# Sub Placement help



## Ciscokid (Jan 1, 2007)

Hello all,
Its been a long time since I have been on here. I finally have some time and money to start playing again.I have been taking samples moving my sub to differnt locations in the room. I would like to know based on my readings, which is the best location. One thing I have noticed is that the impulse is changing with each sample taken. I am not sure what I should be looking for with the impulse and or if that should be a determining factor in my placement. Finally, should I look also for my waterfall peaks to be lower in relation to time? Here are the graphs for each different location. I would appreciate any help teaching me to understand and inturpret my graph.


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## glaufman (Nov 25, 2007)

What's your room like and where are the sub and listening locations?
Do you have a soundcard calibration loaded into REW?


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## Ciscokid (Jan 1, 2007)

My room is rectangle in shape. Approx. 14 wide by 24 feet long. Well actually there is no back wall so the room opens up to my kitchen. So if you consider the kitchen the back wall that is probably 60 feet or so. The sub is located to the left of the center cabinet at the moment. The picture has it on the right. The seating is at 18 feet from the front speakers. I know I have a lot of room issues to deal with. This is why I have been moving my sub around trying to find the best starting point. Sitting facing the screen there is a window to the right of the screen and next to that is the fire place then another window and finally the sliding glass door. On the other side it is a solid wall 18 feet down then there is an opening leading to my laundary room.
I have a radio shack SPL and a Creative Lab USB sound card. I believe its the Creative Soundblast 24. I have loaded the sound card calibration file. See picture below of my room.


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## glaufman (Nov 25, 2007)

I'd say blue, but red is also a possibility. Where is your crossover set? Can you reset the target line based on the scan?
If you really want to improve performance, you can try getting the sub out of the corners, try moving the LP forward or back, acoustic treatments, and EQ.


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## Wayne A. Pflughaupt (Apr 13, 2006)

> I would like to know based on my readings, which is the best location.


I'd say it's a toss-up between the red and blue.

Regards,
Wayne


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## cyberbri (Apr 27, 2006)

What kind of sub? And is putting it to the side or rear of the seating location an option? That will give you more volume and more visceral punch. And like someone else said, I also suggest moving the seating position up. 18' is pretty far back, even for that screen. I'm at about 10' from a 100" screen.


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## Ciscokid (Jan 1, 2007)

Ok now that the football game is over back to testing. 
I have my crossover set to 80hz. I reset the target line. I am not sure what you mean by "move the LP forward"? I played with every setting I have on my sub, tried several different locations and this is what I came up with. My sub has a dial for LOAD, FULL, HALF, and FLAT. I think it has to do with the response. I tested with each different setting and the LOAD setting seemed to be the flatest. It seem to bring down the spike at around 38hz and 48hz while everything else stayed the same. I also added the mains and ran a sweep. What do you think? I think I have a huge issue with the ringing. I am getting waterfall reading all the way out to 800ms. Is my room a lost cause?? 
I have a BFD on the way. What cables do I need to buy in order to hook it up? Sorry for all the questions just trying to learn. Thank you guys for all your input so far.All images are with no correction.


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## Ciscokid (Jan 1, 2007)

cyberbri said:


> What kind of sub? And is putting it to the side or rear of the seating location an option? That will give you more volume and more visceral punch. And like someone else said, I also suggest moving the seating position up. 18' is pretty far back, even for that screen. I'm at about 10' from a 100" screen.


SUB is a Axiom EP500.Moving closer isn't much of an option I was able to get it to 15 feet. My fireplace is just in front and to the right of my couch. As far as moving the sub, I can probably place it to the left of my couch in place of the coffe table. That would be one long XLR cable.


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## glaufman (Nov 25, 2007)

If that back wall is really 60' back, you'll probably get better results moving the listening position (LP) back than forward, but assuming you don't want to do that due to screen size...
Getting the sub out of the corner would probably help... "left of the couch" I'm assuming is on the long wall.
I always like to talk about acoustic treatments before EQ, but you'll probably need specialized absorbers to these low frequencies...
Wayne is your man when it comes to equalizing.


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## Ciscokid (Jan 1, 2007)

glaufman said:


> If that back wall is really 60' back, you'll probably get better results moving the listening position (LP) back than forward, but assuming you don't want to do that due to screen size...
> Getting the sub out of the corner would probably help... "left of the couch" I'm assuming is on the long wall.
> I always like to talk about acoustic treatments before EQ, but you'll probably need specialized absorbers to these low frequencies...
> Wayne is your man when it comes to equalizing.


So as far as treatment goes, will I benefit from to corner traps floor to ceiling. Or will the amount of treatment required out way the visual factor. I know I can get away with the corner traps but going to much further the wife may not approve of. Unless it looks nice. I knew I was going to have issues do to the layout of my room. I would just like to improve as much as possible while keeping the Aesthetics of the room. Thanks again for all the great advice.

Wayne, As far as the BFD goes. I have one on the way and would like to know what cables I will need to hook it up.


