Do we ::underestimate:: room lift?

GranteedEV

GranteedEV

Audioholic Ninja
I think a lot of us here see "6000 cu ft rooms" and instantly think "this person needs a vent to get flat response unless he's willing to pay thousands of dollars..

I'm guilty of it. I won't deny it at all. Yet I'm a hypocrite :p

I'm running a sealed subwoofer with no bottom end equalization. QTC = .58 (not factoring in stuffing though, so it may be a bit lower)

Anechoic Simulated F3 = 33hz
Anechoic Simulated F10 = 17.5hz

Now my basement is pretty big. It's your typical 25 x 17 x 8 (or 10?) family room type area open to the kitchen and some other rooms and a hallway. Pressurizing it on paper is something I don't think I would ever attempt to do.

I ran some sweeps today. Since I was too lazy to set the subwoofer up on its own, it is being run with the receiver high pass filter in place. I did set the High pass filter as high as possible, though (180hz), so most of this response is from the subwoofer alone. Main speakers set to small.

Measurement microphone is a Parts express calibration of the Dayton EMM-6.. at the very least it should be reasonably accurate down to 20hz. Anything lower than that is effectively a crapshoot as the calibration file does not include information below 20hz.

I also managed to audibly clip my marantz for the first time ever... a part of me was happy <_< and the other part was not so much :eek:

1/24th octave smoothing was used.

Sweep 1 (yellow) is somewhat nearfield to the subwoofer. Maybe 8inches. It hopefully takes away as much of the "room" response as possible. The sub is placed near a wall so i doubt it`s perfect though. I can't really explain the bump between 30 and 40hz to be honest, though. On paper though, this sub is around 3db down near that point with a shallow (12db/octave) rolloff.

Sweep 2 (purple) is the so-called sweet spot but in this current positioning it's anything but a sweet spot. This is exactly why measurements are important for this sort of thing... Take a look at the room lift. Even though my FR is ANYTHING but flat in-room(kind of explains why I`ve felt my sub seemed to lack midbass... I realize the importance of placement but I`m kind of lazy and don`t wanna depend on my ears), it`s

Sweep 3 (fushia) is a spot I like to sit at; same couch, but about a seat and a half over. Again, it`s anything but a sweet spot :eek: but the room lift is still pretty identical.

Sweep 4 is the extreme off axis seat. ~45 degrees from the center channel, and just adjacent to the subwoofer. it's a bit closer compared to the other two seats, so i was expecting some different results (also based on what I've heard). The room lift dissapears at this seat though, which is odd, but does seem to explain the reduced "rumble" i've heard at that seat..

Moral of the story... yeah, I should mess around with placement for this sub. Measurements can be eye-opening. I might play around with placement now, but it's like... 350lbs dude... so not fair! ;-;
 

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templemaners

Senior Audioholic
Moral of the story... yeah, I should mess around with placement for this sub. Measurements can be eye-opening. I might play around with placement now, but it's like... 350lbs dude... so not fair! ;-;
Maybe the real moral of the story is you need another sub to smooth out that response! :D

It also highlights the need to include measuring equipment in any budgeting of an audio setup. Otherwise, you're just flying blind.

I do agree about the "seeing the huge cuft size and thinking a ported style sub would work best" line of thinking - I do that too.
 
GranteedEV

GranteedEV

Audioholic Ninja
Maybe the real moral of the story is you need another sub to smooth out that response! :D
:D I'm just waiting for this person to pack the driver up for me :D and then i'll have to build it :(

Anyways I moved it around (ugh) and found a place that gets me a better graph. I'm still not sold on how it sounds subjectively, I think i might end up getting "phasiness" from this placement.... i can't cross over lower than 80hz because of my surrounds (stupid receiver has global EQ) Here's the new graph. That suckout near 100hz is still there. It's high enough in frequency that some bass traps may just take care of it.

And yes, I think anyone interested in an audio should invest in measurement equipment :D Just look at the improvement at the (sweet) sitting spot.

The room lift is all gone though :(

But since i measured it, I can EQ it in :D
 

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its phillip

its phillip

Audioholic Ninja
Whenever my sub gets here I'll try getting rew and using my spl meter and taking little measurements if I'm not too lazy.

I'll probably be too lazy though.
 
S

SafeandSound

Enthusiast
I would try and get some broadbad bass traps in the room that would help.

Not too expensive if you make them yourself from Rockwool or Owens Corning.

Takes some time though to do DIY.

cheers
 

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