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malden
08-11-2014, 08:47 PM
Greetings! My first post..

I have pair of JBL D123 (16 ohms) with LE20's (16 ohms) and LX2 crossovers (ohms not indicated) housed in C38 enclosures. The problem is that the tweeters are blown (I checked the x-overs with a cheap tweeter) but I have a pair of LE20's that are 8 ohms. Can I use the 8 ohm tweeters? They are being driven by a tube amp so if the answer is yes, should I hook them up to the 8 or 16 ohm taps?

Can the 16 ohm LE20's be repaired?

Thanks...

Mannermusic
08-12-2014, 07:25 AM
Greetings! My first post..

I have pair of JBL D123 (16 ohms) with LE20's (16 ohms) and LX2 crossovers (ohms not indicated) housed in C38 enclosures. The problem is that the tweeters are blown (I checked the x-overs with a cheap tweeter) but I have a pair of LE20's that are 8 ohms. Can I use the 8 ohm tweeters? They are being driven by a tube amp so if the answer is yes, should I hook them up to the 8 or 16 ohm taps?

Can the 16 ohm LE20's be repaired?

Thanks...

Hum-m-m. Wonder why the tweeters are failed? May be indicating something else amiss. Did you check the continuity of the tweets - certain they are open? But, I wouldn't be afraid to use the 8 ohm tweeters you have - JBL labeled tweeters differently depending on application with same actual impedance. I'd hook them up the same as now. The repair kits are vanishing rapidly for all the old stuff. A local JBL pro shop could tell you. Used to be approx. $100 ea. Another option is to upgrade to the 075 tweet / N2600 Xover (reading this from a June '64 catalog). Others may jump in here with more info. Those are nice enclosures, worth the effort to restore. Problem we are all having these days is that all that stuff is getting awfully old - like the owners, in many cases! Good luck and welcome to the site.

malden
08-12-2014, 09:04 PM
Yes, both tweeter coils are open. If I use the 8 ohm tweeters with the 16 ohm woofers, does It matter if they are hooked up to the 8 or 16 ohm terminals of the tube amp?

Mannermusic
08-14-2014, 08:44 AM
Yes, both tweeter coils are open. If I use the 8 ohm tweeters with the 16 ohm woofers, does It matter if they are hooked up to the 8 or 16 ohm terminals of the tube amp?

Just stick with the 16 ohm. I'm still wondering why both the tweeters failed. Old gear does bad things at times. Voltage spike from the amp? Wouldn't hurt to check out the electronics. Also trace basic hook-up: tweets to the HF terminals of the crossover, crossover input to the 16 ohm tap on the amp. Would be a shame to blow your second set of tweets.

speakerdave
08-14-2014, 11:10 AM
Tweeter failure can occur when the system has been driven at high spl with an amplifier whose power rating is too small. Amplifier power ratings are set at a particular distortion level, but when over driven the amplifier can put out much more power than the rating and that excess power is largely high frequency distortion artifacts which can overload the tweeter and burn it out. When this happens at a party the second tweeter can be blown while the people are puzzling over what has happened to cause the change in the sound they noticed when the first one went.

If the OP recently acquired these speakers in the described condition this may be the explanation. If it happened during his custodianship, he probably remembers the moment.

Mannermusic
08-14-2014, 03:19 PM
Tweeter failure can occur when the system has been driven at high spl with an amplifier whose power rating is too small. Amplifier power ratings are set at a particular distortion level, but when over driven the amplifier can put out much more power than the rating and that excess power is largely high frequency distortion artifacts which can overload the tweeter and burn it out. When this happens at a party the second tweeter can be blown while the people are puzzling over what has happened to cause the change in the sound they noticed when the first one went.

If the OP recently acquired these speakers in the described condition this may be the explanation. If it happened during his custodianship, he probably remembers the moment.

Hey Dave: Thanks for the input, fits like a glove. Mike

malden
08-15-2014, 09:20 PM
The tweeters were bad when I got them. I'll use the 8 ohm LE20's.