JBL Impedance info please

[JohnInICT]

I'm brand new to this forum and even though I have been researching how speakers, impedance and crossovers work, I still do not feel I have enough knowledge to answer this question on my own. I've been reading a lot of the posts and there are some very knowledgeable members on this forum. I was hoping some of you wouldn't mind sharing some of that knowledge and help me out.

I picked up a set of Lancer 99s. I treated the lansaloy surrounds on the LE 14a's with Brake fluid and they softened up nicely. The speakers sound really good and the grills are nice, but the cabs are a bit rough. I don't know if they are worth putting the funds into redoing the cabs, so I thought about taking the LE 14a's out and putting them in my C38's to replace the D-123's. My question is...my JBL's have the 075 bullet tweets and are 16/32 ohm speakers with the N2600 crossover. What harm, if any would there be putting the 8 ohm LE-14's in them. Would there be any benefit?

Thanks

John

[Horn Fanatic]

I'm brand new to this forum and even though I have been researching how speakers, impedance and crossovers work, I still do not feel I have enough knowledge to answer this question on my own. I've been reading a lot of the posts and there are some very knowledgeable members on this forum. I was hoping some of you wouldn't mind sharing some of that knowledge and help me out.

I picked up a set of Lancer 99s. I treated the lansaloy surrounds on the LE 14a's with Brake fluid and they softened up nicely. The speakers sound really good and the grills are nice, but the cabs are a bit rough. I don't know if they are worth putting the funds into redoing the cabs, so I thought about taking the LE 14a's out and putting them in my C38's to replace the D-123's. My question is...my JBL's have the 075 bullet tweets and are 16/32 ohm speakers with the N2600 crossover. What harm, if any would there be putting the 8 ohm LE-14's in them. Would there be any benefit?

Thanks

John

Hi John -

No harm will come to your crossover, or amplifier by using an 8 ohm speaker. The D123, if it is original, is a 16 ohm driver, however, I have seen them labeled 8-16 ohm. By switching to the LE14 you may notice a frequency hole between the bullet and the LE14 that was filled by the aluminum dome on the D123. If memory serves me correctly, the LE20 in the Lancer 99 is crossed over at 2K, below what the 075 was, even with the sometimes coupled N2400 network. IMO, the D123 is better suited to work in the C38 than the LE14. By loading the C38 with the LE14 you may be disappointed with the results. JBL saw fit to use a, 'one-size-fits-all' approach with box tuning. If you want to use the LE14, I would suggest that you determine the proper tuning alignment for the LE14 in a 2.7 cubic foot enclosure.

I never did understand why JBL used the 8-16, or as in your case, the 16-32 ohm rating. I asked a JBL tech about that 30 years ago, and he told me if I wanted to use the speaker as an 8 ohm or 16 ohm it didn't matter. That in itself doesn't make sense, as the crossover point in any network is dependent on the approximate impedance match of both components at that frequency, however, it is possible to design the corner frequency based off different impedance loads. Paul Klipsch did that very thing with his K-Horn network.

Also, I think folks are too hung up on speaker load impedance. The impedance labeled on the back of speakers is a nominal impedance. It's the DCR that should be of concern. Impedance is frequency dependent. Testing a loudspeaker with a VOM will only give you the DCR of the voice coil. A typical loudspeaker can reach an impedance of 400 ohms before it begins to roll off due to the voice coil inductance.

As for restoring the Lancers, it's up to you. Unless the corner joints are compromised, I see no reason the cabinets couldn't be restored, even if it means a re-veneer job.

Good luck, H.F.