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In Reply to: RE: Magneplanar MG2B strange resistivity posted by marcob on September 01, 2014 at 11:40:57
If you are measuring across the input terminals (#1 and #2) then you are only measuring the impedance of the woofer (+ the inductor which is < 0.5 ohms) as the tweeter is in series with a capacitor which blocks the DC from the meter. You should measure the woofer impedance acros #3 and #6 after removing the jumper at #3 -#4.
To measure the impedance of the tweeter, remove the other jumper (#7-#8), and take the reading across #4 and #8.
I believe the woofer has a double run in parallel so if one of the runs is interrupted the impedance will be twice as high (10 ohms) and the volume will be decreased by half (6 db). The tweeter is a single run and should measure ~5 ohm or if open 0.
Follow Ups:
Thanks a lot!
If I remove the jumpers, 1st speaker (low but good sound) woofer = about 9 ohms, tweeter = about 9 ohms; 2nd speaker (low and arretrate sound) woofer = about 9 ohms, tweeter = about 23 ohms.
But, people rebuilding them told me that there are "internal jumpers" (they mean, they saw soldered pins, internally, duplicating jumpers).
This is unclear to me, so, the speakers returned to the "rebuilder", to check impendance directly on the internal wires.
But I'm quite sure that the problem is internal, and not on the crossover.
Marco
I have no idea how the tweeter could measure 23 ohms! Very weird.
Hopefully, no sheep fence's wires, inside ;)
I'll let you know what they'll find inside (they should already know...but... I let 'em room for a correction ;)Btw, I loved this mg2b, so I hope for the renaissance :)
Edits: 09/02/14 09/02/14
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