Is there anybody building home audio speakers in an infinite baffle style? AFAIK, it’s so common, and popular in some places, in car audio.
1) using the driver in an extremely low Q, such as 0.5 or lower
2) using the driver with its natural roll-off on low-frequency response
3) extremely large closed enclosures
Do these three terms mean the same thing?
Also, what are the criteria for indicating that the drivers are suitable for the infinite baffle enclosure?
1) using the driver in an extremely low Q, such as 0.5 or lower
2) using the driver with its natural roll-off on low-frequency response
3) extremely large closed enclosures
Do these three terms mean the same thing?
Also, what are the criteria for indicating that the drivers are suitable for the infinite baffle enclosure?
Infinite baffle subs are done by quite a few DIYers for home theaters and hifi. Drivers with a high Xmax and low Fs are preferred along with lots of displacement. You’ll find them built as multi driver manifolds too installed in ceilings with attic space above, in floors with crawl space or basements below or sidewalls with adjacent rooms that won’t be impacted by the noise from the back wave such as garages. Two manifolds with two 15-18” drivers will produce and insane amount of very clean bass. We did an install a while back with 18’s in a room that was adjacent to a garage and a Crown Macro Tech 2400 amp and 4 18’s. It was nuts!
The manifold/semi slot loading cuts down on distortion as well as drops Fs a little and raises Q…..all beneficial if done with opposed drivers well built to cut down opposing forces.
The manifold/semi slot loading cuts down on distortion as well as drops Fs a little and raises Q…..all beneficial if done with opposed drivers well built to cut down opposing forces.
To my mind, infinite baffle means something like in-wall mounted speakers.
In your case I think the meaning is closed, sealed box or acoustic suspension speakers.
In your case I think the meaning is closed, sealed box or acoustic suspension speakers.
Yes, but I’ve heard a long time ago that some IB designs could be achieved by using a very large closed enclosure with the driver that requires simply a small box volume, an automotive subwoofer is one of the examples. I’m not sure if it is true?
If it's large enough to completely swamp Vas & Qt, sure. What special advantages you're aiming to achieve is another question though (?). Assuming no other modifications from amplifier output impedance, series R in circuit etc. & just taking system Q in itself, there is no advantage in a chronically over-damped response i.e. < 'critically damped' (0.5) since that is as inaccurate < F3 as strictly speaking anything over 0.707 is (there are caveats to both, but particularly the first). If you over-size the box so severely you'll also be restricting power handling.
Very large traditional large IB installations e.g. Hilliard's glorious 50ton, 300ft^3 per channel Cowan Heights Altec system (I hope it still exists: the house certainly did, last I checked, but with the passage of ~65 years, I suspect the system is long-gone
) were used at the time due mostly to the low Fs, middling-Q, high Vas units employed, the presence of mild EQ etc. Since the world & drive unit characteristics / requirements have mostly moved on from that, and not necessarily for the better, these things tragically now seem to have passed. If ever I had the opportunity though -I know what I'd be doing. 😉
Very large traditional large IB installations e.g. Hilliard's glorious 50ton, 300ft^3 per channel Cowan Heights Altec system (I hope it still exists: the house certainly did, last I checked, but with the passage of ~65 years, I suspect the system is long-gone
) were used at the time due mostly to the low Fs, middling-Q, high Vas units employed, the presence of mild EQ etc. Since the world & drive unit characteristics / requirements have mostly moved on from that, and not necessarily for the better, these things tragically now seem to have passed. If ever I had the opportunity though -I know what I'd be doing. 😉
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The infinite baffle is more related to baffle edge diffraction and half vs. free space radiation.
In relation to loading on the rear side of the driver you might talk about it as system Q (a result of driver Qts, Vas and enclosure volume as Scott says before me) rather than about the baffle type.
Sorry that I am not answering your original question but trying to explain the terms used.
I am assuming sealed cabinet rather than huge cabinet that effectively loads the woofer with atmospheric pressure?
If a small cabinet size is an important objective and fairly powerful amplifiers are available then a sealed cabinet can be a good choice. The efficiency will be down a bit, clean SPL down at bit, bass extension up a bit and distortion up a bit compared to a larger cabinet with a different loading. It is an appropriate choice for a set of 4-8 distributed subs (my case) where the small cabinet size allows more flexible placement around the room.
For large full range 3-4 way main speakers it is unlikely to be an appropriate choice. It becomes one though if there is no requirement to cover the lowest couple of ocaves due to the use of distributed subwoofers (my case). This is also why centre speakers tend to be sealed.
For the many compromises involved in 1-2 ways the appropriateness will depend on a fair few other choices made for the speaker.
Some people are enthusiastic about sealed cabinets for reasons related to transient response. In practise though it tends to be unimportant for larger speakers because the transient response of the room tends to be much worse and this is what we hear when listening to music in the home.
You can use whatever size enclosure you want…..just be sure to model the system with input power to be sure you won’t be bottoming out the driver…….
An infinite baffle is infinite. Not going to happen in practise.
If you take a modeler and keep increasing the volume of the box you will eventually that making the box bigger has little affect on the response. The Q of the system essential becomes the Q of the loudspeaker. So a driver Q<0.5 is to be avoided (unless EQ).
So Scott’s first sentence in Post #6.
In practise this is usually emulated by using the next room as a box or a box large enuff to be no care.
But if a box it needs to be wide enuff that the wall behind becomes an effective part ofthe baffle (the goal is “infinite”)
dave
If you take a modeler and keep increasing the volume of the box you will eventually that making the box bigger has little affect on the response. The Q of the system essential becomes the Q of the loudspeaker. So a driver Q<0.5 is to be avoided (unless EQ).
So Scott’s first sentence in Post #6.
In practise this is usually emulated by using the next room as a box or a box large enuff to be no care.
But if a box it needs to be wide enuff that the wall behind becomes an effective part ofthe baffle (the goal is “infinite”)
dave
Here's an example. It is my own installation done in 2009. It's built into a jutted out corner with a closet behind it. The closet space is just under 500 cubic feet. It is obviously not portable. It has not been "decorated" as I don't have to follow any sort of WAF. Although, it could be and it should be if the owner/installer wishes to have boat loads of fun. These are Acoustic Elegance drivers custom built for me by John. These exact divers are no longer available. The Fs is 16Hz, the Qt is 0.7 The limit in response is dictated by the size of the room. My room is not HUGE, but it is above average. Essentially 19x21 The quality of the bass simply has no peer, but very few folks will pursue this sort of installation, as it becomes part of the house.
Hah, the $1 for the Swedish dictionary was not wasted. Norwegian balkong is English balcony. Norwegian soverrom may match up to Swedish sovrom, English bedroom.
About the next room as speaker enclosure, see post #12 the 4th paragraph.
About the next room as speaker enclosure, see post #12 the 4th paragraph.
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What about the door between the living room and the room behind the woofers? Will the door act as a bass reflex port?
Just watch the door in a mastering studio, or how a drummer has to make his room silent in order to not disturbate the neighbors.
There is a 'magic number' of .39 Qts where the Vas can be used for a general guide to size, where to 'seal' or 'port' the enclosure is just a choice.
The energy of a .39 Qts motor means the cone can largely be immune to limited 'box volume' allowing for tuning at near Fs, for very low frequencies.
Interestingly, "infinite baffle" [closed] speakers can greatly improve with the right amount of internal damping material 🙂
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