Paducah Home Theater Posted October 29, 2014 Share Posted October 29, 2014 (edited) Yeah it's from another company but this is an interesting article. Starting at page 20 it hits on why two subs are recommended. If you're too lazy to read that much, they measured a 16 db gain for the important seats at 36 hz plus being much more uniform up to 55 hz. http://www.harman.com/EN-US/OurCompany/Innovation/Documents/White%20Papers/LoudspeakersandRoomsPt3.pdf Pop quiz on this in the morning. Edited October 29, 2014 by MetropolisLakeOutfitters 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 29, 2014 Share Posted October 29, 2014 I will have to eat some food before I try to digest that. Nice find... 1 Quote Link to comment Share on other sites More sharing options...
Schu Posted October 29, 2014 Share Posted October 29, 2014 do we really need a reasoning why people choose to use two or more sub woofers? I guess so. 1 Quote Link to comment Share on other sites More sharing options...
Chris A Posted October 29, 2014 Share Posted October 29, 2014 (edited) That's part 3 of Floyd Toole's white paper series on "loudspeakers in rooms"...which is actually often-referenced nowadays. Here is a link to the page of all the Harman white papers on the subject of loudspeakers. Edited October 26, 2015 by Chris A 1 Quote Link to comment Share on other sites More sharing options...
WMcD Posted October 30, 2014 Share Posted October 30, 2014 I'm shocked, absolutely shocked, Captain Renault, to learn that two woofers in the front corners lead to optimal results (per page 201). As anyone ever described this before? Give PWK the winnings. WMcD 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted October 30, 2014 Share Posted October 30, 2014 This paper seems to say that subs placed away from the corners in the nulls of the axial dimension yield best results (page 14). Corners would yield good results with room gain for the lows and good imaging for stereo. Based on this paper, having your cake and eating it too would be LaScalas in the corners crossed at 60-80Hz, and two horn loaded subs in the nulls in from the corners. The very back wall would have high pressure at the longitudinal axial, so the rear seats should be in from the back wall to 1/8 of that wavelength. I didn't see him discuss delays when using multiple subs. This is extremely important, IMO. 1 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted October 30, 2014 Share Posted October 30, 2014 Harman has a white paper on subs. It shows the best results are with 4 subs, one centered on each wall. Next best is 4 subs, one in each corner. 1 Quote Link to comment Share on other sites More sharing options...
japosey Posted October 30, 2014 Share Posted October 30, 2014 It's a great white paper. I've read it on numerous occasions and used it when experimenting with 4 subs. 1 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted November 2, 2014 Share Posted November 2, 2014 In the majority of cases, two subs are better than one sub. 4 subs give the best room response. 1 Quote Link to comment Share on other sites More sharing options...
SWL Posted November 2, 2014 Share Posted November 2, 2014 I didn't see him discuss delays when using multiple subs. This is extremely important, IMO. Sure is. 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted November 2, 2014 Share Posted November 2, 2014 (edited) Harman has a white paper on subs. It shows the best results are with 4 subs, one centered on each wall. Next best is 4 subs, one in each corner. I have a pair of THT's and a pair of KPT-684's. The theater area of the shop is about 50wide X 60long X 24high. If I place a THT's facing eachother on the front and back, and the KPT-684's on the side walls facing eachother, what do you think it would sound like? My basic problem is that my shop is currently configured with the THT's side by side offset to the left of the center channel. When you get 30' away, the db is lower than the surrounds, and you can't hear the sub bass as well. In fact, you can't hear it at all when you are in the back 20'. This idea would resolve that. My pre has 2 sub outputs, so I could set exactly 2 delays. I have 2 pro amps without phase adjustment. I could get 2 more amps that have a phase adjustment so I could adjust the phase on one of the sides and one of the front/rear subs. That would give me 4 way phase adjustment as well as discrete control over the gain of each sub. All the subs would be connected with balanced (XLR) DMX cables. My pre has balanced XLR outputs, and the amps have balanced XLR inputs. FYI, I am not interested in building 2 more THT's or going with 4 KPT-684's. Do you think this would work? Edited November 2, 2014 by mustang guy 1 Quote Link to comment Share on other sites More sharing options...
