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BP 1803 "sag"? (1 Viewer)

JimPeitersen

Second Unit
Joined
Dec 7, 2001
Messages
470
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
 

ThomasW

Senior HTF Member
Joined
Nov 6, 1999
Messages
2,282
Here's the formula

http://www.adireaudio.com/Files/Tech...rientation.pdf

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
 
Joined
May 4, 2002
Messages
24
Location
Kuopio, Finland
Real Name
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.
 

John E Janowitz

Second Unit
Joined
Oct 30, 2000
Messages
445
The formulas will tell you a pretty good estimation of the amount of sag you will have right away and give you an idea of whether you sould attempt a downfiring sub or not. There is no formula however that can tell you what will happen over time as the surround and spider become distorted from the continual effects of gravity. It all has to do with the elasticity of the foam or rubber used, the material and coatings on the spider, the amount of wear and tear on the spider and surround, humidity and other climate conditions, etc.

John
 

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