Konnichiwa,
A better solution is a nice "wall carpet", hung such that it is about 1" or so in front of the actual wall, covering the wall behind the Speakers. Look around for nice carpet runners, (deep pile!!!) and let the lady of the house choose some nice persian handmade rugs or the like.
Alternatively you can use classic eggcrate acoustic foam, as long as you have a cloth covering over it whose colour and patter pleases the lady of the house, while being sufficiently sound permable to allow the acoustic oam to do it's job.
Also note that you need to concentrate primarily on the range below 1KHz (hence the loose carpet - it will actually flex absorbing a lot LMF stuff), above that most cone drivers show significant rolloff of real output anyway, which is one of the reasons that Cone dipoles image worth a dman near wall, unlike ESL's for whom close walls are the death of the soundscape....
Sayonara
Nuuk said:I have a 'bag' of foam offcuts, held together with a piece of net curtain (horrible stuff, something like lace, that we Brits put in our windows for privacy).
This 'bag' of foam is attached to a length of timber so that it is held at the same level as the driver but about 18 inches (45cm) behind it. It looks horrible but works quite well and I will make a better looking job when I have the time and necessary materials.
A better solution is a nice "wall carpet", hung such that it is about 1" or so in front of the actual wall, covering the wall behind the Speakers. Look around for nice carpet runners, (deep pile!!!) and let the lady of the house choose some nice persian handmade rugs or the like.
Alternatively you can use classic eggcrate acoustic foam, as long as you have a cloth covering over it whose colour and patter pleases the lady of the house, while being sufficiently sound permable to allow the acoustic oam to do it's job.
Also note that you need to concentrate primarily on the range below 1KHz (hence the loose carpet - it will actually flex absorbing a lot LMF stuff), above that most cone drivers show significant rolloff of real output anyway, which is one of the reasons that Cone dipoles image worth a dman near wall, unlike ESL's for whom close walls are the death of the soundscape....
Sayonara
Well, my speakers are 'backwards' right now, with a sealed woofer and an OB midrange (salvaging parts from my previous speakers). I know it should be the other way round, but that'll have to wait till I'm in larger and more permanent accomodation.
So, the speakers are dipole only from 500Hz up. Would that change the absorption/diffusion technique chosen?
So, the speakers are dipole only from 500Hz up. Would that change the absorption/diffusion technique chosen?
Here's a slightly different viewpoint. I have open baffles using EV LS-8 drivers and a pair of 12" bass drivers on each baffle, biamped. I've gotten excellent results from having the baffle as close as possible to the wall and in the corners. As soon as the baffle is pulled out around a foot, the sound falls apart untill they are almost four feet or so out from the wall. With the close wall corner position, the bass smooths out quite a bit and has a bit better bass reenforcement. My baffles are a few inches from the wall, toed in a bit, and the edge about six inches from the corner wall. Baffles are 30" x 36" in size. It surprised me how well this worked.
Dave
Dave
Thanks. I read your post the first time too I think I could place my speakers that close to the back wall, but I'd probably run into problems with the sealed woofers. And I have a sub in the corner anyway. Looking at your driver sizes, it looks like your speakers are dipoles down to a much lower frequency than mine, so the room loading issues would be different. Or at least, I think they would... not sure.
I think I could place my speakers that close to the back wall, but I'd probably run into problems with the sealed woofers. And I have a sub in the corner anyway. Looking at your driver sizes, it looks like your speakers are dipoles down to a much lower frequency than mine, so the room loading issues would be different. Or at least, I think they would... not sure.
Member
Joined 2003
In my room, my dipoles needed to be well out from the wall, but you-know-who limited the distance to 4'. For SQ, 4' wasn't far enough until I added a layer of felt carpet pad to the backside of the baffles (a few inches behind the drivers). This significantly improved imaging.
As noted upstream in this thread, the felt diminished reflections off the back wall...and carried too far (with a second layer of felt)killed "spacial character"...even when listening position frequency response was held constant.
So, I suggest experimenting with back-side loading. Probably no formula for "one size fits all".
my dipoles
As noted upstream in this thread, the felt diminished reflections off the back wall...and carried too far (with a second layer of felt)killed "spacial character"...even when listening position frequency response was held constant.
So, I suggest experimenting with back-side loading. Probably no formula for "one size fits all".
my dipoles
UP AGAINST THE WALL LINE SOURCE
Flat panel TVs are making "up against the wall" line sources look like an attractive design that might also work in your listening room. McIntosh XRT29 is an example. Technology advancements are making long Xmax, wide bandwidth 6.5" and 8" speakers available that can cover down to below 30 and above 1.5Khz. Low cost tweeters and planar magnetic ribbons are also starting to sound quite good.
Flat panel TVs are making "up against the wall" line sources look like an attractive design that might also work in your listening room. McIntosh XRT29 is an example. Technology advancements are making long Xmax, wide bandwidth 6.5" and 8" speakers available that can cover down to below 30 and above 1.5Khz. Low cost tweeters and planar magnetic ribbons are also starting to sound quite good.
