Altec 288C and 1005B impedance at 630 hz
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| Posted on July 10, 2014 at 19:17:48 | ||
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Posts: 42
Joined: October 28, 2001 |
Hi My Altec 288C have genuine 24 ohms aluminum diaphragms. I made impedance measurement with an Altec 1005B tar filled at 630 hz. The results I had with both drivers is 141 ohms !!! (seems really high) Here what I've done to measure the impedance. I placed a 1000 ohm pot in series with the 288C. I injected a 630hz sinewave to feed the amp with driver and looked at the ac voltage across the pot and the driver. I adjusted the pot so I had the same voltage across the pot and the driver. Last, I measured the resistance of the pot to get the results. AC voltages were taken with my Fluke 24. I tried another multimeter and it was the same. As 141 ohms seems high, does it mean I can't measure correct voltage at 630 hz with my multimeter or 141 ohm is normal ? Thanks
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| JBL, posted on July 11, 2014 at 23:18:28 | |
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Posts: 6135
Joined: June 17, 2000 |
The JBL 2370/2426H measures 3.3Ω DC, but hits about 10X that on the horn with AC.
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