Effect of swapping 8-ohm JBL LE20 with 160-ohm LE20???

[StarMover]

The other day I purchased two sets of vintage JBL speakers at the thrift store, a pair of 4310 studio monitors and a pair of L-77 Lancers, both outfitted with LE20 Tweeters.

The dust cap on one of the 8-ohm LE20s mounted in the 4310 is dented, so I had the idea to swap them out with the perfect LE20s from the Lancers...

but when I pulled the LE20 from the L77, I discovered it to be a 16-ohm driver as opposed to the 8 ohm version mounted in the 4310s. Otherwise, they are identical.

So, should I exchange these tweeters? Will the difference in impedence have any effect on the performance or the sound? :scratch2:

 

[StarMover]

Thanks Dave. I thought not.

I wetted the dust cap with a sponge to soften it up, then used a pin to pop it back out. It looks better, so that'll just have to do.

 

[Steve O]

LE20 Impedance

The other day I purchased two sets of vintage JBL speakers at the thrift store, a pair of 4310 studio monitors and a pair of L-77 Lancers, both outfitted with LE20 Tweeters.

The dust cap on one of the 8-ohm LE20s mounted in the 4310 is dented, so I had the idea to swap them out with the perfect LE20s from the Lancers...

but when I pulled the LE20 from the L77, I discovered it to be a 16-ohm driver as opposed to the 8 ohm version mounted in the 4310s. Otherwise, they are identical.
So, should I exchange these tweeters? Will the difference in impedence have any effect on the performance or the sound? :scratch2:

I have quite a few LE20s laying about looking for a home. The foilcal an the back IDs some as 16 ohm and some as 8 ohm. Guess what? The DC resistance on all is ~3 ohms and the approx AC impedance is 5 ohms. Apparently JBL didn't consider actual impedance of the LE20 all that important both in terms of labeling and of nominal impedance.

Bottom line: Check the impedance of your LE20s. They may be all the same (8 ohms) regardless of what the label states.

 

[Clmrt]

Does anone know of an LE20 app where it was NOT run with a pot?

 

[StarMover]

Interesting.. I just took rating on the label for granted...

That'll suck because I went to the trouble of putting it back in and re-gluing the decorative cover... It was a bitch to get off in the first place without bending it up.

 

[Zilch]

Interesting.. I just took rating on the label for granted....

LE20s all have the same impedance, despite what they say on the foilcal. I measured and reported that in another thread here, the L77 tweeter upgrade thread, as I recall. Manufacturers played fast and loose with the specs back in the olden days. Some still do.

Measure.... :yes:

Does anone know of an LE20 app where it was NOT run with a pot?

There are some with switched-resistor attenuation, the subject L77 being among those:

http://manuals.harman.com/JBL/HOM/Technical Sheet/L77 Lancer ts.pdf

 

[StarMover]

YUP! Despite the label's claim of 16 ohms, the LE20 tweeter actually measures 3.4 DC Ohms.

 

[Clmrt]

d'oh


shoulda said attenuator...