hypothesis can be tested here. Kind of. Equal loudness contour charts actually do substantiate your claim.
Equal loudness contours and audiometry - Test your own hearing
Equal loudness contour chart..
http://en.wikipedia.org/wiki/Equal-loudness_contour
But I have to add, my sealed system is flat to 20hz and that that 20hz sounds perfect relative to the rest of the spectrum. So I would have to say that dipole bass is so different "in room", that it needs to be lifted substantially to sound as "loud" as a sealed system at 20 hz..
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Found what I was looking for:
https://docs.google.com/file/d/0B97zTRsdcJTfY2U4ODhiZmUtNDEyNC00ZDcyLWEzZTAtMGJiODQ1ZTUxMGQ4/edit?pli=1
https://docs.google.com/file/d/0B97zTRsdcJTfY2U4ODhiZmUtNDEyNC00ZDcyLWEzZTAtMGJiODQ1ZTUxMGQ4/edit?pli=1
Very interesting "Post" Floyd Toole (retired) work done by Sean Olive. My take on this is that when using High dispersion loudspeakers (The kind that Floyd and Sean prefer)as opposed to the more controlled dispersion types, the room will will have a lot more high frequency energy bouncing around in it (relatively speaking). This will, I think, be perceived in "normal" rooms as "treble heavy" by the listener and would need compensation in the bass to be perceived as "normal". I do think the best way to Know for sure is to listen only to excellent "purist" recordings of acoustic music containing acoustic bass while judging your system because acoustic bass can sound only one way as opposed to electric bass which can sound pretty much any way you want it to. If acoustic bass sounds thin in the lowest registers relative to its highest registers while your system measures flat (At the listening position), it would need bass compensation..
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Well, in normal situations reflected energy will totally dominate what we hear and what we measure at the listening position. If it measures flat, the total energy is flat, regardless of if its reflected or not. My experience is that a flat measured response sounds too thin in every case, regardless of speaker type and the amount of room reflection.
Linkwitz also believes that a downward trend sounds more natural, but only for pure dipoles, and at 2 db per decade slope.
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Wow! Those are cool in a kind of disturbing way... They make a lot of sense though, except the forward tilting.
Obviously the tilt is for for aiming the high frequency units at the seated listening position. There would be pretty much only one ideal distance you could sit. Like with the larger wilson designs, but worse. At least the larger Focals have very effective multi-driver tilting mechanisms for aiming the drivers to any distance you want.
Speaking of tilt..
http://s1252.photobucket.com/albums/hh571/remlab/
I love the Neo 10 as a mid tweet, but it does sound rather closed in off axis, so I'm going to do some experimenting with this configuration above 9khz.
http://s1252.photobucket.com/albums/hh571/remlab/
I love the Neo 10 as a mid tweet, but it does sound rather closed in off axis, so I'm going to do some experimenting with this configuration above 9khz.
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I think you can use a correction network similar to what is adviced for the Neo 8. According to some reviews of the Neo 10, there is a rising distorsion above 2.5-3 kHz and it is also where it starts beaming. There is another way for reducing the high frequency peak of the Neo drivers. If you remove the plate (with magnets) in front of the diaphragm, the cause for the resonance is ore or less removed - the trapped air between the front and rear plates. Of course this changes the sensitivity of the driver.
JonasKarud posted some measurements after removing one plate from a Neo8.
Note that the response is different between front and back with one plate removed.
The side from which the plate was removed will have the response peak flattened.
DIY ribbon dipole tweeter, reductio ad minimum: Post#185
DIY ribbon dipole tweeter, reductio ad minimum: Post#190
Lumped acoustic model for the trapped air and diaphragm mass for Neo 8 posted here:
DIY ribbon dipole tweeter, reductio ad minimum: Post#196
DIY ribbon dipole tweeter, reductio ad minimum: Post#202
You're not seriously recommending to remove the front plate are you? That's foolish and dangerous and would create worse performance all around.
Greg
I am just mentioning the cause of the peak/distorsion. It would be silly to remove it and just throw it away.
I started experimenting, yesterday, with what I believe is a novel approach to driver usage.
My open baffle is 24× 56" tall, and now has one 1525e Celestion down low, a Scanspeak 1" fabric dome tweeter up high. Mounted sideways on the centre edge, and firing towards the sidewalk, is a Bohlender Graebener Neo 10.
I can't accept the limits of full range drivers I've tried over the years, and no longer accept the hash at crossover points between tweeters and midranges, in multiway.
This actively crossovered 4 slope arrangement seems to load the room pleasingly with midrange, the rising response of the Neo10 working well, nearly 90° off axis, while the tweeter seems well isolated from the midrange, and crossover hash is eliminated, even when crossing over as low as 2500hz.
Amazingly, the sound seems as coherent as a single full ranger, with all the extension and slam of a multiway system, that it is.
The bass driver has a natural 40 hz 4db spike, and with a 6db boost at 50 hz, this is full, rich, neighbour friendly bass.
10 watts each to midranges and tweeters, and
175 watts to the woofers plays as clean and louder than I need, in a 13×25×8' living room.
No need to modify the drivers, just mounting them in a way it took me over 20 years to think of works very well.
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