Bill may be correct with a flat baffle dipole or the Orions, but I've used swept back wings and a top (to cut down on ceiling reflections) plus rear wave attentuation with polyfill and foam rubber. I find they sound best very close to the wall or very far from it with the only problem being in the 2-4ft distance.
I think the answer is that you can make close placement work by attentuating the rear wave and maybe some absorption or diffusion on the wall. Dipole is a very flexible and easily adjustable design that can be made to suit placement needs unlike monopoles that can sound their best with only one placement out away from the walls.
I think the answer is that you can make close placement work by attentuating the rear wave and maybe some absorption or diffusion on the wall. Dipole is a very flexible and easily adjustable design that can be made to suit placement needs unlike monopoles that can sound their best with only one placement out away from the walls.
johninCR said:
Siegfried demonstrate that bass response will be irregular with short wall distance in a dipole, midrange should works but losing the sound width. It makes me sad that such a design needs a big room because more than 4 feet from wall means to have a big room. I think we can say that an open baffled near the wall with some absorption is between dipole and monopole, with the wall, baffle just make a big box with a big port ! Something like this :
An externally hosted image should be here but it was not working when we last tested it.
johninCR said:
OK, nice open baffled, I'd like to try this supravox one, looks beautiful with some of the best fullrange driver :
An externally hosted image should be here but it was not working when we last tested it.
It's nice to have the speakers out from the rear wall, but this true of monopoles as well.
So while your distance isn't ideal for dipoles, it isn't for most others either.
However, because you are going DIY you can adapt. I'd suggest using a digital crossover like the Behringer DCX 2496 or dbx Driverack 260.
Combined with a simple measuring system you can adjust the crossovers and use simple EQ to counter many of the problems you may encounter.
Cheers
Steve
So while your distance isn't ideal for dipoles, it isn't for most others either.
However, because you are going DIY you can adapt. I'd suggest using a digital crossover like the Behringer DCX 2496 or dbx Driverack 260.
Combined with a simple measuring system you can adjust the crossovers and use simple EQ to counter many of the problems you may encounter.
Cheers
Steve
I've already the DCX 2496 wich is the masterpiece of my project. I wanted to build exact Orion and use his crossover in the DCX2496, Siegfried told me that Orion are not a good option if less than 4 feet from rear wall, I believe he's right so maybe I plan to build another open baffled design playing with wall, I like the open baffled design by supravox with high sensitivity full range driver...sfdoddsy said:
I have my OB's about one metre from the rear wall. They sound better as I move them further from the rear wall but in my room, one metre is about the limit before they are too 'opressive' (physically).
Even with this compromise, I would not consider going back to a boxed speaker system.
(I would rather move house to somewhere with a larger listening room!)
Even with this compromise, I would not consider going back to a boxed speaker system.
(I would rather move house to somewhere with a larger listening room!)Hi,
I have a question about something posted earlier in this thread (post #3):
My speakers have an open baffle midrange. Yesterday I took some polyfill batting, folded it over to make a sheet about 2" thick, and staple-gun'd it down on the back of the baffle so it covers the back of the driver. I haven't listened to this for very long, but it seemed to change the sound to something similar to the closed box speakers I've had before. The imaging took on more focus, but the sound also seemed to become flat and boring, if that makes any sense.
Anyway... we want to damp/diffuse the back wave because we aren't in an infinitely large room and we don't want the reflection off the back wall. However, we don't want to remove the wave entirely, or we don't get any interaction with the front wave at all and the open baffle ends up with a monopole radiation pattern, right? Am I on the right track so far? If I am, then the question is, how much is enough? What do people normally do about this? I know this will be a case-by-case situation, so I would appreciate general guidelines and advice here.
It seems to me that I've removed too much of the back wave with my experiment. I can try less polyfill, maybe mount it more loosely so it doesn't cover the back of the driver so completely, or forget about attenuation altogether and focus on absorbing/diffusing the reflection. Dedicated room treatments are out, so it'll probably end up being a combination of attenuation and diffusion using bookshelves and the like. The question is, how much, and which is more important, and things like that.
Thanks in advance,
Saurav
I have a question about something posted earlier in this thread (post #3):
My speakers have an open baffle midrange. Yesterday I took some polyfill batting, folded it over to make a sheet about 2" thick, and staple-gun'd it down on the back of the baffle so it covers the back of the driver. I haven't listened to this for very long, but it seemed to change the sound to something similar to the closed box speakers I've had before. The imaging took on more focus, but the sound also seemed to become flat and boring, if that makes any sense.
Anyway... we want to damp/diffuse the back wave because we aren't in an infinitely large room and we don't want the reflection off the back wall. However, we don't want to remove the wave entirely, or we don't get any interaction with the front wave at all and the open baffle ends up with a monopole radiation pattern, right? Am I on the right track so far? If I am, then the question is, how much is enough? What do people normally do about this? I know this will be a case-by-case situation, so I would appreciate general guidelines and advice here.
It seems to me that I've removed too much of the back wave with my experiment. I can try less polyfill, maybe mount it more loosely so it doesn't cover the back of the driver so completely, or forget about attenuation altogether and focus on absorbing/diffusing the reflection. Dedicated room treatments are out, so it'll probably end up being a combination of attenuation and diffusion using bookshelves and the like. The question is, how much, and which is more important, and things like that.
Thanks in advance,
Saurav
Hi Saurav,
The simple (if a bit tongue in cheek!) reply is use a front horn for mid/top directivity, and then completely control the rear wave!! See my recent posting on Oris front horn/dipole bass, this is what I've just built myself.
I'm using this system hard into a corner (rear and side walls are close). I've also had them pulled out into the room, but there was really very little difference.
I have had dipole mid/top systems in this room before, and the rear wave was a nightmare to control effectively.
Regards,
Jonathan
The simple (if a bit tongue in cheek!) reply is use a front horn for mid/top directivity, and then completely control the rear wave!! See my recent posting on Oris front horn/dipole bass, this is what I've just built myself.
I'm using this system hard into a corner (rear and side walls are close). I've also had them pulled out into the room, but there was really very little difference.
I have had dipole mid/top systems in this room before, and the rear wave was a nightmare to control effectively.
Regards,
Jonathan
I have found the same thing Saurav. You need to have some open space between the driver and whatever you are using the absorb some of the rear wave.
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.
Thanks. I'll see if I can find a way to make a polyfill 'wall' that's some distance behind the driver, maybe at the rear edge of the cabinet that the OB sits on. If you can post pictures of your setup, that would be very helpful.
If anyone else has any advice, I'd love to hear it.
Thanks,
Saurav
If anyone else has any advice, I'd love to hear it.
Thanks,
Saurav
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
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