AudioCircle
Audio/Video Gear and Systems => The Acoustics Circle => Topic started by: kingdeezie on 21 Sep 2014, 03:19 pm
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Hello everyone.
So, I am completely lost. I have a 12x18 room, in which I have squeezed in a pair of GR Research LS6s. I know that the speakers are too big for the room, but I have to use what I currently have for now.
Over the years, I have moved the speakers dozens of time. I even had a professional set up the speakers, but wasn't happen then either.
I have acquired over time, a multitude of bass traps and treatments. I have all 4 corners completely trapped with GIK Tri Traps. I have the back wall treated with 3 Monster Traps across the back wall. I have a GIK 244 across the floor/wall boundary behind the listening position.
Behind the speakers I have three GIK 244s across the middle of the wall. Behind, and to the sides of the speakers, are one GIK monster trap, and two GIK 244s per speaker.
I also have GIK 244s placed along the side wall up to the first reflection points.
Overall I have something like 22 basstraps in the room, and some diffusion.
I still have problems with the bass. While there doesn't seem to be too much resonance, there is a lot of nulling. You can hear like on a bass line, it sounds sometimes like the bass "disappears" on certain frequencies. There also isn't as much definition as I would like either.
The other problem I have is vocal clarity. The vocals seem slightly out of focus and recessed sometimes in comparison to other parts of the music.
At this point I feel like I am not sure what to do from here. I don't know if I need more bass trapping, less bass trapping, different trapping arrangement.
Can a room be impossible to fix with treatments?
Should I just abandon the speakers for good, and try to get something smaller? Will a smaller physical speaker, but with similar extension just sound the same?
Any help would be greatly appreciated.
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Are you using a tube amplifier ?
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Have you measured the in room response of your speakers? IMHO this should be your starting point. REW is free and basic equipment to do the measurements is not too expensive, certainly less expensive than a couple of your bass traps. There are quite a few threads on AC regarding REW.
Best of luck,
Ed
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I am using a tube amplifier, yes. A Manley Neo Classic 250 set.
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Have you played with the settings for Bass on the crossovers?
Have you moved the speakers further into the room to check if it is in fact cancellation from nodes?
Definitely take measurements. Adjust from there. Once I got the bass issues reduced with my LS6's, the vocals improved quite a bit. Some diffusion can help too.
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Have you played with the settings for Bass on the crossovers?
Have you moved the speakers further into the room to check if it is in fact cancellation from nodes?
Definitely take measurements. Adjust from there. Once I got the bass issues reduced with my LS6's, the vocals improved quite a bit. Some diffusion can help too.
I have custom crossovers made by Purity Audio. The bass settings are not as clear on the crossover I have, versus the stock crossover. I have played with them a little bit, but never noticed it making a huge difference.
The speakers have been moved all over the place, using every variation of speaker set up out there. Wilson, Master Set, Vandersteen, etc, etc.
:duh: Can't get it figured out for the life of me.
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If your bass is erratic, might be your tubes. My 2 cents.
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I would start with getting a mic and using REW to measure.
To fix the problem you may need multiple subs to even out the nodes.
Re-positioning the speakers may help.
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I have custom crossovers made by Purity Audio. The bass settings are not as clear on the crossover I have, versus the stock crossover. I have played with them a little bit, but never noticed it making a huge difference.
The speakers have been moved all over the place, using every variation of speaker set up out there. Wilson, Master Set, Vandersteen, etc, etc.
:duh: Can't get it figured out for the life of me.
Try doing something completely different.... If you haven't tried Cardas, give it a shot. Also try the varying odd denominators (1/3, 1/5, 1/7, etc). Have you tried both the long and short walls?
(I'm assuming you're not concerned with a huge sweet spot. My speakers are for me, so if I'm "showing them off", I let somebody else into the good chair)
Move the speakers as far apart as you can while listening to a piece you are familiar with that has a very precise center focus - usually a vocal. Keep moving them apart while they are facing straight forward until the center image goes away. Toe them in just a fraction until the center image returns (a laser pointer can help here).
This is a starting point. Measure the position of the speakers in relation to the room. Figure out what percentage of the room you are at and see if you are close to one of the odd denominator distances. Try moving them to the nearest one (as an example, lets say it's 1/5 of the room width). Now move them away from the front wall a different odd denominator (1/3 or 1/7). Adjust the toe in with the laser so that you like the focus and the soundstage.
