After extensive experimenting with my Magneplanars 1.7's I ended up at 95" between tweeters (inward) and 120" to listening position for a ratio of .792. Note that Jim's book mentions that "For planar speakers with offset line-source tweeters X may be as small as 70-75% of Y" I have my seat set for the best bass in the room and it sounds wonderful to me with a nice 3D stage with a fairly wide sweet spot (no head in a vice effect) so I'm happy. Great book Mr. Smith.
They can be greatly reduced by speaker box placement and in my case also by adjusting subwoofer volume, crossover, phase and notch parametric EQ. One of the reasons I use four subs is to clean up the bass with balanced placement to smooth things out---NOT to blast away with one note bass---that's for SURE! You do not have to leave the room, just leave your chair, move those boxes and attend to how much overall bass you are pumping into the room. Buy a sound pressure meter and chart it out. You have lots of options. You can buy speakers that simply avoid bass notes like perhaps a stat panel or a pair of super tiny S3/5 mini-monitors and such. If you can't handle what it takes to deal with a horrific bass mode room just avoid making bass is always one option. This is why some guys love NOT having a sub! Sometimes they lack the ability to handle hot bass in their room. Treating things is something I am quite familiar with as I own a full set of traps, portable Sonex panels and such for testing rooms and room setups. But treatment is a last resort in many domestic rooms as it looks like butt. I start with treatments to identify where the boom is coming from---where is the blur coming from---which reflections are the pits? Then I work around these areas by avoiding reflections, by lowering the volume of problematic bass notes---typically one or two really strong ones need help--- and by using common sense setups that clean up the bass. Treatments are typically used only if it's OK visually AND it is worth the trouble in that room to use them. Truly awful bass rooms DO occur in the field but using Sumiko you discover a lot of it can be dealt with simply by speaker position. And if nothing at all works then it is time to wall up the corners with bass traps and go hard.
“Bass boomy notes” was some weird spell correction from my I phone. Bass standing waves (what I was trying to say) can not be reduced by speaker or listener position or EQ. Notch filtering is a solution that is it’s own new problem. What’s the difference between a notch filter and just sitting in a null spot? The room is pressurized by the boundaries. Whether or not you dodge the peaks and nulls the entire room resonates with those standing waves. Even the frequencies that are not resonating in the bass are still pressurizing the room. And you will hear all of that. Multiple subs will allow you to do some smoothing of the nulls and peaks by adding more of them but you still have a room that is resonating the bass. If one wants clean extended bass then one needs bass traps. Picking speakers that don’t have bass is pretty close to just leaving the room. Bass/room correction is a tough problem because there is no magic pill. But IMO it is a fundamental element of excellent sound and one that is all too often ignored.
Actually you are quite wrong about this if you just stop and think for a second. Turning down the bass will lower bass volume throughout the entire room, including the standing wave also. Even if you say it won't. And moving a box out of a boomy spot or "mode" into a spot where bass is not being boosted by nearby walls and stuff will also lower the bass volume in relationship to the mids and so forth. So either turning the subs down or moving their boxes can alter how aggressive the bass gets. You can also move the main speaker and lower its bass output by picking the right spot. Standing wave pileup creates "zones" of aggressive bass noise. You need to learn where these pileups occur and avoid them. And it will save a lot of mangling of collateral damage to nearby notes if you avoid using EQ which is ALWAYS a band aid. J. Gordon Holt and I (the guy that founded Stereophile Magazine) were talking about this very subject just before he passed away. My comments were published in a Stereophile issue some time maybe 20 years ago? I was talking about those troublesome frequencies between 20-500hZ. JGH said I was "the only one who truly gets it" which is a comment I treasure coming from the Great One. I have a personal communication somewhere from JGH who was truly impressed somebody else was so into room setup---nobody seemed to know anything about it at the magazine! Nobody seemed to care! Just me and him...Amazing! By the way, I tried notching my bass on my 12 inchers as they were piling up on top of the other sub and the Harbeths. But that really screwed up the tone from going through the filtering of the parametric EQ included with my SVS active subs. Made my system sound like it had a head cold or stuffy nose. I finally set those subs without any EQ "fixings" and just turned them down and moved them until they blended perfectly and did not screw with that beautiful Harbeth tone. But what do I know? I'm just The Doc.
As a near exact analogue, one can also get an idea of what you are talking about by strumming a guitar at different positions along the string, which will excite different resonances even with the same beginning and ending string lengths.
