Trapezoid knock-down volume question

[MysteryCat]

Hi all,
I asked this question in the PE cabs thread but got no response. I'm a total noob at this. For the Dayton 12" driver, the calculator's telling me to build a ported cabinet of 5.8 cu ft, or a sealed box of about 2.7 cu ft. The trapezoid kit is 1.65 cu ft. How does that work? What am I giving up going with this kit?
Thanks!

[rudyjakubin]

Hi all,
I asked this question in the PE cabs thread but got no response. I'm a total noob at this. For the Dayton 12" driver, the calculator's telling me to build a ported cabinet of 5.8 cu ft, or a sealed box of about 2.7 cu ft. The trapezoid kit is 1.65 cu ft. How does that work? What am I giving up going with this kit?
Thanks!

Does the calculator compensate for stuffing?
Stuffing like fibreglass increases the internal volume (25-35%) minus driver displacement (bout .15 cubes)...
Also, if going sealed - where the dip in the lower frequency on the box calculator look for the F3 - F6 point on the chart and that'll be your sub woofer setpoint for you to start out with.

[billfitzmaurice]

Stuffing like fibreglass increases the internal volume (25-35%) .

Stuffing lowers Q of a sealed cab when the Q is well over .8, and it won't lower the Q enough to give the same F3 as a box 25-35% larger. Maybe 20%, and that lowering of Q is accompanied by a loss of broadband sensitivity.

What am I giving up going with this kit?

Model the driver in that size box and you'll see. Some low end extension loss is the trade off for a smaller box.

[1100xxben]

Does the calculator compensate for stuffing?
Stuffing like fibreglass increases the internal volume (25-35%) minus driver displacement (bout .5 cubes)...
Also, if going sealed - where the dip in the lower frequency on the box calculator look for the F3 - F6 point on the chart and that'll be your sub woofer setpoint for you to start out with.

This is an honest question... you'd figure 0.5 cu ft for the driver displacement of a 12" Dayton Sub? I don't know exactly which Dayton driver the OP is referring to, but I'm thinking about the RSS315 for example. I would only figure about 0.15-0.2 cu ft in driver displacement. What's the rationale/your method for figuring driver displacement?

[MysteryCat]

sorry for the incomplete info... The driver is Dayton DC300-8. I used the calculator here: http://www.diyaudioandvideo.com/Calculator/Box/
It looks very simple, so probably not taking stuffing into account. I saw that driver and the trap cabinet kit used in Econowave standard kit. I just wonder how that would work.

[charlielaub]

The trap cabinets work fine. There are many examples for the Econowave. See my post in the tower cabinets thread:
http://techtalk.parts-express.com/sh...7&postcount=31

-Charlie

[billfitzmaurice]

sorry for the incomplete info... The driver is Dayton DC300-8. I used the calculator here: http://www.diyaudioandvideo.com/Calculator/Box/

That will give you the 'ideal' box size based on the driver specs, but 'ideal' means 'as good as can be got', which doesn't tell you all that much. A true box program like WinISD Alpha Pro will give you everything you need to know, with a dozen graph options.

[MysteryCat]

A true box program like WinISD Alpha Pro will give you everything you need to know, with a dozen graph options.

Awesome. I'll check it out. Thanks!