Planar Speakers and Diffusors

Hi Ozzy,

I have been using Line source Dipoles (planars) since 1978. I owned Apogee Divas for 6 years. I currently use Sound Labs ESLs. 

You are headed in the right direction, but someone fed you the wrong information. 

Line source dipoles radiate sound in a "flat" figure 8 pattern. By "flat" I mean there is no sound radiated up or down. In your case the lines source characteristic ends at about 250 Hz. Middle C is 256 hz. For the best imaging you need sound absorption behind the speakers. You want to kill the back wave as much as possible. Diffusers are simply going to increase the number of early reflections, confusing the image more. I use 4" acoustic tile behind the speakers. It is very effective above 250 Hz and dirt cheap. It also looks cool if you get the pattern right. You can get it on Amazon.

At first you might think the sound has become duller, less air, whatever. But, if you are paying attention, voices now hang, well defined in space. Any hint if sibilance behind female voices is greatly reduced or gone altogether. Everything is in better focus. The third dimension becomes palpable. The glare is gone. If you take the tile down you will not believe what you had been listening too!

The problem below 250 Hz is much more difficult. As the wavelengths get longer they are harder to stop or deflect. The wavelength of 250 Hz is about 1 meter. 

Another issue with planar speakers, especially full range or two way types is they HATE making bass. They will do it but it distorts everything else the driver is doing and wastes a lot of power. You can lower distortion and increase your head room by as much as 10 dB by adding two subwoofers and a two way crossover with digital bass management. People think it is difficult to match subs to planars. Not true at all if you do it correctly. It is tougher, but it can be done to great effect. You have to cross up around 100 Hz with a very steep slope of at least 8th order and match the launch time of all the drivers. This can only be done digitally. it is like adding a turbocharger to your car. Two Martin Logan Balanced Force 212s and a DEQX Pre 4 processor would be amazing.

Planars do need to be toed in perhaps a bit more to get that sweet spot.  Mine are toed in so they cross a few inches in front of me.  Plus that eliminates them from directly reflecting off the wall in back of them.  Cannot tell you about diffusers, but I tried absorbers in back of them.  What that did was it took away the spacious sound of the dipoles and most of the soundstage as well.  

Thanks for the responses.

From what I understand, the Clarisys speakers are designed to reflect sound forward and behind the speakers. They use the back wall reflection as part of the open audio design. The Planar design does not radiate any information to the side walls. I have the speakers about 30" from the side wall because the bass seems a little stronger.

I have moved these 250 lb. speakers back/forward/ side to side/ toe in/no toe in and the present placement seems to be the best.

I have also found that the 85" TV screen to also help deflect and improve the openness. I have tried sound absorbers in front of the TV and it seems to restrict the soundstage.

The dealer, SunCoast Audio also advises using No absorption, and when they have them at shows they use some sort of reflective clear screen behind them to eliminate any absorption from drapes etc.

So, I don’t know if these speakers are a different animal than typical Planar speakers, but reflection or diffusion seems to be the way to go.

ozzy

Ozzy - thanks for this discussion - I have been a fan of planer speakers since 1982. I have stuck with Magnapan all these years. Got my Maggie 1.6qrs modified by Peter Gunn when I retired 3 years ago. They keep improving - I guess there is a real issue on Maggie panels when they moved from copper wire to aluminum wire. My Maggie 1.7is do not compete on vocal and horn ‘quality’ vs the modified 1.6qrs. I also have worried about the ‘flat screen TV’ between both systems and it’s affect on sound stage, imaging and sound quality in general. I am also over the Moon happy with The Swarm subs with my Modified 1.6qrs. I am considering some sound absorption panels or a ‘blanket’ over the TV screen during ‘serious listening ‘ sessions.

Mijostyn - I am a retired Chemist - not an Electrical Engineer - how do I cut off my Maggie’s at 100 hertz and let The Swarm take care of all the base requirements for my system?

tom8999,

To cut off the frequencies below 100hz and send them to your subs, you will need some type of electronic crossover.

In the past I have owned the JL CR-1, but I eventually sold it because it wasn’t as transparent as I wanted.

ozzy