Speaker Placement Problem

Posted by: robrob

Speaker Placement Problem - 08/17/13 10:15 AM

Hello, I'm a brand new Axiom owner. I have a pair of floorstanding M60 V3s setup for stereo but they are placed on each side of a large, 65 inch projection TV on a stand. The listening position is about 10 feet from the speakers and they are spaced about 7 feet apart (minimum due to TV). I know this is too wide for the listening position but I can't move the listening position rearward due to space constraints.

The listening room is carpeted with two small cloth covered rockers on either side of the listening position's cloth covered loveseat. The drop ceiling is pressboard with a hard shell painted surface.

I'm getting a horrible mid-freq bump that makes the M60s (and the previous Polk Audio Monitor 60 Series II) sound like crap. The mids simply jump out and howl. I assumed my Polk speakers were not up to my standards and decided to upgrade to the M60s but the problem isn't with the speakers. I have tried another amp but the problem is exactly the same.

I have verified correct polarity at the speakers and amp. I have tried moving both pairs of speakers in and out from the wall and tried toe-in and toe-out and angling the speakers upward and downward. Toe-out helped a little. I have tried moving the speakers away from the TV but I can't get them more than about 1 foot from the TV due to space constraints.

I suspected the large flat TV screen between the speakers might be causing the problem so I put a cloth covered recliner directly in front of the listening position so it blocked the TV but not the speakers. This has helped a lot but it's not a practical solution.

Do you have any suggestions (other than headphones wink )?

Thanks in advance,

Rob
Posted by: Socketman

Re: Speaker Placement Problem - 08/17/13 11:07 AM

Hi Rob, welcome to the forum. Sorry to hear about your troubles. I found a thread over at avs that talks about something similar to what you are describing, maybe read through it. This is most likely something related to the room, some rooms just don't play nice without some treatment. One of our regular members just treated his room for early reflections and came away very impressed with the results. I am sure with a little effort your problem will be minimized or eliminated.

Richard
Posted by: Ken.C

Re: Speaker Placement Problem - 08/17/13 11:17 AM

Hi Rob,

You didn't say what preamp or receiver you're using. Do you have the option of some sort of auto-calibration/correction such as Audyssey, YPAO or MCACC?
Posted by: robrob

Re: Speaker Placement Problem - 08/17/13 12:32 PM

Thanks for the link Richard. I do have a wooden coffee table in front of my loveseat that could cause some serious early reflections. I'll try moving it away.

Ken, I'm running a raspberry pi server into an Aune T1 DAC (pre-out) to a tube amp with only a volume control so I currently don't have a lot of control. This setup does sound fantastic with headphones though.
Posted by: J. B.

Re: Speaker Placement Problem - 08/17/13 12:36 PM

if you don't like moving the coffee table, try keeping some books and discs on it, so it will diffuse reflections.
Posted by: robrob

Re: Speaker Placement Problem - 08/17/13 12:50 PM

I moved the coffee table to behind the listening position and it didn't make a difference. I then covered the TV with a thick blanket and it made a big difference--sounds much better. I'm going to play around with more blankets.
Posted by: tomtuttle

Re: Speaker Placement Problem - 08/17/13 12:58 PM

I don't entirely understand your room configuration.

Treat the side walls? Even temporarily.
Posted by: SirQuack

Re: Speaker Placement Problem - 08/17/13 01:38 PM

I was going to say toe-in, but looks like you've tried that. What AVR are you using and what mode are you listening to in music: Direct, Stereo, PLIIx, etc? Also, did you configure by using setup, dB levels, distance, etc by using built in Mic or manual setup with SPL meter?
Posted by: alan

Re: Speaker Placement Problem - 08/17/13 02:09 PM

I'm going to take a different tack on this. Since you said you have a mid-frequency bump on both pairs of speakers, yet it sounds great over headphones, I'm suspecting the vacuum-tube amplifier. Many tube amps do NOT have smooth frequency response and perhaps the bump is a product of non-linear response in the amplifier and or distortion. Did you try a solid-state amplifier instead of the tube amp?
Posted by: robrob

Re: Speaker Placement Problem - 08/17/13 03:34 PM

I did try a solid-state receiver with the old speakers and the sound quality was the same as the tube amp.

I played around with the side walls by placing the cloth covered rockers near the reflection points with no change in the mid-freq howl.
Posted by: Socketman

Re: Speaker Placement Problem - 08/17/13 03:53 PM

HI rob. Im not sure if you aware of how to determine the first reflection point. I have not done it myself though I have seen it mentioned. It is done with a mirror and preferably a helper. Wall treatments need to be made from material that is specifically designed to absorb certain frequencies. Besides absorption you need diffraction from such things as bookstands ,plant stand etc. If you had a receiver with room correction software you could possibly forgo the room treatments.

richard
Posted by: JohnK

Re: Speaker Placement Problem - 08/17/13 11:41 PM

Rob, welcome. The first point is that the 7' separation is about the least that should be used with a 10' listening distance. The typical suggestion is that the speakers should be separated about the same amount as the listening distance, so the separation should be increased by at least 3'.

