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In Reply to: RE: MCM 55-1220 12" poly cone woofer posted by djk on July 01, 2014 at 22:59:18
Here is the TS data gathered from ARTA LIMP using the added mass method.I used a 28 gram added mass.
The data file on the 55-1220 suggests that they used 30 grams for their measurements, so used an added mass close to that.
Parameter, Value, Dim
Fs, 26.34, Hz
Re, 5.30, ohms[dc]
Qt, 0.28, -
Qes, 0.35, -
Qms, 1.38, -
Mms, 52.95, grams
Rms, 6.819896, kg/s
Cms, 0.000671, m/N
Vas, 423.34, liters
Sd, 670.12, cm^2
Bl, 11.995520, Tm
ETA, 2.37, %
Lp(2.83V/1m), 97.63, dB
, ,
Le, 231.09, uH
L2, 1456.72, uH
R2, 19.62, ohms
L3, 0, uH
R3, 0, ohmsI'll put the data in WinISD and see what happens to the results.
Edits: 07/02/14Follow Ups:
Wow, that is light for a poly cone. Impressive how close to mcms specs.
I ran the TS parameters in LIMP again with a 90 gram added mass.That was right in the middle range of what the program said was the ideal phase shift between the added mass and non added mass measurements.
WinISD said a 3.75 cu. ft. closed box would be an ideal enclosure.
Since that was the size of the box I had, I installed the 55-1220 and let it run full range in the closed box.
I threw a Magnavox horn on top of the box crossed over at 2K cycles first order with L-PAD.
The WinISD plot had the low end rolling off at 100Hz, so there was no deep bass when I listened to it.
Edit: got up this morning and ported the box. It is tuned to 38Hz.
Took a Hz sweep in room.
The horns have a bump in their response.
I might try to work on a notch filter, but it is not critical.
The low end down from 1KHz was better with the 55-1220 compared to the Olsen 12" woofer I had in the box previously.
Edits: 07/03/14
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