Don't be afraid to try something different (sounds like you've tried most things, but you never know. My room is about 15'6 x 17'6", not much bigger in area, but that 12' dimension you have is going to be tough.
Now it's time to play with the bass traps (leave the corner tri traps in place - they're great). Look at first reflection points first and put traps there (Side wall and front wall).
That's where I would start if you haven't done something similar already. I stumbled into a setup that I'm happy with that I never would have suspected - it was purely accidental. Speakers are much further apart than most would think reasonable with a bit of toe in. I have eliminated almost all of the nulls (based on readings from OmniMic)
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According to the link, the speaker designer says the absolute minimum distance between your ears and speaker should be eight feet.
http://www.stereomojo.com/LS6%20review/AV123LS6review.htm
If you sit too close to multi driver speakers these drivers don’t integrate properly and they won’t sound right.
If you put the speakers on the short wall you may be able to get eight or more feet away from them. You may have heard of ‘the thirds’ and ‘fifths for speaker placement. Sevenths are also possible as well as a combination of these. The purpose is mainly to reduce bass problems. You could try ‘fifths’ - speaker drivers and ears about 3‘ 7” in from the front and rear walls respectively with the speakers 2’ 5” in from the side walls leaving around 11’ 5” between your ear and speakers (if my use of Pythagoras’s Theorem is correct!). You could also try fifths on the short wall and sevenths on the long one, giving a distance of 13’ 4” from ear to each speaker. These are just starting points for you to manoeuvre around to try and get it right. Toe in comes after you’ve done this.
Forgive me if you’ve been through all this.
I would think you have plenty of bass traps etc..
I agree with those that suggest measuring. REW is the best way but it’s a lot to learn and set up. Test tones and your ears are easier if less accurate. You could download these for bass frequencies:
http://realtraps.com/test-cd.htm
Using an SPL meter may be useful too.
If you still can’t get it right try an equaliser. I use a Behringer DEQ2496 sitting between my CD Transport and DAC, and after positioning and room treatment, this helps improve things further.
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You haven't mentioned moving the "listening position".
If you haven't, chances are you are simply sitting in a high cancellation area.
Try moving closer, and further away in small (1") adjustments and see if you find any improvement.
Also, I have seldom heard deep bass from large Line Arrays (with smaller 6" woofers) in any room.
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couldn't you say the the vocals recessed is giving it dimension?
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It sounds like you've done all you can to fix the acoustic problem, so maybe the problem is coming out of the speakers. How can that be? This is the Acoustics Circle! DUH!
Maybe broken crossover or a shorted voice coil? Make sure all of the drivers are being electrically driven, not just pushed around by air pressure. Inspect the crossover circuits for connections, shorts, etc. Test the speakers' FR outside, away from reflections.
If you can use REW, do a FR to quantify the problem. Note the null freq. Then move the test mic 1 foot in any direction. The freq of the null should change. If it stays the same, it is because the speakers are "playing" the null. If you hear the null on a specific piece of music, walk around the room listening to that passage. If you here the same exact flaw while standing different positions then it is coming out of the speakers, not caused by the room acoustics.
Use your imagination, you'll figure it out!
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Measure using this - it's cheap and easy to plug into a laptop to get you going.
http://www.parts-express.com/dayton-audio-umm-6-usb-measurement-microphone--390-808
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You've probably already checked this--and it's the out-of-focus vocals that prompt the question--but is it possible that one of your speaker connections to the amp is wired out of phase?
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Well, if you've tried Cardas speaker placement and variations there of, if you've moved your chair to and fro, as well, you are about out of options. You have too much bass energy for your room size. Save your money, sell your speakers and some of all that treatment and invest in a smaller set of speaks. I just couldn't live with blown up bass, personally. Nothing wrong with your room size that a more modest size of speakers shouldn't improve.
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You've probably already checked this--and it's the out-of-focus vocals that prompt the question--but is it possible that one of your speaker connections to the amp is wired out of phase?
great point! even if it looks like the right speaker cable hookup (based on speaker post colors,) go ahead and reverse the SCs anyway, as an experiment, just to make sure the internal wiring is correct. If the two speakers are playing out of phase it would create room nulls that would match your symptoms.
