Why is floor bounce mostly ignored in commercial speakers??

Why is floor bounce mostly ignored in commercial speakers?

I've observed that most manufacturers seem to don't really care about the floor bounce effect in their designs.

Even with 3-ways where you could/should just place the woofer close to the floor and the midrange far enough from the floor for it to be outside the passband of both drivers.

So why is this?

Only reason I can think of is that closer center-to-center distance between woofer and midrange is of higher priority. Although the XO point between these two is usually low enough that it shouldn't really be an issue :confused:
 
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There won't be a single fixed answer to that, more a series of answers for a variety of reasons, some acoustic, some cost, some marketing / aesthetic. The phrase you used 'could / should' is actually a good way of looking at it.

Many could, acoustically speaking. Whether that means they 'should' is another matter entirely, as they have a number of variables beyond pure acoustics to consider. Which is assuming they consider it to be a significant issue in the first place; they may not.
 
To a point / in a lot of cases quite likely -but then, all decisions for commercial loudspeakers are to some extent commercial. No shame in that, they're businesses, not philanthropic institutions, and if they want to survive they have to give the market what it wants, or what they have a reasonable - good chance of persuading them to buy. Just the way of the world.
 
Indeed.

I wouldn't run away with the assumption that it's the sole reason though. Life is not quite so black and white as all that, and there are other factors involved: as noted, some acoustic, some cost, some marketing / aesthetic. DIY construction can help remove some of those restrictions that may, or may not, apply to a given commercial product.
 
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Well, moving the woofer further towards the floor wouldn't really have a huge impact in aesthetics for most designs.

You would at least think the manufacturers targeting hifi community would do it.
Like B&W, Klipsch, etc. But they don't (for the most part).

Makes me think that there's gotta be another reason. Is the audible effect of floor bounce not great enough to care?
 
Really? I wouldn't be so sure about that, re the aesthetics. Speaking purely in the abstract, aesthetics being what they are, what you might consider as having little impact, some others might regard as ugly. And that's assuming the desired baffle arrangements actually allow you to position the woofer at xyz distance from the deck, which is not always the case.

Re hi-fi; let's be honest here. A significant amount (arguably the majority) of commercial hi-fi ran off into rampant subjectivism at some point in the 1980s, and technical performance became a side-issue from the end-user's POV. Once upon a time, many, if not most buyers were quite technically savvy, not least because in many cases they actually had to design and build the gear themselves. As that changed, and off-the-shelf became the norm, a lot of that technical knowledge dwindled, and I think I can safely promise you this: in the UK at least, the technical knowledge of most commercial hi-fi buyers is lousy at best. No reflection on them, although they would probably do themselves and their enjoyment a big favour if they tried to learn.

Is floor-bounce a big deal? It's not ideal, that's for sure, but what with our falling hearing acuity in the LF, coupled with the fact that our hearing primarily 'keys off the peaks' and that the room response generally dominates low down anyway -well, circumstance dependent, but in many cases, it's just one of a factor of junk in the LF that, at least to a point, we listen around, as it were, and many will probably only notice a dulled fundamental if they're particularly focused on it. Obviously, the ideal is not to have it, but many, even quite critical listeners, appear to be able to live with it. Not everyone, but many.
 
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Ok, so if we had an ideal situation, with a 3-way floor-stander and a low enough W-M crossover... how far would/should one place the mid from the floor to avoid floor-bounce? I'll assume an 8' tall ceiling for this exercise. If a 2" tweeter with a 3-1/2" face plate wants to be centered at seated ear height roughly 45" high, then place a 6" mid as close to that as possible. That places the Mid center at around 40" above the floor. (8" below the midpoint between floor and ceiling) Does that reduce the floor bounce enough, or is some device like MTM configuration, or a horn, or an angled baffle required to control vertical directivity further? I'm assuming that floor bounce can't be avoided for the woofers, so any size and height that works below that should be fine. Also, we'd need to place the vertical driver center at least 3' to 4' far from a wall, or toe it in to avoid wall bounce, right?

Is this what we're talking about, or am I missing something? Just looking to get some concrete recommendations, and reasons for them from this thread. Thanks! Six.

P.S. just measured my B&W's and the mid is at 35.5" from the floor, also my Ohm 2's are a different bird (Omnis with a vertical cone aiming down) They have the top of the wood base at 2' above the floor and the top of the metal canister 6" above that. I should measure the B&W's where they are, and then try again with a 10" riser and see what REW shows.
 
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And ceiling bounce? Room modes, corner and room gain? Power compression, off axis response and the rest I forget .......

Because just power consumption, looks and size matter if you don't have any practical knowledge / wisdom about speakers.

And using them right, speaker setup, is just a important as the speakers.


Speaker are seldom setup correct among audiophiles, in venues, at festivals, concerts (U2 Live in Brisbane Horrible sound quality) and at EDM dance parties spending lots of cash.
 
