Acoustic treatment can help but don't expect miracles. Good start, BTW.
These other frequencies can be harmonics or "half-harmonics" of the main frequencies. What I mean by the latter would be, for example, 100 and 150Hz. Start in the corners behind the speakers. If you want to try before you buy, hang blankets,towels, or futons pads and try the test again. |
The room dimensions and speaker positioning are going to dictate the peaks and dips more than anything. Such large nulls would be difficult to treat.
I suggest you move the speakers around the room if possible; maybe to the adjacent wall or even firing across a corner. If you can't achieve good results like that, then perhaps considering a different room (or headphones) would be warranted.
Happy Experimenting! |
You can't/it's difficult to correct for nulls/dips except with placement. The best placement will always have peaks and dips, except with perfect placement in a perfect room
All one can do is smooth out the peaks, With treatment, or with EQ. It difficult to impossible to correct for the nulls, unless you are using EQ with active crossovers.
Good luck! |
You have to understand the nature of nulls, meaning that a null is a depression in frequency response due to cancellation effects based on room interaction.
A null can not be tuned out by passive attenuation which is what room treatments can accomplish. You must redirect the energy by repositioning or by adding more bass energy to compensate for the null.
|
good morning, have you tried THE RULE OF THIRDS for your speaker placement? |
Thats the whole idea. Well part of it anyway. To reduce standing waves (peaks and nulls), along with modal ringing, which is just as important. To absorb or diffuse sound in the room to avoid ringing and flutter echoes, and improve stereo imaging. This is some of the things that acoustic treatment helps with and which EQ cannot. Now about those acoustic resonators....
Bob |
Hi Jim,
Welcome to the wonderful world of measurements. Its seems to me that you have two basic choices.
1. Move your speakers and listening position about until you get the best subjective results and then stop. Trust me, few do better.
2. Get serious about measuring and the post your results so others can coach you through the process of taking measurements and interpreting them. Expect a serious learning curve. You may eventually opt for room correction, but you should be properly informed before spending. New speakers may be far cheaper - or may do nothing to correct the problem. I went for a Tact unit and a sub with my dipoles. I am happy with the results, but it took a while.
regards,
Sam |
What I didn't expect was 10 to 15 hz. wide nulls (-10,-15,even -20 db.) at several other frequencies. No need to panic. This is quite normal. Do as Plato suggests first (try speaker positioning). You will need very serious room treatments for these null problem areas if they are below 60 HZ (and I doubt you can cure them entirely without turning your room into something like a set from Flash Gordon). Fortunately you don't need to cure it entirely. For starters, you can easily reduce the worst bumps with a PEQ. (Bumps are more of a problem due to their masking effect). Although nulls cannot be boosted (can't boost what is not there)....smoothing out the peaks will really help. Try listening to Rebecca Pidgeon The Raven, "Spanish Harlem" and adjust so that you can hear the bass notes evenly and with roughly equal loudness. Good luck... |
When I have these issues, I end up using two tools. The first one is a rough estimator and it's online. CaraQuick Just punch in the dimensions of the room, fill in a little bit about your room (number of chairs, etc.) and then pick a loudspeaker in their dropdown that is close enough to Maggies. Main thing here is you can move your listening positon and speakers around and see the nulls come and go. Then I use a measurement device like the Velodyne SMS-1 ($600) to read my room realtime and deal with the small movements, even if you don't use the subwoofer EQ function. There are cheaper analyzers, but I use it cuz I also EQ my subs. Start with the Cara and at least find out what you're dealing with. |
"New speakers may be far cheaper - or may do nothing to correct the problem".