Mallette Posted November 2, 2014 Share Posted November 2, 2014 "Two subs are recommended..." is misleading. Two are totally unnecessary for full range speakers, defined as per PWK as covering all but the last octave. That octave is inherently non-directional to human hearing. Also, in my experience, the fussy instrument setup and such is only necessary if you are anal or in a hurry...either or both. My sub, shown here as the big box with the port up and the R2R on it, blends relatively seamlessly with the K'horns and I simply have trimmed it over months of listening to various source material and tweaking. Dave 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted November 2, 2014 Share Posted November 2, 2014 "Two subs are recommended..." is misleading. Two are totally unnecessary for full range speakers, defined as per PWK as covering all but the last octave. That octave is inherently non-directional to human hearing. Also, in my experience, the fussy instrument setup and such is only necessary if you are anal or in a hurry...either or both. My sub, shown here as the big box with the port up and the R2R on it, blends relatively seamlessly with the K'horns and I simply have trimmed it over months of listening to various source material and tweaking. MusicRoom.jpg Dave I love the screen you are using for music. Are those meters a functioning applet, or is that a foobar theme or something? Very very cool! 1 Quote Link to comment Share on other sites More sharing options...
Mallette Posted November 2, 2014 Share Posted November 2, 2014 The work as perfectly as I've ever seen in software. Freebies. I'll send you a copy if you want. I don't recall the file being very big. They act just like the big ol' classic Weston's of my younger days. Dave 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted November 2, 2014 Share Posted November 2, 2014 Sure. I will PM you my email address.. Thanks! 1 Quote Link to comment Share on other sites More sharing options...
derrickdj1 Posted November 2, 2014 Share Posted November 2, 2014 Harman has a white paper on subs. It shows the best results are with 4 subs, one centered on each wall. Next best is 4 subs, one in each corner. I have a pair of THT's and a pair of KPT-684's. The theater area of the shop is about 50wide X 60long X 24high. If I place a THT's facing eachother on the front and back, and the KPT-684's on the side walls facing eachother, what do you think it would sound like? My basic problem is that my shop is currently configured with the THT's side by side offset to the left of the center channel. When you get 30' away, the db is lower than the surrounds, and you can't hear the sub bass as well. In fact, you can't hear it at all when you are in the back 20'. This idea would resolve that. My pre has 2 sub outputs, so I could set exactly 2 delays. I have 2 pro amps without phase adjustment. I could get 2 more amps that have a phase adjustment so I could adjust the phase on one of the sides and one of the front/rear subs. That would give me 4 way phase adjustment as well as discrete control over the gain of each sub. All the subs would be connected with balanced (XLR) DMX cables. My pre has balanced XLR outputs, and the amps have balanced XLR inputs. FYI, I am not interested in building 2 more THT's or going with 4 KPT-684's. Do you think this would work? It sounds like the room might be to large for the 4 subs. The four locations you mentioned should give better coverage. I think you have all of us beat when it comes to room size, lol. I bet music is fine but, with movies you may want a bit more. A Mini DSP would allow you to set delays, XO's and adjust the phase to make them work better together. Some bass shakers would round out the boom and you won't need more sub output. I recently got the bass shakers and I don't even care as much about sub output. I wish I would have did this a long time ago. 1 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted November 2, 2014 Share Posted November 2, 2014 My basic problem is that my shop is currently configured with the THT's side by side offset to the left of the center channel. When you get 30' away, the db is lower than the surrounds, and you can't hear the sub bass as well. In fact, you can't hear it at all when you are in the back 20'. This idea would resolve that. My pre has 2 sub outputs, so I could set exactly 2 delays. I have 2 pro amps without phase adjustment. I could get 2 more amps that have a phase adjustment so I could adjust the phase on one of the sides and one of the front/rear subs. That would give me 4 way phase adjustment as well as discrete control over the gain of each sub. A couple things come to mind. If your mains are calibrated to your subs up close they should be calibrated farther away. You may be stepping into a null which will be reduced when you spread the subs out as recommended. You'll lose a few dB of output when you decouple the ft subs from each other In order to take advantage of this configuration, I believe all the subs phase setting should be 0. You're using placement to reduce room nodes, not EQ. 1 Quote Link to comment Share on other sites More sharing options...
mustang guy Posted November 3, 2014 Share Posted November 3, 2014 OK, thanks guys... 1 Quote Link to comment Share on other sites More sharing options...
wvu80 Posted November 3, 2014 Share Posted November 3, 2014 Mustang Guy: I would give you some advice, if I had any. You have such unique knowledge of your listening environment, there is nothing I could add that would be above your level of knowledge or experience with your space and gear. Everybody Else: I have been to Mustang Guy's Speaker Ranch and heard a brief glimpse of what his setup can do, and all I can say is that it is way above my listening experience. The bass is thunderous in a way I have never heard before, not so much loud as it is all-consuming, it's like taking a sonic bath. And I know MG turned the volume level down so save blowing out (pressurizing) my ears. I know you guys like your La Scalas; he runs six. His place sounds better than any cinema I have been to. It's unique to my listening experience. I think you should convert your digs to a jazz bar and charge admission. 1 Quote Link to comment Share on other sites More sharing options...
quakana Posted November 3, 2014 Share Posted November 3, 2014 .....no treble..... 2 Quote Link to comment Share on other sites More sharing options...
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