Turning down the bass is a lot like just leaving the room. You turn down the bass you still have all the problems and you now have less of the actual bass content. You haven’t fixed the problems. You may have made them less egregious but at the cost of the actual bass content that ought to be there. standing waves and untapped room boundaries turn the room into a bass resonator. The *entire* room. Finding the least damaged parts of the room doesn’t fix the damage done to the entire room. Your bass impulse response will be terrible no matter what part of the room you are in. You can’t avoid that. J Gordon Holt had no expertise in room acoustics. Not to say you shouldn’t derive some sense joy from your relationship with him. It just doesn’t change anything regarding room acoustics. and if you are happy with the sound you are getting I’m not going to try to talk you out of that either. But clean extended flat bass doesn’t happen in domestic listening rooms without trapping the you know what out of the bass. And after that you can negotiate the speaker/room/ listener setup with h positioning and other room treatments. And room correction DSP
Should you use traps if you have a single box monster speaker without a separate sub that can be moved to best effect? And you have truly monstrous standing wave problems because the room is absolutely horrific and sonically hellish to work with? Sure. Go get you some traps! For example, if you place a pair of gigantic Wilsons in a terrible room I can see you would have a terrible problem. The occasional room from hell is out there and I have dealt with them in my 50 year career believe me. But most setups are easy to fix with much less mess. Those systems where speaker setup won't solve the problem sufficiently because of rooms that are total POS are pretty rare in my experience. One out of 50? Now that I think about it I used to think just like you. Before I learned about speaker placement techniques like Sumiko I thought a bad room needed treatment. Automatically. By definition. WRONG! The more Sumiko setups I did the LESS I used treatments. Now I rarely run to a treatment solution because it looks amateurish to me in a domestic room. I mean---what was wrong with your setup guy if he can't get your room to sing AS-IS? Ha! And nowadays subs really open up a lot of flexibility when dealing with room mode problems. After all modes become most annoying only at frequencies below 500--and mostly below 100hZ (50-120 is the pits). So just balance out the bass to a good average room response by adjusting your subs while checking for a flat bass curve across the bulk of the room area. That isn't hard to do but it can take some time to get right. Killing the room completely on the other hand, does not automatically increase your enjoyment when listening for pleasure in my experience or that of my clients. And it can look ugly. And not sound appreciably better for enjoyment. And perhaps a bit like living in a laboratory. Fine if you want that. Do you? How about your wife? Ha! How bad are those standing waves in your room anyway? They must be monumental if you can't get around them by simply not agitating them with poor speaker placement or overly aggressive sub output.
If one wants clean extended bass there is no circumstance in which one should not use traps and the more the better. There is no such thing as good bass resonances or reverb in the playback room. Unless that is something you like. It's not how I personally think. This is how true experts in the field of acoustics think. I just listen to real experts. And maybe this is a different end goal. I don't want my room to "sing" I want it to get out of the way of the sound from the system. The only room acoustics I want to hear are the ones encoded in the recordings. A side note. I think you might want to look up the definition of "definition." I'm not sure how room treatments look "amateurish" given that you will be hard pressed to find an actual professional playback facility that doesn't have extensive room treatments. It may not look pretty but it looks the opposite of amateurish. If one is really concerned about that. I'm not. Yeah, multiple subs add flexibility for trying to smooth out nulls and peaks in the room. But they don't fix the standing waves or improve the impulse response. They don't cure bass reverb. It is a very reasonable additional tactic for bass management but not a substitute for room treatment. Killing the room is not a risk. Anechoic chambers start at +$1,000,000.00. No one is going to accidentally build one in their home. What people enjoy is subjective. The less you hear the listening room the more you hear the recording. What anyone likes is their call. I do agree that it can look bad. I didn't build my listening room for looks. I built it for sound quality. I understand that not everyone has dedicated listening rooms and in many cases the solution that best suits any individual will involve compromise. But IMO if one is in pursuit of state of the art sound you begin with bass trapping the room as much as is possible. Again, there is no other way to get clean extended bass. I'd rather not make this about me and my room. If you want to get into a pissing contest I'm not really interested. But if you really want to compare measurements of your room vs. my room I guess it might be interesting to others who may be reading this thread to see what really works. What I would recommend to anyone reading this thread is a book called "Acoustics of small rooms" by Mendel Kleiner and Jiri Tichy. It covers the physics of room acoustics and sound in general in depth and also goes deep into practical solutions for fixing room acoustics. Both authors were actual professors of Acoustics, one at Chalmers University of Technology and the other at Penn State University. They are real experts on acoustics.
It's not quite so drastic as you describe. My room is pretty good and nowhere near terrible without treatments. My room is even better with early/corner reflection treatments and some bass traps that have the speakers disappearing and singing. I am also a proponent of any type of noise reduction and vibration control. The less noise, the more music. My room isn't huge and with two windows and two doors there are not many options to be moving speakers and other gear/ furniture all over the place. I have a dedicated listening room so treatments and isolation devices are not a problem. Right now I'm not hearing any issues with room eq and soundstage, in fact it sounds amazing. I have to pinch myself to make sure I'm not dreaming.
