Making of M2
By Man-Sun Huh
21 Feb 2000
2nd step: Measurement of Unit characteristics
Measurement of Thiele-small parameter of bass unit is very important. Cabinet design is very much dependant on the thiele-small parameter. And it's very usual case that parameter in the spec. sheet and measured one is not same. I measured five W17E002 units with LMS & LEAP. (I measured only one most standard unit for Vas.) I was quite impressed that measured values of W17E002 are quite similar with the spec. sheet. SEAS seems to have a good quality control system.
|
Serial #
|
40/96-029
|
40/96-030
|
40/96-031
|
28/96-137
|
28/96-138
|
Meas. AVG.
|
Spec. sheet
|
|
Fo(Hz)
|
33.33
|
32.44
|
35.05
|
32.98
|
33.11
|
33.41
|
34
|
|
Qms
|
2.73
|
2.50
|
2.77
|
2.78
|
2.72
|
2.65
|
2.4
|
|
Qes
|
0.39
|
0.36
|
0.39
|
0.40
|
0.40
|
0.39
|
0.37
|
|
Qts
|
0.34
|
0.31
|
0.34
|
0.35
|
0.35
|
0.34
|
0.32
|
|
Vas(Liter)
|
30.9
|
|
|
|
|
30.9
|
29.5
|
On the contrary, measurement of thiele-small parameter of tweeter unit is not so critical for the design of loudspeaker.
3rd step: Cabinet design
With measured thiele-small parameter, one can design cabinet with the support of loudspeaker design programs. There are many kinds of loudspeaker design programs. LEAP, CLIO, Calsod, ... You can find some freeware program in this SBP too. I used LEAP & LMS for design and measurement.
I simulated many kind of bass alignment and decided to go to bass reflex system. I prefer acoustic suspension system but SEAS woofer can't provide enough bass with acoustic suspension design. I selected Bessel alignment and It requires enclosure volume of 12.57 liter and duct tuning frequency of 36.4Hz.(QB3 Alignment has almost the same result.) Fig.2 shows the enclosure design Fig. 2. Enclosure design plan.
|
Top