How would changing speakers change the room acoustics?
bob |
Either acoustic treatment such as tube traps or electronic EQ can help. Neither is easy to do but both are worth it |
Speaker and/or listener placement along with capacitive style low frequency traps can help. The first thing is to figure out why you have the nulls. Are they uniform around the room (a suckout), are they caused by a piece of furniture (I've gotten my share of surprises here), or are they a basic function of room dimensions. I won't go into great detail for any of these, but rule out furniture first--remove anything that might be causing the problem and remeasure. Second is to map the room with your problem freuqencies--do they vary relative to the wavelength of that frequency? If so, it's a basic room mode issue. Placement can be a big help here as can the traps. Now one thing you need to be aware of is there will always be one frequency at the centerline of the room that will be peaked, and another nulled. There is very little you can do about this with parallel walls. Calculate F1 and F2 for the width and that will tell you what those frequencies will be (this assumes you sit at the centerline of the room as most people do--while it has modal issues it typically has the best imaging). Now if there are other freuqencies you can see if you have an 1/4 wavelength cancellations. Are the speakers 1/4 of a wavelength off a boundary of that frequency? If so, they are cancelling that frequency out to some degree and should be moved to a distance that helps balance other peaked modes. Sounds easy--but it's a little more daunting because you'll find you will fix problem A reduce problem B and create a new set of problems. Here is a link which may be of more help on this issue. Rives Audio Listening room tutorial. There are also some good software programs such as Cara and RPG room optimizer that can help you as well. |
Thank you all for your responses. I was hoping to see 7 or 8 posts saying that's easy, diffusion. But I posted to leverage your experience before purchasing and it has already paid off.
Did a little more testing and review of the data. Found some hope in speaker placement and an interesting (and depressing) overall trend.
The room is a 60' long X 30' wide irregularly (almost a backward L) shaped finished basement. There is a "stadium" wall 9' wide at a 45 degree angle in one corner. That is where the system is set up, shooting out into the long part of the room. The only wall parallel or perpendicular to the speakers is the angled "stadium" wall. I think this contributes to the lack of boomy nodes.
The really serious nulls (-20 db.) are very location dependant. Move your head (or the meter) a foot or two and they change. Common sense seems to say that you would never be able to eliminate all the 2, 3, 4 hz. wide strong cancellations at a single position.
I moved the 1.6's straight back 5 inches and most of the nulls improved 4 or 5 db. I don't know if I like how it sounds as much (soundstage), but I may have to move my listening position to correspond to speaker movements. Classic chasing your tail.
The disturbing overall trend is.... the 1.6's probably average -7 or -8 db. from 80 hz. to 290 hz. (the range of this test CD is 10 hz. to 300 hz. in 1 hz. increments). That seems like a lot. A quick review of old Stereophile freq. response graphs shows the speakers fairly flat from 50 hz. to the crossover @ 600 hz.
Care to venture an opinion of the trend?
FYI- The 1.6's are -15db. @ 35hz., -7db. @ 40hz. -3db. @ 47 .hz or so. Didn't change a lick with speaker movement or starting SPL.
Jim S. |
Again, THANK YOU ALL for taking the time to post your thoughts, even as I was typing the extra information above. I would have posted more at first but didn't want to complicate what may have been a simple situation.
You have provided a multitude of great places to start.
And the measuring will not be... the be all, end all. I was just very impressed with the clarity in our friends heavily treated, dedicated room and was hoping to add a little bit of that to my system. It may be that I can't get there with the components I have, but, any room improvements will be in place as I move on.
Will update as I try your suggestions.
Jim S. |
The worst room I ever heard had one 8' diagonal wall in the rear corner. It had two 300Hz nodes just in front and to the side of the listening position that were painful, even with music. I helped him get some materials for DIY tube and panel traps and that helped quite a bit, except aesthetically.
You might have to completely rearrange the room with the speakers on the long or short wall. The good news is you have lots of room to deal with and, apparently, bass is not the problem. It's easier to deal with higher frequencies. |
Ngjockey,
Thanks for the reference information. I was actually hoping the nonparallel walls would be helpful, not detrimental. Such is life!
I have some work to do. I now have an idea what to look for. I will do more detailed measuring with the easy modifications and see if I can't find a pattern as you and others have suggested.
