Elevating subwoofer about two feet off the floor


Acoustic Sciences Corp recommends elevating the subwoofer about 2' off the floor http://www.acousticsciences.com/products/subtrap

see photo in link above ... has anyone tried raising their subs that high off the floor? Did it sound better?
tweaknkeep
Wow I never heard of this product but thanks for bringing it up.
When I first got my velodyne dd10plus subs (I also sell them) I had a bit of trouble getting them to blend with my TAD CR1’S, which have very articulate bass. I had a pair of sisitrum stands 22" tall that used to use for a previous speaker (the TAD’s have their own stand) and on a lark decided to try them under the subs. No one could tell me if they would work or not since the subs were designed with the 6db gain the floor provides and in fact I was discouraged from doing so. I found the stands to be of great benefit and now have good blend with the mains, making much more in the room realism. And late night lowered level listening is enhanced by bumping up the subs level or using a lesser slope.
If anyone in the NY area wants to hear this unusual set up, PM me.  
That's a surprise....I would think the floor refection would be helpful.
Interesting find. I can see this working with subs that are either light in weight or not constructed tightly-so that you can control the 'boomyness'.
I wish I could try a pair with my Vandy 2w's and see if they make a difference, but I have already spent too much on my stereo.

I think you’ll find that "good" subwoofers are voice by the designers/manufacturers to take into account the floor (even wall) re-enforcement to get the FR as flat as possible in their operational range.

By raising them, they my very well roll off too early and maybe not give the low bass the were designed to do.


Cheers George

Subwoofers "voiced"? There is no voicing possible at subwoofer frequencies. Danny Richie of GR Research addressed this issue recently on his website, in regards to the x/o mod he designed for the new Elac speakers. Voicing involves frequency ranges of larger swathes than a mere 90Hz (10-100Hz). Not even any tailoring, really, as woofers are crossed-over from at too low a frequency to allow or require that. The floor and wall reinforcement you mention effects all subwoofer frequencies relatively equally (in comparison with midrange and tweeter drivers) as far as the subs themselves go, though the dimensions of any given space have an enormous effect on the sound of all subs in that space. With subs it is pure output and room dimensions that are involved, plus non-voicing issues such as distortion at Hz at SPL, time domain behavior (as revealed in waterfall plots), mechanical issues such as motor power versus driver mass, enclosure resonances, etc.

If you remember the work Roy Allison did after he left Acoustic Research, he addressed the issue of floor reinforcement or cancellation from woofers located at certain distances from the floor in his Allison Acoustic speakers by putting the woofer at the bottom of the cabinet, and crossing over to them at a lower than common frequency, with the midrange and tweeter drivers put at ear level. He didn’t voice the woofer, unless you consider floor-loading voicing!

"Voiced" can be an expression of getting it right in the surroundings it’s in. whether it be bass mids or treble or combinations of all.

Moving a sub back and forward in a room to get it phased right to the mains is also call "voicing".

It can measure flat in an anechoic chamber, but then has to be "voiced" for domestic situations (eg: next to a floor).

So I stand by what I said above, that a good sub that’s designed to sit on the floor will be "voiced" to sound right (flat if you wish). By raising said sub high off the floor may be counter productive to it’s designers "voicing."

BTW if you put Roys’ designed corner speaker out into the middle of the room they had no bass, they were "voiced" to get reinforcement from the room and or floor boundaries. And others like Bose with their shocking 901 had no bass if they weren’t near and facing the wall, and their are many others as well, Linn Isobarics etc, all "voice" to be next to a boundary whether wall or floor.

So a good designed subwoofer will sound it's best where it was designed to be, not 10' off the floor.  


Cheers George

Any omnidirectional, long wavelength, (deep bass) is going to bounce around the room creating complex patterns of interference. As you move the source of that wave (your speaker, or in this case, subwoofer), away from a nearby, reflective surface (the floor) you change the frequency and amplitude (severity) of the quarter wave interference.  So, I guess the answer depends on the relationship between your sub and the floor and other walls in your room.  As a practical matter, it's hard to believe that this makes sense unless you have multiple subs and are trying to randomize the sub to wall/ceiling/floor distances.  In that case moving one sub off the floor could make sense.
The farther the subwoofer is off the floor the less the magnitude of vibration force the subwoofer transmits to the floor and thus to electonics, turntables, CD players, etc.

