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Cannot hear bass unless standing on bed?

post #1 of 17
Thread Starter 

The title of this thread may be a little wonky, but long story short, my room is a very awkwardly dimensioned, with 9ft ceilings. Somehow I managed to find a blueprint of my floorplan:

 

 

 

Essentially, not limited to my room specifically, all lower registers of bass, all lower bass extension can only be heard when your ears are close to the ceiling, as in, standing on a chair, or on a bed, or anything that will elevate your ears as close to the ceiling as possible. It doesn't matter what speaker, placed where or at what volume, deep bass can only be heard if elevated. Now I don't know if this is a speaker placement issue which I highly doubt since it's like this across the entire floorplan, but what is this caused by? Isn't bass supposed to stay low to the ground and not go up to the ceiling? The entire condo is carpeted, if that makes any difference.

post #2 of 17
Quote:
Originally Posted by akinari-kun View Post

...., but what is this caused by? 

 

http://en.wikipedia.org/wiki/Room_modes

 

cheers

post #3 of 17

interesting, and makes sense.

 

From many years ago when I was deep into car audio & the related shows/competitions, I recall that 1 of the initial items to consider when tuning the audio system in a car was the resonant frequency of the cabin...which was typically in the bass region.

post #4 of 17

Oh, and regrets if this is already addressed, but ensure that your speakers are wired in phase. If they're out-of-phase, you will experience audio cancellation.

post #5 of 17
Quote:
Originally Posted by akinari-kun View Post

The title of this thread may be a little wonky, but long story short, my room is a very awkwardly dimensioned, with 9ft ceilings. Somehow I managed to find a blueprint of my floorplan:

 

Essentially, not limited to my room specifically, all lower registers of bass, all lower bass extension can only be heard when your ears are close to the ceiling, as in, standing on a chair, or on a bed, or anything that will elevate your ears as close to the ceiling as possible. It doesn't matter what speaker, placed where or at what volume, deep bass can only be heard if elevated. Now I don't know if this is a speaker placement issue which I highly doubt since it's like this across the entire floorplan, but what is this caused by?

Bass distribution in a room is highly dependent on the position of the speaker and listener.

Quote:
Originally Posted by akinari-kun View Post
Isn't bass supposed to stay low to the ground and not go up to the ceiling? The entire condo is carpeted, if that makes any difference.

Bass distribution is a three dimensional problem.  Bass does not stay low to the ground, that would be a myth.  Carpeting makes not difference to the way bass propagates.  

 

In your floor plan you haven't shown where your speakers and subwoofer are, but that wouldn't help too much anyway as far as suggestions for improvement.  Bass waves terminate at boundaries, which means walls, ceilings and floors.  Where two walls and a ceiling and floor meet, there is a buildup of bass.  The best bass for a given listening position depends on the location of the subwoofer.  It's pretty much impossible to predict the optimal position, though.  If you want to find it, one easy way is to put your sub in your favorite listening position, right on the seat, but so the driver is free to move. Then disconnect your other speakers and play something with a lot of bass.  Next, crawl around the room listening.  You'll find places where the bass is stronger and weaker, but there will probably be one spot where it's the best.  That's your best location for the subwoofer.  Put it there, connect your other speakers, and listen.  You'll also now benefit from room calibration systems found in many receivers.   Calibration features like Audyssey will check for speaker phase problems too, though you should do that yourself before you do anything.  There is probably a phase switch on your sub, try that in both positions to see how that changes your bass.  

 

Even with good bass in your listening position there will be other locations in the building where bass is strong.  Many will be near walls, ceilings and floors, which is normal.  

post #6 of 17
Quote:
Originally Posted by jaddie View Post

Bass distribution in a room is highly dependent on the position of the speaker and listener. Bass distribution is a three dimensional problem.  Bass does not stay low to the ground, that would be a myth.  Carpeting makes not difference to the way bass propagates.

Exactly. This short article is mainly about home recording, but all the same principles apply to hi-fi and home theater too:

Acoustic Basics

--Ethan
post #7 of 17
Thread Starter 

Ah that definitely clears things up. I'm not using a subwoofer, just a lowly 2.0 system, however my Fostex PM0.4n studio monitors are arriving next week so I just wanted to figure out if it was possible to somehow calibrate my room setup so that the low frequency sounds would not only be audible near the ceiling.

post #8 of 17
Quote:
Originally Posted by akinari-kun View Post

....I just wanted to figure out if it was possible to somehow calibrate my room setup so that the low frequency sounds would not only be audible near the ceiling.

Yeah, sorry, it doesn't work that way.  

post #9 of 17
Thread Starter 

Time to sell the condo lol

post #10 of 17

well you could just take out the middle bedroom walls to get a big enough area to qualify as an "acoustically small room" - then treat, use Geddes multiple sub approach

 

SVS Realizer will be cheaper

post #11 of 17
Quote:
Originally Posted by jcx View Post

well you could just take out the middle bedroom walls to get a big enough area to qualify as an "acoustically small room" - then treat, use Geddes multiple sub approach

 

SVS Realizer will be cheaper

Wow.  So you REALLY love the SVS Realizer, huh?  You've mentioned it like 46 times.  Too bad the thing is so expensive, or I'd give it a whirl. 

post #12 of 17

for "loudspeakers in a room" sound there really isn't any other headphone product that comes close - so if your rooms are impractical dimension for good speaker setup without overwhelming early reflections

 

and you post your query in a headphone forum...

 

the Smyth Realizer is mentioned a tiny fraction of the time compared to people asking/recommending amp/tubes/headphone or even cable changes for improved imaging, sound stage - the Realizer really deserves the publicity - actually does something about the issues

 

as for price/value proposition - I think it beats as an example - the pretty packaging of industrial power chip amps that show obvious crossover distortion in their datasheet THD vs level curves which garners a few posts - http://www.head-fi.org/newsearch?advanced=1&action=disp&search=%22dark+star%22&titleonly=0&byuser=&output=posts&replycompare=gt&numupdates=&sdate=0&newer=1&sort=relevance&order=descending&Search=SEARCH


Edited by jcx - 4/18/13 at 8:58pm
post #13 of 17

Don't get me wrong, I appreciate the personal recommendation, and I have no doubt that I personally would love it.  It's just that at $33000 - $4100 it's quite a bit to spend for only one person's listening pleasure.  It takes the thing into the realm of the very wealthy, very fanatical, or perhaps professional.  I doubt many of the common folk here could even dream if owning it until the process, which can no doubt be done far more affordably, finds its way into the $500-$1000 realm. On the other hand, a family entertainment room or home theater can entertain quite a group, even if the sound quality is compromised, and you can do pretty well with a budget of $4K for that.   And well under $500 you can get really good sound with headphones.  I just can't get behind the thing as practical yet, which is why the frequent recommendation seems odd to me. Though like I say, I'm pretty sure I would love it, if I could afford it.

post #14 of 17
HA! HA!

I love the elaborate answers when the floor plan makes it obvious what the problem is. THE FREAKIN BED IS FILLING THE FLOOR AND SUCKING UP THE BASS. The solution is simple. Get a futon.
post #15 of 17

A mattress is what, about a foot thick?  A box spring has very little absorption in it. The mattress is not really diaphragmatic, so just as a thick 1' absorber it starts to loose its effectiveness when a 1/4 wave is 1', which about 250Hz.  At 1/10 of that frequency it's not doing much, even if it's off the floor, which may bump the cutoff frequency down to 125.  If the mattress were a diaphragmatic trap, I might agree.

 

Deep bass is mostly affected by the position of room modes which relate to boundaries.  


Edited by jaddie - 4/26/13 at 6:32am
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