Attachments
Hello Saurav,
I have my Supravox dipoles near a library on the back with good results. I have also experimented a worst sound when separating from the wall, until they are about 1.5 m away from the wall, then the sound improves again.
I tried the same as you, attaching foam to the basket, and, while image improved, the dynamic qualities we love in dipoles got spoiled, and some funny nasal coloration appeared.
So, trying to have it all, I'm about to try a cardioid approach, having the absorbing stuff inside a box opened back. I have prepared also a perforated back panel to try.
Regards,
Roberto
I have my Supravox dipoles near a library on the back with good results. I have also experimented a worst sound when separating from the wall, until they are about 1.5 m away from the wall, then the sound improves again.
I tried the same as you, attaching foam to the basket, and, while image improved, the dynamic qualities we love in dipoles got spoiled, and some funny nasal coloration appeared.
So, trying to have it all, I'm about to try a cardioid approach, having the absorbing stuff inside a box opened back. I have prepared also a perforated back panel to try.
Regards,
Roberto
Dipole sound
Sayonara,
I have done it like what you said.
Nuuk,
It is not that expensive. I bought that wall rug for about AUD$250, i.e. about 100 pounds. It is 100% wool and it is quite thick. If I spent 100 pounds on equipment I won't get that type of improvement on sound. I said that because I bought HiFi in London before.
* * * * * *
I am now building my dipole speakers. I am wondering if that carpet would make the sound too dead. What do you think? Sayonara? Any advice? What frequency ranges would be affected by wool materials?
The trouble is that the centre could be too dead while on the sides the uncovered walls could make the sound too bright. That affects stereo imaging. I am thinking about installing additional 2 small thin rugs on the sides underneath the 2 wall lights.
* * * * * *
I think that a dipole needs to be more than 1 metre away (sorry I can't think in feet) is for stereo imaging. The sound bounces back from the rear wall therefore there is a delay from the original direct sound. The distance determines the delay. If the delay is too small, the reverberant sound will get mixed into the direct sound in our accoustic sense and it will sound terrible. If the delay is long enough then we will sense it as reverberant sound that adds into the atmosphere.
So basically adding absorbing materials would only reduce the reverberant sound but would not fix the problem.
Please correct me if I am wrong.
Regards,
Sayonara,
I have done it like what you said.
Nuuk,
It is not that expensive. I bought that wall rug for about AUD$250, i.e. about 100 pounds. It is 100% wool and it is quite thick. If I spent 100 pounds on equipment I won't get that type of improvement on sound. I said that because I bought HiFi in London before.
* * * * * *
I am now building my dipole speakers. I am wondering if that carpet would make the sound too dead. What do you think? Sayonara? Any advice? What frequency ranges would be affected by wool materials?
The trouble is that the centre could be too dead while on the sides the uncovered walls could make the sound too bright. That affects stereo imaging. I am thinking about installing additional 2 small thin rugs on the sides underneath the 2 wall lights.
* * * * * *
I think that a dipole needs to be more than 1 metre away (sorry I can't think in feet) is for stereo imaging. The sound bounces back from the rear wall therefore there is a delay from the original direct sound. The distance determines the delay. If the delay is too small, the reverberant sound will get mixed into the direct sound in our accoustic sense and it will sound terrible. If the delay is long enough then we will sense it as reverberant sound that adds into the atmosphere.
So basically adding absorbing materials would only reduce the reverberant sound but would not fix the problem.
Please correct me if I am wrong.
Regards,
Sorry I forgot to attach the photo
An externally hosted image should be here but it was not working when we last tested it.
Hi mbon,
All the above comments and advice seems very helpful, and there are clearly some excellent experiences out there.
A common thread seems to be the issue of speaker positioning to overcome the mid-range reflections, which I think will always be a problem with a close rear or side wall. I tried myself with this and gave up.
The solutions offered (i.e. suppressing the back-wave) strike me as a compromise (as are most things of course!), but why not engineer a more suitable solution to your problem. Why not consider something like the Orion (or many other dipole) bass system, but with a directional mid/top?
Having just done something similar myself I can strongly recommend a combination along these lines.
Regards,
Jonathan
All the above comments and advice seems very helpful, and there are clearly some excellent experiences out there.
A common thread seems to be the issue of speaker positioning to overcome the mid-range reflections, which I think will always be a problem with a close rear or side wall. I tried myself with this and gave up.
The solutions offered (i.e. suppressing the back-wave) strike me as a compromise (as are most things of course!), but why not engineer a more suitable solution to your problem. Why not consider something like the Orion (or many other dipole) bass system, but with a directional mid/top?
Having just done something similar myself I can strongly recommend a combination along these lines.
Regards,
Jonathan
I suppose that it is all relative but ALL my drivers cost less than that!
I may try smaller bits of carpet behind my speakers (I have some offcuts from the floor carpet but if you take a look at my listening room, you will see a carpet like yours will make it a bit dark in there!
An externally hosted image should be here but it was not working when we last tested it.
(Speakers shown are my two-way actives, not the open-baffles)
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