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In Reply to: RE: I have a hunch. posted by grantv on November 14, 2015 at 19:07:12
I recently bought some new GIK Polyfusors for the FW. They are rounded Diffusors. They look good but work marginally at best. How well do you Diffusors work? Big difference?
Follow Ups:
Big, no (define big I guess :)). Worth it, absolutely. It took a few hours, but the soundstage definitely improved.
Grant,
Big compared to Mye stands, naturally! LOL.
I take it the few hours time was time spent experimenting with positioning?
My experience with the GIK Polyfusors is that it makes a small improvement if the Maggies are closer to the FW (within 4-5 feet). As I get the panels further out from the FW, they don't seem to help anymore and may actually blur things a bit.
I have not experimented with other types of diffusion.
That doesn't surprise me. The main advantage of the diffusors is that they make the acoustical space seem larger. Both increasing time and lowering amplitude will have a similar effect psychoaoustically. So if the speakers are far enough away from the wall, you don't gain much from the diffusors, because the time to first reflection is longer and the amplitude of the reflection lower.
Adding on to this thought, I think it also gets to why I prefer no treatment as the speakers get substantially further from the FW.
As expressed in earlier posts, I believe there are tradeoffs in getting the speakers further from the FW. You gain awesome depth and sounstage size, but after five feet or so the bass starts losing punch*, and at further still, the images and transients start getting less snappy and concrete and more "ethereal."
The worst I ever heard my Maggies sound was when I tried them with no back wall at all (firing to the rear into a huge open air room). Currently I am running my 3.7i's about 5+ feet with diffusion behind (though the improvement is marginal) while I run by IIIa's eleven feet out from FW in a shoebox shaped room with no treatment at all. Tomorrow I will probably try something else.
I did once ask Wendell if there is any distance from the FW which is too far out for his speakers. Oddly, he answered "no."
*Limage set ups compensate partially for the bass by moving the speaker closer to the SW.
I think that what happens with the bass as you move the speakers out is going to be idiosyncratic to some degree, since it depends on the z-axis room modes in your specific room and whether the speakers are in a node or antinode or somewhere in between. But you also have the reinforcement/cancellation from the front wall reflection and that will just depend on distance to the wall. The one firm rule seems to be that best bass and best imaging are never in the same spot!
Regarding backwave -- it's artificial reverb, really, in both omni/cardioids and planars. And stereo needs it -- in an anechoic chamber, stereo sounds like it's coming from a narrow slit between the speakers. So the main problem you have is the conflict between the room reflections and the reflections in the original acoustic space. Low distances make the acoustic seem smaller (less soundstage depth) because the ear determines depth by timing the first reflection -- if it hears a loud first reflection and it's short, it will say there's a wall a short distance away. Both initial time delay and amplitude of the reflection are used to make the calculation.
So further out is better for orchestral music but not necessarily for chamber music or other music that was recorded in a smaller space or up close. But it should do little harm to the latter because you'll hear the first reflection in the recording. And note that modern recording studio control rooms are designed to suppress the early reflections *entirely* at the listening position. They then use diffusion at the rear of the room to create a diffuse sound field with low interaural cross correlation and having the desired Rt time (much deader in a studio than you would want at home, because you want to hear every detail on the recording and these are smeared by reverberation).
Add to that the fact that recording venues have very different reverb times -- it's impossible to come up with a one-size-fits-all solution.with conventional two-channel stereo.
Me, I always get stuck with rooms that are too small so I've never had a chance to get the speakers far out from the wall -- the farther out I move them, the better they sound to me.
Good discussion, Josh,
Yeah, I agree it is room (and room treatment) dependent. In multiple rooms with multiple planars my experience is that there are tradeoffs between soundstage depth and image solidity/transient snap. After four or five or six or whatever feet (depending on model and room and treatment) you start gaining one and losing the other. Each of us has different models, in different rooms with different personal preferences and equipment, so the final optimal spot differs. It is like you said, the spot for best bass may not be the spot for best overall tonality or imaging either.
I also suspect that Magnepan designers recognize this and when they voice the speaker they optimize it within these loose parameters, just as they loosely optimize it for expected toe in or driver alignment.
I personally love the sound with the speakers as far away from the FW as I can get away with. I like to hear a soundstage where the instruments are all "floating" behind the plane of the speakers, and though the proximity to the FW affects stage depth, it doesn't strictly limit it either (the stage extends beyond the wall). But I can only get away with so much before feeling I have given up too much in other qualities. This is actually more true for me for solo instruments and small ensembles than large orchestras. I LOVE hearing a solo guitarist sounding like a real sized person sitting on a real chair in real space with a real sized guitar perhaps ten or twenty feet behind the speaker (indeed, I find many high end speakers can't handle the solo guitar test at all). Then a vocalist enters, three feet to the left and standing slightly forward. I can get some of this effect with the speakers closer to the FW, but not as much, not as convincingly. But if I pull them out too far....
It is a fun and rewarding hobby.
I've never heard them pulled out too far, because I've never had a listening room large enough! In the rooms I've had, the farther the better.
Magnepan designs for an average room -- no way they can cover all eventualities -- which is why they suggest the DWM for large or bass-shy rooms. Conversely, he compared Tympanis in a small room to a trumpet in a telephone booth.
I don't know what your experience is, but with the MMG's it always seemed to me that the sense of depth was a compromise between the distance to the rear wall and the recording venue -- my brain seems to split the difference.
That being said (and forgive me if this is kind of disjointed -- tired and typing this in a train station) modern control rooms use a reflection-free zone, which is essentially equivalent to speakers that are far from the wall with lots of diffusion behind them, and they don't lose attack -- they tend to sound very clinical because they have a low Rt time, a drier acoustic than most home rooms have or should have. So what I'm wondering is whether the problem with moving the speakers out is that the room is too reverberant?