I guess the only way to know for sure is to buy a pair and try them with subwoofers. Who know what kind of damping 
Actually, the question is whether raising the subwoofer off the floor about 2' will make it sound better. No need to purchase the bass trap that ASC is selling.
Another case of selling people something they likely don't need…bass naturally bounces around the room, and that's a reality that I personally don't mind as it sounds natural to me. If it doesn't, I turn my subs up or down a little.
Tweak, the bass trap has damping materials, which I believe would cause it to affect the sound, rather than simply elevating it.
My REL's are down firing. I've always found that they sounded less boomy when I moved them out of the corner and more into the center of the room. They tightened up more when placed away from any walls, though it requires a bit more volume in those positions.

Then on a lark, I turned them upside down. Yes, I did place a cutting board on their upturned feet, figuring they would need something to simulate a floor. That's the ticket. tight, precise, invisibly integrated. I heartily endorse anyone to try this and see if it works for you. 

Hey, everyone, I asked this question last week because I could not do the test myself. My speakers were out for repair so the whole system was down. Today, the speakers were returned so I got to work. I raised one of my two SVS subs off the floor 11" inches by setting it on concrete cinder blocks with Herbie's footers under the sub. Personally, I think ASC is on to something. Raising works for me. The bass blended better with rest of the music.

I only posted their photo as an example. If you need a bass trap, then yes, their product would be helpful. But my room already has bass traps, so I just wanted to see what raising the sub would do.
This should not be surprising; smashing a wave into the floor is never optimum. 
I have been using the ASC sub trap for many years. If you own a sub, you owe it to yourself to try one out...I did, and have never looked back. I feel raising the sub off the floor a few feet gives the sub a much better chance of integrating the low frequency's into the room,a more vertical distribution if you will...away from the room boundary of the floor itself,giving a tighter presentation overall.

With the bass trap centered at 70 Hz,the sub also has a chance of being heard without buildup of room modes. A win win if there ever was one.
I have my small sunfire sub sitting on a speaker stand. It definitely improved performance. A big heavy sub will be a challenge to get off the floor but if you can do it it will help
Alan
It was all I could do to move my pair of JL Audio F113V2's around at all, interesting concept, elevating subs.  The JL Audio's and Velodyne's all have microphones and EQ routines, to "tune" them to the room (I imagine also taking into account the reflections off the floor).  I don't see why one of these wouldn't "tune" properly if elevated.

In my case the room had all sorts of "non-musical" resonances, after installing ten bass traps (with the help of a calibration microphone, and the Room EQ Wizard software) I finally got the subs "dialed in" to the room.

Bass traps are not for everyone...have a very low WAF rating...
hey ejr1953,

Thanks for the tip about Room EQ Wizard.
i have 2 JL subs. they sounded far more integrated w the mains (magicos) when i elevated them 3" off the floor by way of maple stand.

improved further when i ditched their stock soft feet for cone footers. 

i leave it to armchair theorists to disagree w/ my experience. floor boundaries good for more bass, but less integration w/ mains.
Glad to know I'm not the only one who hears a benefit from raising the subs.  
I have my 2 JLs on Auralex subdude stands. They are inexpensive and work very well. Bass became more defined and propulsive.
I believe the Harmon-Kardon paper on bass reproduction, the basis for the concept of subwoofer "swarms", recommends locating subs at varying distances from the floor, thinking of the room in terms of a 3-dimensional volume, not a 2-dimensional floor.
Okay, so I pulled the trigger and purchased an ASC sub-trap. Will report findings soon.
I have my REL S5 on a Symposium platform which elevates it about 3"..It sounds much better than when on the carpeted floor..
Okay, coming back full circle to the beginning of the question: is it useful to elevate the sub? I bought a full round ASC tube trap that measures 20" diameter and 30" high. I placed the trap just to the right side of the right channel KEF LS50 monitor speaker and set an SVS 2000 sub on top. I think the result was phenomenal. Tight tuneful bass that was in the middle of the sound stage. You can see the tube trap here:  http://www.ebay.com/itm/371567367597?_trksid=p2060353.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
Hmm tweak you must be in NYC since they were only doing local pick up.   I might have gone for these myself if I had seen them.   
I know this thread is old but I just raised my subs about 2 feet off the floor.  I use small Pinacle subs that are dipolar.  My idea was to get the subs out of the mess that is floor level.  

