Welcome! Need support, you got it. Or share your ideas and experiences.
Return to Planar Speaker Asylum
195.158.167.62
Hi
I want to experiment a bit with the Cardas golden rule method to get rid of dips and resonances in my current setup, but I am a bit confused about the results I am getting following those rules. So please help me out on calculating the position for my MG 1.6 QRMy room is 5.07 meters wide, 4.85 m deep and has a 2.56 m ceiling height.
According to the Cardas method, for a horizontal room, where the speakers are set up across the wide wall, it says: multiply the distance from the back wall by 1.618, then you get the optimum distance of the speakers from the side wall (Link to Figure F)
So far, so good. For dipole speakers, there seems to be another Cardas rule: ceiling height multiplied by 0.618 results in the optimum distance of the speaker to the back wall. (Click and scroll down to Dipole speaker placement) This calculation seems to be important for optimum bass response and clarity.
In my case, the above would mean the following:
Multiply ceiling height 2.56 m by 0.618 = 1.58 m distance of the Magnepans to the rear wall.
According to the other, the "horizontal" rule, you multiply those 1.58 m by 1.618 (which results in 2.55 m) to get the distance of the speaker to the side wall. But 2.55 m distance means for a 5.07m wide room: the speakers meet in the center!!!!Even if I take this measure only as a reference point and draw a line to the back corners and move the speakers along this line: even if I only allow a distance between the speakers of 2 meters, then the distance to the back wall would be only 0.8 meters... Not a good setting for the Maggies, I guess: too close to the back wall!
So: basically I am stuck, unless I got something majorly wrong here.
Let me add one final remark. I dug into this matter, since with my current setup, that I found acoustically by moving the speakers around until I found the best imaging possible (the center of the Maggies is 1.58m from the back wall (funny, huh, a Cardas value by coincidence!) and 1.45 from the side wall, slightly toed in), I do get a big dip in the important range between 100 and 140 Hz (up to 20 dB, measured!).
I hoped, that with the Cardas Method, I could avoid dips and resonances as best as possible and get a better bass response. At the moment, as I said, I am stuck, though, because calculations seem to guide me to some strange results.Your help in this is greatly appreciated
Follow Ups:
for spacing from sidewalls to the centers of bass panel portions.This will be 1.4 meters for a 5.07 meter-wide room. The center of the left bass panel portion will be 1.4 meters from the left wall, and similarly the center of the right bass panel portion will be 1.4 meters from the right wall. There will be 2.27 meters between the centers of the bass panel portions, so, with the tweeters to the outside, you should have good sound-stage width.
Keep the centers of the bass panel portions (you have to guess where the center is by peering through the socks with a flashlight) in these locations if you rotate the speakers. If your cables will reach, I recommend you try rotating the speakers so they face away from each other. Be sure to reverse the leads if your source will not permit easy polarity inversion, and to treat the first-reflection areas on the side walls. You will need to sit close enough to hear the full treble from your Quasi-ribbon tweeters.
Hi Al
thanks for your post.
The only thing I did not understand was "try rotating the speakers so they face away from each other". Do you recommend the speakers not to be toed in towards the listener, but towards the outside?
If so, how close do I have to sit to the speakers to hear "full treble" and still get a good soundstage?
Hi Joerg,The normal position for Maggies is facing the listener, perhaps with some toe-in. There is usually a choice of whether to place the tweeter sections towards the side walls or towards the center, and it comes down to trying them each way to see which gives the better overall balance and sound-stage.
However, there is another way to use them. Turning them so they face towards or away from each other can give a very interesting performance improvement in some rooms.
This topic has been discussed in this forum a few times. I learned about the trick from Liz and David Hare at Stereo Unlimited in Walnut Creek, CA (a Bay Area city about two hours from my house), who are the Magnepan dealers in this area. I then found out it has been posted here before.
The Hares do this with true-ribbon MG 3.6 speakers, and mine are MG-20s. There is one user here who does this with quasi-ribbon Maggies. The only requirement is that your listening position has to be within the dispersion arc of the tweeter sections of the speakers. This is easy to do with the ribbon models, as their dispersion arcs are nearly 180 degrees. By sitting closer to the center line through the speakers, you can be within the tweeter dispersion arc of the quasi-ribbon speakers. You can tell where this is by simple listening.
Having the speakers face away from each other allows use of shorter speaker cables, and is the only way mine would work with the cables I have. This means I am hearing the back wave of the tweeter first, so I reverse the polarity with my Wadia 861 (unless I have a disc that I know has reversed polarity in the recording, but that is another topic). Reversing the speaker cable leads accomplishes the same thing.