"I've never heard them pulled out too far, because I've never had a listening room large enough! In the rooms I've had, the farther the better."
Yeah, I have a twenty foot room, a thirty five foot finished basement, and an alcove which opens up to an area of more than ten thousand cubic feet of space. The speakers gain depth, but lose transient snap and dynamics as you move them out too far. The tradeoffs is more severe for the newer 3.7 i's with tape (suppressing back wave) than with older IIIa's. However the tradeoffs in my opinion starts at about five or six feet.
"Magnepan designs for an average room"
Yeah, and I suspect they design/optimize for an "average" distance from the FW, and that they are specifically reducing that distance over the decades to make their speaker more WAF friendly. My guess is the tape on the new I models is part of this trend.
"...always seemed to me that the sense of depth was a compromise between the distance to the rear wall and the recording venue -- my brain seems to split the difference."
Yeah, this sounds right to me too.
".... modern control rooms use a reflection-free zone, which is essentially equivalent to speakers that are far from the wall with lots of diffusion behind them, and they don't lose attack -- they tend to sound very clinical because they have a low Rt time, a drier acoustic than most home rooms have or should have. So what I'm wondering is whether the problem with moving the speakers out is that the room is too reverberant?"
Maybe, or maybe it is due to the tradeoffs in WHAT is being reverberated. If you get it too far from the FW, it seems to shift to lower, muddier reverberation. Indeed, one trick some find to add snap further from the FW, is to move it closer to the SW. Obviously Limage uses this, but another version I have used is the one where you align the speaker at a 45 degree angle near the SW, allowing a gain of energy off the side wall. I have no idea why this works, but it does tighten things up a bit if out beyond eight or ten feet. The problem is you get an echoey effect.
I actually suspect the issue is rooms are not reverberant enough, at least at higher frequencies. A lot of Limage setups seem to me to be in bright under damped rooms and Limage discourages FW treatment.
Questions....
Not a bad room! I envy you the space.
The tape on the new models is nothing new, my Tympani IVA's have it and it's mentioned in one of Jim Winey's patents. It suppresses modal resonances at the center of the diaphragm and makes the motion of the diaphragm more pistonic.
Check out some photos of Magnepan's listening room -- it's your basic shoebox shape, with your standard planar arrangement (listening distances, etc.
It's hard to know what's going on in your room. Rooms differ so dramatically! But conventional wisdom would say delay at least 10 ms (5"), diffuse at early reflection points (and elsewhere in the room), break up slap echo with just about anything, adjust Rt *broadband* to a value suitable for dipoles (see Linkwitz's site for some figures -- the room will typically be much liver than a room for an omni because the dipole dumps 4.8 dB less sound into the room). Bass trapping as needed. Beyond that, I think it depends on the specific room, e.g., how close the side walls are to the speakers, whether it's symmetrical, etc.
The manual that came with Magnepan 1.7's advises setting the speakers apart 50-60% of the distance from the listening position.
The manual tells you to start there and then move them apart until you start to lose the center image, and then move them back again. That would give you the widest possible image without a hole in the middle.
It isn't correct.
Stereo loudspeakers should be at +/-30 degrees from the listening access -- the standard established by Blumlein when he, well, invented stereo. That's what recordings are mixed for and some unconventional loudspeaker arrangements aside, they never sound right otherwise.
"Stereo loudspeakers should be at +/-30 degrees from the listening access"
Is this a recommendation for an equilateral triangle? (30 plus 30 equals 60, thus the other two angles are 60 as well?)
Yep.
When you 6 or even 8 panels, sometimes contiguous others not, what would you recommend to be placed "+/-30 degrees from the listening access"?
Tweeter, or maybe half way between the mid and the tweeter? The 11 kHz range is particularly important for lateral localization.
With Tympanis I hear a different spread for the woofers than I do for higher frequencies but in the IVA's this produces a pleasant spread with a slight vagueness in the imaging of instruments with low fundamentals, rather than a major disturbance as it did in the 1D. Also, this is listening too close -- the farther you are the less you'll hear that issue because the angular separation is lower.
But whatever happens the higher frequencies are more important for localization -- my computer speakers have a sub crossed at 350 next to me, and I never notice it there.
Same findings re the FW. The closer they are the more important they are. As for placement, I placed them center of diffuser to center of mirror point for speakers. Ensured the entire panel with a mirror to FW would have diffuser...
Hey Swami I too just got the polys in the front corners behind the speakers ML'S or Maggie'S and they worked great for the center till I put some 2D diffusors in the centers and the whole image vanished
Thanx Bill
Edits: 11/15/15
Cameraman,
So you have Polyfusors behind and to the side, and some other type of diffusion in the middle? The image vanished?
Maybe I used the wrong words
Once I put the 2D skylines in the center the image was less stable I also have 1D's at the first reflection points
Thanx Bill
Edits: 11/16/15
Have you tried moving the speakers closer together? The reflection will tend to pull the image towards the center at short distances so you may be losing that.
Also, hard to tell from the photo, but it looks like the skylines are too close to the center, you want them at the first reflection points -- the points at which you see the center of the speakers in a mirror.
Thanx Josh at this point the 2D'S are just sitting there and not mounted maybe this week if I am lucky
Thanx Bill
I'd try them without the skylines. Can you split the skylines in two? I'd be curious to know how they compare to the QRD's when used at the first reflection point.
I have QRD'S at the first reflection points not in the pic
Thanx Bill
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