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If you read Floyd E Toole's "Sound Reproduction" you'll find out that below the transition point (roughly 140 Hz for a given room) sound travels in waves (above that in rays). Toole (worked for the Canadian Research Center and later Harmon International) explains that these lower frequencies, in a residential sized room, behave like a shallow bath tub where you move your hand back and forth along the length of the tub to make waves. As the waves bounce off the end they return to interfere with the next waves, either adding amplitude or canceling. Where this occurs is frequency and room size dependent, so no amount of EQ or treatments can resolve this (short of total absorption). The solution as mentioned in a post above is multiple subs. Search Audio Circle for "swarm".
We are conditioned to certain sound environments, the typically sized/furnished residential room (like yours) is one of them, so lots of treatments shouldn't be necessary. In fact your room would seem to be approaching an anechoic chamber (total absorption that produces a very unnatural sound).
And sorry to say your room is a setup for echo, with length = 1.5 times width and width = 1.5 times height. This could explain all your issues. "Sound Reproduction" also explores the thinking behind proper room ratios and gives a suggested range based on results from several researchers.
And yes, an array should only be used far-field (much larger room than what you've got). You'd be much happier with a pair of stand-mounted speakers and multiple subs crossed over at the transition frequency (check out Duke LeJeune here at Audio Circle for his swarm offering).
Audiophiles should really start with understanding how rooms affect sound and provide speakers that complement the room, but few do. Instead we go for glamour and technology in obtaining impressive gear.
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WOW! Thanks everyone for the advice. There is a lot to digest on this thread, in terms of information.
The only thing I have left to do at this point, is measure it would seem. That is the most reasonable, in both price and execution, thing to do at this point in time.
It also seems to be the common running recommendation here. I am going to put an order in for that mic that Tyson posted (thank you), and I'll get started on measuring as soon as it arrives.
I'll post the graphs here as soon as I have them, and you guys can tell me what the situation is.
Thanks again for everyone's input.
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Measure using this - it's cheap and easy to plug into a laptop to get you going.
http://www.parts-express.com/dayton-audio-umm-6-usb-measurement-microphone--390-808
I don't want to detract from this thread too much, but are you saying that this Mic plugs right into the USB port on a Laptop and works with REW? It used to be considerably more complicated than that.
Will any USB Mic now work with REW?
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The comment that they may not produce deep bass is incorrect. The LS6 plays into the 20's, but the 6's and 9's are known ("notorious" might be more descriptive) to overload rooms. Traps, diffusion, professional advice, and lots of time moving things around are what it took to finally get my LS9's right. Measurement will certainly be the most likely path to good results.
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WOW! Thanks everyone for the advice. There is a lot to digest on this thread, in terms of information.
The only thing I have left to do at this point, is measure it would seem.
You mentioned in your original post that, at one point, you had a professional set up your speakers. Well, didn't this guy perform lots of measurements? If not, what "professional" service did he provide?
Also, can you post pics of your room and setup? That would be helpful.
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I don't want to detract from this thread too much, but are you saying that this Mic plugs right into the USB port on a Laptop and works with REW? It used to be considerably more complicated than that.
Will any USB Mic now work with REW?
Yes, it plugs directly into a USB port without a separate USB audio interface. Any USB mic would work with REW, but unless it comes with a calibration file, the accuracy and results would be questionable.
Steve
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This is the one I purchased to use with REW, it is calibrated and comes with calibration files.
http://cross-spectrum.com/measurement/calibrated_umm6.html
Scotty
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You mentioned in your original post that, at one point, you had a professional set up your speakers. Well, didn't this guy perform lots of measurements? If not, what "professional" service did he provide?
Also, can you post pics of your room and setup? That would be helpful.
The setup was done more with a mathematical methodology. He had a formula based on my room measurements that he believed gave optimal positioning points for avoiding nulls and peaks for both the speakers and the listening position.
Since this person also recorded and mixed, he had his own references that he used to ascertain the effectiveness of the positioning. By, I am assuming, comparing what he created when mixing, versus what he was hearing in my room.
This person did this for me, more as a favor. I wasn't charged for the room setup. He initially came over to set up my turntable, and stayed to fix my speakers. But, he seemed pretty satisfied with the results, after spending a couple of hours positioning.
