Consider the physics of the situation. I'd also ask questions about whether the room was "closed", or if an open doorway or window was present in one or both tested rooms.
Personally I wouldn't like to be using pressurization zone effects for lf response below the room's Schroeder frequency since I find it to not be a pleasant experience--sort of like living inside a field drum or an auto interior.
Chris
... turns out the Acoustical Soc of Amer had a session on multiple-channel subs, May 2005, and a bunch of authors from U.Montreal (Braasch, Martens, others) seemed to support the notion that something is lost with mixed bass.
But the effect (kind of presence-versus-absence rather than any kind of bulls-eye localization) as one author presented it, related to a feeling of sound envelopment. In particular, the wider the spacing (like alongside your ears, I suppose) led to real nicer envelopment (which I suppose is akin to Toole's ambient warmth advocacy).
So maybe there's something good-sounding about woofers sitting where your headphones normally are located. But the effect may not be easy to define.
Again, sometimes easy to think you are hearing low bass when it isn't really there (I've just been watching the sub-amp flashing lights during Berlioz' Te Deum which is about as bassy as you'd think any acoustic music would be.)
Ben
But the effect (kind of presence-versus-absence rather than any kind of bulls-eye localization) as one author presented it, related to a feeling of sound envelopment. In particular, the wider the spacing (like alongside your ears, I suppose) led to real nicer envelopment (which I suppose is akin to Toole's ambient warmth advocacy).
So maybe there's something good-sounding about woofers sitting where your headphones normally are located. But the effect may not be easy to define.
Again, sometimes easy to think you are hearing low bass when it isn't really there (I've just been watching the sub-amp flashing lights during Berlioz' Te Deum which is about as bassy as you'd think any acoustic music would be.)
Ben
With winter approaching I decided to start using my fireplace as a fireplace again instead of a subwoofer cabinet. After a few days I really do miss the sub so now I need a new home for my JBL 2245H. I'm trying to decide between a coffee table sub (voice coil about four feet from my head) and an infinite baffle very close to my listening position using the wall behind my couch (voicecoil anywhere from 1 to 5 feet from my head). My speakers (heavily modded VMPS FF1) are about 12 feet from my listening position. Both solutions put the sub much closer to me than my mains, which I'm starting to think is a good thing.
What crossover point did you have in mind? And slope?
Subs have little influence on imaging music right up to maybe 120 Hz. But in the new world of DSP where many of us can explore time alignment like never before, I've heard audible benefits from getting the time alignment right. In other words, if you have DSP you can compensate for path length; but without DSP you aren't able to strive for the best sound.
DSP, in addition to timing and crossover control also gives you some EQ to compensate for a poor sub location.
I'd be concerned about the residual crud in your system when there is no sub signal. Can you hear noise coming out of the driver when near your head when there's no bass signal? That sure affects imaging and sense of S/N.
B.
Subs have little influence on imaging music right up to maybe 120 Hz. But in the new world of DSP where many of us can explore time alignment like never before, I've heard audible benefits from getting the time alignment right. In other words, if you have DSP you can compensate for path length; but without DSP you aren't able to strive for the best sound.
DSP, in addition to timing and crossover control also gives you some EQ to compensate for a poor sub location.
I'd be concerned about the residual crud in your system when there is no sub signal. Can you hear noise coming out of the driver when near your head when there's no bass signal? That sure affects imaging and sense of S/N.
B.
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YES. Once upon a time at the CES show, Q-Logic showed an automotive chair with a big subwoofer right behind it. You just hear some music when you came in, but when you sat in the chair the bass got super strong.
So I would go with the wall, or possibly under the couch (?) over the coffee table location. I would hypothesize, based on Roy Allison's papers and some research done at Alpine, that the wall is a better location acoustically that the coffee table insofar as loading the woofer is concerned. And far better to be in the predictable nearfield (negating room modes, I should also think?) than in the not-close, not-far field of a coffee table.
