Is there any harm is "oversizing" a sealed enclosure for a woofer (~500hz and below)

[Fusion916]

Thinking about a active xo 3 way line array with a line array of mids, 1 tweeter and one woofer on the bottom with the following arrangement:

M                                        M
M                                        M
M                                        M
M                                        M
     T                             T
M                                        M
M                                        M
M                                        M
M                                        M
W                                        W

I will use a high SPL tweeter which will match the SPL of the line array mids. Don't care about the SPL of the woofer because it will be going on a different amp. Obviously to fit the line array the box will be oversized for the woofer. What are the problems associated with this?

[killa]

depends on how low you go. You trade power handeling for a bigger box. What are you trying to do?

[Fusion916]

Line array with mids, tweeter and woofer all in one box as shown above

[rpb]

Line array with mids, tweeter and woofer all in one box as shown above

I don't think it will matter. You can add filler to reduce the volume if needed. The mid chambers need to be isolated from the woofer unless they are a sealed back type.

[jmb]

As you increase the enclosure size, the excursion of the woofers will increase, leading to a greater chance of distortion or potentially driver damage. It would be best to model your enclosure with one of the softwares available to try to avoid these issues. As rpb indicated, more power will lead to more excursion; a smaller box helps to provide more counter pressure to this helping to limit this.

Jay

[fastbike1]

You can always internally limit the portion for the woofer.

[michiganpat]

or go with a bigger woofer

or at least one with a higher Vas

if you're going sealed woofer, I'd probably shoot for a System Q of around .75.

[Fusion916]

or go with a bigger woofer

or at least one with a higher Vas

if you're going sealed woofer, I'd probably shoot for a System Q of around .75.

I thought the ideal Q was 0.707?

[Sydney]

I thought the ideal Q was 0.707?

Qtc .5 Critically damped - transient perfect.
Qtc .577 Bessel response - max flat delay.
Qtc .707 Butterworth response - max flat amplitude response with minimum cutoff.

[WernerM]

Qtc .5 Critically damped - transient perfect.
Qtc .577 Bessel response - max flat delay.
Qtc .707 Butterworth response - max flat amplitude response with minimum cutoff.

Sydney,
This maybe a "stupid" question, but can you explain those definitions in laymans terms? IOW, can you define the differences for me?

[Sydney]

Sydney,
This maybe a "stupid" question, but can you explain those definitions in laymans terms? IOW, can you define the differences for me?

Not stupid at all
To quote Vance Dickason (LDC) "The closed box is the simplest of all loudspeaker designs, consisting of an enclosed volume of air and the loudspeaker or driver. It's electrical and pneumatic circuits are analogous to a second order high pass filter with the response controlled by the resonance and the associated damping"
Basically these use the same terms that filter designers use to describe transfer functions ( named after the Mathematicians who developed each transfer function equation ).
What it does is indicate how the system acts at cutoff - see below

Note: that for QTC values .707 and below the response rolls off below reference, but for values above .707 the response rises before falling ( a ripple ).
A crude analogy is adjusting a spring and weight system; like a car with air shocks and adjusting the ride - from hard and taunt to loose and spongy - ie how it responds to a transient ( a shock).
Subjectively some consider a QTC in the .5 range to be excessively taut and over-damped. Higher QTC ( >1 ) are often perceived as warm.

[rpb]

With a typical woofer, the box for a Q of .5 needs to be about three times the volume that is required for a Q of .7.

A Q of .9 is about as high as I would consider for my use if I needed a small box. Things change depending on the TS parameters, but for a random example. Woofer Qts of .35, and Vas of 3 cu-ft.

.5 box size 2.9 cu-ft.
.7 box size 1 cu-ft.
.9 box size .5 cu-ft.