Open baffle speakers near a rear wall

[bumpy]

My speakers sit 1 metre from the rear wall, albeit at a bit of an angle to it. This is getting about as close as one should really go with OBs and I have always had slight reservations that this will adversely affect SQ. Despite it sounding wonderful, my main concern was that part of the emitted sound from the rear of the drivers will hit the wall (as expected) and then next hit the rear of the baffle causing unwanted reflections and resonances.

I walked behind the speakers and, shouting loudly at them, could clearly hear this effect.

So I put sound proofing on the rear of the baffles, firstly just one so I could compare the changes while playing music. Similarly I propped up a transistor radio playing music behind the two speakers. Listening from my chair in front, the tranny was much clearer on the sound proofed speaker.

So I did the rear of both panels.

What an improvement to clarity! A side effect is that the music sounds a little slower and I put this down to the fact that the black area between notes is not corrupted by a continuum of reflections.

It's worth noting that this type of sound proofing only has a worthwhile effect on mid to high frequencies, and that the proofing should not obstruct the genuine signal coming from the drivers.

PS
My original pictures were upright. I have no idea why they were turned through 90 degrees.

[Puffin]

I use OB's that have a thick damping panel fitted by the manufacturer. Mine are just over 1metre from the rear wall and sound fine to me.

[bumpy]

I use OB's that have a thick damping panel fitted by the manufacturer. Mine are just over 1metre from the rear wall and sound fine to me.

What do you have?

[Puffin]

EAR Primary Drive.

[bumpy]

EAR Primary Drive.

Not an easy speaker to find info on. Do they have damping on the front as well as the rear

[Puffin]

I have lifted this from the "Show us your speakers" thread as I put a pic up and got an enquiry about them :-

Hi Neil, there was a thread I posted about them as they had a problem when I got them but I can't find it by searching. The voice coils were rubbing, but they are a very unconventional design. The bass unit has no conventional surround the rubber has been removed and the cone bonded to the planar panel. I suppose it give the 10" unit a much larger area to radiate. However, I think the design was flawed in that the planar panel is only secured at the four corners. To fix the rubbing coils I had to make wedges to place around the perimeter of the panel and this effected a cure...sort of, later on I had to add more as some strange buzzing noises started.

There is very little info on the net about these. All I could find from EAR is a show report from the US where they were demonstrated. Tim De Paravicini is said to have designed them, but he did not make them. I emailed him and he gave the info as to who had made them, but I didn't get any further. There were two sizes going to be available. I don't know if mine are the smaller or larger of the two. They were to have retailed around the £5,000 mark, but I have never seen anything to suggest that they were in fact ever sold.

Here is a vid I posted some time ago.

http://theartofsound.net/forum/showt...Drive+Speakers


The review I mentioned is here.

http://www.newaudio.it/ear_yoshino.htm

They were originally covered in quite a thick velvety type material which I had to remove to fix both rubbing voice coils. They were a pig to remove and would certainly not have gone back. I have made some conventional front panels now.

[bumpy]

Thanks Rob, I have owned several bits of EAR gear. Tim has a very good reputation.