Forgot to address this...
When the back-wave is relatively coherent, as in this case, the room reflections seem to be not only benign but to add to the feeling of a "live music event" taking place, and it's not just my opinion, but that of a panel of six highly trained listeners who have evaluated this system using their own reference music: all commented positively in general and four specifically about this "very real feeling" aspect.
Along with this, by angling the toe-in of the speakers it is possible to situate the 90 degree off axis point (where the OB has much less output across the range) so that it is on the first reflection from the closest wall, so it becomes possible to greatly reduce the effect of that reflection. It also lends itself to being able to adjust the proportion of early vs late reflections. The easy tunablilty factor is greatly increased.
Yes, I agree as long as said back-wave is not fairly coherent with what is coming from the front. I was prepared to try and absorb most of it to attain more of a cardioid response but when I measured the back-wave it was surprisingly consistent with the front, all the way up to 7KHz+.
When the back-wave is relatively coherent, as in this case, the room reflections seem to be not only benign but to add to the feeling of a "live music event" taking place, and it's not just my opinion, but that of a panel of six highly trained listeners who have evaluated this system using their own reference music: all commented positively in general and four specifically about this "very real feeling" aspect.
Along with this, by angling the toe-in of the speakers it is possible to situate the 90 degree off axis point (where the OB has much less output across the range) so that it is on the first reflection from the closest wall, so it becomes possible to greatly reduce the effect of that reflection. It also lends itself to being able to adjust the proportion of early vs late reflections. The easy tunablilty factor is greatly increased.
There is a lot of testosterone in the air.
My first question is, do "box colourations" equate with "sounding boxy", or is this a syllogistic fallacy?
Again, this seems to be begging the question. You did suggest that it might be simply monopole/dipole preferences in the OP. Has anyone done comparisons of boxed monopoles versus boxed dipoles? Or, perhaps more to the point, OBs compared to boxed dipoles?
I think "sounding boxy" is way too hard to define and it means different things to different people. I think of "boxy" more the sound of a poorly tuned ported enclosure. I think of imaging issues from sharp edges. I have heard OBs that imaged terribly, and sealed boxes that are amazing. If I do say so myself, I have a set of 6L MDF boxes Daton/Vifa that have issues, but "boxy" is not one of them. They are hard to localize because the sounds are so clearly defined.
"Boxy" redux
Indeed!
When I was adjusting my reference system, which uses two sealed woofers in cylindrical enclosures, there was a definite "boxy" or "chesty" resonance that was driving me crazy. I just couldn't find just what it was in the enclosures that was causing it. Well, it wasn't the enclosures! It was a pair of vertical modes caused by the distances of the twin woofers from the floor and the ceiling. A little fine-tuning of the room eq (yes, at 1/24th octave resolution) and voila, the coloration was finally gone.
So sometimes the "boxy" ain't from the box.
The above described problem simply did not show up with the Open Baffle design, again because the OB doesn't excite the vertical modes nearly as much.
Indeed!
When I was adjusting my reference system, which uses two sealed woofers in cylindrical enclosures, there was a definite "boxy" or "chesty" resonance that was driving me crazy. I just couldn't find just what it was in the enclosures that was causing it. Well, it wasn't the enclosures! It was a pair of vertical modes caused by the distances of the twin woofers from the floor and the ceiling. A little fine-tuning of the room eq (yes, at 1/24th octave resolution) and voila, the coloration was finally gone.
So sometimes the "boxy" ain't from the box.
The above described problem simply did not show up with the Open Baffle design, again because the OB doesn't excite the vertical modes nearly as much.
Boxy to me means a loudspeaker that sounds on the whole fine, but at certain frequencies sounds wrong. Like you've got your favourite singer singing away and they sound great, except that on certain notes you can hear that something isn't right, the timbre changes in the wrong way, a resonance somewhere has become excited and it colours the sound.
It's easy enough to hear for this simply by using headphones or a different pair of speakers. If the artefact you find displeasing goes away with the cans, then it's not part of the recording and is being added by the system in some way.
It's easy enough to hear for this simply by using headphones or a different pair of speakers. If the artefact you find displeasing goes away with the cans, then it's not part of the recording and is being added by the system in some way.
As a footnote, those interested by the concept of :
can have a look at these pages, the double bass array and a wiki article with some links
can have a look at these pages, the double bass array and a wiki article with some links
Yes, very much like that.
The Double Bass Array that FollGott did is exactly what inspired the array I described, modified by the idea you could use less subwoofers as in John Kreskovsky's "dipole" subwoofer array. The variant I did had elements of both, but primarily it was similar to the DBA.
I did a custom install for a client and used the modified version I described, it worked very, very well with the subs on the corners on the floor, within less than +/-1.5 dB all the way past 120Hz, no need for eq at all. Very even bass throughout the room, no peaks or cancellations anywhere near the main listening areas. Made things very, very simple. (Like FollGott, the sub array was being fed a summed mono bass signal BTW). It is the best subwoofer solution I've heard to date.
