Absorbers, diffusers for speaker placement... [Archive] - Audio & Video Forums

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Nasir
12-06-2009, 02:52 PM
I need some input from you gentle folk out there regarding a real world problem.......
Well, it all started after having bought a demo set of Finalsound electrostatic speakers!! But this problem applies to normal speakers as well, so I am counting on a lot of suggestions and experiences.
The easy part was getting these thin and tall speakers past the wife and after hooking them up, it was a delightful sound to behold needing 2 subwoofers to have an enveloping bass. So far so good as first impressions go.....
When I started to do some serious listening, the problems arose: distance from back wall ( front wall to some) was too small and began to sound better as this distance was increased. Speaker placement techniques such as Cardas and WASP to name a couple all came up with distances that would most certainly alter my marital status!!!
With the my better half only allowing a maximum of 40cm ( 16 inches ) from the wall behind the speakers I turned to other methods of reducing the reflected waves from behind the speakers to get a better sound stage with a respectable depth. Not too much to ask, I thought to myself.....
Although electrostatic speakers are dipoles, I would appreciate any comments, experiences and suggestions in the use of diffusers and or absorbers to scatter reflected waves or reduce their intensity in a way that benifits listening . Even if they been used with normal speakers, I am pretty sure somehow this forum would benefit from it,,,, could be of help to others out there.
Lastly, what sort of depth perception should one expect?

JoeE SP9
12-06-2009, 06:54 PM
I've already given my suggestions for diffusion. Absorbing the rear wave from dipolar speakers is not recommended by anyone anywhere.

The actual amount of depth perceived is dependant on the recording. Most studio recordings have little or no depth. Classical, Jazz and any minimally miked and tweaked recording should give good depth. Direct to Disk recordings almost always have excellent depth because they have no studio buggering applied.

BTW:
I have several friends with Maggy's who move their speakers away from the wall when listening and back against the wall when not in use. Everyone can't leave them 4Ft (46 inches) from the wall like I can. The problem doesn't really apply to "monkey coffin" speakers. Most of them have no rear wave to contend with. Rear ports not included.

Nasir
12-07-2009, 03:46 PM
Hello JoeE SP9,
Believe me, Ive tried pipes and other large cylindrical objects without any real improvement. I also tried the internet and there are a wide variety of absorbers and diffusers and a lot of claims being made...
Also, it is clear that we do not want to absorb the rear wave as thick rolled carpets behind the speakers could, tried that and not pleased with the sound!
Checked out some serious literature also on the internet and they seem to advise the use of diffusers that are not that easy to make either, although a couple of DIY articles are encouraging. It seems that the diameter of the cylinder for dispersion should be half the wavelenght to be diffused, suggesting 2.5 cm ( 1 inch ) as the smallest cylinder size. Wood is probably the easiest to work with or I could try used batteries of differing sizes.....
So before I embark on such an undertaking, it woudn`t hurt to hear some opinions, experiences, etc...

yogo
12-15-2009, 08:05 PM
Information about Final that you find needed for future purchases...

http://hometheaterreview.com/embattled-final-loudspeakers-files-for-bankruptcy-in-belgium/

Nasir
03-31-2010, 08:23 AM
I have since my last post, constructed 3 diffusers and will comment on the results after some decent amount of testing soon......

E-Stat
03-31-2010, 08:52 AM
I have since my last post, constructed 3 diffusers and will comment on the results after some decent amount of testing soon......
Diffusion is the key and the first reflection points are a good place to start. You want to ensure that the rear wave does not mix with the frontal wave and "confuse" the image. To really appreciate what they can do, however, you really need to pull them out from the wall when the wive is away. I'm kinda spoiled in that I have a dedicated room where I have free reign over that. Since my stats are full range, distance also affects bass linearity. With my setup, the optimum setting was about eight feet out. Not to say that would be the case with yours, but a couple of feet will improve the apparent image depth.

rw

poppachubby
03-31-2010, 09:53 AM
I agree with Joe. The best effort will be spent finding the sweet spot, with the correct distance AWAY from the wall. You will then need to move them back and forth for sessions. Might I suggest Magic Sliders...great product.

If this is no good I suggest finding new speakers or a new wife.

Sir Terrence the Terrible
03-31-2010, 10:20 AM
It is never wise with ANY speaker to use diffusion at first reflection points unless the object is to create diffused non specific imaging(not advisable for imaging specific speakers like the front speakers). Diffusion at the first reflective point is more applicable to surround speakers where specific imaging is not required.

Diffusion is best used above the speakers(on the ceiling), on the side walls well out in the room, and along the back walls. The best advice given here is to move the speakers away from the nearest walls, as that reduces the amplitude of the reflections from the nearest wall. When that is done, then you start talking about the absorption versus diffusion/reflection values. In two channel setups, absorption should be used at a minimum, and diffusion and reflection should be used more. Absorption should be used at first reflection points in the frontal hemisphere to the sides of dipole type speakers, but not behind these types of speakers.

Nasir
03-31-2010, 02:05 PM
Thank you for your quote of the year, Poppachubby, Im beginning to like you: "new speakers or a new wife" indeed..... I cant afford either!!!! It would be cheaper to demolish the wall behind the speakers which leads to the kitchen. Hey, maybe the wife wont mind it that much since she is always complaining about having to slave over the kitchen stove.....

E-Stat
04-01-2010, 05:35 AM
It is never wise with ANY speaker to use diffusion at first reflection points unless...
Mea culpa. Indeed first reflection points should be absorbed.

rw

Feanor
04-01-2010, 05:57 AM
So what are we to conclude?

Seems like diffusion for dipole rear wave and absorption for front wave first reflection.

In my case I deflect the rear wave. In my situation it works well. Currently my Magneplanars ar 3' from the wall behind which is best, but I have used this deflect sucessfully down to about 18".

http://gallery.audioreview.com/data/audio//500/MaggieSetup.jpg

E-Stat
04-01-2010, 06:16 AM
Seems like diffusion for dipole rear wave and absorption for front wave first reflection.
That approach has always worked for me. I was thinking one thing and writing another. SL makes a diffuser intended for use behind dipoles.

SALLIE (http://soundlab-speakers.com/accessories.htm)



Currently my Magneplanars ar 3' from the wall behind which is best, but I have used this deflect sucessfully down to about 18".
Do you note any change in bass response?

rw