Can Someone Look at my SPL Graph and Give me Advice on What's Going On with My Room? - Page 2 - Home Theater Forum and Systems -

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post #11 of 14 Old 09-25-14, 01:52 AM Thread Starter
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Re: Can Someone Look at my SPL Graph and Give me Advice on What's Going On with My Room?

Thanks Bryan!

Any thoughts on what could cause weak sound pressure below 125hz? BTW, when I can I will post the SPL graph without smoothing, but I can't get to that computer right now. I can say that there are a few nulls and a couple of peaks below 125hz, with the highest peak at 80hz, buy that peak just reaches the average level of SP for frequencies above 125hz, while the nulls are quite low. I don't have a lot of resonant or cancelled frequencies below 125hz, just overall lower sound pressure, as clearly reflected in the smoothed graph above. (Some have advised a subwoofer, but from everything I've read, that will just make things sound worse in my fairly small, rectangular room.)

I should mention, however, that when I listen to music I am familiar with, the low bass frequencies don't seem weak, but then I listen to classic rock, not electronica or rap. Do you think the low SPLs in the low end is a problem I should worry about, or am I over thinking this?

On another "note", any advice on the continuous SPL drop starting above 3500hz and continuing through 20khz?

Any advice would be greatly appreciated.

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post #12 of 14 Old 09-25-14, 08:14 AM
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Re: Can Someone Look at my SPL Graph and Give me Advice on What's Going On with My Room?

My gut tells me that the speakers are just not capable of filling the room all that well #1. #1 - if you don't look at it as a wide null but more a peak (narrow and broader) from about 125-400, then it's a different story. If you get rid of that one single peak about 125, then you're essentially at +/-5db which is what you strive for in a non-purpose built space. If it were me, I'd be concentrating on looking for what is giving you that peak and the generally hot level up to 400.

You can do a sub most certainly and it pretty much never will hurt you more than it can help in a situation like this AS LONG AS you're willing and able to put it where it needs to be. If not, then it can make things worse certainly.

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post #13 of 14 Old 09-26-14, 05:58 AM
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Re: Can Someone Look at my SPL Graph and Give me Advice on What's Going On with My Room?

marsx wrote: View Post
Dear Wayne,

You posted a few responses to my thread which was entitled - "My Room is Eating Low End - From 45hz -150hz - Any ideas to help"

I believe I have figured out the problem after much reading and would like to hear your opinion on the matter. As I posted, my room (13.75' x 11.25' x 8') demonstrates a significant overall lower SPL from 20hz to about 125hz of about 10dbs.
My office is almost exactly the same volume as your room and I have no problems getting good low end down to 30 Hz, even with the door open.

I think Bryan nailed it when he said “My gut tells me that the speakers are just not capable of filling the room all that well.” I mean, your Yamaha HS50 speakers only have 5” woofers, and the NS10’s only have 7-inchers. You simply can’t expect much bass much below 125 Hz with speakers like that. Sure, your JBL 4410s should do better than that, but as mentioned in your other thread, if you’re sitting anywhere near the center of the room you aren’t going to get much low end from them either.

So how am I getting good low end in my office that’s the same size is yours? Simple: I have a good 10” subwoofer. If I turn it off and just run my desktop speakers with 5-1/4” woofers? Not much happening below 100-125 Hz - no surprise.

I hope this doesn’t sound rude, but IMO you’re chasing your tail trying to figure out what’s wrong with your room (if indeed that is the issue). In the unlikely event that there is a fundamentally problem with it, it will probably require a massive reconstruction to fix it, and I doubt you’re willing or able to do that.

You can easily solve this problem with a subwoofer, it’s as simple as that. It’s a tried-and-true approach that’s been working great for audio applications for more than 25 years now: The mains can be located for optimal imaging, and the sub separately for optimal bass performance. Cross it over at the usual 80-90 Hz and all your bass problems will be relegated to the sub, which will make them easy to deal with. You’ll be able to locate it for best response, and then clean up with a parametric EQ and/or bass traps. Then turn it up loud as needed to compensate for that middle-of-the-room bass “hole.” Bingo, you’re in business.

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post #14 of 14 Old 09-26-14, 09:57 PM
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Re: Can Someone Look at my SPL Graph and Give me Advice on What's Going On with My Room?

Agreed, which is exactly what I was hinting at back in my first post.

Do you have a friend (with a pair of more capable speakers) that would let you borrow them to try in your room? Might be the fastest/easiest way to test our theory. And my curiosity is peaking now.
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