Xoc1 6F TH

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hi jim
ive looked at the imp plot of the th 221.
the first spike is around 10 hz that why it doesnt show on the graph
the second spike is around 32 ,the dip after that upwards is around 45 hz.
i dont beleave the th 221 is tuned that high.
i realy think its tuned @~25 hz,wich is about 7hz lower then fs.
the moment a driver is mass loaded ,the resonance changes right?

i'm not saying your wrong,just willing to learn :)
 
Not that I disagree, but I don't remember the 21" suggestion.
Hi Justin,

In my e-mail from 12-4-2012 I suggested as a fourth option, to put a couple of 21" (in reflex or TH) combined with some other TH's.

But as guideline for diameter vs high efficiency you can use the following for extended LF PA drivers;
12inch = 50Hz to 55Hz for -3dB
15inch = 40Hz to 45Hz for -3dB
18inch = 33Hz to 40Hz for -3dB
21inch = 26Hz to 33Hz for -3dB

The problem of tuning very low and still want to use them all the way up to 80Hz, it is difficult to keep them efficient between 50Hz and 80Hz. It is the region where you need most energy! For that reason 21" PA systems are usually combined with other, more efficient systems.

This still intrigues me...a lot.
By using a dual driver setting you increase the system efficiency and you have more reserves.
 
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