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MAN!
I think its time to just get some headphones, and be done with this mess.
I took some measurements, and I either don't have the microphone setup properly, or my room has the WORST acoustics on the planet. It looks like I have no room treatment at ALL!! :duh: :duh: :duh:
(http://i475.photobucket.com/albums/rr114/kingdeeziesgym/Measurements/sweep.jpg) (http://s475.photobucket.com/user/kingdeeziesgym/media/Measurements/sweep.jpg.html)
Where the hell do I go from here?
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First thing is to change the "y" scaling to 5dB.
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How do you change it? I only see how to limit the range.
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First thing is to change the "y" scaling to 5dB.
Also adjust the range to 45-105dB
I also sent you a PM.
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Man,
Measuring was probably the worst thing I could have done!
I feel completely horrible now.
There are 30DB swings in the bass region with a crap ton of treatments! There is a huge null in the high 100s.
Depressing.
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(http://i475.photobucket.com/albums/rr114/kingdeeziesgym/Measurements/sweepcloseup.jpg) (http://s475.photobucket.com/user/kingdeeziesgym/media/Measurements/sweepcloseup.jpg.html)
That is a closeup from 20HZ-300HZ.
Like a six flags ride.
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Never rely on measurements to tell you what something sounds like. They are only guidelines. Your ears are the most important measuring device.
It is like some of my female personal training clients relying on the scale to tell them when they are "in shape".
Now if your ears are not hearing what you like, THEN the measurements may tell you where to start and specifics of the anomalies.
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Man,
Measuring was probably the worst thing I could have done!
I feel completely horrible now.
There are 30DB swings in the bass region with a crap ton of treatments! There is a huge null in the high 100s.
Depressing.
Don't feel bad, most rooms are horrible, and to fix that null at 50Hz would require very deep bass traps.
You should be able to fix that with additional subwoofers.
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Don't feel bad, most rooms are horrible, and to fix that null at 50Hz would require very deep bass traps.
You should be able to fix that with additional subwoofers.
The Null at 50HZ is the least of my problems.
What about the raging null at 150HZ+ ? That is around the vocal range correct?
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Never rely on measurements to tell you what something sounds like. They are only guidelines. Your ears are the most important measuring device.
It is like some of my female personal training clients relying on the scale to tell them when they are "in shape".
Now if your ears are not hearing what you like, THEN the measurements may tell you where to start and specifics of the anomalies.
I really hope you're kidding. This is the WORST advice I've ever seen in the acoustic circle. It's a FACT that it will sound better. There is no denying it. :duh:
What is your position within audio? I need to know what to stay away from. :thumb:
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I really hope you're kidding. This is the WORST advice I've ever seen in the acoustic circle. It's a FACT that it will sound better. There is no denying it. :duh:
What is your position within audio? I need to know what to stay away from. :thumb:
I think maybe you misinterpreted what JC was trying to say, which was simply to trust your ears first. I can't agree more. A set of measurements can only inform the listener why speakers may or may not sound good. They can't explain what they sound like. Frequency response and other measurements merely explain aspects of a speaker, but not all aspects that affect the sound waves that reach our ears.
I'd never go buy a pair of speakers just because they measured flat. I'd have to hear them first. A flat frequency response is not insurance that they'll sound good. I think this goes without saying.
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That is correct, I have heard hundreds of rooms, speakers, and components that were claimed to have incredible measurements, that "sounded" horrible, and others that did not measure as well that sounded "right".
But, I also said that "if" it sounds bad, looking at the measurements can be the right place to begin.
It is the old "obs" versus "subs" discussion, that is as old as AUDIO.
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BIG +1 to the last couple of posts. :thumb:
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Good job on the measurements, now you have a baseline. Next step - move the speakers forward toward you by 2 feet and re-measure.
Then move you listening seat forward and backwards and remeasure each time. This will give you a very good idea of the overall behavior of your room and let you work with its acoustics instead of fighting against it.
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The Null at 50HZ is the least of my problems.
What about the raging null at 150HZ+ ? That is around the vocal range correct?
150 is not of concern for vocals (maybe baritone).
IMO the 50 Hz null is going to be the hardest to fix.
