ken kaz Posted March 16, 2008 Share Posted March 16, 2008 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 1 Quote Link to comment Share on other sites More sharing options...
mas Posted March 17, 2008 Share Posted March 17, 2008 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 isthat you are sitting in a null determined by the room dimensions. AndSW placement in the corners will drive and reinforce this null to thegreatest 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. Quote Link to comment Share on other sites More sharing options...
htxpert Posted March 27, 2008 Share Posted March 27, 2008 Hello Ken,I have some quick questions for you before I give you sometips. First what frequency is the x-over set at on the Integra? Ifyou have it set at a low frequency like 40-60 Hz does the LFE level outputincrease when you select THX processing? Tip1: Disable the subwoofer in the back of the room and play a continuouslow frequency test tone though the subwoofer located in the front of the roomat a loud level, THX reference would be a good choice. If you have a DVD withsubwoofer frequency test tone use that to generate the low frequency, If you don’thave 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 primarysubwoofer walk to the front of the room and slowly walk back to the listeningposition and beyond noting the differences in LFE output. Adjust your seatforward or back to the first practical position that had the most LFE, sometimesonly a foot forward or backward will make a big difference. Tip2: Move the primary subwoofer from the front of the room andposition it at the listening position leaving the secondary subwoofer at the back ofthe room disabled. With a low frequency tone playing in repeat through thesubwoofer located at the listening position start at the front left corner ofthe room and crawl along all four walls slowly noting what positions reproducethe most LFE. If you have an SPL meter you can use that but you should notesignificant differences depending on where you are in the room. Once you havecompleted this figure out what location are suitable for the subwoofer andplace it there. Now that you have the primary subwoofer placed at the practicallocation that produced the most LFE sit in the listening position and measurethe LFE output with your SPL meter, if you don’t have an SLP meter you willjust have to mentally note the amount of LFE. Once you get a good reading andfeel for the amount of LFE change the phase of the subwoofer and re measure theamount of LFE at the listening position. If your subwoofer has a variable phasestart at 180 degrees and work back from there. Set the phase at the positionthat produces the most LFE. You have now completed setting up the primarysubwoofer. Setting up two subwoofer that have different specificationsin the same room can be a little tricky without an acoustical analyzer but itcan be done with a little patience and trial and error. Installing a secondsubwoofer in the room should help to even out the frequency response in a largeroom. To install the secondary subwoofer try installing it directly opposite ofyour primary subwoofer on the opposite wall. Once this is completed calibratethe secondary subwoofer to reference level, since you have two different subwoofersyou might want to calibrate the primary subwoofer to -5db below reference andthen calibrate the second subwoofer to reference level with both subwoofers reproducing the LFE tone. Ifdone correctly this will insure that your primary or better subwoofer locatedin the primary position will be reproducing the majority of the LFE while the secondaryor lesser subwoofer will be used for fill in. This may or may not be a correct solutiondepending on your room dynamics. Typically a +75 dB reading in most rooms usingan SPL meter will end up sounding dry and a little week because there is anerror reading low frequency’s using an SPL meter at the lower end of thefrequency range. Generally adding +3-+5 dB to the adjusted subwoofercalibration will correct the calibration error. Relying on Automaticcalibration software regardless of manufacture is NOT and alternative for lowfrequency calibration. Now that you have both of your subwoofers calibratedswitch the phase on the secondary subwoofer, if you heard or measured an increasein SPL at the listening position this means the secondary subwoofer may be cancelingout the primary subwoofers LFE output at different frequencys or it could bethat the secondary subwoofers position interacts better with the room dynamicout of phase. If this occurs you will need to set the secondary subwoofersphase at the position that reproduced the most amount of LFE with the primarysubwoofer reproducing the LFE in conjunction with the secondary subwoofer andrecalibrate. Although this is not an optimal solution for installingsubwoofers in a high end system it should get you in the ball park withoutusing an expensive audio analyzer and equalizer. I hope I dint miss anything but I may have considering I have only had one cupof Java and it’s early. Best regards, Ray Quote Link to comment Share on other sites More sharing options...
dtximages Posted April 1, 2008 Share Posted April 1, 2008 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. Quote Link to comment Share on other sites More sharing options...
artto Posted May 30, 2008 Share Posted May 30, 2008 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. Quote Link to comment Share on other sites More sharing options...
BE36 Posted June 13, 2008 Share Posted June 13, 2008 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. Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted June 14, 2008 Share Posted June 14, 2008 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. Quote Link to comment Share on other sites More sharing options...
Guest " " Posted June 14, 2008 Share Posted June 14, 2008 it's been 90 days...maybe it's solved Quote Link to comment Share on other sites More sharing options...
IndyKlipschFan Posted July 10, 2008 Share Posted July 10, 2008 Hmm great advice and no feedback? My only problem with newbies!!! Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted July 11, 2008 Share Posted July 11, 2008 last visit April 10, 2008 maybe he fell in... Quote Link to comment Share on other sites More sharing options...
Beesley Posted September 7, 2008 Share Posted September 7, 2008 Bump Quote Link to comment Share on other sites More sharing options...
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