I can eliminate the furniture 1 piece at a time and make sure it is not a suckout issue. There is an open stairwell right around the corner from the listening position that may be providing a broad suckout. Not as easy to deal with, but I can work a temporary solution for testing.
Anyway, thanks for your time and advice!
Jim S. |
Did you take in to consideration the fact that the Radio Shack SPL meter is not acurate? There is a page that shows the corrected calibrations for that specific meter. So your room may not be as bad as you thought. I will try to find that info for you if you dont already have it. |
Here it is, I knew I seen it somewhere.. :)
http://forum.audiogon.com/cgi-bin/fr.pl?htech&983682086&openflup&1&4 |
Possibly putting a diffuser behind each speaker could help since you're dealing with cancellations from the rear output waves colliding with that of the front wave.
I had a room similar to yours and it was kind of tough finding the best speaker position and the best listening position. I had Acoustat dipoles and I recall that the bass was all over the map depending on which wall the speakers backed up to and where the listening seat was. With a lot of trial and error, you can probably find a configuration that will work pretty well. I remember that the Room Tunes worked very well in that room as did some home made Helmholz resonators (like the Argent room Lenses). Good Luck! |
Plato,
Thanks for the encouragement. I will work at it and see what I can learn.
Soundgravy,
No, I did not know the Rat Shack SPL meter was seriously inacurate. I will reread the thread (probably many times) and try to understand. Thanks for posting.
BTW- Do you guys miss Sean? (From the RS meter thread, and many others, that Soundgravy cited.) He really relished the technical and did a lot of work to solve problems. I notice he doesn't post as much as when I started following Agon threads.
Jim S. |
60 by 30 L
you could build a room in a room and get a great setup
that's a cavernous space to fill |
the 1.6's probably average -7 or -8 db. from 80 hz. to 290 hz. (the range of this test CD is 10 hz. to 300 hz. in 1 hz. increments)....
FYI- The 1.6's are -15db. @ 35hz., -7db. @ 40hz. -3db. @ 47 .hz or so. 1 - don't measure in 1Hz increments. No speaker/room will measure smoothly at that level. Use either broad band noise or a slow moving sweep type signal to measure. 2 - Are you interpreting your measurements correctly? Rather than a broad dip from 80 to 290Hz, do you really have a boost in the 40 to 80Hz octave? If so, it's a fairly common problem that in relatively easily solved. How does the overall bass level compare to midrange (400 to 2000Hz) levels? |
Onhwy61,
Understand your first point. I am trying to look at trends over 20 to 30 hz. ranges. Started with the LF as it seems from previous threads that is where the largest gains for the effort come from.
I was thinking about your second point last night and wondering the same thing. Am I misusing or misunderstanding the info? The CD I am using for LF is from Real Traps. The CD has a white noise track to set a start level. I have assumed that start level would correspond to an SPL baseline and db. readings above that baseline level were bumps and below were nulls. That may be correct, but not necessarily so. If not correct, the data is valid (the amplitude swings are still there), but the description and amplitude I had assigned to null and bump are invalid.
Anyway, I should have done a little more prep work and broader data gathering before posting. I may have jumped the gun. Back to work on it.
Audiotomb,
Yeh, I wish I had 1800sq.ft. to play with. It is an odd shaped room that follows the contours of an irregular foundation. Because of the backwards L shape with a few extra zig-zags thrown in, the usable space is much smaller There are framed in steel support columns and beams. Also seperate rooms for laundry/storage, furnace/water heater and a bathroom with a Jacuzzi. Why the previous owners put the Jacuzzi in the basement is anybody's guess? Sounds a lot bigger than it is.
Thanks for your observations.