Right away there was improvement. At first I thought they were louder but now I don't think so.  Now I think they're just more integrated and clearer. 
It is just a frequency response thing. If you had room control you could make the woofer sound the same and be more efficient and probably go even lower. If you have control of frequency response on the floor or in a corner is always going to be better. But if there is a response aberration and lifting the woofer helps and you have no other way of dealing with it you are stuck.  

mijostyn
"If you have control of frequency response on the floor or in a corner is always going to be better. But if there is a response aberration and lifting the woofer helps and you have no other way of dealing with it you are stuck."

Total BS. Are you still pitching this crock to your customers at Best Buy? Obviously, you don’t think the OP should trust his own ears.

In his follow-up post, the OP said:
tweaknkeep OP
"Okay, coming back full circle to the beginning of the question: is it useful to elevate the sub? . . . I think the result was phenomenal. Tight tuneful bass that was in the middle of the sound stage. "

taxonomy
I know this thread is old but I just raised my subs about 2 feet off the floor. . . Right away there was improvement.


I have a Rythmik sub and so far its has been sitting on the floor spiked with moderate results. I have done measurements using REW and there were a couple of suck outs and FR was not even. After reading this thread I decided to try it out so with the help of some stack of books I raised the sub 12" off the floor. Did my measurements again and was surprised to find that all the suck outs were gone and now the FR was pretty much flat. Adjusted the phase, xover and gain and I am enjoying a sub that is very well integrated with my monitor speakers. Its worth trying it out. 
Never hurts to experiment.Another thing to try is turn them to face the wall and move them closer or farther and hear what happens.
Have your cake 🎂 and eat it, too. Isolate the subwoofer with springs. Then you isolate the front end electronics from mechanical feedback AND take advantage of the proximity to the floor. Problem solved! 🤗 I’m pretty sure isolating the sure also reduces cabinet resonance. Three, three mints in one! 😀
Steakster you need to lower your dose of Adderall. I never implied anyone should not trust their own ears with their own systems. That does not mean I have to trust anyones ears with my own system. I will go where the science takes me long before I trust anyones hearing including my own. The people I help with their systems are not going anywhere near a Best Buy. I do so only by specific request and as a favor. I did work for Luskin's (RIP) when I was in medical school to help pay for tuition. It was a mid Fi store and a rat race. Far worse than Best Buy. That is the place they use to wire the speakers out of phase so the salesmen could sell the cheap crap they were being spiffed on. I always tried to sell the best equipment and failed miserably. The best equipment was always more expensive and people were more interested in cheap. If I work with anyone now it is generally money no object. What Fun!!
I am no where near money no object myself and never will be but I still get to build incredible systems in my dreams:) 
Geoffkait unless your subwoofer weights over a ton the last thing you want to do is "mount it on springs." You will not isolate other equipment from it at all. Get a recording with test tones. Put on the 20 Hz track and turn it up. If your system will produce it at all the entire house will start shaking including the refrigerator and your wife. Low frequency sound waves are very powerful. You ever been around a sonic boom?
Subwoofers are best served locked down tight. There is an issue with the stiffness of the floor. Concrete is always best. 
Post removed 
Uh, there is no 20 Hz information on virtually any recordings. Most people are lucky if the get flat FR down to 35 Hz in the room. Putting the sub on springs greatly reduces energy of all frequencies transmitted from the sub cabinet via the floor to the front end electronics. This is especially true for speakers and subwoofers since the Fr of the iso system is much lower than the lowest frequency the speakers or subs can produce. By the way, as shown in max Townsend’s YouTube video, isolating speakers or subs reduces cabinet resonance as well as isolates front end equipment. Two, two mints in one! 🤗
mijostyn541
 "entire house will start shaking including your wife."
Perhaps now I won't need the movie and wine?  

mijostyn
. . . unless your subwoofer weights over a ton the last thing you want to do is "mount it on springs."

Uh, no. Springs are precisely why these IsoAcoustic Stage 1 Isolators work so well.

geoffkait
isolating speakers or subs reduces cabinet resonance as well as isolates front end equipment.

IsoAcoustics has built their entire company around this statement.
http://www.isoacoustics.com/isoacoustics-speaker-isolation-technology/

Mass loading on top of subwoofers is another approach to reducing cabinet resonance. But, it leads to more problems. If the sub is spiked to the floor, the energy travels along the floor to the audio rack holding the front-end components. Shaking source components is never a good idea.