Audio Asylum Thread Printer

Get a view of an entire thread on one page

FAQ / News / Events

Video Asylum

Question for SUB-experts out there:

206.100.159.2

[ Follow Ups ] [ Post Followup ] [ Video Asylum ] [ FAQ ]

I have my H.T. set up in a 14' x 17' room with the speakers about 8' apart and the Subwoofer in the right corner, about 6 inches away from each wall. About 12' back is my listening position on an L-shaped sectional couch. The couch is placed so I sit in the prime listening position on one end of the couch that is parallel to the plane of the TV screen and front speakers (obviously) My problem is this: In this position the bass from the sub is pretty good, but the lowest frequencies are a little weak here. When I sit in the corner of the sectional couch, I am sitting left of center of the prime listening postion but the sub produces the most even output here. The lowest notes can be heard with the most clarity. I have tried turning the volume of the sub up while in the prime listening position, but it only increases what I hear there already - plenty of mid to upper bass, but not enough low end. I have turned my sub in various postions in the corner, to no avail. I thought about trying the left corner of the room but the sub cable isn't long enough. Any thoughts?
My theory is that the sectional is acting like a "funnel" funneling all the lower bass waves into that corner of the sectional. Is there any way to adjust the phase of the sub to get better output at the listening postion? Any other suggestions? Am I suffering from a case of pesky room nodes? Am I crazy?
Speakers: Mission 774 Sub DefTech PF15TL
One other question: In theory, won't the strongest output from a sub placed in the corner be in the diagonally oposite corner of the room?
Thanks for your thoughts!!!!

Follow Ups:

Thanks! other info on system: WSB 11:16:09 01/27/00 (2)
In case someone has further advice here is some more info. about my system:
Denon Avr3300 reciever
3 Marantz MA-500's for mains, center channel (These are being shipped presently - not yet installed)
Mission 774 mains, 77c1 center 77ds rears. DefTech. Pf15tl sub
Pioneer 525 dvd
Rotel rcc945 cdp
Soney Wega tv
Monster 10 ga. 4rcl speaker cable
Monster THX subwoofer cable
Audioquest Ruby interconnects
All speakers set on small with all bass below 85 Hz. to sub.
Denon has built in 85 Hz. crossover so I have the low pass on the sub bypassed. The gain is between 1/4 and 1/2 way up. The Phase is set at 0.
Carpet floors over a concrete slab - This is good to keep boominess out of the floors, but the sub doesn't pass those low end freq's through the floor for that rumbling bass like it would with a suspended wood floor. There is a noticeable difference in low end from sitting on the couch, to sitting on the floor right in front of the couch - the sub vibrates the couch but not the floor. One can actually "feel" the bass alot better upstairs throught he wood floors than when standing in the same room of the H.T. on the concrete slab floor.
Thanks for your suggestions everyone! Any other sub "tweaks" are welcome!
- Re: Thanks! other info on system: Bob Wanamaker 13:14:41 01/27/00 (1)
  WSB,
  Hmmm...
  > > > One can actually "feel" the bass alot better upstairs throught he wood floors than when standing in the same room of the H.T. on the concrete slab floor. < < <
  IMO this indicates that you have a room mode going on that is reinforcing some frequencies and nulling out others. Concrete actually conducts bass frequencies fairly well; you won't lose anything by having concrete floors.
  You might want to consider some room treatments to even out the low end, if moving the sub isn't an option/doesn't help. Do a search through the archives for information on TubeTraps, room treatments, etc.
  - will do! Thanks for your help! (nt) WSB 14:21:22 01/27/00 (0)
    .
I'm definitely sub-expert... Bob Wanamaker 18:01:27 01/26/00 (1)
... in just about all things audio!
However, a couple of things spring to mind: there's a lot of room modes going on in the low frequencies, which makes it pretty tough to call without a lot more detail about your room. You may have a mode cancelling, or reinforcing, in one part of the room and not another.
Try putting your sub on a chair in your prime listening position, then walk around the room and find where the bass sounds the best. Then put the sub there, and put yourself back in the listening position. Quite a few times this will help you find the best position.
Don't be afraid to play around with positioning. In my listening room, moving the subs a couple of inches excites a room mode at 80Hz by something like 15dB.
- Re: I'm definitely sub-expert... ROBERT G 23:23:21 01/26/00 (0)
  The first thing I would do is reset the AVR or Pre-amp setting as someone might have DRC, LFE ATT, or Lvl screwed-up and to simplify details start from scratch. Second set your speakers (front large, center small, rears small, and sub yes/plus if you have the appropriate other Mission setups I think you have like their matching center and rears). Check all speaker wire connections because if any one speaker is firing out of phase and is in a bass enhanced section of the room mode could actually muffle the bass effect from the listening positioning. I don't know what sub-woofer cable you use but if you are not at least using a monster THX sub-cable (the lowest I recommend) then you might not get a good signal. While playing some music loud set the sub at middle of the gain setting (normally this is way too loud but is easier to set phase) and adjust the phase of your sub (if this is noticibly louder when you adjust phase then that is the correct setting). I don't know if you're an experienced hobbiest and I don't mean to insult you but if your sub's power cord is plugged into your AVR it's now time to give it it's own outlet (I am amazed at how many people plug a sub or amp to the low output accessory outlet of most AVRs as now the AVR and the sub now competes for current drawn from the bare-bones cord that comes with their AVR). Positioning the sub follow the person's advice who posted before me and in addition buy a cheap TV lazy-susan (Walmart for about $5) put about a 2' x 2' board on it, then your sub, and as music plays have someone turn the sub to find out what is the best firing facing for performance (you would be amazed how this tightens bass performance and well as enhance output by using the better room modes). You might have to also see if everything in that room is on the same circuit and how much power is being drawn from all items as well as maybe removing the sub from a line conditioner (though this tightens bass, it will sometimes effect dynamics and extension when the amp draws the most juice). If the sub is on a carpeted surface you might have to buy spikes to couple it to a more firm surface (wood or concrete). Worst case scenerio set all speakers to small and direct all bass to the sub as some gear will limit the signal to the sub if any speakers are set in the large setting. Can you do all of us a favor, list some of the other equipment in use AVR/pre-amp/amp, interconnects (namely sub, CD player, and DVD player avoid optical connections), line conditioners (if used), and potential room treatments (if used) as someone else on this site might can offer a better solution than I.

This post is made possible by the generous support of people like you and our sponsors:

You can not post to an archived thread.