Jim S. |
I'm with Onhwy61....you probably have typical room bass boost. You need to tone down those bass bumps rather than boost 80 to 300 Hz. Secondly, above 200 Hz...you are dealing with wavelengths of roughly 5 feet...don't expect any kind of smooth response here as movements of a couple of feet of the SPL meter will give you nulls when playing pure test frequencies. (for example quarter wavelength cancellations off the back wall behind the speakers is typically evident with a series of nulls from 40 up to 500 Hz depending on speaker placement) See this link Quarter Wave Cancellations Explained The above is why I have soffit mounted my speakers into a heavy braced wall cabinet. This is most important for larger three way full range speakers and is why you see soffit mounting of studio main speakers in almost all studios. (The difference is very audible as you can imagine by looking at the frequency response curves shown in the URL example I gave you above) Finally, I suspect a 1 Hz pure single frequency test tone with an SPL meter is likely to lead to frustration unless you are an expert like Rives and know how to interprete it. For example, imagine (in theory) that your speakers are perfect ( zero distortion ) then you will get enormous peaks and nulls with single pure frequency test tones (as the ONLY frequency in the room is exactly what you input to the speaker). Alternatively, imagine your speakers are more normal or typical (with 50 % distortion in bass frequencies when played at louder SPL levels ) then you will get a beautifully smooth balanced SPL response when playing pure single frequency test tones (because not all the harmonic distortion will be affected by the room in the same way as the fundamental - and SPL meter will pick up the average) How's that for counter-intuitive.....two different speakers placed in the same position in the same room and the better speaker SHOULD measure far far worse! How's that for counter intuitive....an amplifier with higher amounts of harmonc distortion may actually sound more balanced compared to a perfect amplifier with zero distortion, as it is less ruthless on room modes. All this is because nulls will be their very worst when you have pure single frequencies.... So be very careful interpreting 1 Hz pure frequency test tones! (It is unlikely that kind of purity is actually coming out of your speakers unless they are incredibly good and you have an amplifier with very low harmonic distortion) |
Ok, I got it. To do a really serious analysis and correction, I am in way over my head and resources.
But, believe it or not, what everyone has generously posted makes sense and has helped my understanding. I just don't know enough to know how to make a direct quantum leap in results (it ain't gonna happen overnight). I do know that a little knowledge is dangerous, so I will go slow, keep studying, keep measuring, and keep experimenting. I will post the setbacks and breakthroughs.
Thanks and Best Regards to All,
Jim Still |
Jim:
I like your attitude--and I think it's exactly right. You won't make that quantum leap overnight--but you can read, understand, try some things, and make progress over time. I wish everyone would deal with their room. Whether they hire a professional or take some sound advice (pun intended) and work through the issues themselves over time, the room is almost always the limiting factor in good sound.
I would recommend the book Alton Everest Master handbook of Acoustics. It's available through Amazon and is an excellent overview on the subject. |
I had a deep null in mid to low bass right where I wanted to sit. Then I noticed that the bass would almost blow your hair back in other parts of the room. I made a series of bass traps and I wouldn't have believed anything could be so effective. It's still slightly peaky at certain frequencies but not bad. I'll probably get a digital eq eventually.
BTW, my listening room (built before I moved into the house) is of horrendous dimensions. Very close to 1 x 2 x 4. |
Per Shadornes' reco I purchased Rebecca Pidgeon, The Raven. Shadorne is absolutely correct. On "Spanish Harlem", the bass sequence cleary shows intensely audible bumps. Dumm, BOOM, BOOM, - BOOM, BOOM, Dumm, - BOOM, Dumm, Dumm. It is not subtle, nor musically pleasant.
I have heard the BOOM and new it existed in the setup. I use the bass boost from the room nodes to alter (amplify) the lower-mid bass for some of the music I like. But taken as a single note, it really sounds horrible, bloated, and out of place.
Very enlightening. The Raven is pretty good music too.
Best Regards,
Jim Still |
Stilljd,
I am glad this helped. It is an idea straight from recording engineer Bob Katz and his book on Mastering.
The single biggest benefit is that this track gives you a clear idea of just how room modes affect real music. |
I have discovered a new way for the CIA/FBI/DOD to coerce information from suspects. Make tham listen to test tones all day! Doing room measurements manually with a CD and RS SPL meter is agonizing and time consuming.
