HELP NEED MORE BASS

[ken kaz]

Here is my issue. I have a large basement room 30x15. I am using half of it about 15x15 for my HT. I have Chorurs IIs, academy, and 4 heresy IIs for surround. All driven by rotel amps. The room has a cement floor. I want bass you can feel. I have a SVS PB ultra 2 in the front right corner and a SVS CS ultra (driven by a carver 1.5) in the back corner. I just bought a Integra 9.8 in hopes that the audssey would help on the lack of bass ( It did, a bit) Last night I had people over and the kids were watching the Bee movie while the adults were upstairs having drinks. There were a couple of times that (upstairs) i thought the house was going to come off the foundation. I went downstairs and noted the passages in the movie. Later on, I replayed the passages while I was down stairs. Decent bass, but quite frankly there is quite a bit more upstairs. I am considering another sub, but I think I have plenty since the house is literally moving. HELP! My friend thinks i should put 2x4s on the concrete, then tounge-in-groove plywood covered with carpet. He says that this will allow the room to move. He blames the whole mess on the concrete. Has anyone else been in my boat? Thanks Ken Ka

[mas]

A 30x15 room and using 15x15 of it for HT...The only thing lacking in contributing to the problem is a 9, 12, or 15 foot ceiling!

The easy money is
that you are sitting in a null determined by the room dimensions. And
SW placement in the corners will drive and reinforce this null to the
greatest degree.

Adding more bass or magic processors will not remove a null.

You might want to move your seating position or change the dimensions of the room. I suspect the former is easier.

[htxpert]

Hello Ken,
I have some quick questions for you before I give you some
tips.

First what frequency is the x-over set at on the Integra? If
you have it set at a low frequency like 40-60 Hz does the LFE level output
increase when you select THX processing?

Tip1:

Disable the subwoofer in the back of the room and play a continuous
low frequency test tone though the subwoofer located in the front of the room
at a loud level, THX reference would be a good choice. If you have a DVD with
subwoofer frequency test tone use that to generate the low frequency, If you don’t
have a DVD you can down load tones here.

http://www.stompaudio.com/index.php?main_page=index&cPath=6793

With the test tone now being produced from the primary
subwoofer walk to the front of the room and slowly walk back to the listening
position and beyond noting the differences in LFE output. Adjust your seat
forward or back to the first practical position that had the most LFE, sometimes
only a foot forward or backward will make a big difference.

Tip2:

Move the primary subwoofer from the front of the room and
position it at the listening position leaving the secondary subwoofer at the back of
the room disabled. With a low frequency tone playing in repeat through the
subwoofer located at the listening position start at the front left corner of
the room and crawl along all four walls slowly noting what positions reproduce
the most LFE. If you have an SPL meter you can use that but you should note
significant differences depending on where you are in the room. Once you have
completed this figure out what location are suitable for the subwoofer and
place it there.

Now that you have the primary subwoofer placed at the practical
location that produced the most LFE sit in the listening position and measure
the LFE output with your SPL meter, if you don’t have an SLP meter you will
just have to mentally note the amount of LFE. Once you get a good reading and
feel for the amount of LFE change the phase of the subwoofer and re measure the
amount of LFE at the listening position. If your subwoofer has a variable phase
start at 180 degrees and work back from there. Set the phase at the position
that produces the most LFE. You have now completed setting up the primary
subwoofer.

Setting up two subwoofer that have different specifications
in the same room can be a little tricky without an acoustical analyzer but it
can be done with a little patience and trial and error. Installing a second
subwoofer in the room should help to even out the frequency response in a large
room. To install the secondary subwoofer try installing it directly opposite of
your primary subwoofer on the opposite wall. Once this is completed calibrate
the secondary subwoofer to reference level, since you have two different subwoofers
you might want to calibrate the primary subwoofer to -5db below reference and
then calibrate the second subwoofer to reference level with both subwoofers reproducing the LFE tone. If
done correctly this will insure that your primary or better subwoofer located
in the primary position will be reproducing the majority of the LFE while the secondary
or lesser subwoofer will be used for fill in. This may or may not be a correct solution
depending on your room dynamics. Typically a +75 dB reading in most rooms using
an SPL meter will end up sounding dry and a little week because there is an
error reading low frequency’s using an SPL meter at the lower end of the
frequency range. Generally adding +3-+5 dB to the adjusted subwoofer
calibration will correct the calibration error. Relying on Automatic
calibration software regardless of manufacture is NOT and alternative for low
frequency calibration. Now that you have both of your subwoofers calibrated
switch the phase on the secondary subwoofer, if you heard or measured an increase
in SPL at the listening position this means the secondary subwoofer may be canceling
out the primary subwoofers LFE output at different frequencys or it could be
that the secondary subwoofers position interacts better with the room dynamic
out of phase. If this occurs you will need to set the secondary subwoofers
phase at the position that reproduced the most amount of LFE with the primary
subwoofer reproducing the LFE in conjunction with the secondary subwoofer and
recalibrate.

Although this is not an optimal solution for installing
subwoofers in a high end system it should get you in the ball park without
using an expensive audio analyzer and equalizer. I hope I dint miss anything but I may have considering I have only had one cup
of Java and it’s early.

Best regards,

Ray

[dtximages]

Good luck man, That has been my complaint with my basement. See my threads about room treatments and nulls. the other night my friend was downstairs watching and elton john concert dvd, i was upstairs above the basement, my teeth were chattering because of the bass below me. but my seating position has a null. for now, im going to try major bass trapping to see if perhaps my problem isnt really just a null. that should smooth out the bass, but we'll see if that helps the dead spot. i really think that the dimensions of the room are the main culpret. plus in a basement you get zero wall/floor reinforcement. that can be good if treated correctly, but could also sound like "less" bass.

[artto]

MAS hit it on the head. Move around. At some place you'll surely find the bass absolutely oppressive.

The dimesions & proportions of the room, relative to where you are sitting/listening, is contibuting to the problem.

[BE36]

Ever hear of noise cancellation head sets.

Same signal 180 degrees out of phase will cancel each other out, hardly any sound is heard.

If you have phase angle adjustment on one of your subs try different phase angles. When I had Forte IIs working against my Velodyne 1500 the phase angle made a huge difference. There are 4 settings on the Velodyne, 0, 90, 180, 270. To varing degrees 2 of the setttings; all most no bass. The other 2 much stronger with one being the clear winner.

Placement both listener and speaker do make a big difference but 2 speakers can easly cancel each other out and make a bigger difference.

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

I am in a 24 x 15 basement. HT in a 10 x 15 area.

[colterphoto1]

Unless there is a solid partition, your sub 'sees' a 30x15 room. This is really quite enormous. At 8 feet height, that's 3600 ft3, requiring the THX sub system for substantial bass.

Like the guys said, placement is everything. DO NOT sit against the back wall whatever you do, bass builds up along walls and in corners.

Upstairs, you had 'floor shock' because of the framing of the house- you really could FEEL the bass. Downstairs on the concrete floor you lost that visceral sensation.

[Guest " "]

it's been 90 days...maybe it's solved

[IndyKlipschFan]

Hmm great advice and no feedback? My only problem with newbies!!!

[colterphoto1]

last visit April 10, 2008

maybe he fell in...

[Beesley]

Bump