For the last two years I've run my 4 FTW21 drivers in a pair of sealed enclosures. One was a footstool (with a cheap IKEA futon on top of it, drivers facing down, castors giving excursion clearnace). The other was exactly the same dimensions but stood up behind the couch drivers facing the rear of the couch. Tactile response was so impressive that I didn't need the Crowsons and I never got a complaint. I mostly play movies though and listen to music in bed with some cans.
I recently ripped apart the crude unfinished MDF cabs and was going to build 4 'flanking' subs and place them beside the mains, but now I'm wondering if that is a mistake and should just go back to the same design, in ply and finished with white Duratex and a proper futon made for the footstool. FWIW the identical enclosures were so I could rotate them every 6 months or so to reduce potential suspension sag.
Nearfield is really nice though.
It is. I've tried it and it works well for a smooth and tactile low frequency response.
Problem is that usually only one person in the room benefits. Or may be two if they're sitting close together. Everyone else gets subpar performance.
Maybe the solution is one subwoofer for the critical listening position, and other subs to fill the rest of the room
Agreed, but I only need to satisfy the one or two people that are sitting on my 2 seater couch. My box faces are the exact same size as the hard section of the leather couch frame.It is. I've tried it and it works well for a smooth and tactile low frequency response.
Problem is that usually only one person in the room benefits. Or may be two if they're sitting close together. Everyone else gets subpar performance.
Maybe the solution is one subwoofer for the critical listening position, and other subs to fill the rest of the room
If I had say 2 rows of 4 seats, I'd do the combined approach; either near and far field subs or far field subs and a bunch of Crowsons.
This is going to be ridiculously east to implement. I'm going to use the baffle I made for my fireplace sub and add three sides the width of the woofer depth, 7 inches. My carpeted cement slab will work fine for the bottom. This gets placed up against the wall right behind the couch. There is a very large under stair closet behind the couch, so I will vent the backwave into the closet with hundreds of 1/4" holes into the closet. Voila! Instant near field infinite baffle sub.
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Unless your hundreds of holes are equal or greater than the JBL 2245H diaphragm area (Sd) they will act as a ducted port equal to the combined area of the drill holes.
Cutting a speaker (or greater) size hole would take a lot less time than drilling the equivalent area out one 1/4" hole at a time.
Hi,
There is an pre-print from the 45th Convension, reprinted in the first Loudspeaker Anthology:
Low-Frequency Loudspeaker Assessment by Nearfield Sound pressure Measurement, by Keele.
It describes using nearfield measurments instead of using an anechoic chamber. From the Conclusion, "measurements using nearfield technique show excellent agreement with more traditional test methods"
Small has earlier described how to measure pressure inside a box to predict free field responce.
/örjan
There is an pre-print from the 45th Convension, reprinted in the first Loudspeaker Anthology:
Low-Frequency Loudspeaker Assessment by Nearfield Sound pressure Measurement, by Keele.
It describes using nearfield measurments instead of using an anechoic chamber. From the Conclusion, "measurements using nearfield technique show excellent agreement with more traditional test methods"
Small has earlier described how to measure pressure inside a box to predict free field responce.
/örjan
H have completed this project (except for the cosmetics). The voicecoil is about 24 inches from my head, at my lower spine height. The crossover is 50Hz LR/4. The "cabinet" is a very large under stair closet. I'm rolling off the mains, VMPS Super Tower III Special Ribbon Edition with double free swinging ribbon tweeters. The extra tweeters helped get balanced sound for listeners of varying heights, a mod suggested by Brian Cheney. I am extremely happy with the results.For movies, I crank the level up 2dB to get some visceral impact.
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Agreed. I just cut a 20 x 20 inch square out of the drywall and saved it for when I move, in the off chance that the new owner isn't an audiophile.
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It is. I've tried it and it works well for a smooth and tactile low frequency response.
Problem is that usually only one person in the room benefits. Or may be two if they're sitting close together. Everyone else gets subpar performance.
Maybe the solution is one subwoofer for the critical listening position, and other subs to fill the rest of the room
Agreed. That's how I do it. I turn down the room subs 6dB when listening solo. It's the best of both worlds.
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