Just toying with different ideas.
What are the pros/cons/effects of having the port (TL opening, port...) firing downwards the floor?
How do you model this?
I like full range speakers, mine is a ML TQWT.
Most likely my next speaker will be one as well (or TL or something along those lines?).
Getting the most/best bass from these full rangers is always a fun challenge.
I'm thinking one could have some fun with designs if the opening is allowed to fire into the floor.
What are the pros/cons/effects of having the port (TL opening, port...) firing downwards the floor?
How do you model this?
I like full range speakers, mine is a ML TQWT.
Most likely my next speaker will be one as well (or TL or something along those lines?).
Getting the most/best bass from these full rangers is always a fun challenge.
I'm thinking one could have some fun with designs if the opening is allowed to fire into the floor.
I saw something about this in the subwoofer forum a couple of years ago. Obviously an important issue is the height off the ground. Its worth a search.
Josh
Josh
Since this is posted at the FR forum, I'm thinking that you're not asking about sub woofers.
I'd imagine that the spacing above, and surface material of the floor could have some acoustic affect on the results, but my intuition is that a design that doesn't fire directly (perpendicularly) to the floor might yield smoother coupling to the effective listening area - i.e. less ripple from reflections back through the port/vents.
as to modeling it, there must be someone experienced with that who would care to post?
I'd imagine that the spacing above, and surface material of the floor could have some acoustic affect on the results, but my intuition is that a design that doesn't fire directly (perpendicularly) to the floor might yield smoother coupling to the effective listening area - i.e. less ripple from reflections back through the port/vents.
as to modeling it, there must be someone experienced with that who would care to post?
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GM's MLTL for the Jordan 92 has a floor-firing port. In the original design (the 31" version) it has a 45 degree reflector directly below it, built into the stand, to better couple the port to the room. On that basis, I'd imagine a down-firing port should be fine, as long as there's a few inches clearance. Any potential bad effects are likely to be swamped by the room.
All the metronomes have downfiring ports. There is some info in that thread about optimizing the port.
dave
dave
IINM, many Metronome builders have noted improvements with hard reflecting surfaces (ceramic/granite tiles, etc) under the enclosures if the floor is carpeted
I have started reading the Metronome thread... It's a long one.
Like chrisb says, I'm not thinking subwoofer.
This is a consideration for my next fullrange speaker.
Now for an afterthought or two...
As we are all aware of, one is often forced to use a bsc to fix the bass.
A port firing down should radiate in 2Pi space. (Am I using that term correctly?)
What I mean is the sound from the port is radiating all around the speaker and thus there should be no baffelstep for the port? -> better bass response?
Like chrisb says, I'm not thinking subwoofer.
This is a consideration for my next fullrange speaker.
Now for an afterthought or two...
As we are all aware of, one is often forced to use a bsc to fix the bass.
A port firing down should radiate in 2Pi space. (Am I using that term correctly?)
What I mean is the sound from the port is radiating all around the speaker and thus there should be no baffelstep for the port? -> better bass response?
I guess so . Low frequencies are omnidirectional , beaming starts as frequency raises .
Putting the port below would be useful taking into account where and how the speaker (box) shall be positioned . If it needs space around , but space constraints doesn't permit that , it's a good solution .
Speakers should be positioned far away from the walls ...well , depends on which project...some speakers sounding ugly ,if positioned near a wall (don't matter if and where a reflex port is used)give a correct sound reproduction.
Actually a downward firing port will radiate into 8pi in a corner, 4pi against a wall. Yes, the low frequencies are omni but the boundary reinforcement still takes place.
It's possible to compensate for baffle step in maybe a dozen ways, including building a "bump" or rise into the desgin at just the right place (whether that bump is built into the cab, or the driver), using a horn design, using the widest possible baffle, EQ, a second rear-firing driver, a 1.5 design etc.
By itself, putting a single-driver cab near/against the wall doesn't by itself totally eliminate it (it just makes the step shallower but maybe so shallow as to make it irrelevant compared to the room factors). Even a BiB has to worry about baffle step. The only cab without baffle step is where you put the driver right into the wall (infinite baffle) in my extremely limited experience.
