Carpet/cloth or felt enclosure for an OB

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Hello everyone. I want to ask here about an idea that ocurred to a friend of mine while helping me figure out ways to deal with bass in open baffle speakers, room interaction and keeping bass "boxless". I have built a prototype using 2 alpha 15a drivers in a baffle, an open frame on the back and wrapping that frame around with a blanket of felt material. The idea is to create some delay between the front and back wave of the speaker but using some kind of non resonant, "breathing" material that can allow the use of smaller baffles and or lower QTS drivers and also help dissipate part of the signal that can reflect on the rear walls and eventually get to my listening position. I made a test wrapping only the right channel and did a mono test. The image went inmediately to that side and the bass increased noticeably compared to the left speaker. and no strange sounds or noises are present...opinions??


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I had this on my mind. Pillow mounted midrange showed these resistance enclosures works. I can´t do it here cause my two cat´s would tear these down but just like you have done allready and filled with cheap pillows to make it more snug fit, could start to make some noise without them large bass excursions.

What you acquire is:

-Less boost needed to eq
-less voicecoil ventilation noise (dont know if even issue with 15A)
-directivity measurements looks better down to 400hz cause pillows damps a little

HI Juhazi,

You are experimenting in a new area of science. Just be sure you know what you'll loose.

The issue with an OB design is that you want the radiation to be equal front and back so that they cancel at the sides. Any carpeting or damping will mess with the entire principle.

Also, carpeting and baffling won't delay the output so much as damp and diffuse the output. Maybe you can find this useful! If you want to lengthen the back wave but keep it more coherent you need to build hard surfaces with a longer pathway. Think folded horns.

Just make sure you understand all the benefits of an OB design should have so you have a good idea of what you are experimenting with.


I have tried the effect of damping materials on the rear radiation of open baffle speakers. To my ears it was generally an improvement, and you can have the speaker nearer to the rear wall which is an advantage in a smaller room. Try looking up "boffle",which is a development of your idea.
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