Secondly, since reflections or refractions from the TV appear to be at least part of the problem, the speaker drivers should be at least a few inches forward of the TV surface, to lessen those effects.
Posted by: robrob

Re: Speaker Placement Problem - 08/17/13 11:51 PM

Thanks John, I'll try widening the speaker separation but the Axiom stereo setup guide say to place them less than the listening distance:

"You want to avoid the sense that you are getting sound from two boxes at the front of the room. That may happen when the two main speakers are too far apart. I don't like excessive physical separation: if you sit 12 feet back from your speakers, try separating the two main speakers about 6 to 8 feet. With direct-radiating speakers like the M60s, I usually angle them in very slightly towards the listening area (you may have seen this referred to on our message boards as 'toe-in'). You can tell when it's right because a vocalist will seem to appear, phantom-like, locked dead center between the two speakers. If you separate front speakers by more than 10 feet, it's often difficult to achieve an unbroken front soundstage."

I have tried placing the speakers about 6 inches forward of the TV screen.

Vocals are so hollow yet harsh. I'm going to try the M60s in another room temporarily to see what they sound like.
Posted by: brwsaw

Re: Speaker Placement Problem - 08/18/13 01:22 AM

Have you tried spacing them 8' apart? How about 9'?
Posted by: J. B.

Re: Speaker Placement Problem - 08/18/13 06:47 AM

movies should be listened to with the L/R speakers just flanking the side of the tv; and something like an equilateral triangle for music. just like JohnK says.
i chose the music setting (wide separation) because overall
the results are better.
try both for a while.
Posted by: SirQuack

Re: Speaker Placement Problem - 08/18/13 08:58 AM

not sure you answered my question, what mode are you using: direct, stereo, PLiix, etc? My m80's are seperated about 9-10ft in the theater room, front row is about 8-9 ft back, and 2nd row is more like 13-14ft, and there are no issues. The m60's should be as forgiving as the 80's.

my guess it is a room issue, what is your floor and walls like? if you have hard surfact floor, try throwing a carpet piece or something between you and the speakers.
Posted by: Adrian

Re: Speaker Placement Problem - 08/18/13 09:10 AM

It sounds like a room issue to me as well, since both sets of speakers seem to having the same issue or at least some issue besides the speakers. As Randy pointed out, what kind of flooring do you have? carpeted or some kind of solid surface, hardwood/laminate etc.
Posted by: Ken.C

Re: Speaker Placement Problem - 08/18/13 09:34 AM

Randy, he's using a tube amp.
Posted by: MarkSJohnson

Re: Speaker Placement Problem - 08/18/13 09:59 AM

Welcome. I'm coming in late...

Did you verify that all drivers are working (not likely if your Polks sounded similar)?

Is it _possible_ that you're otherwise used to a "California-sound" that's bass and treble heavy? I know that this is not likely in that you probably have had the Polks for awhile, but every once in awhile someone drops by with new Axioms and posts that they feel disappointed in the sound and we later find out that they've been listening to _really_ inaccurate speakers for the last ten years!
Posted by: robrob

Re: Speaker Placement Problem - 08/18/13 03:51 PM

I'll try separating the speakers out farther. I haven't done it yet because of obstructions but with some work I can spread them out.

As I said in the first post the floor is carpeted and has a pretty thick pad beneath it. The walls are drywall. The room is about 17 feet wide and 30 feet deep. Ceiling is at two levels, about 9 feet over the speakers (drop ceiling) and about 7.5 feet over the listening area (drywall).

I do believe it is a room issue because both sets of speakers with two amps have the same nasty hollow vocals and mid freq spike.

I have a set of Cambridge Soundworks bookshelf speakers in the family room + subwoofer that sound great--very clean and transparent. I may try the M60s in that room just to see how they sound.
Posted by: SirQuack

Re: Speaker Placement Problem - 08/18/13 07:09 PM

or it could be where you are sitting in relationship to the depth of the room, you say 10ft back, how much room is behind you? If you move back further, if you can, does the sound change. You could just be sitting in a null, or half way position which would not be good.
Posted by: robrob

Re: Speaker Placement Problem - 08/20/13 07:39 AM

I moved the speakers around some more. Moving them out to 10' of separation (equilateral triangle) didn't help much. I moved them forward about 1 1/2' in front and 2' wide of the TV and that helped but I think that was more of a near field effect. I also moved myself around the listening area with little effect. I'm thinking the hard, high gloss drop ceiling may be the primary culprit.

I'm still planning to try the M60s in the family room and try the family room's good sounding bookshelf speakers in the problem room.
Posted by: cohesion

Re: Speaker Placement Problem - 08/20/13 08:10 PM

Any way to hang a big net or blanket full of pillows below the drop cieling long enough to test if it helps the problem?
Posted by: SirQuack

Re: Speaker Placement Problem - 08/20/13 11:00 PM

I have 3 acoustic panels on my ceiling
Posted by: robrob

Re: Speaker Placement Problem - 08/22/13 08:35 PM

Originally Posted By: cohesion
Any way to hang a big net or blanket full of pillows below the drop cieling long enough to test if it helps the problem?


That's a good idea. I'll try sticking some towels up between the ceiling tiles to act as temporary acoustic panel.
Posted by: CatBrat

Re: Speaker Placement Problem - 08/22/13 09:50 PM

Monkeys would work too. But, they are hard to catch and forced to stay in one place for long.
Posted by: robrob

Re: Speaker Placement Problem - 08/22/13 10:30 PM

I've always wanted an excuse to buy a monkey. Hmmmmm.