It's possible to compensate for baffle step in maybe a dozen ways, including building a "bump" or rise into the desgin at just the right place (whether that bump is built into the cab, or the driver), using a horn design, using the widest possible baffle, EQ, a second rear-firing driver, a 1.5 design etc.
By itself, putting a single-driver cab near/against the wall doesn't by itself totally eliminate it (it just makes the step shallower but maybe so shallow as to make it irrelevant compared to the room factors). Even a BiB has to worry about baffle step. The only cab without baffle step is where you put the driver right into the wall (infinite baffle) in my extremely limited experience.
rjbond3rd> This is my major concearn with the FR speakers.
It's wonderful not having a crossover so I'd rather not add the extra bsc if it can be avoided.
With the cabs I've been toying with the baffel step usually appears around 500Hz +/- 150Hz give or take.
Is it even possible to build a bump that big?
I mean... it's a biggie.
Since we're talking one driver it's kind of unlikely the driver will have such a bump. We're left with the cabinet.
Bi-pole speakers is a solution but arn't you supposed to loose imaging and such? Plus the extra expense...
I'm all ears when it comes to new ideas for solving the baffel step.
It's wonderful not having a crossover so I'd rather not add the extra bsc if it can be avoided.
With the cabs I've been toying with the baffel step usually appears around 500Hz +/- 150Hz give or take.
Is it even possible to build a bump that big?
I mean... it's a biggie.
Since we're talking one driver it's kind of unlikely the driver will have such a bump. We're left with the cabinet.
Bi-pole speakers is a solution but arn't you supposed to loose imaging and such? Plus the extra expense...
I'm all ears when it comes to new ideas for solving the baffel step.
Hi markusG,
Regarding bipoles and imaging, you can limit the second driver so that it only outputs from baffle step down (a .5 driver) using an inductor of suitable value on the + of the second driver.
Horns have a bigger payoff but are obviously harder. For inspiration, check out: AUDIOMANUFACTURE BOENICKE AUDIO W20SE AUDIOPHILE LOUD SPEAKERS
Regarding bipoles and imaging, you can limit the second driver so that it only outputs from baffle step down (a .5 driver) using an inductor of suitable value on the + of the second driver.
Horns have a bigger payoff but are obviously harder. For inspiration, check out: AUDIOMANUFACTURE BOENICKE AUDIO W20SE AUDIOPHILE LOUD SPEAKERS
Hi there rjbond3rd: Thanks for the information on the "Boenicke Audio W20SE". Everytime I think there is nothing new in audio, someone has an fantastic idea like this. ...regards, Michael
Hi J. Michael,
Cool -- those speakers had an unbelievable soundstage and really open bass. The drivers fire at the sidewalls (except the forward-facing ones which only work from 2k up).
So you're surrounded in reflected sound, but you get some focus from the tweeters. The designer was happy to chat about it at RMAF, where I heard them. Try to visit this October, maybe he'll be there: Rocky Mountain Audiofest 2010
Or if you are near Dallas, in just a week and a half is the LSAF which looks to be really great this year: Lone Star Audio Fest
Or if you are near Detroit, this weekend is AKFest: Audiokarma/AKFEST 2010
Cool -- those speakers had an unbelievable soundstage and really open bass. The drivers fire at the sidewalls (except the forward-facing ones which only work from 2k up).
So you're surrounded in reflected sound, but you get some focus from the tweeters. The designer was happy to chat about it at RMAF, where I heard them. Try to visit this October, maybe he'll be there: Rocky Mountain Audiofest 2010
Or if you are near Dallas, in just a week and a half is the LSAF which looks to be really great this year: Lone Star Audio Fest
Or if you are near Detroit, this weekend is AKFest: Audiokarma/AKFEST 2010
Nothing new there. Just that CNC is making commercial manufacture of these kinds of things possible.
dave
or "practical" in terms of precision and "efficiency" of fabrication time - still rather costly on materials, whether solid woods, stacked laminated ply/MDF/PB or even Corian, etc.
I'd be concerned re the long term reliability of a large enclosure carved mostly from a single solid piece of hardwood, even if well sealed before closure.
and of course the "superiority" of any particular enclosure / bracing topology over others is subject to as much friendly debate as the type of drivers installed therein 😀
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