Ever Thought of Hanging Magnepans?

Hi Barry,
I have to disagree with that limitaion of its effects. Sure, first reflections cause some problems and can with any speaker when we are discussing side wall effects. What I am talking about are full range, first order, rear wall reflections that are only possible with bipole and dipole speakers. The planar speakers are the ones that have the additional problem of having their driver membranes distorted by these reflections. Saying that it is only an issue at extremely high levels is failing to realize that the panels are creating sounds at much lower levels with very slight movements of their ribbons. Surely, it is at higher levels that cause the gross distortion of the panel due to air pressure changes, but at moderate levels, when the panels are too close to the rear wall without any sort of absorbtion or diffusion, these rear wall reflections still have a tremendous effect on the sound. They actually come back and hit the rear of the speaker panel directly. They cannot avoid it due to its size and shape. Some of the lowest frequencies might pass although there isn't so much true LF output from them, where midbass really gets hammered. It bounces back and forth and hits the panel as they try to make tiny pulses to create HF sounds, thus distorting those frequencies as well. Surely the reflected sound that does make it back to the listener is going to be at wildly varying time spacing at varying frequencies. By taming those rear reflections, you are solving a lot of problems other than simple first reflections.

This sort of direct, rear wave reflection and distortion is heard in many conventional box speakers from the sound of the drivers bouncing around inside the box and interacting with the drivers. That is why speaker designers add acoustic absorption materials inside of the speaker boxes. Many speaker companies go on about the improvements in the latest designs to address these internal reflections whether by difussion (curved panels, ie, no parallel sides, or by the use of odd bracing and shaped blocks to diffuse the back wave in a box with parallel sides) or by absorption (stuffing the box with fiberglass, wool, polyfill, etc) and typically in high end speakers by both methods. The drivers are further shielded by individual boxes within the box in the best speakers, in other words, each driver has its own acoustic space so that it is uneffected by the other drivers. At that point, the speaker is either tuned to the anechoic chamber or to a common room size and placement scenario (best shot at flat response in-room IMO). This gives the box speaker the advantage of being able to be placed more freely in a room with the only concerns being distances and perhaps first reflection points along the side walls. Now, when we compare the design (or lack thereof) of a panel speaker to this, we can use the analogy of a single driver design of large diameter in a box with a wide front baffle and shallow depth, and with no internal dampening, such as would be found in early, cheap speakers or modern, urip-off products, such as "white van" speakers made for show rather than actual performance. I am not saying that the planar speakers are made merely for show, nor am I saying that they wll all sound as bad as a "white van" speaker but I am using the analogy to illustrate very similar the effects of the rooms rear wall on a panel and the rear wall of that cheap speaker on its large, light, full range driver. Ideally, both products should have dampening and or diffusion placed between their drivers and their respective rear walls with tte wall of the cheap speaker being the rear wall of its cabinet itself. These are hugely distorting effects and are not considered to be first reflections by speaker designers as they will not likely reach the listener in a direct fashion, but through distortions in the main drivers direct sound.

So will the limitations and problems of a light and large planar speaker and its placement be overcome by its theoretical advantages of being light and large?! That's a very complicated question and is what fuels the polarization (pardon the pun) among panel speaker fans and dynamic speaker fans. Surely, they can't both be wrong? Yes they can... It's all about designing a speaker with the greatest advantages and the least disadvantages, so it's a game of trade-offs as with most other things audio related. I'm perhaps obviously in the dynamic speaker fan camp (at the moment anyway ) as you might tell by my pointing out the flaws in a planar design. I do see and hear the flaws of both types however. There are actually many other advantages of a conventional dynamic speaker, which I am not going to address here as it would take forever and isn't totally on-topic, but let's just say that it is extremely important to control the rear wave of both types of designs if you want the best performance from either of them.
-Bill

 

Thanks Mike, I was looking for that page from Green Lantern, and I couldn't find it again.

 

I once "thought" about hanging a pair from the ceiling above my bed parallel to the ceiling, floor and bed.

 

but it would have blocked the mirror?...
-Bill

 

Solved the problem...

I found a good deal on a pair of 2.6r's with the real ribbon tweeter that runs up the top half of the speaker, thus all the high frequencies will fire over the couch and into my ears!

 

They will, eh? OK...
-Bill

 

Plenty of space for the mirror in the middle

 

Hi Bill

We definitely see (and hear) this differently.

Every speaker, whether planar or quasi-omni monopole (i.e. box) radiates its bass in all directions. At least that is true of every speaker I've ever experienced. Further, the bass energy coming from any speaker in my experience, is considerably stronger than treble energy.

If you don't think your favorite box speakers are radiating energy directly toward what is behind them, I would suggest taking them outdoors (to eliminate any room reflections) and standing behind them. If you can hear them (and I'm betting what you hear will be tilted toward the bass), they are radiating energy to the back.

The real difference is that dipoles will also radiate treble energy rearward. And I understand this is the point you are making. Again, unless the speakers are too close to the wall behind them and/or the playback levels are up to where the listener's ears are endangered, I don't see planars are more difficult than any other speaker. In fact, since they tend to energize only the front to back mode of the listening room, in some ways they, by design, eliminate 2/3 or the potential room issues. Of course, this assumes they are properly placed but then, bad placement for any speaker means all sonic bets are off.

Every speaker needs to be properly placed or the results will not be the best it can deliver.
Every listening room needs some attention paid to its acoustics. Expecting optimal results without this would be like expecting a smooth ride with underinflated (or overinflated) tires.

Just my perspective. I understand you have a different one.

Best regards,
Barry
www.soundkeeperrecordings.com
www.barrydiamentaudio.com

 

Huh? Never heard of that before... Anyone want to second that?