I thought I'd play with this because (a) I have the parts lying around. (b) It requires calculations way above my pay-grade.
My spare room is 2.5 x 3m yet, remarkably contains a double bed. I long been of an advocate of that modelling my be helpful for benchmarks, and those building PA systems but speaker performance is largely dependent on location.
Long story short . . . I'm looking at one of those tall, skinny floor-standing speakers that were once all the rage, and it's all alone - useless without its partner, doomed to a landfill . . . or is it 48ltr box which, laid on its side slides neatly under a bed or can be tucked behind a sofa?
I've got a couple of 8" woofers lying around, a stereo TPA3116D2, and a 90w laptop power supply - so let's see what I can see. For the purposes of this project the cabinet must be ported, the drivers are the drivers, and the cabinet's volume cannot be changed. The port is the only tuning mechanism.
The software simulation of the cabinet is embarrassing, a disaster. But the software doesn't know the cabinet is performing in a room with an effective 250mm ceiling height. It kinda begs the question: if high were a company like Bo$e trying to create a niche market in under-bed subs, how would I tune my cabinets?
30hz in an 8 x 10 room is a struggle, 40hz with a ceiling height of 250mm is a pyrrhic endeavour but we can tune for +6db at 55dB and our customers will report that our under-bed systems have wicked, dirty bass.
My spare room is 2.5 x 3m yet, remarkably contains a double bed. I long been of an advocate of that modelling my be helpful for benchmarks, and those building PA systems but speaker performance is largely dependent on location.
Long story short . . . I'm looking at one of those tall, skinny floor-standing speakers that were once all the rage, and it's all alone - useless without its partner, doomed to a landfill . . . or is it 48ltr box which, laid on its side slides neatly under a bed or can be tucked behind a sofa?
I've got a couple of 8" woofers lying around, a stereo TPA3116D2, and a 90w laptop power supply - so let's see what I can see. For the purposes of this project the cabinet must be ported, the drivers are the drivers, and the cabinet's volume cannot be changed. The port is the only tuning mechanism.
The software simulation of the cabinet is embarrassing, a disaster. But the software doesn't know the cabinet is performing in a room with an effective 250mm ceiling height. It kinda begs the question: if high were a company like Bo$e trying to create a niche market in under-bed subs, how would I tune my cabinets?
30hz in an 8 x 10 room is a struggle, 40hz with a ceiling height of 250mm is a pyrrhic endeavour but we can tune for +6db at 55dB and our customers will report that our under-bed systems have wicked, dirty bass.
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(a) To calculate response, the TS parameters of the parts must be known.
(b) The calculations don't require pay, but do require inputs.
I don't know how high you are, but an effective 250mm ceiling height puts you in the garden gnome height range 😉
I don't know how much of the post you actually read or your level of comprehension but I feel compelled to point out the following:
(a) "The software simulation of the cabinet is embarrassing", indicates a simulation has been performed therefore TS parameters are known. (b) Placing a sub, under a bed, placed in the corner of room creates a secondary cabinet consisting of two walls, the floor and a substitute ceiling being provided by the underside of the mattress. I would assume this creates an unusual environment for standing waves, further amplified by the small dimensions of the room.
The point of the question: knowing in advance the location of the speaker, would it be better to pre-emptively tune the cabinet with a degree of room correction.
Surtsey, I admit my level of comprehension of what you find "embarrassing" is limited.
Post the TS parameters, and the simulation and we may be able to help you interpret the results.
Mattresses can be open or closed cell foam, or thin mats over box springs, combinations of materials that vary as much as speaker cabinet construction. The mattress "ceiling" may be largely acoustically transparent to sub frequencies, while creating an acoustical HP filter to upper frequencies. Without measurement or further description, any understanding of the acoustical environment the mattress creates is conjecture, it may function as a "bass trap" or a plenum/resonator, or a combination of the two.
Speaker simulation and radiation angle (free space, half space, quarter space, eighth space) do not simulate room response.
Tuning the speaker differently won't correct room response, but may result in a response at a particular listening position that would be preferable to you. Simply moving the speaker to different locations under the mattress will result in huge variations at the head of the bed and other positions in the acoustically small bedroom.
Art