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## glaufman (Nov 25, 2007)

Noone but you and your wife can say whether the visuals will outweigh the benefits... but when it comes to bass traps, more=better almost always. They can be made to look nice. Wayne and I often say the commercially available ones don't do much as you get below 100Hz, but there's also tuned absorption, and I just saw some data I'm still mulling over on corner traps and chunks that on initial impression seem to be good down to 50 or 40Hz... for more info you can go over to our Acoustics forum...


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## Wayne A. Pflughaupt (Apr 13, 2006)

Like Greg said, more is better with bass traps, and the the better they work at the lowest frequencies, the bigger they are. That often adds up to aesthetic problems if your system is set up in a family room.




Ciscokid said:


> I think I have a huge issue with the ringing. I am getting waterfall reading all the way out to 800ms.


Not unusual, especially at the lowest frequencies (like, below 40 Hz). Fortunately, it looks way worse than it sounds.




Ciscokid said:


> Wayne, As far as the BFD goes. I have one on the way and would like to know what cables I will need to hook it up.


A cable with a 1/4” phone plug on one end, and an RCA on the other. You can get a stereo cable and separate the two, and you’ll have two cables, one for input to the BFD and one for output to the sub amp.










Regards,
Wayne


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## Jason_Nolan (Jul 4, 2008)

If anyone can find out a way to take car of the 40hz and under ringing that's feasible, I'd love to know myself.


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## Jason_Nolan (Jul 4, 2008)

Uh, care...anyway^


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## Ciscokid (Jan 1, 2007)

Wayne,
From your past experience will it help to move the sub to the left of my seating area on the long wall? All I would need to do is purchase a longer XLR cable to make the connection.

My sub is currently hooked up via XLR connection, is this going to matter (for connection to the BFD)? Also what else will I need to make the connection to my computer? Or do you recommend manually applying the settings.

Frankie


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## Wayne A. Pflughaupt (Apr 13, 2006)

I’ve never had good results locating a sub at the center of a wall, but I’ve never tried it with two asymmetrically-placed subs like you would have. Best to just measure and see.




> My sub is currently hooked up via XLR connection, is this going to matter (for connection to the BFD)? Also what else will I need to make the connection to my computer?


 Not sure I understand. What would you be connecting the computer to?

Regards,
Wayne


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## Ciscokid (Jan 1, 2007)

Wayne A. Pflughaupt said:


> I’ve never had good results locating a sub at the center of a wall, but I’ve never tried it with two asymmetrically-placed subs like you would have. Best to just measure and see.
> 
> 
> Not sure I understand. What would you be connecting the computer to?
> ...


Let me clarify. I currently have my sub connected via XLR to my receiver. The BFD if I understand correctly will connect between my receiver and my sub on one of the channels. Correct? If so can I use XLR cables to make this connection or should I use the RCA to 1/4 phone plug cables. 
The second question is, do I need any other connections in order to use my computer with REW to send filters to the BFD or should I just input them manually.


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## glaufman (Nov 25, 2007)

I didn't think the new sub position Frankie was speaking about would be "centered" on the wall... just simply out of the corner, and thereby exciting less modes (hopefully)...
I've never tried this, but it intrigues me: since we know that listening 38% of the length from either the front or back wall can do wonders for avoiding peaks and nulls due to modal effects, and since we know that LP and sub placement go hand in hand, I'd love to see someone try locating the sub 38% from a given corner and compare the result to that of placing it in the corner...

As for nulling ringing at 40Hz, big big bass traps, and lots of 'em, might do the trick, might be more palatable to have tuned absorption as opposed to broadband... But for this type of work I try to defer to Bryan over in the Home Acoustics sub-forum...


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## Wayne A. Pflughaupt (Apr 13, 2006)

Ciscokid said:


> Let me clarify. I currently have my sub connected via XLR to my receiver. The BFD if I understand correctly will connect between my receiver and my sub on one of the channels. Correct? If so can I use XLR cables to make this connection...


 Correct – just get a second XLR cable and you’re in business.




> The second question is, do I need any other connections in order to use my computer with REW to send filters to the BFD or should I just input them manually.


In order for REW to send filters to the BFD, a MIDI cable is needed, as well as a sound card that supports MIDI. Personally I don’t see the need for it, as REW tells you right there on the screen what filter parameters to dial in.

Regards,
Wayne


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## Ciscokid (Jan 1, 2007)

Ok I just received my BFD. I connected it and now I am having some issues setting it up. I hooked up up via XLR connection. From the Sub out of my pre/pro (Outlaw 990) to the input of channel 1 BFD then from the output to the sub. I have read the BFD guide. I put it in bypass mode with the sub off I then went into the speaker setup and set the input level.(+5 got me where I need to be) Then I turned on the sub and still while in bypass mode I set the output level of the sub and all other speakers with AVIA. Now comes my problem. I fired up REW loaded cal files and attempted to set my sound level. I can change the sound level on my Pre/pro but it has no effect on the sub. I do see the lights on the BFD rise to the point of clipping. I tried to take it out of bypass mode and still my volume on the pre/pro has no effect on the sub output sound level. What am I doing wrong?? I guess now I should move my post over to the BFD section. I would also like some help on setting the filters. Is there some step by step cheat guide to help with this. Thanks again for putting up with lack of smarts


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