Axiom Home Page Forums General Discussion Home Theater Searching for the most effective way 2 direct bass

Wow, I just had a very eye opening event happen to me. As anyone who's ever read a thread of mine knows, I couldn't be any happier with my M80's.... UNTIL NOW!!! I've written about my own experiments with speaker placement before, and how I've very carefully positioned them to deliver the best sound at my seating location. I've been satisfied beyond my wildest expectations with the amount of bass that these babies produce, however just this morning I was reading some very small print on the screen of my tv, so I got up and sat on the edge of my coffee table which is only about 4 feet from the tv, where as my usual seating position is 17 feet from the tv. I was of course listening to music as always, but what I wasn't expecting was how hard the bass was hitting my chest from that distance! It was crazy, it was as if I'd cranked the bass levels up ten notches... ON THE EP800!!! And seeing as there isn't an EP800 in my living room to crank, I was completely shocked!

So I started doing some experiements, moving from spot to spot and discovered that my captians chair sits in a bass lull (or whatever that word is used to describe an area where bass cancels itself out). I do hear and feel the bass, but not as strong as in other area's. So I'm wondering how to get my seat out of this bass lull without having to move my speakers, as I feel they are in their prime location otherwise. Is this where bass traps and all that come into play?

It's not an urgent matter, I've been perfectly happy with their performance to date. In effect this would just be a bonus on top of an already outstanding set-up. So I can take my time and build these things myself and experiment with them to see if I can redirect the bass into this area. It would also be of great benefit once I get a subwoofer system in place. If I was missing this much bass from the EP800, I can only imagine what it would have sounded/felt like with proper room treatments to maximize my listening experience!

I think one of these companies should come out with a program that takes a complete picture of your room, and shows you visually what's going on inside of it. So that I could see first hand where the bass is strong, and where it's weak. That way when I put up bass traps and other room treatments I could see what makes the biggest impact as far as improving the bass response in my seat. Because that's the most important area anyway. The other seats are only filled with customers from time to time, and the music isn't played at a level where you feel the bass all that much, so leaving those seats in a lull wouldn't be an issue at all. All I'm concerned with is directing as much of the bass as I possible can towards the captians chair.

Any and all suggestions are greatly appreciated!

Based on my experience your actually noticing at least 2 things.

First and the reason I often recommend that people get bookshelf speakers and a good subwoofer or two is that it’s often impossible in the real world to position a pair of towers for both the best imaging and the best bass simultaneously. If you move either your speakers or your seat then you change the dynamics of both.

The second thing I think your noticing is the chest thumping impact of mid bass, one of the reasons I’m considering getting:

MBM-12 Mid-bass Module

Not only is that chest thump different than the deep rumbling bass it’s also directional which much better simulates the feeling of a real world explosion. To get that you both have to move a lot of air and have the drivers fairly close to you. In my apartment I sat only about 6’ from my M80s and had that impact at safe listening levels, but in my house the larger screen necessitates a wider placement of the L/R mains to maintain proper imaging with the screen. This in turn requires I sit further away 8‘-12’ (still experimenting) to keep the front soundstage from collapsing to the nearest speaker. Even at 8’ it’s getting to far away to get that chest thump I’m use to unless I pump it up to 100dB which is way louder than I’m willing to listen.

So while bass traps certainly wont hurt the mid bass and will certainly help overall you might want to consider trying something like the HSU Mid Bass Module if other tweaks don’t get you what you now know you’re missing. Now you also know why I like my M80 center especially when I could sit up close. The chest impact of the Balrog growling . . . .

Its called REW and it works very well, but takes some effort to set up and learn. IMO, if you are interested in optimizing your room setup, this software is indispensable. Without measurements, you have no idea what is going on.

FWIW, what you heard in that spot could also be over-emphasized bass.

As fredk mentioned REW seems to be the cheaper but harder to learn product for learning the frequency response at your listening position. A popular bass management device to use with REW is Behringer's Feedback Destroyer. Others include the Audyssey based device sold by SVS and Velodyne's SMS-1.

Using a Radio Shack SPL meter and a DVD of test tones can give you a rudimentary look at what kind of FR you are getting at your listening position once you plot out the points. You will obviously lack decay information that REW can give, but at least it's a start.

The other thing I was going to add is just because you get more bass in one point in the room, doesn't mean that's the proper amount of bass. Just as standing waves create nulls that suck out bass, they also create peaks where some frequencies build up.

Bass traps will help to smooth out both of these by absorbing the reflections back into the room which cause the standing waves.

There's also no way to get a picture of the bass response through out a room. You can compute the peaks and nulls for one frequency, but a different frequency wave will overlap in completely different places. The best you can do, is get an idea of the response for one point in the room at a time.

Thus the never ending struggle for audio enthusiasts to tweak their rooms.
The laws of physics, walls and sound is easy enough to understand but practicality of controlling...sheesh.
It is enough to drive people mad.
Some here may already be in that state.
Perhaps medic8r can help.
He is now in Georgia.