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JBL Crossover Question:

AMFADAVE

AMFADAVE

New Member
l100t_crossover.jpg



I am really a novice when it comes to electronics and all the crossover discussions.
I have recently bought a pair of JBL L100 (I think A's since there is an A after serial number)

I also have a pair of upgrade crossovers that were from a L100T speakers.

My question is can I put the L100T crossover into the L100A speakers and forget the adjustment pods on the L100A speakers?

Or is this going to ruin the L100A's and cause a fire?

Attached is a pic of the crossovers. My apologies in advance for my ignorance.
 
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You can certainly use the L100T crossovers and abandon the pots; it won't hurt anything. However, the L100T crossovers are designed for somewhat-different drivers and speakers, so the sonic results would be unpredictable. I will wait for someone more knowledgeable about the crossovers to opine whether it could be a good idea.
 
Zonker92 said:
You can certainly use the L100T crossovers and abandon the pots; it won't hurt anything. However, the L100T crossovers are designed for somewhat-different drivers and speakers, so the sonic results would be unpredictable. I will wait for someone more knowledgeable about the crossovers to opine whether it could be a good idea.
Click to expand...
I guess that is in reality my question....what is it going to sound like?
 
I'd be surprised if the new L100T crossovers would work effectively for the L100A's. While they're both 3-way designs, with 12" woofers, none of the drivers are the same between the 2 models of speakers. I'll keep researching, to see if I can find crossover schematics. But, I'd hold off for now.
 
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I think you should give it a go in one speaker and compare it to the other unmodified....the midrange in the 100a had a horrible peak that the 100t crossover may make less noticeable and the tweeter will be handling more of a range that would be advantageous versus the midrange driver.
 
It's not going to sound very good. The L100 is best to just clean the pots, replace the few caps with some nice SoniCraft parts. Even the Jantzen crossover takes some of the fun out of that model. If your looking to get some great improvement to that speaker you'll have more than crossover work to do. That said adding a brace and some other bits can give that speaker a great new life. You could also consider changing that fiberglass packing with some Black Hole 5 and some sheets of Sound Coat.
 
The L100A uses a 3rd order crossover (across the tweeters and mids) with slightly different frequencies, compared to the 2nd order L100T crossover. That probably benefits power handling in the A version.

L100A

jbl-l100-crossover-upgrade-07-dennis-murphy-crossover-schematics.jpg

L100T

NL100T3.jpg
 
embrown057 said:
It's not going to sound very good. The L100 is best to just clean the pots, replace the few caps with some nice SoniCraft parts. Even the Jantzen crossover takes some of the fun out of that model. If your looking to get some great improvement to that speaker you'll have more than crossover work to do. That said adding a brace and some other bits can give that speaker a great new life. You could also consider changing that fiberglass packing with some Black Hole 5 and some sheets of Sound Coat.
Click to expand...

Thank You for the helpful reply
 
wallacefl said:
I think you should give it a go in one speaker and compare it to the other unmodified....the midrange in the 100a had a horrible peak that the 100t crossover may make less noticeable and the tweeter will be handling more of a range that would be advantageous versus the midrange driver.
Click to expand...

I can actually try this comparison without making any changes that couldn't be reversed. Thank you for the helpful reply
 
Maybe I can change to another question for you guys.
I have a Kenwood 600 Supreme that is getting recap and refurbish.
I have a pair of JBL 100A and a pair of JBL 4311
What speakers would you pair up with the Kenwood 600?
I can always sell these JBL's and get something the Kenwood 600 would be best paired with.
Thanks in advance
 
You can try both, but the 4311's reconditioned correctly should be a good match. It depends on the type of music you listen to. Room acoustics and placement seems to be the hardest battle for most to overcome.
 
Zonker92 said:
That’s not a factory crossover. Is that the Murphy’s design?

Except for the earliest models, factory L100 crossovers have only high-pass filters on the midranges and tweeters; the woofers run full-range.
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No not factory. I bought it on eBay but it's for a L100T not L100A that's why I ask the question....what happens if I put this crossover in a L100A? Nobody seems to know for sure but logic says it won't sound right.
 
AMFADAVE said:
No not factory. I bought it on eBay but it's for a L100T not L100A that's why I ask the question....what happens if I put this crossover in a L100A? Nobody seems to know for sure but logic says it won't sound right.
Click to expand...

I know for sure as the circuits are entirely different. You would get sound, but it won't sound good.
 
AMFADAVE

I agree with StimpyWan, Zonker92, F1nut and others who said the L100T crossover should not be used in the L100A. The drivers in those two speakers are different, and they require different crossovers.

The crossover that StimpyWan showed in his 2nd post was designed specifically for the L100A. I've built it and it sounds quite a lot better than the original JBL crossover for the L100A. You can read more about that design here https://forums.audioholics.com/forums/threads/the-vintage-jbl-west-coast-sound-becomes-the….25014/.

You can always try the L100T crossover in your speakers. I don't think it will cause damage to any of the drivers. But, like the others said, I don't think it will sound good.
 
This is what should be in the L100A. Very different from that of the L100T, Murphy's, or Gravesen's designs.
5916-JBL_L100A_ts.jpg
 
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