As long as you are moving the speakers around, I suggest giving this method a try. It gives a better balance between direct and ambient sounds on most of my recordings. If you hear too much ambience, then the method may not be suitable for your room, or you may have a mechanical resonance in your equipment (this happened to me, and I got better sound after I found and fixed that problem). It is important to treat the first reflection areas on the side walls with this method. These are the places where you would see the reflections of the tweeter sections if the walls were covered with mirrors. Dispersion and absorbtion are both important for these areas. It is still important to treat the section of the wall in front of you where you would see your reflection if that wall were covered with mirrors, but, with the sideways speaker position, it seems to require less of this area to be treated.
Good luck.
Hey Al,I just relocated to SF, and when I get things set-up to my liking, you'll be more than welcome to hear for yourself how the Quasi ribbons do with the sideways placement.
I'm in the phone book for Santa Rosa.
Awesome, I can't wait!!It will be a while until I call you...with my move and the holidays, I would say definately after the new year.
Sorry... That message number is not valid.
I am having a hard time factoring ceiling height as a major contributing factor. I "suspect" that has meant for point-source dipoles, not line-sources. I would be more interested in room position in the direct firing direction. There must be some golden ratio that minimizes comb filtering. Off hand speculation is that the distance from the speaker to its back-wall should be equal to the distance from listener to his back-wall, which's in opposition to the speaker's back-wall. I also like toing-in just enough to put the side-wall's 1st reflection point in the dipolar null.
♪ moderate Mart £ ♫ ☺ Planar Asylum
whare " space " is roughly ¼ of the room depth.
♪ moderate Mart £ ♫ ☺ Planar Asylum
states that you can place the speakers anywhere along a line where the distance from the side wall is equal to 1.618 the distance from the back wall (behind the speakers).I.e if your speakers (measured to center bass) are 1 m from the back wall they should be 1.618 m from the side walls (if you didn't figure that out already :-))
How does this compare to your setup, Mart?
Regards,
"Panel or dipole speakers such as Apogees and Magnepans cancel their side waves, so a formula of .618 x the ceiling height can be used for determining placement from the rear wall. Most box speakers radiate low frequencies in all directions thus a formula that places the speaker to rear wall distance at 1.618 the side wall distance should be used.Speaker placement, simply stated
The distance from the center of the woofer face to the side walls is:
Room Width times .276 (RW x .276)The distance from the center of the woofer face to the wall behind the speaker is:
Room Width times .447 (RW x .447)This is all you need to know to place speakers in a symmetrical, rectangular room!"
**********************************************************
This seems to me to say that one should use the 0.276 times Room Width rule for distance to side wall for Maggies. Is there another rule that relates distance to rear (front of listener) wall to side wall spacing for Maggies?
Yeah, that side wave dipolar cancelation was my unstanding. I maximized it by toing-in the speakers to position the null at the 1st reflection point. I still don't grasp the application of the classic golden 0.618:1:1.618 cube ratio being employed by dipolars. It is the speaker enclosure interior acoustic space ratio to overlap 3D standing-waves to flatten response. FWIW, the actual equation is (Sqrt[5] ± 1)/2The reason for the equal spacing for rear walls is to cancel the 1st principle reflections. That is, ideally, the out-of-phase sound "reflected off the rear wall behind the speakers" cancels the in-phase sound "reflected off the rear wall behind the listener" . It's another null. The equidistance translates into a time-aligned, equal & opposite signals.
PS: Your ratios are quite well suited for narrow rather than wide rooms (IE: short wall vs long wall) positioning.
♪ moderate Mart £ ♫ ☺ Planar Asylum
The above rule is found at letter/diagram F.If you try to apply both the dipole "ceiling rule" at A AND the "horizontal room rule" at F, the speakers end up very much in the middle of the room, depending of course on the ceiling heigth and how wide the room is.
I suppose this is an either/or choice and a matter of golden taste, not golden mathematics?
Anyone with experience?
with the system across the short dimension.The Cardas position per the site instructions gives the best bass of any I've tried, and I've tried a lot of variations.
The room is unfortunately too close to a 2:1 ratio for the width to height, so there is a strong bass null in the center. I'm trying to think of how to make some of Jon Risch's bass traps to be acceptable to my wife...
whare " space " is roughly 1/3 of the room depth & the toe-in angle works out such that the Maggies seem to be aimed at listener.
♪ moderate Mart £ ♫ ☺ Planar Asylum
Looks like the law of thirds? Either that or law of fifths have both worked well for me in the past before I started using CARA for a more analytical approach.
Sorry... That message number is not valid.
Sorry... That message number is not valid.
don't loose your patience and read on where you pointed us with the second link...
This post is made possible by the generous support of people like you and our sponsors: