Where do I begin, if I want to improve the sound in my room? Other advice needed...

George_W_K · 01-31-2004, 05:53 PM

Hey guys,

If you click on my Theater icon above, I have pics of my room for a better picture of what I am dealing with room-wise. You can go immediately to the "What the Room Looks Like Section". I have limited bandwidth since it is a free site, so if you are kicked out, it'll let you in eventually. Thanks, in advance for any help you all provide. Now on to my MANY questions.......

Thanks to this forum I have really put together a decent list of HT equipment. I have a little more to buy when the funds allow, but overall, I like what I have put together. Now, I'd like to look ahead in improving the room my set-up is in. After reading through this section of HTF I see that the room is as important as the equipment, if not more so. So, where do I begin? What do I need to look for in improving my sound? What areas do I need to research?

There is one thing I already know I'd like to improve on. I have a SVS 20-39 PC+. It produces bass well enough, but I know there is a lot that I am missing. My buddy Ferdinand recently bought the 20-39 PCi and in his room, it really shines. He showed me the opening scene from Martix: Reloaded and the vibration of the floor and couch was amazing. Feeling the low bass was a very nice effect I'd like in my room. I have Bass Shakers installed in my couch and while it gives a nice effect, they aren't as effective as Ferdinand's sub without Bass Shakers. Is there anything I can do to improve this in my house? What is causing the lack of vibration? Here is my theory, but please let me know if it is only part of the problem, or wrong completely: My house is built on a slab. Ferdinand's room is smaller, and he has a basement underneath. Are both of those factors as important as the other? Another buddy of mine, LaMarcus, moved his PCi from his basement to his upstairs and reported a huge improvement in bass. I don't totally remember the size of his living room, but it's probably at least as big as mine, if not bigger. So, this is leading me to belive that having a basement underneath is a huge factor.

I know I am babbling, so let me summarize. My house is on a slab. My exterior walls are not insulated. How do I improve my sub's vibration of the room? Will it automatically improve if I insulate and sound proof the room? What if I build the room on a riser? Do I need a bigger sub? What other factors do I need to worry about?

Obviously, bass in not the only sound I want to worry about, I want my room to be very accoustical over the entire frequency range. Please help.

Wayne A. Pflughaupt · 02-01-2004, 09:23 PM

That is indeed some nice equipment, George – congratulations!

Quote:

After reading through this section of HTF I see that the room is as important as the equipment, if not more so. So, where do I begin?

I don’t really see anything that jumps out as a problem. You have a carpeted floor and soft furniture that offers some absorption. At the back there is the non-symmetrical walls, the staircase and a glass cabinet – all of which should reduce slap-back and help with diffusion (the cabinet especially).

About the only thing I’d suggest, if you think further improvement is warranted is more diffusion for the rear walls. Things like wall hangings (i.e., picture frames) and a bookcase would further help with dispersion, if you think it is warranted. However, unless the room sounds like it has an echo or reverb happening, I wouldn’t worry much about it.

Also, if you can find a way, I think you’d be happier if you could find a way to aim the rear speakers at the listening area. If not, boosting the treble a little in the rears would compensate somewhat – the Yamaha may have some EQ options for this.

Quote:

Will it automatically improve if I insulate and sound proof the room?

This is a common misunderstanding. The purpose of insulating/soundproofing is to keep sound from escaping the room (i.e., so as to not disturb parties that don’t have your enthusiasm for this hobby

). Soundproofing has absolutely nothing to do with the acoustics inside the room.

Quote:

My buddy Ferdinand recently bought the 20-39 PCi and in his room, it really shines. He showed me the opening scene from Martix: Reloaded and the vibration of the floor and couch was amazing. Feeling the low bass was a very nice effect I'd like in my room.

What is conspicuously missing from your rig is a dedicated parametric equalizer for your sub. Since your sub isn’t EQ’d, what is probably happening is that your sub level (from the receiver) is determined by the frequency the sub plays hottest. If that happens to be a high frequency – say 50Hz – that would put the frequencies most responsible for vibrating everything (frequencies lower than 50Hz) at a lower level – perhaps too low.

