# BP 1803 "sag"?

Discussion in 'Home Theater Projects' started by JimPeitersen, Aug 6, 2004.

1. ### JimPeitersen Second Unit

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I've got a question for all the guys with a BP 1803/1804, or experience with them (Kyle, Jack, Thomas, Craig, etc.) One of my 1803's have been in a sonotube (5 cu.ft. LT) for close to two years. I was looking closely at it the other day, and noticed that it may be sagging. Can anyone remember if these were rated for long-term horizontal applications? Thanks,
Jim

2. ### ThomasW Cinematographer

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Here's the formula

BP-1803 T/S Parameters

Fs= 25.0
Re= 3.6/4 ohms
dB/2.83V/m=95
Xmax=51.9mm p-p
Qts= 0.35
Vas=279.4 literes
Sd =1210 sq cm
Bl=N.A.
Fmax=300
EBP=65.79
RMS 1000+ watts
Fs = 25.0 Hz
Re = 3.6 Ohms
Qms = 7.22
Qes = 0.38
Qts = 0.35
Cms = 130.0 uM/N
Mms = 300.0 grams
Sd = 1217.0 cmsq
Vas = 279.4 liters
SPL = 92.1 dB
X-max = 45mm p-p
Power = 1000+ watts

3. ### JimPeitersen Second Unit

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Thomas,
JP

4. ### Janne Ahonen Extra

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Janne Ahonen
Actually, sag can be calculated directly from fs (derivation skipped, this is result if you combine all the equations in Adire's paper):

sag = ga/((2*pi*fs)^2)

where ga is gravity acceleration (ca. 9.81 m/s^2), and fs in Hz. Sag unit is therefore, in meters.

WinISD pro driver editor calculates sag percentage (see advanced parameters -> gloss).

Regards,
Janne.

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