Jim S. |
I said I would try follow-up with the setbacks and breakthroughs. I do not know how to post the graphs in this format so I will just try to accurately describe the highlights and observations.
I spent 2 days measuring under the most controlled circumstances I could manage. Focusing on speaker position, this is what I found.
Started at my established listening position. Speaker centerlines - 50" from back wall, 83.5" apart, 36.5 from angled (45deg) sidewalls, and 115" from listening postion. Speakers were tilted back 4 degrees (guess, one washer in the bottom of the stand mount, will measure exactly later).
I will descibe the sequential set up for 7 different test runs with the Real Traps Test CD, because the measured results changed very little.
#0.. Baseline
#1.. Changed tilt to upright.
#2.. moved speakers straight back 6".
#3.. moved speakers forward 12".
#4.. moved speakers toward each other 6" each.
#5.. moved speakers back 6".
When I sat down and graphed the numbers...
Steady rise from 53db @ 32hz. to 63bd @ 38hz
6db drop @ 42hz. rising steadily to 76db @ 55hz.
9db dip @64hz rising to 77db @ 70hz.
Drops to 67db @ 86hz.
Rises to a steady 69bd @ 90hz. to 118hz.
Starts to dip steadily @ 118hz. to 53db @ 138hz.
Broad null for 10hz.
Rises steadily to 67db @ 172hz.
Things get real eratic at this point with wide 2,3,4hz wide swings down to < 50db and back up. Does seem to be another deep (<50db) broad null at 230hz. to 270hz.
In general terms, and to my untrained eyes, I have a big boost from 45hz to 82hz with a little dip thrown in the middle of that, another small dip @ 85hz, and 2 serious nulls @ 135hz to 175hz and 230hz. to 300hz.
Experimenting a little more
#6.. Opened laundry room door, checking for suckout.
Virtually no change. (big surprise).
#7.. Pulled single speaker out into middle of room (13' from back wall, facing into open area) and measured @ 2' with mono source. (closed LR door)
Same pattern of boosts and nulls, just a little less dynamic. Who would have thought? The tones really started to audibly oscillate @ 105hz through 135hz. Reinforcement/filtering, who knows?
Really surprised me how little the pattern changed through all 8 tests. I took the time to listen to familiar music in-between each test run and the position changes were easily perceptable.
At this point, I have some acoustic reference material coming for study so, although I can recognize the pattern, I don't know what it really means.
Other interesting (to me) observations. Putting the 1.6's closer together than I remember trying before starts to push the sound stage to the front of the speakers instead of behind and starting to produce the clarity in the vocal registers that I was seeking at the start of this. Despite the nice clarity, it is too bright to listen to anything but female vocals and acoustic instruments in that position and the soundstage is too narrow.
Next step... read a little theory and build some really big DIY bass traps to test.
Please forgive the typos, mispellings, and my grammar.
Regards,
Jim S. |
I don't trust readings below 100 Hz for reasons of speaker and instrument inaccuracy. However, the dips centered around 125 and 250 Hz are definately room related. I would suggest focusing on those and hope for ancillary benefits below.
Playing those test tones, you should also be able to find the nodes by walking around the room, probably by ear. I would be willing to bet that there are two nodes parallel to the speaker plane. I mention this because it might lead to the easiest solution, by experimenting with speaker/trap location. Start with traps in the corner.
If you're ambitious, you can try DIY panel traps. There isn't much in the way of designs and plans available on the net but you'll get the vague idea with research. I built some using 1/8" hardboard for the panels. Some basics are covered online through the Sound On Sound articles, "Room for Improvement" (5 parts in DIY section). Geared toward studios and pros. At least, they aren't selling anything. |
Ngjockey,
Thanks for the advice and sources. I found a couple of DIY bass traps recipes on AA posted by Jon Risch. I can afford to put together a couple of 18-20" tube replicas to test. They seem to be rather narrow range in absorption and if big enough can work down into the double digit frequencies.
