As I mentioned, floor bounce, which is better described as the "Allison Effect", is a very interesting suckout in a loudspeakers performance which leads you on to considering the whole loudspeaker/room interaction.
If you do your homework, which is not what the Lazy Student does, you reach this impressive understanding of the effect of the floor on the bass performance from Roy Allison:
All this THEORETICAL STUFF is all well and good, but "WHAT DOES IT MEAN IN PRACTICE?"
Stuff like this, which is the wall mounted Acoustic Research MST:
Aspects of the design I like there... especially those cone tweeters.
Or a much more expensive design we just saw:
One of my heroes in this forum, Joachim Gerhard, also got interested in floor bounce, He got to this:
The Quintessentially German Loudspeaker of the 70th. Modern Interpretation.
TBH, I don't want to get into MTM or MTTM lobing and combing. You either get it about dispersion or you don't. The inverse square law of power at heart. Where we get to, IMO, is the room greatly influences the loudspeaker's sound. For sure, a bit of damping like carpet and rockwool on the walls clears up the midrange clutter. The bass is more difficult. For that you need to know about wall-mounting and floor bounce.
If you do your homework, which is not what the Lazy Student does, you reach this impressive understanding of the effect of the floor on the bass performance from Roy Allison:
A Glorious Time: AR's Edgar Villchur and Roy Allison Allison Part 2 | Stereophile.comRoy Allison said:
All this THEORETICAL STUFF is all well and good, but "WHAT DOES IT MEAN IN PRACTICE?"
Stuff like this, which is the wall mounted Acoustic Research MST:
Aspects of the design I like there... especially those cone tweeters.
Or a much more expensive design we just saw:
One of my heroes in this forum, Joachim Gerhard, also got interested in floor bounce, He got to this:
The Quintessentially German Loudspeaker of the 70th. Modern Interpretation.
TBH, I don't want to get into MTM or MTTM lobing and combing. You either get it about dispersion or you don't. The inverse square law of power at heart. Where we get to, IMO, is the room greatly influences the loudspeaker's sound. For sure, a bit of damping like carpet and rockwool on the walls clears up the midrange clutter. The bass is more difficult. For that you need to know about wall-mounting and floor bounce.
Was reading up on this not long ago- floor bounce, floor gain etc
Not sure if it was Jeff Bagby, but one well known designer suggested not putting a bass driver too far down- ie bottom of baffle. Cant remember the reason.
Magico need floor gain to boost the system sensitivity of their sealed drivers, sometimes these are relatively small in diameter. Because of the gap to the mid, Magico usually have a mid only.slightly smaller, I guess for good reproduction of male vocals.
Not sure if it was Jeff Bagby, but one well known designer suggested not putting a bass driver too far down- ie bottom of baffle. Cant remember the reason.
Magico need floor gain to boost the system sensitivity of their sealed drivers, sometimes these are relatively small in diameter. Because of the gap to the mid, Magico usually have a mid only.slightly smaller, I guess for good reproduction of male vocals.
I've been tempted to add another 12" to my 12" 2-way (28" tall) that sits on the floor now.
I like what I have, just trying to get closer to the midbass that my double 15's had, even at low volumes.
Usually when I lift speakers off the floor, i lose bass, so adding another woofer under it (like a midbass module), may not help me get more bass than what I have.
I like a deep impact-full 2 way with 1 crossover up at 1,200hz.
I got sensitive to crossover in bass region I guess from years of double 15 crossed at 750hz........
Any thoughts / opinions ?
I like what I have, just trying to get closer to the midbass that my double 15's had, even at low volumes.
Usually when I lift speakers off the floor, i lose bass, so adding another woofer under it (like a midbass module), may not help me get more bass than what I have.
I like a deep impact-full 2 way with 1 crossover up at 1,200hz.
I got sensitive to crossover in bass region I guess from years of double 15 crossed at 750hz........
Any thoughts / opinions ?
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If you can measure - try the woofer at various heights. If your already have close floor placement, then use bricks / blocks. If too high - put the enclosure on its side and do the same. My placement was largely due to aesthetics and to keep the woofer above "foot kicking" distance - since there are no grilles, such that a clumsy walker doesn't boot it in!
