2425H impedance

[davidpou]

Hi everyone,

I just bought (yesterday) 4430 speakers (and I am soooooooo happy with them).
I had just one question (to start with certainly): I measured both 2425H impedance and find 3.3 ohms. The TS of these drivers seems to state that they should be 8 ohms, which means I should find between 5 and 7 ohms, shouldn 't I ?
They are working fine and are so close in value (actually 3.3 in one and 3.4 in the other)...; do I have picked up the wrong TS ?
Thanks

[Earl K]

Your ( dcr ) measurements of the 2425H are ( ballpark ) correct .

All these type of lower impedance drivers should have been more accurately labelled ( by JBL ) as 6 ohms .

By calling them 8 ohms , ( actual 6 ohm drivers ) appear to be louder ( than the competitors, such as Altec ) and allows JBL engage in a type of ""slight-of-hand" cheating that ( impresses ) the uninformed .

:)

[martin2395]

You measured the DCR of the diaphragm, it's a different thing than driver impedance.

3.3 Ohm DCR is normal for a 8 Ohm driver, my 16 ohm Radian 1245-6 have DCR of around 6.8 Ohm.

[davidpou]

Thank you guys.
both measurments being similar I thought it was what to expect, but your answers create a complete peace of mind...
They are one (aged ) owner and he was listening classical on them .... his son told me his father has been pushed by the seller at the time and he have now some (very) small plastic BOSE.... some people do not know what they have or just what to do with it.... I will surely feed them with some grooove.... their life is just starting at 18 years old.

thanks again for you answers

[speakerdave]

Especially with a horn-loaded driver the increase in ohms from DCR to impedance will be more than one might expect.

[Russ53]

Hello boys and girls. My name is Russ and I'm new to this forum. I have a problem that I hope you can help me with. I have a pair of custom JBL's that I've had for 36 years. I bought them from the original builder and they're absolutely wonderful. I've had many offers to buy them but I won't part with them. Lately, however, I've noticed that the high's have disappeared from one of them. I took the tweeters and the crossovers to Orange County Speaker in Garden Grove, CA. and they found that one of the crossovers had a burned 10mfd cap. It's all been fixed and now here comes the question. What ohm reading should I expect to have on the LE20 tweeters at rest? They are rated at 16ohms and all I get is 4.4 +/-. I've been told that this is ok by one tech and then another said that it's not and that the tweeter(s) are bad. I get the same reading on all 4. The readings were taken with a Fluke 87.

Here is a list of the components which are an LE14 bass, a 2105 Mid and the LE20 tweeters. Two per speaker wired in parallel. The crossovers are Bozak N-104A. I tried to download images but was unsuccessful.

I hope you can help me. Thanks and thank you as well for this wonderful forum.

[Earl K]

Please read this ancient thread about the correct DCR for a le20 tweeter (http://www.audioheritage.org/vbulletin/showthread.php?3133-LE-20-resistence)

:)

PS ; Simply ignore the 16 ohm label ( especially if the crossover isn't being redesigned & you are simply putting a working system back to the way it was ).