Dec 5 Auralex SubDude Video Review
Shortly after I posted the video of my Media room I received an email from listener Rob telling me about a $50 device that can make a big difference in the quality of my subwoofer. He spoke so highly of the device I decided that it was worth a try to check it out!
He was talking about the Auralex SubDude. The job of the SubDude is to prevent sound from transmitting through your subwoofer to the floor and surrounding surfaces.
The Auralex Subdude is a 15X15X3 inch pad that you place under your subwoofer to decouple it from your floor.
So how did it work?
We watched a scene from The Last Mimzy loaded with low frequencies. We were surprised by our results. The bass actually got louder. We figure that less of the sound went into the floor and more made it into the room. While watching Die Hard 4 we noticed that machine gun fire felt tighter and more precise. My wife was the most happy because the SubDude actually blocked much of the LFEs from being heard downstairs. The SubDude might be the best $50 I have spent on my theater!
They also sell the GRAMMA and Great GRAMMA for bigger subwoofers.
Video:
Reader Comments (8)
Awesome! I am SO pleased that you found the SubDude to make a worthwhile improvement. I try not to use hyperbole when recommending that people decouple their subwoofer and speakers, but I do make very strong statements because it typically takes that level of persuasion in order to get people to try it!
So it comes as a great relief when other people discover that decoupling really does improve the sound both inside and outside of your theater! Results do vary, but I have yet to come across anyone who found zero improvement with a decoupling device in place.
One thing that can make the SubDude/GRAMMA's improvement less noticeable is if the subwoofer or speaker was already sitting on top of a very thick carpet pad and carpet. Essentially, a thick carpet pad will already act as a decoupling device. However, most subwoofers and speakers have "feet" or some sort - either "spikes" or just small, rubber feet that stick out from the bottom. These "feet" will typically sink deep into any carpet and will often sink deep enough to still couple the subwoofer or speakers to the floor. So even with carpet, the SubDude/GRAMMA can often still deliver a noticeable improvement.
Ara mentioned that the bass in his theater actually sounded louder with the SubDude in place and surmised that perhaps the reason was because more bass was entering the room due to no longer entering the floor. This isn't actually the case. What is actually happening is that - without the SubDude in place - the room itself is shaking in sympathy with the subwoofer. In essence, the walls, floor and ceiling all end up acting as huge speaker surfaces. They shake along with the shaking of the subwoofer and, as a result, produce sound waves of their own. These sound waves (which are a clear form of distortion) interact with the soundwaves coming from the subwoofer - in exactly the same way that reflected soundwaves interact with the direct soundwaves. In other words, the shaking of the walls/ceiling/floor creates destructive and constructive interference when the soundwaves created by the shaking walls/ceiling/floor interact with the direct soundwaves from the subwoofer AND the reflected soundwaves.
The bottom line is that decoupling greatly reduces one major source of distortion and one major source of additional soundwaves within the room. With fewer instances of either destructive or constructive interference, the result is a somewhat flatter frequency response within the room. To be clear, both the direct soundwaves and the reflected soundwaves still exist, so decoupling is NO panacea for frequency response! But you DO eliminate the soundwaves that were the result of shaking walls/ceiling/floor, so that has an audible effect!
Some people experience LESS bass volume when they add the SubDude. That would be because the shaking walls/ceiling/floor happened to be creating constructive interference at that person's particular seating location. In Ara's case, it is very likely that the shaking walls/ceiling/floor happened to be creating destructive interference at his seating location, so that is why the bass seemed to get louder with the SubDude in place!
Regardless of whether the shaking walls/ceiling/floor happen to create either constructive or destructive interference at your particular seat though, you can expect to hear "tighter" bass with a decoupling device in place. And that is because, regardless of your room acoustics or seating location, reducing additional distortion soundwaves will always result in fewer instances of either constructive or destructive interference. As I said earlier, that means some measure of improvement in the frequency response and you are also removing a major source of distortion, which is always a good thing ;)
WoW,
if it does really improve the sound quality of sub woofer,i'll have to buy one also!. But small problem,i have a down firing sub from hsu research,will that be problem if i buy one?. Or it won't matter?. Thanks
I wonder if this will make a difference on a concrete surface with thick carpet already on top.
@Mark - the GRAMMA riser works extremely well with HSU's down-firing subwoofers. HSU's subs have "cone" feet that elevate the bottom of the subwoofer so that there is a gap between the bottom surface of the sub and the platform beneath it. Dr. Hsu has actually said that his down-firing models (like the VTF-2 MK3 for example) work best when firing into short-pile carpet. That just so happens to be exactly what covers the top surface of the Auralex GRAMMA! HSU's down-firing subs and the Auralex GRAMMA are perfect compliments to one another!
@Rob H. Thanks for the reply,i guess i can go ahead and order one he he.
thanks again for the info. :)
@Mr VI
Your question comes up all the time. I will answer it in two parts:
First, re: concrete - having a decoupling device in place absolutely makes a difference when you have a concrete floor! Many people are under the misconception that concrete is inert. Concrete is FAR from inert. Concrete moves and shakes. Typically, a concrete floor or walls will have more mass than typical wood-frame construction. So it takes more energy to get more mass to move. But when that greater mass DOES move, it actually transmits sound energy more effectively because it is a denser material. Ever seen that famous film of the concrete bridge rolling like a wave when a strong wind got it moving at its resonant frequency? Concrete is anything but solid and inert!
In your case, what might actually make the SubDude/ GRAMMA less necessary is your thick carpet. As I said, a thick carpet pad will already act as a decoupling device. The question is whether or not your subwoofer or tower speakers have managed to couple to the floor simply by crushing the carpet under their weight or if they have "feet" of some kind. If your subwoofer or speakers have "spikes", "cones" or "nubs" on the bottom, you can be fairly sure that those "feet" will sink deeply enough into your carpet that they will act to couple your subwoofer/speakers to the floor. If your sub/speakers have "feet", then the SubDude/GRAMMA will very likely still make a noticeable difference. If your sub/speakers do not have any "feet", then it is much harder to predict. The whole point though is to "float" your subwoofer/speakers so that they do not couple with the floor. If your carpet pad and carpet already achieves this "floatation", then the SubDude/GRAMMA won't make much of a difference. But any sort of "feet" will pierce or sink deeply, and just a very heavy sub/speaker might simply crush even thick carpet.
One easy way to predict: if you go into another room while bass is playing, can you easily hear the bass in that adjacent room? If so, your subwoofer is almost certainly coupled to the floor! As Ara said, with the SubDude in place, the "bleeding" of bass into other rooms is cut down dramatically! If your thick carpet is already effectively decoupling your subwoofer, you won't have this "bleeding" of the bass into other rooms to begin with!
Regardless though, concrete is never a reason to forego decoupling. Concrete construction will shake and decoupling makes a very noticeable improvement, just as it does with wood-frame or metal-frame construction.
@Mark - you're welcome!
I got my first GRAMMA back when I got my first HSU VTF-3 Mk.2 subwoofer. I had it in my parents' concrete basement and, without the GRAMMA at first, we could hear the bass throughout the entire house and the small windows in the basement would shake and rattle like crazy, as would one of the side walls!
With the GRAMMA in place, there was a dramatic difference! Bass in the rest of the house was much quieter. And the windows and that side wall only shook and rattled at a handful of specific frequencies (the specific resonant frequencies of those materials, where the sound energy in the air alone was enough to activate their movement).
Without all the extra distortion and rattling, the sound quality was obviously tighter, clearer and better delineated.
Thanxs for the review I would not have known of this product. And it is awesome! Thanks again and keep up the fine podcasts Dana