Hi,
I'm interested in building a high quality DIY subwoofer. Actually, one per channel.
However, the room circumstances require that the subwoofers be mounted flush with the wall, about 2m high.
The question becomes, in a generic sense, what is the appropriate way to compensate for or simulate the low frequency response with this type of placement?
FWIW, I'm using the PORTED.XLS spreadsheet from http://www.diysubwoofers.org/prt/ as a starting point.
Thanks and regards,
Rob
I'm interested in building a high quality DIY subwoofer. Actually, one per channel.
However, the room circumstances require that the subwoofers be mounted flush with the wall, about 2m high.
The question becomes, in a generic sense, what is the appropriate way to compensate for or simulate the low frequency response with this type of placement?
FWIW, I'm using the PORTED.XLS spreadsheet from http://www.diysubwoofers.org/prt/ as a starting point.
Thanks and regards,
Rob
What's behind the wall? Is it a partition or will the enclosure be inset in a solid wall, or perhaps just the drivers?
I've been thinking of doing this in my loft-converted-sound room, so I'll be interested to see what happens here. It will look good, and off course you have the benefits of a very large (infinite?) baffle.
I've been thinking of doing this in my loft-converted-sound room, so I'll be interested to see what happens here. It will look good, and off course you have the benefits of a very large (infinite?) baffle.
Hi Rob
Putting a sub close to a wall will mean that it will radiate into half space which will give you a theoretical 6 dB boost in output compared with a sub in free space (the same as putting it near the floor). In your case the next closest surface will be the floor at 2m away. Assuming that you will not be driving the sub above around 100 Hz it will be "acoustically close" to the floor too, and so will now be radiating into 1/4 space, giving another 6 dB boost. Depending on how far away the side walls are you may get another boost. In practice the boost is not the full 6dB compared with mounting it further away from the surface in the room - maybe only 3dB or so.
In terms of the net result on the frequency response its hard to say what will happen. You may find a net boost up to at certain frequency at which the speaker is no longer acoustically close to the side walls. The dominant effects are likely to be from room modes which will depend on your room shape and where you and your subs are parked in the room.
Mick
Putting a sub close to a wall will mean that it will radiate into half space which will give you a theoretical 6 dB boost in output compared with a sub in free space (the same as putting it near the floor). In your case the next closest surface will be the floor at 2m away. Assuming that you will not be driving the sub above around 100 Hz it will be "acoustically close" to the floor too, and so will now be radiating into 1/4 space, giving another 6 dB boost. Depending on how far away the side walls are you may get another boost. In practice the boost is not the full 6dB compared with mounting it further away from the surface in the room - maybe only 3dB or so.
In terms of the net result on the frequency response its hard to say what will happen. You may find a net boost up to at certain frequency at which the speaker is no longer acoustically close to the side walls. The dominant effects are likely to be from room modes which will depend on your room shape and where you and your subs are parked in the room.
Mick
Following this to the DIY link page and scrolling down to
Visual Ears has the potential of answering your questions
as long as you don't have Windows XP.
http://diyaudio.com/links/index.php?PID=28&PHPSESSID=&sr=10&pp=10&cp=2&PHPSESSID=
Visual Ears has the potential of answering your questions
as long as you don't have Windows XP.
http://diyaudio.com/links/index.php?PID=28&PHPSESSID=&sr=10&pp=10&cp=2&PHPSESSID=
Thanks for the responses.
The space in question is part of a cut-out in the wall designed to accomodate an entertainment center. The bottom half is occupied with an armoire, leaving a space approximately 2' x 2' x 4' above.
I figure I can mount two smallish subwoofers, and still have room for a shelf for amplifiers.
Anyway, the space is constructed out of sheet rock, with the usual for California stucco treatment.
I'm wondering how dependent the bass boost phenomenom is on frequency, i.e., can it be modeled?
I'll check out the link, but I do have XP.
Regards,
Rob
The space in question is part of a cut-out in the wall designed to accomodate an entertainment center. The bottom half is occupied with an armoire, leaving a space approximately 2' x 2' x 4' above.
I figure I can mount two smallish subwoofers, and still have room for a shelf for amplifiers.
Anyway, the space is constructed out of sheet rock, with the usual for California stucco treatment.
I'm wondering how dependent the bass boost phenomenom is on frequency, i.e., can it be modeled?
I'll check out the link, but I do have XP.
Regards,
Rob
Unless Visual Ears has changed since I played with it, it won't tell you what bass boost that you'll get from mounting speakers close to surfaces - only the room modes, which will generate peaks and troughs through the room. Worth a play anyway.
The boost will not be dependent on frequency over the range of your sub for the closest two surfaces (rear wall and floor) because all your bass wavelengths will be large compared to the distance to the surfaces. eg at 100 Hz the wavelength will be 3.4m. Only the side walls will produce significant frequency dependent boost. I'm afraid I can't give you any equations on this.
Mick
ps If you're mounting you subs in the cutout you may have problems with the walls singing along with the sub.
The boost will not be dependent on frequency over the range of your sub for the closest two surfaces (rear wall and floor) because all your bass wavelengths will be large compared to the distance to the surfaces. eg at 100 Hz the wavelength will be 3.4m. Only the side walls will produce significant frequency dependent boost. I'm afraid I can't give you any equations on this.
Mick
ps If you're mounting you subs in the cutout you may have problems with the walls singing along with the sub.
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