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Discussion Starter · #1 ·
Still planning out first DIY build and surely overthinking this, but maybe that is half the fun:innocent:

I already purchased a BASH 300 amp (maybe too soon) and am hemming and hawing between various 12 and 15" drivers. currently looking at the RE SEX series as well as the Alpine SWR series. I have a bigger room to fill (22 ft x 13 ft x 8 ft) so figure that a 15 might be preferred, but am surprised to find only about a 3db difference between the 12 and 15 inch versions across the board. wondered if higher input power would make a difference, but am surprised to see not much difference when I model with 300w or 600w (recommended max RMS)I get substantial difference in cone excursion and port air velocity....shouldn't there also be more db?:ponder:

The 12s are appealing as I seem to get a nice flat curve from 20hz up with a much smaller volume (ie 3.5 ft^3 vs 6 for the 15) so what am I missing?:huh:
 

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It takes double the input power to create a 3 db increase in SPL; that's why you're only seeing a small increase in output going from 300 to 600 watts. You're not missing anything in your modeling, you're on the right track. Higher power past a certain point costs a bunch, but doesn't make a big difference, so your BASH 300 will serve you well. Have fun with this- that's the point!

Tom
 

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Discussion Starter · #3 ·
Thanks Tom...is that about what I should expect difference wise for a
12 vs 15....about 3db and a bit lower extension? How noticeable a difference is 111 vs 114 db anyway?
 

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Discussion Starter · #5 ·
If that is the case, what is the advantage of a 15 over a 12? Low end extension and the just noticeable volume?
 

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The larger cone can move more air than the smaller one, but it requires more power to do that; there's no defeating the laws of physics. The larger cone can produce a lower frequency with a smaller movement than the smaller cone, and at a higher spl, but control and power required are trade-offs- the smaller cone is easier to control, so has better transient response (accuracy) within its range, all else being equal.
Each design is a series of compromises between goals. You have the BASH 300, and a given space to fill, a certain acceptable volume/size for the cab, a certain budget, your own ears to please. I prefer a Q around .6-.7, other people like .9 or .5; none is "right," each is a preference. As a first build, I chose a cab volume and amp, then substituted different drivers in different sizes in the box, tried venting versus sealed, all to the end of experiencing different Qs and designs to find what I preferred. (I used a 3 foot cube pre-built box from PE with different baffles. Part #302-847 and #302-862.)

Tom
 
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