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I have a pair of 2405 tweeters and in preparation for listing them for sale, I took the dcr reading, and was wondering if the low reading I got was indicative of any problem with them. On my cheap ohm meter they read 5.7 & 5.8ohms. My neighbor had a fluke meter and it said 5.3. I just took one over, since my meter shows they are very close in dcr.
mike, in the Phoenix metro
DCR is listed as 6.25 +/- 10%, so down to 5.625 is in spec.
I'd say if the diaphragms are in good shape, should be fine.
Thanks, that answers my question.Quote:
Originally Posted by JeffW
Hang on, I think I concluded this thread too soon. I got out some Mills 5ohm 1% resistors and they read 6.6ohm. So this proves the 5.7 reading is probably considerably higher than the actual dcr. So, at this point I would accept the neighbors meter reading of 5.3ohm, and consider that it could be even lower. 5.3 is a deviation from 6.25 of 15%. This is out of the 10% range. Would that indicate any specific problem with these tweeters?Quote:
Originally Posted by sidney8151
Mike in the Phoenix metro
That they are both close to the same is a pretty good indication that they aren't too bad off. I can't say for certain how close JBL was able to hold to the 6.25 +/- 10% spec over the years, you'd need to know what the actual DCR values of these particular coils was when new, I guess.
Seeing as how replacement diaphragms are seemingly no longer available, I'm not sure a tenth of an ohm here and there is the greatest obstacle these drivers will face going into the future.
Quote:
Originally Posted by JeffW
Yikes, now I want to keep them. Oh well, I can only protect so much of what I have. Thank you JeffW.
2405H JBL factory DCR spec is Min. 5.7 and Max. 6.7 ohm. When measuring don't forget to subtract the multimeter's residual resistance to get a valid reading.