DC resistance for 2121 and LE15a

[hoto]

Hi

I have pairs of LE15A and 2121 , need to replace the surround, but what to make sure theose speakers are good before put the new surround on (DIY), forum member "chas" told me that I can measure the DC resistance to tell if the speakers still WORK, but I don't know the DC resistance on both , can someone help me with the spec.??

BTW, if someone can SHOW me how to measure it on the ohm meter step by step will help me a lot.

Thanks in advance.

[speakerdave]

Expected direct current resistance for an 8 ohm (impedance) driver would be in the area of 5 or 6 ohms. For a 16 ohm driver DCR would be 9 to 11. But what Chas is suggesting, I think, is to check and see if the resistance is zero (shorted) or infinity (broken). In either case, unless the problem is in the lead wire, the voice coil is no good, and the driver will need to be reconed.

As for operating a meter. That's a pretty basic question and I don't see how anyone can SHOW you on line how to use one. I suggest you read the instruction book for your meter, if you have one, or find a book on the very basics of electricity.

Regards,

David

[Guido]

As from the JBL Field Manual:

The 2121 should measure 5.4 to 6.6 Ohms
The 2121H should measure 6.2 to 7.4 Ohms
The LE15A should measure 7.6 to 9.2 Ohms

It would be very interesting to know why the 2121 and 2121H measure different. :confused:

[GordonW]

The 2121H probably has a very slightly longer-length winding on the voice coil. More wire== higher DCR. With the stronger magnet available on the ceramic ferrite versions, it's possible to have more wire and still not lose significant efficiency...

Regards,
Gordon.