I repaired a void woofer with an original spare, I did a test sweep and I heard that the sound is lower, I measured the impedance curve and the peak fs is low
green= original
blue = repaired
green= original
blue = repaired
Send a 20Hz signal (amplified so that the cone moves a fair bit, but not too much) for a week or so to that woofer... and see what happens...
At the resonance frequency an loudspeaker peak impedance Zmax is related to a loudspeaker electro-mechanic parameters Zmax= BL^ 2/ Rms, BL is the force factor and Rms is the suspention mechanic resistance. So, you should check wheter BL is decreased (the magnet is demagnetized) or Rms is drastically increased (due to bad centering of the coil ?)
You can estimate BL factor by using a weight of known value and measuring DC current required to return the cone to rest position.
The method is quite simple.
1. Assume, that a loudspeaker cone is in the horizontal position and is in rest.
2. We have a mass of known value (measured with scales) that we add on the cone. In order for the cone to relax to a new rest position, some time is required, depending on the viscoelastic properties of the suspension (a couple of minutes is quite enough).
3. When the cone with added weight is in the rest position, you should connect the loudspeaker to DC voltage source and adjust the current through the coil so that the membrane returns to its original position without an additional weight. Write down this current value.
4. Now, when the current I and the weight m values are known, you can evaluate the BL factor using the Second Newton law:
I*BL= m*g, --> BL=g*m/I = 9.81*m/I.
Many times DIY reconers when using a non drop-in kit get the coil height wrong.... So the coil is not centered in the magnet field ...This gives low output.....I have also seen Peavey factory basket kits were the coil height is wrong with low output...
well try and give this driver some exercise and remeasure see if that improves things.
and even after as many recone's as i've done, i've surprised myself with forgetting to remove shims and the occasional inadvertent glue globs...not that i think that's the case here.
and even after as many recone's as i've done, i've surprised myself with forgetting to remove shims and the occasional inadvertent glue globs...not that i think that's the case here.
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Fs is around the same, so it looks like spider and suspension are fine.
The impedance curve suggests lower BL. Unless you whacked half the magnet off the motor, the only other possible cause for that is an issue with the coil. Maybe it's either way out of the gap, or there are a lot less turns in the gap (compared to the original coil).
The impedance curve suggests lower BL. Unless you whacked half the magnet off the motor, the only other possible cause for that is an issue with the coil. Maybe it's either way out of the gap, or there are a lot less turns in the gap (compared to the original coil).