As Recomended move the speakers and retest, but before you do that take 2 more with the speakers where they are, one in front of the current spot by 2ft, and one behind.
Then again take three measurments with the speakers moved.
This will help you see what can be fixed the easy way (moving speakers and or listening position).
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I really hope you're kidding. This is the WORST advice I've ever seen in the acoustic circle. It's a FACT that it will sound better. There is no denying it. :duh:
What is your position within audio? I need to know what to stay away from. :thumb:
+1.
Best,
Anand
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+1.
Best,
Anand
-1 Do people not read through threads and others' responses (addressing what has been said and misinterpreted), before posting a completely pointless response of their own?
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Another vote for multiple subs. Easiest thing in the world to, borrow a subwoofer with extension to 20hz, place against the back wall of the listening room and operate 180 degrees out phase. This should help flatten out the response curve. The suck out at 150HZ could be some kind of floor or ceiling bounce cancellation. Also depending on how far the speakers are located from the front wall it could also be a cancellation problem resulting from a multiple of the distance the speakers are from the rear wall. I also have a notch at the about same frequency which is made doubly bad by a combination of two walls that are multiples of the same frequencies wavelength away from my speakers.
If the out of phase sub-woofer located on the rear wall helps flatten out the frequency response below 150Hz you have a clear direction to go.
Either place multiple small subs around the room ala Duke Lejunes swarm system or two subs at the rear wall of the room, 180 degrees out of phase. It appears that the Behringer iNuke amplifiers with DSP/variable digital delay built in, will allow you to cancel out the bass waves coming towards the rear wall before they can reflect off of the wall and cancel out the bass which causes most of the peaks and nulls see in the bass response curve.
Both approaches will even out the bass response curve everywhere in the room instead of just at the listening position.
You might measure the speakers with no room treatment to get a base line on how bad it is and then experiment with room treatment location if possible. Maybe relocating the room treatments will improve their effectiveness. If you are using the REW measuring software you might look at the RT 60 values which indicates how long it takes the bass energy at various frequencies to decay down by 60db you also look at the RT 30 values.
As far as the vocal intelligibility is concerned, the sheer amount room treatments may have impacted how they are perceived as an unfortunate unintended by-product of trying to solve the bass problem.
One question, is your listening room located in a basement?
Scotty
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Bass traps are kind of worthless if they are not tuned to absorb at the problem frequencies, so they might actually be making things worse. Multiple subs is the way to go.
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What about the raging null at 150HZ+ ? That is around the vocal range correct?
That's floor bounce, for all intents and purposes disregard. Move your mic up or down a foot and see how that suckout changes, it's just a measurement artifact.
A couple thoughts. Room treatments will not 'fix' a speaker. And measuring bass in room is at best, inaccurate.
So to combine those two points, it's possible your speakers are simply way out of balance and are voiced to be way too bass heavy. Room treatments will not change that if it's the case. Also it's very possible that things like that big bass bump shown around 30hz don't really exist.
The proper way to measure would be 2 different data sets:
- The speakers in a much less room influenced environment, like the back deck. Measure at 2m with a gated and ungated with complex smoothing. That will give you a good idea of what the speakers are doing.
- Then measure the speakers in the room, but not FR, measure RT60 and similar energy storage. That will tell you what the room is doing.
Either your speakers aren't doing what you want, or the room isn't. Or both. But until you separate the two pieces you'll just chase your tail.
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Bass traps are kind of worthless if they are not tuned to absorb at the problem frequencies, so they might actually be making things worse. Multiple subs is the way to go.
That's true, and not true ... depending on the definition of bass trap.
Many people think 2" wall panels are bass traps, they're not. Bass trap means bass has similar absorption numbers to other higher frequencies, that means much thicker than 2" panels. You won't make things worse with even broadband absorption of a real bass trap, but you can make things worse with too much narrow band absorption.
Can't remember Chris if it was in this thread or an email, but I did suggest removing some of the thinner panels from the room that primarily absorb 200hz and up. See if removing some of that narrow band absorption will help to bring up the midrange/treble, and help to balance things.
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If he can move the measuring location even a few inches and measure a completely different response curve below 150Hz we know that the room treatments have had very little effect on the bass resonance behavior of the room.