I also have my eye on a corner, angled just off (4-5') the left speaker, that houses a fireplace. Not sure that is the problem, but I never did like that fireplace anyway.
I can't knowledgably comment on the meter accuracy or my testing accuracy. One thing that gives me some confidence in the measurements, are the repeatability I am observing. And the fact that the 70-80hz boost correlates to Shadornes recording reference. If the bass note progression is described correctly (and I believe it is), the third note in the beginning progression is consistantly much louder.
Do I just not understand all that is involved? Certainly possible/probable!
Regards,
Jim S. |
"If you're ambitious, you can try DIY panel traps. There isn't much in the way of designs and plans available on the net but you'll get the vague idea with research."
All you ever wanted to know about bass trapping and acoustics is available at Ethan Weiners site Real Traps. Designs for bass traps or buy his product. The best money you will spend in audio and a real ear opener. Dont wait, we all should have done this from the very beginning. Why didnt anyone tell me this years ago? I dont know how anyone can be serious witout them, you will finally hear your equipment for what it is.
Bob
|
Jim, Check out this Standing WavesIf the speakers are 53" from the back wall then you will get a first dip at around 64 Hz followed by another at 128 Hz and another at 256 Hz... This is a common problem for all freestanding speakers. Of course, your ACTUAL room response will include all kinds of other standing waves; but rear wall quarter wavelengh cancellations will dominate the omnidirectional upper bass and lower mid range frequencies up to roughly 500 Hz, as it is the closest wall to the speakers, the surface is roughly equidistant to the listener, and therefore the wall produces the strongest and broadest coherent signal that aligns and either reinforces or cancels the primary speaker signal reaching the listener across the room. This effect is well known. Being a detrimental first order effect it is worth worrying about as it dominates. Therefore most studios (who can afford and need to do it right or the mix will not transalate) will mount main speakers into a wall and completely eliminate this first order problem and leaving only third order effects from side walls/ceiling and a second order effect from rear wall (behind the listener). So the rear wall behind the listener is the NEXT biggest problem after fixing the quarter wave front wall nulls (Studios often put plenty of rear wall absorption to counter the effect or they try to ensure the listening postion is far enough away from the rear wall for this effect to remain small enough, or they will mix in a nearfield configuration far from all walls and where primary signal is very strong due to the proximity of the speaker to the listener). You can ignore sharp eratic 2,3 or 4 Hz nulls above 172 Hz. The half wavelength of 172 Hz is roughly 3 feet so moving your microphone a foot or so will make likely make a significant difference at these frequencies (as you approach one side reflection or another the null shifts around...so trying to fix these kind of nulls may only shift the problem somewhere else by a foot or two or several hertz). This is all high school acoutsic physics - no rocket science. I use "order" in a liberal fashion first order is the worst detrimental effect, second order is the next bad effect, third order is even less of a problem etc. It often makes me wonder why megabuck systems make little effort to deal with this well known, easily understood, and well documented problem. The above is not the same as Room Modes. Room Modes is a similar problem of standing waves but is much more complex. Room modes tend to dominate the ultra LF below 100 Hz but odd things can sometimes happen at higher frequencies in peculiar circumstances where dimensions happen to couple with eachother at certain frequencies at the listener position. |
BTW: 128+64 = 192 HZ may also be another problem null area with speakers at 53" from rear wall...of course given other room modes/rear wall effects you may not clearly see every one of these dips, as the rear wall quarter wave cancellation effect, as seen by your microphone/SPL meter, is already combined with lots of other reverberant effects in the room.
Disclaimer: Fixing rear wall quarter wavelength may then lead you to see other problems more distinctly. So it is no cure all. For example it won't eliminate the problem of very bad room dimensions or lack of absorptive surfaces/furnture and acoustic treatment. In my experience it improves imaging and clarity in the lower midrange but does nothing for what are often huge room modal bumps below 60 HZ. |
Acoustat6,
I have read through the Real Traps site and a lot of Ethan Winer's posts on AA. Learning a lot.
