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Cone excursion question

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0krizia View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 0krizia Quote  Post ReplyReply Direct Link To This Post Posted: 09 April 2021 at 6:20am
Maybe I should have specified tuning better...

I usually tune my boxes around 33-43 hz. 
My designs are made with extra large ports (above 50% of cone surface area) this is because I want to take advantage of the low cone excursion at port tuning by boosting at tuning to force more output. 

With a boost at tuning, im thinking maybe the pressure is already high through the port, this protect the cone from high excursion at frequencies below tuning during music? 
With a tuning at say 42 hz and With such large ports, im thinking maybe a bass beat around 55 hz with almost no activity below 45 hz will then result in next to no pressure inside the large port(s), this might make the pressure inside the enclosure around 55 hz so low the cone moves like it is in free air. 

Does this make any sense or is my logic faulty?  

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madboffin View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote madboffin Quote  Post ReplyReply Direct Link To This Post Posted: 08 April 2021 at 9:38pm
Don't forget that your amplifier will have a subsonic filter incorporated in its design. Is that what's causing the effect you have seen?

If you want to test a speaker at frequencies below 20Hz of so at high power, you really need an industrial amplifier (as used for driving vibrator tables etc) with a frequency response down to DC.
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0krizia View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 0krizia Quote  Post ReplyReply Direct Link To This Post Posted: 08 April 2021 at 8:08pm
When I use winISD to simulate designs, the graph do not reflect reality. If I for example add a 6 db boost (Q=4) at 6 hz below tuning, the cone excursion below tuning spikes way over maximum cone movement above tuning, however when I test this in the real world, my designs usually bottom out above tuning first. Anybody knows how this can be the case? 






Edited by 0krizia - 08 April 2021 at 8:19pm
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