I don't think he has too much speaker for the room, as it doesn't exactly look like he has so much room gain below 100hz that his bass has a subjectively louder quality than the rest of the frequency range. Of course I could be wrong having never heard his system in his room.
Did Chris describe his room as sounding kind dead from mid-range on up.
Scotty
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If he can move the measuring location even a few inches and measure a completely different response curve below 150Hz we know that the room treatments have had very little effect on the bass resonance behavior of the room.
The FR is going to change as you move around the room, effective room damping or not. That's why looking at decay times is a much better indicator of how the room is performing, FR is room+speakers and that's 1 too many variables.
I don't think he has too much speaker for the room
The "too much speaker for the room" ideology for the most part is a myth. A 60hz wavelength is 18' long whether it's coming out of a 5" woofer or an 18" woofer. The speakers balance is what matters. The only truth to the myth is that larger speakers will tend to have woofers close to the floor which increases gain, and potentially larger speakers will be closer to rear and side walls, again increasing boundary compensation. But that's not a function of the size of the speaker, the same would be true if you put a monitor with identical FR balance in the same room location.
as it doesn't exactly look like he has so much room gain below 100hz that his bass has a subjectively louder quality than the rest of the frequency range. Of course I could be wrong having never heard his system in his room.
It's hard to say for sure looking at a small image on a 20db scale, but to me it looks like the bass level is about 6-10db up from the average midband level. That's some pretty serious imbalance.
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Hi Vapor
Put the woofers of your speakers close to the floor,worked best for me,it acts as a baffle for bass
the mids place them close to the tweeter and the tweeter at the top of your speakers
great technigues... :green:
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So, a lot of information in this thread.
I don't have any thinner panels in the room. Most of my panels are listed as bass panels by GIK acoustics. I only have one panel that is actually a reflection panel.
The rest of my room is mostly Monster and Tri Traps, with some 244s as well.
The problem is not the midrange or highs at all. It is 100 percent bass. There are definite peaks and valleys that I can hear throughout music as I am listening. It doesn't sound tight, punchy, or even.
Now, of course, unless the speakers are broken (doubtful), then I doubt that is the problem. Many people have these speakers in their rooms, and have presented with significantly better graphs then above in their rooms.
I live in a townhouse, and the room is tiny. I don't think multiple subwoofers is really going to be a viable option.
I think at this point, if I can't fix the problem by positioning, I think I have to get out. Maybe get a headphone setup or something like that.
Its been years of trying to get this room to sound right, and it just isn't fun anymore.
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Why would you give up completely?
I would start with removing all treatments and measure again.
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JRace is right - you've never measured your room without any treatments. Best to do that first, then add back the treatments, one at a time, listening and measuring as you add each one.
Using multiple subs is one way to address intractable room interactions. Another way is to use OB bass instead of closed box bass. OB interacts with a room quite differently than box speakers. I do think that a line source is probably a poor fit to a tiny room.
At this point I think you have 2 options:
1. Stick with your current speakers, and use a combo of acoustic treatments and EQ to get it sounding decent. If you go this route, I'd strongly continuing down the measuring path we've outlined here. In addition, once you get speaker position and listening position optimized (as much as possible), check out the miniDSP DIRAC - it is the most sophisticated (smartest) room EQ solution I've seen.
2. Try an OB solution. I'd recommend starting with something cheap and super easy, like the Hestia project documented right here on AC - http://www.audiocircle.com/index.php?topic=108003.0 I think you will be surprised how well OB's do in the bass region compared to box speakers, especially in a room like yours.
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First off - you have GIK products. Definitely feel free to send me an email and I can work you through getting the best out of what you have. My email is on our contact page, or just my first (dot) last initial @gikacoustics.com. To make a couple of quick points:
Your measurements are actually not nearly as bad as many many other measurements we see every day. Some of the major issues are large dips which can, often, be solved by finding better speaker or listening positions (or both). Also, you're only viewing the frequency response graph - which is the graph that contains the least amount of information about your room to look at. The waterfall (and similarly the spectogram) inside REW can tell you a lot more about the sound in the room. For a more in depth discussion on waterfall graphs and decay times, see here: http://www.gikacoustics.com/understanding-decay-times/
Decay times are largely the biggest factor in how we perceive the sound of a room, and is likely why, even though your frequency response wasn't perfect (it never is), the room still sounded excellent to you - because the decay was controlled well. Know that even professional purpose built studios will have +/-10 dB at listening position throughout the range.
