Small observation on down firing subs - Blu-ray Forum

got rice · 01-30-2009, 10:29 PM

Ever since I bought my klipsch SUB-12 I have read many threads and noticed that people who have hard wood floors will place a piece of carpet under it to remove some of the boominess and keep it from dancing across the floor.

However the ones with carpet add a MDF to replicate the sound of hardwood floors, tile, marble etc.. this apparently helps with the "muffled" response the sub produces on carpet.

Why is this? I have carpet and want to know should I add a MDF underneath or will I get the boominess of hardwood? Which I would like to avoid.

got rice · 01-31-2009, 11:09 PM

Anyone?

Why are people trying to replicate the flooring of what they don't have?

Blu-Dog · 01-31-2009, 11:21 PM

Quote:

Originally Posted by got rice

Anyone?

Why are people trying to replicate the flooring of what they don't have?

I wouldn't do it.

The problem with any sub, not just the down-firing ones, is usually "room gain" from reflective wall, ceiling, and floor surfaces. I have had only tile floors with subwoofers, never a problem - it's the walls and ceilings that drive me nuts.

The only think you have to worry about with the SUB-12 is that it likes going for a nice walk in the middle of a movie. I got some non-skid feet from Home Depot, end of problem, and they sound great sitting on hard, solid stone.

It's the surfaces that are a lot further away that cause echo, and that delay - the "room gain" at loud volume - that really plays havoc.

Rob J in WNY · 01-31-2009, 11:37 PM

Blu-Dog pretty much nailed it. The features of the overall room design will have more to do with the sub's overall sonic performance at your listening position. However, I do believe that some folks who place subs on hardwood floors have had to deal with a bit of "floor modulation" of the sound - a little coloration of the bass due to a downfiring sub causing vibrations of flooring which is not solid enough to avoid vibration. Not so much boominess, but the floor itself annoyingly vibrating.

Check out my setup in the gallery photos. You will see that I have placed my Polk Audio PSW125 (which, btw, has a downfiring port) off to the side of my couch, beneath. This is a good place for it to produce rich bass at my preferred listening position (the couch). Obviously, my floor is carpeted. I was concerned that the port was pushing against the carpet, so I elevated my sub with a wood panel to ensure proper port venting. My primary concern was that the port was being choked off by the carpeting. The sound from my sub is pretty nice, depsite horrible room acoustics. I cannot place the sub anywhere along the common wall with the front speakers. Where it is sitting, I have no boominess at all, but sometimes my windows near the sub rattle a bit, reminding me of where the sub is located.

Blu-Dog · 02-01-2009, 04:31 PM

Quote:

Originally Posted by Rob J in WNY

Blu-Dog pretty much nailed it. The features of the overall room design will have more to do with the sub's overall sonic performance at your listening position. However, I do believe that some folks who place subs on hardwood floors have had to deal with a bit of "floor modulation" of the sound - a little coloration of the bass due to a downfiring sub causing vibrations of flooring which is not solid enough to avoid vibration. Not so much boominess, but the floor itself annoyingly vibrating.

I forgot about that - I've been on concrete slab floors using tile for the last three decades.

Beta Man · 02-01-2009, 04:38 PM

It seems that when ever this is discussed, there is some confusion due to some people talking about the orientation of the ports..... and others about the orientation of the woofer......

got rice · 02-01-2009, 08:19 PM

[QUOTE=Rob J in WNY;1571248]Blu-Dog pretty much nailed it. The features of the overall room design will have more to do with the sub's overall sonic performance at your listening position. However, I do believe that some folks who place subs on hardwood floors have had to deal with a bit of "floor modulation" of the sound - a little coloration of the bass due to a downfiring sub causing vibrations of flooring which is not solid enough to avoid vibration. Not so much boominess, but the floor itself annoyingly vibrating.

Yes this make total sense. For me I don't have a dedicated room for HT that has full enclosure with four walls. I have a great room that adjoins to the kitchen so the acoustics is not as good in certain sitting positions.

I temporarily moved the sub to the corner next to the couch and noticed a signifigant improvement in the sonic performance. Now I just have to get off my lazy butt and run the cables.

Any suggestions?Should i run cables under carpet past fire place then along base boards or through the walls and ceiling?

01-30-2009, 10:29 PM	#1
got rice Senior Member Member since:Jan 2009	Small observation on down firing subs Ever since I bought my klipsch SUB-12 I have read many threads and noticed that people who have hard wood floors will place a piece of carpet under it to remove some of the boominess and keep it from dancing across the floor. However the ones with carpet add a MDF to replicate the sound of hardwood floors, tile, marble etc.. this apparently helps with the "muffled" response the sub produces on carpet. Why is this? I have carpet and want to know should I add a MDF underneath or will I get the boominess of hardwood? Which I would like to avoid.

02-01-2009, 04:38 PM	#6
Beta Man Moderator Top contributor Member since:Jan 2008 Location:Juuuuuuuust A Bit Outside.... Home Theater Gallery:4 Blu-ray collection:268 Blu-ray reviews: 18 Trading Score:25	Fyi It seems that when ever this is discussed, there is some confusion due to some people talking about the orientation of the ports..... and others about the orientation of the woofer......

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01-31-2009, 11:09 PM	#2
got rice Senior Member Member since:Jan 2009	Anyone? Why are people trying to replicate the flooring of what they don't have?

01-31-2009, 11:37 PM	#4
Rob J in WNY Blu-ray Guru Member since:Dec 2008 Location:'Western' N.Y. State (MEMBER OF THE "ECPP")™ Home Theater Gallery:24 4K collection:30 Blu-ray collection:486 iTunes collection:1 Blu-ray reviews: 15	Blu-Dog pretty much nailed it. The features of the overall room design will have more to do with the sub's overall sonic performance at your listening position. However, I do believe that some folks who place subs on hardwood floors have had to deal with a bit of "floor modulation" of the sound - a little coloration of the bass due to a downfiring sub causing vibrations of flooring which is not solid enough to avoid vibration. Not so much boominess, but the floor itself annoyingly vibrating. Check out my setup in the gallery photos. You will see that I have placed my Polk Audio PSW125 (which, btw, has a downfiring port) off to the side of my couch, beneath. This is a good place for it to produce rich bass at my preferred listening position (the couch). Obviously, my floor is carpeted. I was concerned that the port was pushing against the carpet, so I elevated my sub with a wood panel to ensure proper port venting. My primary concern was that the port was being choked off by the carpeting. The sound from my sub is pretty nice, depsite horrible room acoustics. I cannot place the sub anywhere along the common wall with the front speakers. Where it is sitting, I have no boominess at all, but sometimes my windows near the sub rattle a bit, reminding me of where the sub is located.

02-01-2009, 08:19 PM	#7
got rice Senior Member Member since:Jan 2009	[QUOTE=Rob J in WNY;1571248]Blu-Dog pretty much nailed it. The features of the overall room design will have more to do with the sub's overall sonic performance at your listening position. However, I do believe that some folks who place subs on hardwood floors have had to deal with a bit of "floor modulation" of the sound - a little coloration of the bass due to a downfiring sub causing vibrations of flooring which is not solid enough to avoid vibration. Not so much boominess, but the floor itself annoyingly vibrating. Yes this make total sense. For me I don't have a dedicated room for HT that has full enclosure with four walls. I have a great room that adjoins to the kitchen so the acoustics is not as good in certain sitting positions. I temporarily moved the sub to the corner next to the couch and noticed a signifigant improvement in the sonic performance. Now I just have to get off my lazy butt and run the cables. Any suggestions?Should i run cables under carpet past fire place then along base boards or through the walls and ceiling?

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