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Old 19th December 2010, 05:10 PM   #1
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Default Pipe open at one end

Hi, I'm working at the idea of a speaker that uses a low compliance, high Qts driver ( fs 100Hz Qts 1) in a constant area column, of around 1m high, say 400mm wide 200mm depth, open at the bottom (the whole 400X200 mm surface), against the floor.
Would this produce a reinforcement at say 70/80Hz, and Does it make a difference (the position along the line) of driver's center, to the closed end? Asuming adecuate stuffing , of course.
I still do not own the MJK soft yet, so I'm not able to simulate the behaviour of this, so only a gross guessing..
Thanks
J
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Old 19th December 2010, 05:46 PM   #2
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Quote:
Originally Posted by Mosquito View Post
Hi, I'm working at the idea of a speaker that uses a low compliance, high Qts driver ( fs 100Hz Qts 1) in a constant area column, of around 1m high, say 400mm wide 200mm depth, open at the bottom (the whole 400X200 mm surface), against the floor.
Would this produce a reinforcement at say 70/80Hz, and Does it make a difference (the position along the line) of driver's center, to the closed end? Asuming adecuate stuffing , of course.
I still do not own the MJK soft yet, so I'm not able to simulate the behaviour of this, so only a gross guessing..
Thanks
J
Hello,
Sounds like a transmission line to me!
The length of the tube plus the stuffing determines the phase at the far end of the tube.
The stuffing working with the Qts of the driver determines the damping of the speaker (goal 0.71 total Q)
Have at it!
This is the stuff that keeps people up at night.
Saturday the stuffing goes in the turkey.
DT
All just for fun!
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Old 19th December 2010, 06:50 PM   #3
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We here save the Turks and eat steaks
Maybe I need to clarify a bit. I do not ask "what type of driver will do best"
For a number of reasons the driver is as it is, I need to optimize the enclosure for this particular driver. And yes, it falls in a sort of not folded, very short, transmission line.. a rectangular tube bah..
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Old 19th December 2010, 07:29 PM   #4
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Hello,
When I said “have at it” my reference was to do a little trial and error. Your enclosure is likely a little long an thin (having TL properties) it will also have internal resonance, sound bouncing around like you singing in the shower or one note bass that is where the stuffing comes in.
To get your creation to reinforce around 70 to 80 Hz here is my trial and error recommendation; close off the open end with plywood and drill 50 mm holes in it until it sounds good to you! When you have drilled too many holes backup one.
Steak does sound good!
DT
All just for fun!
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Old 19th December 2010, 07:49 PM   #5
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Thanks!, Good advice.
Now I`ve to get out to buy some bottles for the 24 nite
Cheers
J
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Old 19th December 2010, 08:39 PM   #6
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by Mosquito View Post
Hi, I'm working at the idea of a speaker that uses a low compliance, high Qts driver ( fs 100Hz Qts 1) in a constant area column, of around 1m high, say 400mm wide 200mm depth, open at the bottom (the whole 400X200 mm surface), against the floor...Would this produce a reinforcement at say 70/80Hz,.. so only a gross guessing..
FYI,All just for fun!

b
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Old 19th December 2010, 08:57 PM   #7
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sacre bleu! many thanks bjorno! It's pretty much like I envisioned trough my third eye!
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Old 19th December 2010, 09:31 PM   #8
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Originally Posted by Mosquito View Post
sacre bleu! many thanks bjorno! It's pretty much like I envisioned trough my third eye!
Hello,
Fun indeed!
Do you know the woofer name brand model or TS parameters for b to plug into the software, that could make it “real” fun?
DT
All just for fun!
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Old 19th December 2010, 09:46 PM   #9
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Yes, I do.
http://profesional.beyma.com/pdf/12GA50E.pdf
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Old 19th December 2010, 10:47 PM   #10
bjorno is offline bjorno  Sweden
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FYI:

b
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