I suggest getting a test disc with 1/6-octave sine waves and plot your room’s low frequency response. You’ll probably find that it leave much to be desired. I also suggest doing a search on “BFD,” Behringer Feedback Destroyer” on the DIY forum and the Speakers/Subwoofer forum for more information on room response and EQing subs.

That said, I think it needs to be pointed out that the goal of superior sub performance is smooth response, not tactile vibration. If it gets you the latter, fine, but that’s not the objective. I don’t think you want to build a riser – the ceiling is pretty low as it is.

Hope this helps.

Regards,
Wayne A. Pflughaupt

Tim Bargar · 02-02-2004, 12:15 PM

A couple of things would probably help your interior acoustics. First is the imaging for the front speakers. I can't remember for certain when I looked at your HT (I can't get into the site now), but I didn't see anything on the walls behind them (absorptive panels) to eliminate early reflections, which will adversely affect imaging. The same along the side and rear walls at the reflection points would also help in that respect. Some advocate a material called linacoustic lining the side and rear walls up to ear height, and the entire front wall, for that very purpose.

Second would be some bass absorption and, as Wayne pointed out, equalization. From what you describe, what you are sensing at your friend's HT is a tactile sensation. His sub is vibrating things in the room, which you are feeling. His floor is a bass resonator. Sit in the chair and you feel the floor vibration. You don't get that because your floor is concrete. If you want the same feeling, then put in a riser or something else that will resonate when contacted by the low frequency sound waves. Then put a chair on it and you'll feel the vibration.

But a riser doesn't improve the bass response in the room....unless it is built to be a tuned bass absorber. You could also put in a broadband bass absorber or two. The absorbers will decrease bass peaks. Then you have to deal with the bass nulls. This is handled by some equalization. This will improve the in-room bass response. The best way to determine exactly what needs to be done in the room for acoustics is have somebody trained in interior acoustics perform real time analysis in the room. Check out the web page for the Home Acoustics Alliance.

Neil Joseph · 02-02-2004, 02:55 PM

To echo one thing already mentioned, when my current equipment was in the basement of my old house, it lacked the bass and sonic impact that it currently has, now that I have the setup installed in the great room, with the garage below. The wood floor really increases the impact to the point where even my meagre sub provides some chest impact. And I have not even finished building my DIY sub yet. Your sub should be enough to provide you with good results so definitely try the room acoustics first.

George_W_K · 02-02-2004, 03:17 PM

Thank you for all of your replies. You've definitely given me a lot of the information I was looking for. I am glad that I don't have to worry about soundproofing the room as much as I thought. Maybe eventually, but right now, there's no one for me to disturb.

Wayne, I have a quick question. You asked me to move my rear speakers more towards the listening area. I have them aimed right at the main couch. Should I aim them differently, or does the picture of them not show that too well?

Thanks again, now I have to figure out what to do first....

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Wayne A. Pflughaupt · 02-02-2004, 04:55 PM

George,

Quote:

Wayne, I have a quick question. You asked me to move my rear speakers more towards the listening area. I have them aimed right at the main couch. Should I aim them differently, or does the picture of them not show that too well?

It appears that they are behind the couch, and aimed at each other, not the couch. I apologize for my inability to decipher a two-dimension photo.

Don’t Martin Logans generate sound from both the front and back of the planar drivers? If so, I’d approach Tim’s recommendation to dampen the walls behind the speakers with caution. That could definitely affect the speaker’s ambient qualities (which are derived from reflections from the rear wall). I recommend consulting with ML before taking that approach.

Regards,
Wayne A. Pflughaupt

George_W_K · 02-02-2004, 05:28 PM

Quote:

I apologize for my inability to decipher a two-dimension photo.

Wayne,

While that answers my question, I hope that I didn't insult you, as that was not my intention. I know that most of the guys in this builder forum know a lot more than I do about accoustics and what not, and if you knew of a better way for my speakers to be, I was all for it. So, I didn't know if you were aiming to improve my sound, or if my photo wasn't a good shot. If I came off the wrong way, I apologize.\

Thanks again,
George