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mystery garage sale speakers....

How many 1" holes in a 3/4" thick front baffle are required to be the equivalent of one 4" diameter port, 6.25" long in order to tune the cabinet to the same frequency?
 
Zilch said:
How many 1" holes in a 3/4" thick front baffle are required to be the equivalent of one 4" diameter port, 6.25" long in order to tune the cabinet to the same frequency?
Click to expand...
:scratch2: Probably not as many as it takes to fill the Albert Hall.:D :smoke: :smoke: :smoke:
 
Ok now that I look at those parameters, I can't see that working with 1" holes. The holes would have to be closer to 3/8" because the ratio of opening to depth is somewhee under 2 to 3.:smoke: :smoke: :smoke:
 
Oh, CRAP!

Y'mean I'm supposed to have an ANSWER? :p:

Hint: The ratio is not an issue.

[Well it IS, actually, but not in the sense you're thinking.... ;) ]
 
This is what I did with my enclosure, mine were missing the drivers so I improvised!
 
How many 1" holes in a 3/4" thick front baffle are required to be the equivalent of one 4" diameter port, 6.25" long in order to tune the cabinet to the same frequency?
Click to expand...
V = pi*r^2*h
Each little cylinder port has a volume of pi * (0.5 in)^2 * (0.75 in) = 0.589 in^3

The big cylinder port has a volume of pi * (2 in)^2 * (6.25 in) = 78.540 in^3

(78.540 in^3) / (0.589 in^3) = 133.3 little holes
 
I remember working out the answer using BB6P, but not what it was, so here goes again:

Put a favorite woofer (LE14A) in a 4 cuft box. 4" port 6.25" long tunes it to 29.34 Hz. Nice. :thmbsp:

Unlock the vent dimesions and lock the frequency. Change the vent diameter to 1" and increase to number of ports until the length is 0.75".

At three holes, the length is 0.606"; with four holes, it's 1.148". BB6P doesn't resolve half-holes. :p:

O.K., what hole diameter for four holes yields the same tuning? Set number to four, and vary the diameter until the length is 0.75". Answer: 0.8831"

In all of these cases, the vent velocities are off the chart; we're whistlin' "Dixie" here.... :yes:
 
If I were to guess, I'd say the Lafayette Radio connection is strong. They look like Criterion 88 cabinets, but I don't recall the drivers in that unit. Lafayette did private label Foster horns and I believe they used some McGregor drivers as well. If I were to guess, I'd say it was at least connected to Lafayette Radio.
 
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