Ok, so if we had an ideal situation, with a 3-way floor-stander and a low enough W-M crossover... how far would/should one place the mid from the floor to avoid floor-bounce? I'll assume an 8' tall ceiling for this exercise. If a 2" tweeter with a 3-1/2" face plate wants to be centered at seated ear height roughly 45" high, then place a 6" mid as close to that as possible. That places the Mid center at around 40" above the floor. (8" below the midpoint between floor and ceiling) Does that reduce the floor bounce enough, or is some device like MTM configuration, or a horn, or an angled baffle required to control vertical directivity further? I'm assuming that floor bounce can't be avoided for the woofers, so any size and height that works below that should be fine. Also, we'd need to place the vertical driver center at least 3' to 4' far from a wall, or toe it in to avoid wall bounce, right?

Is this what we're talking about, or am I missing something? Just looking to get some concrete recommendations, and reasons for them from this thread. Thanks! Six.

Using a simple calculator: Floor/Ceiling Reflection Calculator

Woofer placed 25 cm above floor equals ~1 KHz.
Mid placed 100 cm above floor equals 250 Hz.
Meaning a XO at 500 Hz should leave most of the bounce out of the passband for both drivers.

The new beta version of XSim also works well in simulating both floor and ceiling bounce with different driver placements and XO's.
 
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^: SBIR calculator

Does that reduce the floor bounce enough, or is some device like MTM configuration, or a horn, or an angled baffle required to control vertical directivity further? I'm assuming that floor bounce can't be avoided for the woofers, so any size and height that works below that should be fine.

Yes vertical aligned configuration can help to 'reduce' the floor bounce effect. It does as the drivers have different pathlength they will exhibit different 'suck out' ( notch) frequency.
Once summed acoustically instead of one deep notch you then face three less severe ones spanned over a wider freq range.

The point being to find a sweetspot versus the physical dimension of drivers, box conxtraints and frequency of interest ( to mitigate the notch).

You can use FIR in tandem with vertical aligned drivers to have controlled vertical directivity too : Horbach-Keele filter is all about that.

Horn or waveguide helps with controled vertical directivity but it doesn't garantee you it won't happen ( it is one thing some of MEH ( synergy) builders discovered).

Floor ( or ceiling or walls) bounce can't be avoided, this is the nature of reproduction within a room.
 
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Go to classicspeakerpages(.net?).
There are two forms of Roy Allison's explanation of boundary reflections(incl floor bounce-induced cancellation). The short version is in the Allison One Series brochure(3 pgs or so).
The long form is fourteen pages with examples of what doesn't work(and why) as well as his solutions, worth reading.


By the way, he kept the woofers close to the floor, crossed at 300, so your idea is in the ballpark.
 
This floor bounce, or Allison effect is all well and good, but what does it mean in practise?

Stuff like the Allison 1 loudspeaker, at least according to Roy himself:
A Glorious Time: AR's Edgar Villchur and Roy Allison Allison Part 1 | Stereophile.com

628055d1501378412-classic-monitor-designs-allison-speasker-jpg


stereonomono - Hi Fi Compendium: Allison model ONE

Of course it don't mean a thing without a crossover:

628056d1501378412-classic-monitor-designs-allison-crossover-jpg


Which ends up like this, I expect:

687003d1529097418-passive-passe-steen-duelund-2-828427-2root2-png


Roy Allison was not only a believer in mounting the bass close to a boundary. He also thought wide dispersion mattered. His speakers actually used those horrible room reflections for the overall sound. He might have been onto something with this expensive approach. The beauty of diy is you can try ideas, and either fly or crash and burn!

I'd certainly like to try the IC20:

628054d1501378412-classic-monitor-designs-allison-ic20-speaker-jpg


A beauty, IMO. Much to enjoy there. :D
 
P.S. just measured my B&W's and the mid is at 35.5" from the floor, also my Ohm 2's are a different bird (Omnis with a vertical cone aiming down) They have the top of the wood base at 2' above the floor and the top of the metal canister 6" above that. I should measure the B&W's where they are, and then try again with a 10" riser and see what REW shows.

So, below is a comparison using REW of my B&W DM640 on the floor 1/24th octave smoothing. (Midrange at 35.5" above the floor (Green) and with a 12" riser (Red) Microphone was at 45" above floor 8' away which is the main listening position. Speaker is near the front-right corner of the room, the room has a 9' ceiling, nearest wall to the microphone is 6' away to the right, the wall to the left is 8' away.

Looks to me like I should be getting some 12" risers permanently, since the red trace has a 5db swing (flatter) between 200 and 2000 hz vs a 10 db swing for the green trace. I'm relatively new at generating and interpreting graphs, but it seems that there is less room interaction to the midrange with the midrange 12" higher (at the same height as my ears) which bears the OP's hypothesis.

Comments? Sixto. - still learning how to attach images inline.

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Thank you!

Go to classicspeakerpages(.net?).
There are two forms of Roy Allison's explanation of boundary reflections(incl floor bounce-induced cancellation). The short version is in the Allison One Series brochure(3 pgs or so).
The long form is fourteen pages with examples of what doesn't work(and why) as well as his solutions, worth reading.

Thank you for this information! Here is a link to the longer article: Technical Articles by Roy F. Allison | The Classic Speaker Pages

Sixto