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Get familiar with the reaction system: Introducing the Reaction System
JBL L100 Resto
Figured I would start a new thread for the JBL‘s that I’m going to disassemble and buy some parts for like, foam for the tweeter, that’s missing new foam for the grills. We’re gonna do a little bit of repainting some black in the back. There’s a few chips we’re gonna try to fix some of the veneer. That’s kind of scuffed up over the years, we’re not gonna go crazy on it, but I wanted to post some measurements before I teared apart.
Comments
This is the original instruction manual that I got with them and if you look at how they measured the sensitivity is 1 watt input produces 78 DB at 15 feet. I’m not gonna measure them at 15 feet. I’m gonna measure them at 2 feet to keep reflections down.
https://www.jfcomponents.com/
Presence= midrange , Brilliance =tweeter
Red= Presence 0. Brilliance 0.
Orange= Presence -5. Brilliance 0.
Gray= Presence -5. Brilliance -5.
https://www.jfcomponents.com/
Red= Presence 0, Brilliance 0.
Orange= Presence +5, Brilliance 0.
Gray= Presence +5, Brilliance +5.
https://www.jfcomponents.com/
What if you measure with them sitting on the floor in a corner? Was probably a very common practice in those days.
That woofer looks to be a monster on paper.
Ok now I know what the pots do I set them to this FR curve at 1 meter on tweeter axis.
They’re much better to listen to now.
https://www.jfcomponents.com/
Distortion at 1 meter around 3.3v
https://www.jfcomponents.com/
About a 1/2” inside port, that is right next to the tweeter.
https://www.jfcomponents.com/
All right, I’m done with these measurements. Let’s see what’s inside.
https://www.jfcomponents.com/
https://www.jfcomponents.com/
https://www.jfcomponents.com/
https://www.jfcomponents.com/
In cabinet
https://www.jfcomponents.com/
Looks like a 3.0uF on tweeter and a 8.0uf on midrange and letting the woofer naturally roll off.
https://www.jfcomponents.com/
PB wood!!!! Lol
https://www.jfcomponents.com/
Those measure much better than I would have guessed. I always knew the woofers were some pretty serious drivers, but those mids are some stout little buggers too!
troels gravesen did an upgrade on the L100 Century.
http://troelsgravesen.dk/JBL_L100.htm
My kind of speaker. I might have to stop by and listen.
Possible inexpensive substitute for grill foam:
https://foambymail.com/product/acoustical-1-pyramid-foam.html