Also note that, depending what you're looking at, you usually want to take measurements with single speakers at a time - not both - otherwise you can introduce comb filtering to the measurement that actually isn't in the room.
Dips around 100-200 Hz are normally caused by SBIR, which you can read up on here: http://www.gikacoustics.com/speaker-boundary-interference-response-sbir/
Changing the position of speakers or putting panels between speakers and wall boundaries can reduce these effects.
Of course like I mentioned, please drop me an email. I just wanted to pose some solutions and ideas to the thread so if others wander in with the same issues and questions, they aren't lost!
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kingdeezie - I suggest you accept Alex Reynolds offer. I used their advice in the past and am very happy.
GIK sell Soffit Traps which absorb deeper than Tri-traps.
I too used REW to help get my room better. This is what I did:
First I measured with REW and microphone to get a reasonably accurate picture. Then I use test tones and my ears to finish. Then I check with music.
With REW I place the microphone (m/f) exactly where each of my ears will be when listening. For measuring the left speaker, the m/f is placed where the left ear will be.
For finding the best speaker and ear positions, I only use 20-500Hz plots and am looking for the smoothest response; that is fewest peaks and dips. Make a plan of the room and mark the positions of the speakers and listening chair/ear/microphone for each measurement. Unless you have side firing woofers you needn't worry about toe in yet. Use just one speaker to start with and then when you've found the best position(s) for that, try the other one. Start off roughly where you think it might sound good, measure, make notes, then move speaker, measure etc.. Use large movements of the speaker to start with - say one foot - and then home in on the best areas with smaller movements. However even the best location will leave some problems. The object is to minimise them (I tame the worst peaks later with an equaliser). The dips I have, which look awful on the charts, do not seem to have an impact on the sound. This illustrates a key point, as John Casler tried to point out; these charts are only a guide to getting good sound. For getting the best sound for you, you must use your ears.
Microphones don't hear like your ears. For one thing your ears hear differently as you age, or suffer hearing damage. For another our ears (or rather our brain) can differentiate sounds. Microphones pick up everything. Indeed in my room I couldn't rely on measurements of 50Hz and below because of background noise (from traffic and other things I presume which I hardly notice. REW can measure background noise).
To finish off the measurements then, I use test tones and my ears. I play a full run of 1/3 octave test tones and write down how they compare with each other. I did this for both speakers at the same time. I then adjust my equaliser and repeat. In this way if you have a weakness in hearing this should cover it. I can't hear much above 10kHz, and 6.3 and 8kHz require a 4dB boost to be level with other frequencies.
Then I play music. I found that a very few tracks were boomy with some bass and, using test tones which go from 10-300Hz in steps of 1Hz, which I got from here:
http://realtraps.com/test-cd.htm
I found that 42 and 43Hz had peaks. I was able to knock these down with my equaliser. Incidentally with these test tones I found the large dips had no effect on the sound. Perhaps they are so narrow as to have little effect.
I'm not saying that all this has resulted in the world's best listening experience, but what it has done is improve what I hear from my system. It took me some eight months to get to what I have now. I found there were two speaker and ear locations in my room that gave the best measurements. These corresponded to roughly 'the thirds' and 'the fifths' - speakers and ears one third or one fifth in from each wall and ears the same from the back wall. After a four month trial I found 'the thirds', whilst interesting for three dimensional sound, never seemed quite right. Either this was because I hadn't done it right, or because the Red Book CDs I play - mostly studio recordings - just didn't offer the right information. So now I use 'the fifths' for a wider but shallower soundstage, and that's what I prefer.
Room measurement is complicated but I consider it essential for adjusting speaker and listening positions. Ultimately it must be based on what you hear and how the music sounds to you.
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Thanks to everyone that responded in this thread over the last few days. Ive been fighting off a stomach bug for the last few days, so I haven't had a lot of time to mess with the speaker set up.
Alex, I will definitely send you an email to see if there is anything I can do with the traps I have now that might improve the response. I have a combination of monster traps and 244s behind and to the side of the speakers on both sides.
I am hoping to feel better by this weekend, that way I can get some work done around here to try and improve the response.