My set up guy had nothing to do with treatments. Just speaker placement, meaurements rake angle, leveling, etc. I believe the speakers are set up perfect. I measured the room frequencies, dimensions and added treatments as recommended by the ASC consultant.
My wife or daughter have never mentioned the room treatments. The wife has mentioned a dislike for wires. When she comes into the room she focuses on the music.
I measured my setup. About 0.87, rather than 0.83. Tried the latter, but because of room dimensions, my chosen spot is better for me. @Doctor Fine - The 90° you were thinking of may have come from the ideal setup for Blumlein playback. My speakers are too directional for me to try that for one recording, but I'm told it's impressive.
All we need do is realize the decimal of .83 is the same as the fraction 5/6ths (well, it’s really .83333333 but who’s counting). Tweeter Separation x = 5. Distance of Tweeter to ear y = 6. Now substitute numbers till your heart’s content. If x = 1 meter, 100 cm then y = 1.2 meters, 120 cm. X=50”, Y=60” X=15’, Y=18’ Etc,etc…..
Agree 100%. Most rooms can be made very entertaining simply by setting the speakers up to kick ass. You added treatments and it got tighter and cleaner which you like. It perhaps got closer to "studio spec" or what I call "reference grade" which makes your setup great for judging the differences between recordings etc. I build studio rooms to work in that ballpark. You absolutely need to be able to hear differences clearly as you make a recording from scratch. No time for fooling around at that level. But for a domestic room that needs to be used by the family---it may look nicer without treatment and not sound so bad the spec is wrecked. i.e. you can still judge differences correctly. And can still get in the "reference grade" ballpark even if a little loosey-goosey with the spec. Sounds may just not jump out and bite you like a "dry" room would have done. But as I have tried to point out---a good sounding coloration caused by a room is not always bad. It can even ADD a lifelike flavor to your playback. There is nothing wrong about an "intimate sounding room" that ADDS some cool resonance and warmth like a nightclub as long as it doesn't get muddy or boomy. IF you always wanted to own your own nightclub for that sort of thing, more power to you. Apparently, you prefer more of a studio type flavor. That's really cool! And congratulations for stepping up and taking measurements and curing problem modes and tuning the "display" you are getting off your setup. It IS exciting once a set starts hitting hard. And make no mistake---it simply HAS to reflect on the talent of the owner to get the install nailed down. Might even swell your little ego brain a bit! At a reference level or close to it. It changes your appreciation for the recording process itself. May even widen your level of what is an "acceptable quality recording" once you hear the real deal coming from your setup. But that's another subject entirely. The Doc
imo I think you hit the nail on the head: it came from 5/6, or more precisely the inverse or 6/5, or 1.2 x speaker spacing is easier to understand. Lol Or to the speaker face plane 1.09 x spacing. Easier to measure from mid point to seat.
I think it's actually easier to measure the tweeter to tweeter distance using a Bosch laser device and then do the same for Y by holding the laser device at the ear and locate the tweeter from the chair.
Using a laser device does give a very precise measurement for certain, though as the above post suggests, not many people have these. As I understand Jim Smith's message, this 83%/5/6th's, etc., is just a ballpark kind of thing, not really a precise measurement point kind of thing. While a speaker can certainly sit still as a statue, a human is far less likely to do so to say the least. I only know for certain that I cannot sit still as a statue when listening to music. Yet I read numerous posts with percentages with decimal points. And now there is the laser measuring device. All in the search for the magic listening spot. Good Luck is all I can say. I first heard speakers set up with the Master Set method, the abbreviated version of John Hunter and Stirling Trayle's Sumiko method, at RMAF 2007. It was the best music playback sound I had ever heard, and I didn't have to sit in a magic spot. I learned and taught myself how to do this, though it took a long time to get proper success. It can be time consuming and is not easy to do from scratch, but it can be done.
Agreed 100%. Don't have to be in a vice-like grip with my head to enjoy the music/soundstage myself. I can easily move left/right without losing focus. Moving front/back changes bass, which is normal. Used master setup myself, result though is around the 83% mentioned here.
Did a quick measurement this weekend and moved the speakers 6" further apart so they're at the 'magic' 0.83 ratio. Previously set up on the 1/3rds ratio using the train track tape method. In doing so I found that the right speaker was previously and inadvertently 4" closer than the left and that has made far more difference in setting the cymbals more central. Will give it a few weeks and a range of albums, but for now it sounds slightly wider without the centre broken up, and speaker 'disappearing' much the same - does on some albums but not others. Interested to know what recordings others use to test the speaker disappearing trick.
One reason we shared this was that the formula has been proven out in thousands of detailed setups. Stirling does a fantastic job as well but sitting in the center chair is required for best results on his setups as well.