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Doing simulations, I still can't get how Gradient can get away with a downfiring woofer...
With normal listening distances between 2,5 and 3,5 meters the floor bounce ends up being around ~300 Hz. Which means the woofer needs to be crossed at about 500 Hz to cover the dip somewhat properly. But they cross at 250 Hz
With normal listening distances between 2,5 and 3,5 meters the floor bounce ends up being around ~300 Hz. Which means the woofer needs to be crossed at about 500 Hz to cover the dip somewhat properly. But they cross at 250 Hz
Since you have 12", two = a 'fat' 15", so [4] 'on the floor' to match/best the dual 15" 'on the floor', though of course means a new, wider cab.
Right, you lose the floor's mirror image and even if on the floor it's much reduced at > 3x driver radius, so the closer to the floor the better the mirror image and of course it must be perpendicular and setting on a massive, etc., no carpet, etc., floor for max efficiency, though even my carpeted 'floating' floor does fine, though they calculate in the 300+ lb/ea., so maybe just having really heavy speakers is sufficient.
If near a wall or corner all these 2pi guidelines can get really blurry, so strictly a worst case scenario so may can get by with dual 12", optimized room placement.
GM
I use 4 sheets of Echo Eliminator acoustic cotton placed on the concrete floor midway between the speakers and my listening position.
Each sheet is 2x4 feet, 2 inches thick. They are available in several colors and actually look sort of OK. I use any extra to line speaker cabinets. I was able to buy a discontinued color for much less.
A cheaper, similar product is ATS Acoustical Cotton Batts. The color and texture are not pleasing on the floor.
Acoustic cotton absorbs as well as dense fiberglass, so 2" sheets won't absorb much below 100Hz but virtually 100% above 250 Hz. Acoustic specifications are at the web site.
Does it sound cleaner/better? Hard to say for sure but I feel better using it.
I first installed large sound absorbing panels hung from the high ceiling as otherwise the concrete floor makes the room have way too much echo. It is pleasant now. Adding the floor sheets doesn't change the room echo that I notice.
I keep the speakers 4 feet away from the back and side walls, in a 14x29 foot room.
Each sheet is 2x4 feet, 2 inches thick. They are available in several colors and actually look sort of OK. I use any extra to line speaker cabinets. I was able to buy a discontinued color for much less.
A cheaper, similar product is ATS Acoustical Cotton Batts. The color and texture are not pleasing on the floor.
Acoustic cotton absorbs as well as dense fiberglass, so 2" sheets won't absorb much below 100Hz but virtually 100% above 250 Hz. Acoustic specifications are at the web site.
Does it sound cleaner/better? Hard to say for sure but I feel better using it.
I first installed large sound absorbing panels hung from the high ceiling as otherwise the concrete floor makes the room have way too much echo. It is pleasant now. Adding the floor sheets doesn't change the room echo that I notice.
I keep the speakers 4 feet away from the back and side walls, in a 14x29 foot room.
People focus on floor bounce because ceiling bounce depends on a huge range of height.
Modern UK houses usually have very low ceilings, so the top of the speaker is getting dangerously close to midway. My ceiling was 19ft, causing a serious lack of bass. I added a mezzanine, that has left me with 9ft and a much smoother bass response.
Modern UK houses usually have very low ceilings, so the top of the speaker is getting dangerously close to midway. My ceiling was 19ft, causing a serious lack of bass. I added a mezzanine, that has left me with 9ft and a much smoother bass response.
Significant problems with that approach. Separating two in room signals is beyond the ability of processing. Then, when they cancel you can't boost them as there is nothing to boost.
It isn't. You get a lot of comb filtering from the floor and that certainly effects the sound quality as well. It's just that we have gotten used to it because it's practically difficult to treat it. But after experimenting with minimizing it, there's no doubt in my mind that leads to a definitive improvement.
A CBT speaker avoids the problem altogether.
The crossover here has little to do with the reflections from the floor above Schroeder. It's related to the dispersion pattern.
A thick carpet is very band limited and will only absorb higher frequencies. Besides, a carpet is also quite reflective of many frequencies. Whether it's better than nothing is something each has to decide.
How does a CBT array do that? Would a normal array suffer floor bounce or is it mostly a point source problem?
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