Sealed or Closed Enclosure

• $V_b<Vas$

Pros

• Efficient
• Low distortion
• Easier to build
• Smooth base dropout
• Some varies of box volume is not effect much

Cons

• Low Efficiency

Qtc

Qtc = Total Q (speaker + box) Qts = Qms and Qes Qtc = Qbox and Qts

Qtc	Response Peak	Character
0.500 (Linkwitz-Riley)	0	Critically damped, lowered SPL, huge enclosure
0.577	0	Optimal driver damping, lowered SPL, best transient response, huge enclosure
0.707 (Butterworth)	0	Usually considered the “optimum” alignment by most designers, gives excellent transient response, low bass performance and power handling, and flattest response curve before F3. Enclosure may be fairly large.
0.850	+0.69 dB	Good alignment if optimum is to large an enclosure, generally very good performance with only slightly accentuated (non-flat) bass, good low bass response. Medium sized enclosure.
1.000	+1.25 dB	Best compromise enclosure. Much smaller box than optimum, fair transient response and low bass performance, more noticeable midbass peak. Medium-smaller sized enclosure.
1.100	+1.83 dB	Maximum power handling and efficiency, smaller sized enclosure, more pronounced midbass peak. Smaller enclosure.
1.300	+3 dB	Driver may sound noticeably boomy, especially smaller drivers with higher Fs and Qts. Fair (or worse) transient response and compromised low bass response. Pronounced mid-bass peak makes the enclosure louder but less accurate. Small enclosure.
2.000	+6 dB	Very boomy and muddy, poor transient response and low bass performance. Very small enclosure.

> 0.7 call Chebyshev

Q Value

Ql loss of the box Qa loss of the absorb material

For sealed boxes (lined):
Ql=15
Qa=20

or some other combo to get Qlt=~10

For sealed boxes (stuffed):
Ql=15
Qa=8

or some other combo to get Qlt =~5

Stuffing

Isothermal propagation?? Stuffing dumping material in the box can increase box size

Box Volume ($V_b$) Calculation

$V_b=\frac{V_{as}}{(\frac{Qtc}{Qts}{)}^2-1}$ $\frac{V_{as}}{V_b}=(\frac{Qtc}{Qts}{)}^2-1$

Vb = Vas / ((Qtc/Qts)**2 - 1)
 
Vas = Vb * (Qtc/Qts)**2 - Vb

$f_b=f_s\cdot \sqrt{\frac{V_{as}}{V_b+1}}$

fb = fs * (Vas/(Vb+1))**0.5
 
fb = fs * (Vas/(Vas / ((Qtc/Qts)**2 - 1)+1))**0.5
 
fb = fs * ( Vb * ((Qtc/Qts)**2 - 1) /(Vb+1))**0.5
 

$f_3=\frac{f_b}{\sqrt{2}}\cdot \sqrt{(\frac{1}{Q_{tc}^2}-2)+\sqrt{(\frac{1}{Q_{tc}^2}-2{)}^2+4}}$

f3 = fb / 2**0.5 * ((1/Qtc**2 - 2) + ((1/Qtc**2-2)**2 + 4)**0.5)**0.5