not sure but I fixed it 
I've not encountered any problems with line breaks being removed before....
Hi Paul
To add a little more
TLs work better with multi-fold lines whose walls are lined with egg crate acoustic foam, experiment on different foam thicknesses. Ensure that you have unrestricted air flow.
To add a little more
TLs work better with multi-fold lines whose walls are lined with egg crate acoustic foam, experiment on different foam thicknesses. Ensure that you have unrestricted air flow.
Ported /Passive Bass reflex designs
use of golden ratio or non parallel surfaces goes a long way in dealing with standing waves, however foam helps in internal decay and increases the speakers overall resolution. At bare minimum use foam on at-least three adjacent walls. On the other extreme use egg crate acoustic foam walled labyrinth between driver and port to ensure foam does its work (ensure labyrinth is no where near 1/4 wave of port tuning), have unrestricted air flow to port
Other techniques include borrowing from http://www.paraglidingteam.nl/PPGTechnics/sound and noise/Mufflers/1155795969.pdf
different techniques of negative feedback in solid state amplifiers introduces interesting dimensions on differences between active crossover systems and passive crossover systems in handling reflections reaching the speaker
use of golden ratio or non parallel surfaces goes a long way in dealing with standing waves, however foam helps in internal decay and increases the speakers overall resolution. At bare minimum use foam on at-least three adjacent walls. On the other extreme use egg crate acoustic foam walled labyrinth between driver and port to ensure foam does its work (ensure labyrinth is no where near 1/4 wave of port tuning), have unrestricted air flow to port
Other techniques include borrowing from http://www.paraglidingteam.nl/PPGTechnics/sound and noise/Mufflers/1155795969.pdf
different techniques of negative feedback in solid state amplifiers introduces interesting dimensions on differences between active crossover systems and passive crossover systems in handling reflections reaching the speaker
Thanks!
I bet this line break won't work either! Funny, never used to have the problem...
I've always just used cheesecloth for this, although recently I've toyed with the idea of replacing the fiberfill with magnetized steel wool, carefully oriented so as to be repelled away from the rear of the driver by its own magnet.
On second thought, I'll probably just stick with the cheesecloth.
On second thought, I'll probably just stick with the cheesecloth.
You may be correct but you need to show measurements to prove it. For instance build two identical, folded lines and use foam to line one of them as you choose, then use polyester fiber in the other (but being absolutely sure the fiber density and location has been optimized). Swap the same driver between lines and measure SPL vs frequency for both driver and terminus, as well as impedance vs frequency for the driver. Then you can make claims that are backed up by your results.
Paul
Paul
Thanks, Jim. So my off-the-cuff hairnet suggestion wasn't too far off the mark. Might even be more suitable if you want to go synthetic - India is hot, humid and prone to bug infestation, so synthetic materials will probably last longer.
Anything magnetic in close proximity to the speaker is not a good idea, IMHO. Might mess up the characteristics of the motor.
Yup, synthetic hair net sounds like a not-bad idea too, provided the weave is not too coarse.
The magnetic steel wool idea was my feeble attempt at humor. (It gets a bit dry around here at times.) I was trying to "think outside the box," but that isn't really possible in this case anyway.
The magnetic steel wool idea was my feeble attempt at humor. (It gets a bit dry around here at times.) I was trying to "think outside the box," but that isn't really possible in this case anyway.
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"Outside the box".... now, in this context, that is funny.Yup, synthetic hair net sounds like a not-bad idea too, provided the weave is not too coarse.
The magnetic steel wool idea was my feeble attempt at humor. (It gets a bit dry around here at times.) I was trying to "think outside the box," but that isn't really possible in this case anyway.
Seriously, what do you think of putting a plastic mesh dome cover over the back of the driver? Like the things you use to keep flies off your food.
An externally hosted image should be here but it was not working when we last tested it.
I think a dome like that would certainly work, although it might be overkill in most normal stuffing situations. My experience is certainly limited compared to many others here, but I haven't had much trouble with stuffing "invading the personal space" of drivers, even after many years in the box. It seems to stay put reasonably well, especially with a layer of the aforementioned cheesecloth.
