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subwoofer placement
#149898 10/22/06 01:59 AM
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Ok, I'm at it again. I'll try to make this short and sweet.....

As most of you know my front wall is 15ft wide. I have my 2 m60's, 1 vp150, and 1 EP500 up on the stage below my screen. I was talking to a guy from Triad Speakers the other day over on AVS, and he said he has found the best overall placement of his two subs to be at the "third wav". Sounded like the center of the drivers are the same distance from each other, and from the left/right walls. I believe his wall was 11ft wide, so the subs were exactly 3'8" from each other and the walls. This has given him a very flat response, tight, even, and extended result. Prior to having two subs, he said just placing one at the "third wav" gave great results.

I've trying to move my EP500 from side to side to find the best location on my stage. What the heck is the third wav and how do I calculate? Is this saying to just divide the width by 1/3rd which would be 15ft / 3 = 5ft? Right now I've moved the EP500 back to dead center, I just can't make up my mind..

Thanks, Randy


M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85


Re: subwoofer placement
SirQuack #149899 10/22/06 02:27 AM
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I forgot to mention I've tried the sub crawl, but not sure I heard much difference to my ears, didn't use the spl meter at the time. I will also try jakeman's suggestions below from another thread for calibration. Just concerned about placement...

1. Turn off auto-calibration.
2. Calibrate all your speakers first to 75db.
3. Measure distance then set delay for each of them. You may want to set the surround speakers to slightly more delay for effect.
4. Turn off sound to all speakers.
5. Set the subwoofer volume to -7 (a quarter of the way down to leave you some room for fine tuning).
6. Run the LF sweep on S & V and adjust gain at the sub so the needle spends most of its time at 75db at your favourite seating position.
7. Go and move the sub around to see if you can get less flucuation on the SPL metre at 75db.
8. Play sound through the mains and sub.
9. Flick the phase switch to see whether 0 or 180deg has more SPL at the seating position. Leave the phase at the higher setting.
10. Measure the distance to the sub and input the delay setting for the receiver. Many subs benefit from increasing delay another 3-5 feet than the measured distance depending on room acoustics, so experiment.
11. Test with your favourite music or movie. I you want more bass increase your receiver setting not the gain at the sub.
12. Start over again at #1 and fine tune your calibration.


M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85


Re: subwoofer placement
SirQuack #149900 10/22/06 03:42 AM
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Randy, I'm not familiar with what Triad suggests, but it's very likely that you've interpreted it correctly, i.e. one-third of the way in from the side wall. It doesn't strike me as a universally superior location. For example, with two subs the paper by Dr. Toole's people at Harman(which I believe you've read)suggests center of side walls or center of front and back walls as being good locations for the two. Right in the corner is still a good spot for a single sub unless the room is nearly square, which might make that one-third out location better.


-----------------------------------

Enjoy the music, not the equipment.


Re: subwoofer placement
SirQuack #149901 10/22/06 03:02 PM
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Hi Randy

I've never had much luck with the quick placement formulae because nodes will vary considerably from room to room, so one persons placement doesn't always translate to another's room.


From the pics of your great looking room, I'd say you still have a few challenges finding ideal placement because of its large irregular layout. I had a similar situation with my irregular space until last year when I built another small wall to seal the room. The larger the volume the more difficult it will be for one sub to pressurize the room.


With only one sub your situation may actually work better with the 500 in the corner. FR will be less linear but the overall result could be better depending on your seating position . Generally speaking I've found one-third to one-half distance from a corner works best with one sub if your goal is flatter response. As you move closer to the corner you benefit from more room gain but less linear FR. Given the size of room and layout a second EP500 along the front wall or one on the frontwall and another on a sidewall should really perform well.

Another suggetion would be stay with one 500 and get an SMS-1 to equalize FR at the main seating area. It's graphical display will also help you pinpoint the ideal placement.


John
Re: subwoofer placement
jakeman #149902 10/22/06 03:15 PM
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Randy. As I looked again at your room layout, one spot jumps out which is left midwall 10-12 feet down from the left corner. Besides better FR it is nearfield the seats which will provide more output to the seats in that large space. I'd check that spot before the left corner.

If it was my space I would go with mutiple subs.


John
Re: subwoofer placement
jakeman #149903 10/22/06 04:39 PM
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>>> If it was my space I would go with mutiple subs.

What??? Mr. Jakeman would actually go with *multiple* subs? Say it ain't so.



Rick
Our Room

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Re: subwoofer placement
RickF #149904 10/22/06 07:36 PM
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Rick I'm afraid its true. They call the condition multipleaxiomsubwooferitis. Its been know to afflict otherwise healthy people, especially males, who live in large rooms.


John
Re: subwoofer placement
jakeman #149905 10/22/06 08:15 PM
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Drank a few too many beers at the Oktoberfest thing last night so I have decided it’s safer to screw around with my speaker calibrations than power tools today.

While messing around with the Avia DVD and the LFE test tones part of the DVD and subwoofer calibrations (with my RS meter), I noticed that when the LFE test tones cycle from L/C/R/SR/SL, the LFE noise is considerably lower on all channels other than the R and L mains. It's right about 10 DB lower actually. I have the X-over set to 80 on all speakers (they are all set to small of course) and I’ve set the AVR sub to a -6 and all the speakers are reading as close as possible with pink noise. I’ve tried everything on my AVR settings (it’s a HK 7300) and I can’t change this phenomenon. The HK also has an option to select L/R, Center, Surround or Surround back. I’ve tried them all and there is no difference.

So my question is, how am I to set the gain on the sub?? Do I match the mains or do I match the other channels??

Re: subwoofer placement
michael_d #149906 10/22/06 10:57 PM
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Turn up the sub?


I am the Doctor, and THIS... is my SPOON!
Re: subwoofer placement
Ken.C #149907 10/23/06 01:31 AM
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Quote:

Turn up the sub?




But how much? To match the Mains or the other speakers? If I match the center for example, the sub DB will be about 10 higher than it is now.

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