Thanks,
Jim S. |
Shadorne,
Thanks for your input again. I have read your suggested links and am trying to assimilate the info. I would like to make a couple of smart changes and not a couple of hundred dumb ones. But, to be honest, I am something of a slow study.
As I see it, I have a room mode boost peaking at around 75hz., and a set of cancelation nulls peaking at 127hz and 250hz., with a few anomalies thrown in to confuse the uninitiated (me). Makes me wish I hadn't cut most of Senior year in High school.
It fits what you have described. I keep trying to figure out how the angled walls off to the sides of the speakers fit in. Maybe they really don't change the equations!
If the analysis is that straight forward, surely there is some corollary that dictates the solution is going to be complex!!!!!
I have unknowingly played with positioning that would significantly change quarter wave cancelation when I first got the 1.6's, 6 yrs. ago, and was trying to optimize bass output. At the time I didn't like it, but now I am wondering if it wasn't reinforcing the bass (or more accurately covering up for lack of bass) of the Maggies with a room mode and cancelations.
Anyway, more food for thought. THANKS for the info and analysis. I will try to post meaningful information and conclusions as things go forward.
P.S. I can mount the 1.6's into the wall behind them (soffet mounting taken to the extreme). It opens into a laundry room. Might try that someday.
Best Regards,
Jim S. |
OK, this is not supposed to work with Magnepans but you have to follow the trail and see where it leads, if that makes sense.
I try what is written in the Genelec sites, that Shadorne has lead me to, about positioning to avoid 1/4 wave cancelations. According to everything written (their manual and everywhere else I have read) about positioning Maggies, they should be as far out from the back wall as possible.
Well shoot.... I do the calculations on the site, follow their recommendation to keep back wall distance 1 meter or less, and figure I am trading one set of cancelations for another. Low and behold, I move the speakers back from 50 some odd inches to about 30" from the back wall and play Patti Smith's Gung Ho, (not exactly an Audiophile recording but what the hey). OMG, the bass is up a notch and very clear! I mean, it is not subtle.
Ok, so I measure with my limited means and where I thought I would have traded an 60 or 90hz. null for a 110hz. null. the 60 was still there, the 90 wasn't as deep and the broad 100hz. to 160 hz. deep null was just gone. Replaced by a slight bump.
Ok, what is going on? I do the calculations for a 1/2 wave and it should be close to the 1/4 wave but instead there is a null at 230-240hz. Back to reading!
Anyway, what shouldn't work with Maggies does. At least in my room.
In all fairness it does generate some other issues. The tweeters are now close enough to the back wall and directionally pointed at the listening position to beam. Also brings into play reflections from a patio door behind and to the left of the LP that wasn't a concern before. Lessened those effects by tilting the speakers back a little.
FWIW,
Jim S. |
Jim,
The Maggies should still respond to the same physics in the bass as Genelec describes, however, they radiate front and back in ALL frequencies (not just the LF below 500 Hz) and, therefore it will be recommended to have them as far out as possible - say in the middle of the room. (Soffit mount is not an option and will kill that beautiful atmospheric/ambient sound from the higher frequencies going in all directions). I have not owned these kind of speakers, however, the best demo I have heard was with these type speakers towards the middle of the room. |
Shadorne, you're a good man. You have helped through the foolishness and learning.
I think it goes something like this.... Place the 1.6's for the best soundstage coherence? Trap for standing waves and trap for quarter wave cancelations? Readjust, remeasure, readjust?
Absorb and diffuse for the rest? I still don't understand the rest, but I have some reading material coming that I hope will help.
Everyone that shared their advice was correct in their way. Measurement, placement, appropriate treatments are part of the equation. You can quit anywhere along the process you are happy with the results.
And....... yes, I am headed for a little bit of "Flash Gordon", but what the heck, life is getting really short!
And, yes, 8' out into the room puts the quarter wave cancelation at 35hz. Yes, it does sound really, really good, if not practical.
Cheers, and Good Evening,
Jim S. |