Agreed, but with a dome like that in place (you also get small ones for condiments and for children to play with) you can experiment with other stuffing materials. Eg, small thermocoal balls - what they use for making thermocoal sheets etc.
I find this one a cool idea: http://www.holgerbarske.com/wp-content/uploads/2014/11/jbl1811_03.jpg
Small and cheap IKEA pillows. Guess what I bought when I visited IKEA the last time ?
Regarding the proximity of stuffing to the drivers: In a book by Colloms there is the mentioning that fibers can show a somehow hysteretic friction behaviour which may increase distortion if too close to the drivers.
Manger for instance writes that one should not go closer than 6 cm to their driver with stuffing because this would be detrimental to sound quality.
Regards
Charles
Small and cheap IKEA pillows. Guess what I bought when I visited IKEA the last time ?
Regarding the proximity of stuffing to the drivers: In a book by Colloms there is the mentioning that fibers can show a somehow hysteretic friction behaviour which may increase distortion if too close to the drivers.
Manger for instance writes that one should not go closer than 6 cm to their driver with stuffing because this would be detrimental to sound quality.
Regards
Charles
Hi Paul its actually a matter of convenience and the ease of use, the absorption index can be manipulated
I have used pillows before, however different pillow casings provide varied results to the level of day and night difference.
You might be missing out on the best characteristics of your speakers
You might be missing out on the best characteristics of your speakers
I find this one a cool idea: http://www.holgerbarske.com/wp-content/uploads/2014/11/jbl1811_03.jpg
Small and cheap IKEA pillows. Guess what I bought when I visited IKEA the last time ?
Regarding the proximity of stuffing to the drivers: In a book by Colloms there is the mentioning that fibers can show a somehow hysteretic friction behaviour which may increase distortion if too close to the drivers.
Manger for instance writes that one should not go closer than 6 cm to their driver with stuffing because this would be detrimental to sound quality.
Regards
Charles
Hi Paul
As you can see from the following video, the sealed section uses fiber, while the bass reflex ported uses straight acoustic foam
https://www.youtube.com/watch?v=JMV6RlQx2BE
As you can see from the following video, the sealed section uses fiber, while the bass reflex ported uses straight acoustic foam
https://www.youtube.com/watch?v=JMV6RlQx2BE
https://www.youtube.com/watch?v=WiawUUnD-kw
Sunfire utilize a passive cone that serves two roles as a damper as well as passive driver
https://www.youtube.com/watch?v=683FoCDilOE
https://www.youtube.com/watch?v=XMTFnC6atOE
On the second video 23rd second you can see that PMC evolved to such a level they were willing to try an audio valve that opens only on certain bass tones or exculsions
https://www.youtube.com/watch?v=VPzHMMhMkPo
This subwoofer kit uses foam
Sunfire utilize a passive cone that serves two roles as a damper as well as passive driver
https://www.youtube.com/watch?v=683FoCDilOE
https://www.youtube.com/watch?v=XMTFnC6atOE
On the second video 23rd second you can see that PMC evolved to such a level they were willing to try an audio valve that opens only on certain bass tones or exculsions
https://www.youtube.com/watch?v=VPzHMMhMkPo
This subwoofer kit uses foam
Can you predict with confidence from modeling what the results will be using foam lining? I find it not at all inconvenient to use polyester fiber and I can model its predicted effects quite accurately, so if I build exactly what I model, I will get the expected results. I should say, though, that I've found a stuffing density of 0.75 lb/ft3 to be almost universally optimum, needing only to use different stuffing lengths from the beginning of the lines to achieve what I want. That allows me to use Dacron batting, instead of loose fill, which is 1 inch thick and has an inherent density of 0.75 lb/ft3. No weighing is necessary as you just cut it into rectangles that mimic the internal dimensions of the line and layer it in without any compression of teasing, and it stays put.
Paul
Paul
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