As happens far too often, a recent change I made that was supposed to be a small, simple tweak to my home theater equipment wound up turning into a much more involved project and a major time-suck. At the end of it, I know a lot more about acoustical problems in my room, but I also came away thinking that perhaps ignorance was bliss.
When I built my home theater, I worked very hard to soundproof the room so that noise from my movie-watching wouldn’t disturb my wife (and later, my kids) upstairs. Nonetheless, as good as I was able to get it, 100% soundproofing is practically a pipe dream in a real home environment. Short of tearing the entire house down and rebuilding from scratch, I had to settle for “very good” rather than perfection. Deep bass sounds in particular are extremely difficult to stop and can travel all through a house no matter what you put in the way to block them. For most of the content I watch, my soundproofing does its job and my family never hears anything. However, loud, explosion-filled action movies can sometimes result in bass transmission and even rattling upstairs.
In addition to this problem, I have struggled to get even bass response in my theater room, even after upgrading to a very high-quality SVS subwoofer. This has more to do with room acoustics than with the subwoofer itself. Specifically, in doing measurements while playing bass sweep test tones, I noticed a dip around the 60 Hz range. This is apparently very common in many rooms.
I held no illusions of finding a quick (much less cheap) fix for either of these issues. I had basically resigned myself to dealing with them until I decided to give the SVS SoundPath Subwoofer Isolation System a try. The idea behind this so-called isolation system is that placing a subwoofer on a floor (which most people do) results in a lot of energy transmission into the floor, which consequently causes rattling and travels through other adjoining surfaces. By raising the subwoofer higher up off a floor, you reduce the amount of that energy waste. According to the product listing:
“The SVS SoundPath Subwoofer Isolation System works with nearly every subwoofer brand and model to improve bass performance while reducing floor and wall vibrations, noise artifacts and complaints from neighbors or roommates. De-coupling a subwoofer from the floor results in inherently tighter and cleaner sounding bass. It’s also the next best thing to sound-proofing and ideal for carpeted rooms, hardwood floors or any space where room rattles, buzzes or vibrations are present.”
Those are some awfully big claims for what amounts to a set of padded rubber feet. “The next best thing to sound-proofing”? Knowing how difficult soundproofing actually is, that’s pretty hard to swallow. Even so, the product is not terribly expensive and I figured that I had little to lose in trying it. I can’t think of any scenario where using these would hurt my sound quality. Worst case, I’d notice no difference.
Jumping Down the Rabbit Hole
When I received the SoundPath feet, they were extremely easy to install and took barely a minute to attach. I wish I could say that there was nothing more to it and I experienced an immediate improvement in both bass quality and soundproofing, but that’s not quite what happened. Making one small change quickly spiraled into needing many more changes.
First off, any change to audio equipment like this, even as little as moving a speaker or subwoofer, requires a fresh Audyssey calibration to ensure that my automated room EQ processing can account for the new variables. As I explained earlier this year, my convoluted three-AVR Dolby Atmos setup makes running Audyssey much more complicated than an average user.
Having gone through that process, I ran some more bass sweep tones. Sadly, the 60 Hz dip was still present. No surprise, these little feet couldn’t fix that – not that I expected them to. The manufacturer made no such claims, and I knew that, realistically, raising the subwoofer up a couple inches couldn’t correct the root of the problem.
At this point, I basically abandoned my original interest in the SoundPath feet and became obsessed with that 60 Hz dip. I conversed extensively with a friend who’s an audio expert and came to the realization that this dip was caused by: 1) my subwoofer placement, and 2) the location of my primary listening position. Forget anything else I may have had in mind, now I needed to fix that.
My home theater room is fairly long, and when I originally installed my projection screen and equipment, I placed my recliners at roughly a halfway distance so that I could use the space behind them as an office area.
It turns out that this left the seats very close to a room mode – basically a null point in the soundwave where certain bass note frequencies cancel out. Even though my subwoofer was producing those notes, they’re not audible in that position. My first step in correcting this was to move my seats forward a little bit to get them further away from the mode. Unfortunately, moving them really far forward where the bass was optimal would essentially leave me with my face pressed up to the screen. It’d also be pretty lousy for the sound from all my other speakers. I did my best to find a compromise, but nothing I tried was quite perfect.
Next, I decided to pull my second subwoofer (the older one from before my upgrade) back into service for a dual-sub configuration. Ideally, when running multiple subwoofers, they ought to be identical, or at least have equivalent specs. I can’t do that at the moment. I can’t afford another new sub, so I have to make do with what I have and hope for the best.
After I purchased my SVS subwoofer, I did a Sub Crawl and settled on putting it near the front left corner of the room (Position 1 below).
When using two subwoofers, the typical advice is to place them opposite each other, either with one in the center of the front wall and one in the center of the back wall, or in opposite diagonal corners. I started by trying the latter approach. Due to my furniture and other room constraints, the closest I could get were these spots:
Unfortunately, that neither sounded nor measured very good, probably because the first subwoofer isn’t actually in the exact front corner, and my room is irregularly shaped with the back half being a narrower width than the front half. Whatever the reason, it didn’t work and I’d have to try something else.
Sadly, I can’t put a subwoofer in the center of my back wall because I have a desk there (and nowhere it can be moved to). That’s out of the question. After lengthy discussions and math calculations, what I decided to try was placing one subwoofer in the center of the front wall, and the other right in the middle of the mode, behind my seats in the approximate center of the room.
The theory here is that placing Subwoofer 2 right in the null will cancel out the mode, allowing Subwoofer 1 to do its job better. Much of the math involved is above my head, but this was recommended as the most promising option.
Is It Any Better Now?
My results with this new setup are mixed, as I feared. On the plus side, bass sweeps measure a little better in the 60 Hz range. I still have a little dip there, but much less of one. Using two subwoofers has largely flattened that out. This is good news.
The bad news is that I have basically no bass activity below 30 Hz now. Whether that’s due to my room mode issues or the fact that one of my subwoofers is technically inferior to the other (or some combination of the two problems), I can’t say for sure. What it comes to is that I’m lacking infrasonic bass at the moment, which is a bummer.
Fortunately, not every movie soundtrack incorporates bass that low, and almost no TV shows do. The majority of what I watch in my home theater these days is TV, so I’m not having an immediate crisis to upgrade my subwoofers and change my configuration around again. On balance, fixing the 60 Hz dip is probably more important than anything below 30 Hz. A lot more bass activity happens in that higher range.
Nevertheless, I’m disappointed. More work is needed. Eventually, I’m going to have to save up and replace my secondary subwoofer with another at least as good as my primary sub, and I’ll probably need to do a lot more experimentation with where I place them.
What About the Feet?
As for the original tweak that started this whole process, I honestly don’t think I can give a fair review of the SoundPath isolation feet. I changed too many other variables in my room to know how much (if at all) the new subwoofer feet affected my results or improved my sound quality. It wouldn’t be fair of me to write them off completely, but what I can say is that I did not find them to be a miracle cure. Bass issues resulting from room acoustics are too complex for any simple fix, and true soundproofing requires a lot more effort and expense than just decoupling one subwoofer from the floor.
Ironically, moving my primary subwoofer to the front of my home theater room may have resulted in slightly more bass transmission upstairs, because the front wall it sits next to now runs directly up to the middle of my living room.
I think I’ll keep the feet in place, though. They aren’t hurting anything. If they do help even a small amount, I might as well leave them be.