I'm wishing I could do something similar in my own room, but it has openings to adjoining rooms, making the task more difficult. Also, since I have a great fondness for good servo-subs, the cost of doing it would at a minimum $3K if I use Rhythmik and a lot more if I go with one of the better Velodynes.
The Double Bass Array that FollGott did is exactly what inspired the array I described, modified by the idea you could use less subwoofers as in John Kreskovsky's "dipole" subwoofer array. The variant I did had elements of both, but primarily it was similar to the DBA.
I did a custom install for a client and used the modified version I described, it worked very, very well with the subs on the corners on the floor, within less than +/-1.5 dB all the way past 120Hz, no need for eq at all. Very even bass throughout the room, no peaks or cancellations anywhere near the main listening areas. Made things very, very simple. (Like FollGott, the sub array was being fed a summed mono bass signal BTW). It is the best subwoofer solution I've heard to date.
I'm wishing I could do something similar in my own room, but it has openings to adjoining rooms, making the task more difficult. Also, since I have a great fondness for good servo-subs, the cost of doing it would at a minimum $3K if I use Rhythmik and a lot more if I go with one of the better Velodynes.
It would seem that box air resonances are fairly controllable above 200Hz with wadding with closed box and getting the ratios right. Controlling cabinet resonances fall into the thick rigid, and thin flexible and damped approaches. I see them as different solutions with something to be said for either.
Below are the diffraction effects from a 60x40 cm standmounter which has been bafflestep compensated in the bass section to a reasonable degree, and the same basic design wallmounted and recessed into the wall to give an effectively flat front baffle with minimised diffraction effects and the 6dB wall boost you'd expect.
Some significant colouration from diffraction alone with the standmounter, along with loss of efficiency.
You can draw your own conclusions, but it certainly gives some insight into what direction a box design should head.
Below are the diffraction effects from a 60x40 cm standmounter which has been bafflestep compensated in the bass section to a reasonable degree, and the same basic design wallmounted and recessed into the wall to give an effectively flat front baffle with minimised diffraction effects and the 6dB wall boost you'd expect.
Some significant colouration from diffraction alone with the standmounter, along with loss of efficiency.
You can draw your own conclusions, but it certainly gives some insight into what direction a box design should head.
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I like your thinking - we always knew wide baffles had their benefits, just makes some folk nervous about 'imaging'. I remember a bloke called Steve or Simon (?) wrote up on some testing he did with some friends in Yorkshire - they were surprised by some good imaging performance from some OB's despite their width.
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One really has to sit back and have a good laugh. Quite a lot of experience here. Many of the posters seem to be native or very skilled English speakers, and yet, "boxy" has different meanings to all of us. That has got to be darn tough on the rest! One thing that stands out. Just about everyone who has put forth a definition has tied it to a problem to address. A simple comment brings forth quite a lot of information.
Steve, were those plots measured or simulated? When I measure a sharp edge box of about that size, I get a lot more diffraction effects. 1/2 inch radius helps a ton. This weekend I hope to do direct comparisons to 1" if I can work in the shop. It was 105 F out there today. about 95% RH. I am way too old for that.
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Hi tvrgeek, It's the start of a long weekend in Ontario and it's similarly warm - forecasted stay warm and nice for the whole weekend. Can't complain about that 
So, your name being tvrgeek - would this be the TVR as in the kind of sports car from the Old Country that I used to lust after ?
What might be a nice conclusion to this thread are some guidelines to follow when building box speakers so as to address the problems being raised - how should I design my next box speaker so that it doesn't sound boxy ??
So, your name being tvrgeek - would this be the TVR as in the kind of sports car from the Old Country that I used to lust after ?
What might be a nice conclusion to this thread are some guidelines to follow when building box speakers so as to address the problems being raised - how should I design my next box speaker so that it doesn't sound boxy ??
No, diffraction effects are worse than a single suckout, David. They are a whole multiple of peaks and suckouts at ever increasing frequencies. Hard to equalise.
Lose the back of the box? Well you lose the bass with it.
I come back to Steen Duelund's beautiful thought model of the speaker box and the room:
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The two interact most greatly. So do the ratios of their sizes and dimensions. You could damp the room as carefully as you do the cabinet. No reason why you can't put felt on the OUTSIDE of the side panels of the speaker box or the room's walls. You can get creative.
My ideal speaker would probably use another room as the loudspeaker box! Which is not far off what open baffle is doing if you think about it.
As Bigun says, we ought to be zooming in on how to build the BEST box loudspeaker now. That IS interesting. I expect it's been done already amongst the myriad designs...
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I think I can shoulder the blame for some of that. Way back in post #2 I took the approach of how the box affected the driver vs. how the driver affected the box. The only boxy sound I am familiar with is what happens to the mids when in a box vs. OB, or close to it. I have seen what appears to be a number of different examples, none of which apply to what I was describing. So if I am at fault for the wayward nature of this thread then shoot me.
Or smarten up and learn what the term means.