psg Posted September 8, 2013 Author Share Posted September 8, 2013 You will get the most standing wave trouble in the middle of the room. That is your problem here. The sub should be touching the wall on the side, and 18" from the wall the mouth is facing. Under the DVD racks would be perfect. The side of the sub against the wall under the DVD's, and the mouth 18" from the right wall pictured. Interesting! You are the first to suggest placement right up against the wall. I'll give it a try to see how it measures later this week (I have several 12-foot freshly painted suspended ceiling metal tracks sitting there now). Moving the sub there permanently would when removing the DVD/CD racks since they would be hard to get to with a 30-inch wide sub in the way. For the record, I had tried it facing the back wall, 18 inches away. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted September 8, 2013 Share Posted September 8, 2013 Interesting! You are the first to suggest placement right up against the wall. Doesn't BFM recomend that also? Quote Link to comment Share on other sites More sharing options...
mustang guy Posted September 9, 2013 Share Posted September 9, 2013 You will get the most standing wave trouble in the middle of the room. That is your problem here. The sub should be touching the wall on the side, and 18" from the wall the mouth is facing. Under the DVD racks would be perfect. The side of the sub against the wall under the DVD's, and the mouth 18" from the right wall pictured. Interesting! You are the first to suggest placement right up against the wall. I'll give it a try to see how it measures later this week (I have several 12-foot freshly painted suspended ceiling metal tracks sitting there now). Moving the sub there permanently would when removing the DVD/CD racks since they would be hard to get to with a 30-inch wide sub in the way. For the record, I had tried it facing the back wall, 18 inches away. I did not actually recommend that, Bill Fitzmaurice did. Once again, here are the placement instructions for the THT: Placement Boundary loading should be used whenever its practical to do so. Having subs next to a wall gets you 6dB of additional sensitivity below about 80Hz, and putting them in a corner an extra 12dB. In most cases youll have best results with the cabinet mouth on the floor against one wall, about 18 inches from the adjacent wall. If the cabinet mouth is a quarter-wavelength from a boundary there will be up to a 24dB deep cancellation at that frequency. Within the nominal bandwidth of the THT a quarter-wavelength ranges from 19 feet at 15 Hz to 2.8 feet at 100 Hz, so middle of room placement usually wont work well. "On the floor against one wall" - this means against the wall, as in touching the wall. "about 18 inches from the adjacent wall" - this means the mouth is 18" from a wall. Try swapping the bike and THT, and have the THT under the DVD rack facing the right wall. Quote Link to comment Share on other sites More sharing options...
psg Posted September 9, 2013 Author Share Posted September 9, 2013 Should have read that more carefully 3 years ago then! [] Cool, something to try anyway. [Y] Quote Link to comment Share on other sites More sharing options...
mustang guy Posted September 10, 2013 Share Posted September 10, 2013 Should have read that more carefully 3 years ago then! Cool, something to try anyway. Not your fault, the placement instructions were poorly written IMHO. Quote Link to comment Share on other sites More sharing options...
RRFL Posted September 19, 2013 Share Posted September 19, 2013 Should have read that more carefully 3 years ago then! Cool, something to try anyway. Not your fault, the placement instructions were poorly written IMHO. This is a link to the BF site with photo's of my 1st experiment. It starts from the final installation and works backwards. You can see how the mouth is positioned 18" (out from the corner of the room), Note that there are 3 ways to achieve this. In this is case the speaker is wall mounted and pointing down towards the floor. The walls are brick and the floor concrete with carpet. http://billfitzmaurice.info/forum/viewtopic.php?f=5&t=17511 Quote Link to comment Share on other sites More sharing options...
psg Posted October 2, 2013 Author Share Posted October 2, 2013 Very nice! And a great idea too!! [Y] Quote Link to comment Share on other sites More sharing options...
psg Posted November 8, 2013 Author Share Posted November 8, 2013 Just thought I'd top up this thread... it took me a long time, but I finally stained the sub and found a better location for it along my back wall. The frequency response varies a lot between my four seats and the music sweet spot. Here it is at some locations after some manual EQ on a miniDSP, with gains of up to +5 dB and reductions of up to -5dB. Note that the sub mean level is about 6 dB below the mains, so even at +5dB I am still reducing the gain structure. Running through the RCA-plug version of the miniDSP drops the output by about 7 dB, so if you want to use one make sure you can accommodate the gain structure. The magenta one is pretty nice, I think. If I want to run a movie with the sub hot, then I have a volume control since it is fed by a single channel of my previous HK receiver (the 40-lbs avr325). Quote Link to comment Share on other sites More sharing options...
jason str Posted November 9, 2013 Share Posted November 9, 2013 Looks good. Do you hear your sub or just the rattling CD's mounted to the wall there ? I have a picture just over mine and it has fell off the wall more than a few times. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 9, 2013 Share Posted November 9, 2013 Looks great Pete. Seems not all that long ago that we were building these things. Quote Link to comment Share on other sites More sharing options...
psg Posted November 9, 2013 Author Share Posted November 9, 2013 It was not long ago because I just finished mine with stain! As for rattles in the CD rack, surprisingly it's the doors at the other end of the room and a light ficture on the opposite wall that do most of it! Anyway, I am happy with it all and finally realizing that I lost 7 dB in the miniDSP reassured me that I don't need another sub. I have lots of headroom left. This things is more efficient than Klipschorns. Quote Link to comment Share on other sites More sharing options...
Sancho Panza Posted November 9, 2013 Share Posted November 9, 2013 Sweet!!! I want 2; each with a Heresy on top. Quote Link to comment Share on other sites More sharing options...
mustang guy Posted November 9, 2013 Share Posted November 9, 2013 Just thought I'd top up this thread... it took me a long time, but I finally stained the sub and found a better location for it along my back wall. The frequency response varies a lot between my four seats and the music sweet spot. Here it is at some locations after some manual EQ on a miniDSP, with gains of up to +5 dB and reductions of up to -5dB. Note that the sub mean level is about 6 dB below the mains, so even at +5dB I am still reducing the gain structure. Running through the RCA-plug version of the miniDSP drops the output by about 7 dB, so if you want to use one make sure you can accommodate the gain structure. The magenta one is pretty nice, I think. If I want to run a movie with the sub hot, then I have a volume control since it is fed by a single channel of my previous HK receiver (the 40-lbs avr325). It looks like the red line isn't suffering from standing waves like the pink and gold ones. Are these reading taken with different sub positions or different microphone locations? Quote Link to comment Share on other sites More sharing options...
psg Posted November 9, 2013 Author Share Posted November 9, 2013 At a few of the seat positions. The good thing is that they go away when the XO is set to 40Hz, so I get them for LFE but not for stereo music. I need bass traps, but that seems to be a hit or miss proposition. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 11, 2013 Share Posted November 11, 2013 Have you seen how adjusting phase affects your plot? Quote Link to comment Share on other sites More sharing options...
psg Posted November 11, 2013 Author Share Posted November 11, 2013 Shouldn't very much. The XO is set to 200Hz for those plots to get the sub output measurements rather than the KHorn output. But I guess it depends on how steep the filters are. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 11, 2013 Share Posted November 11, 2013 Shouldn't very much. The XO is set to 200Hz for those plots to get the sub output measurements rather than the KHorn output. But I guess it depends on how steep the filters are. I didn't know you set it that high for the graph. You're right, it shouldn't affect the results. Quote Link to comment Share on other sites More sharing options...
jason str Posted August 2, 2014 Share Posted August 2, 2014 Bump. Quote Link to comment Share on other sites More sharing options...
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