JBL Loft 30

jr@mac

These are on loan from Nick Claus to serve as my work speakers - that 1 hour a day I get at my desk, anyways. 



The gray line is raw tweeter response, the pink line the raw woofer response, the yellow line is system without the grill, and the red line is the system with the grill.



Distortion, SPL accurate at 1M, grill in place. 



Same conditions, but with grill removed. 



The 4" woofer would probably make a much better midrange than a midbass. 



I did not test it very loud. It went to hell not much louder than this. 



Looking at the distortion curve, I am convinced the addition of a waveguide was for diffraction and possibly directivity control - but my god, look at that distortion under 2K. Something I think needs to be a topic of discussion more often is that the fundamental isn't the only thing the horn boosts - event though some proponents of wave guide design will imply there is a free lunch in that sculpted plastic. Not sure we would be able to cross any lower with or without the waveguide in place on this tweeter. 



Both drivers free air impedance.



Modeled factory response - I think I know why they call it the "Loft" series



Modeled factory impedance. Safe enough for the glow in the dark fans



Modeled bass extension, give or take. Sounds like it, too. 



Crossover model, minus the poly switch in series with the tweeter. That would kick in any louder than the distortion testing I was doing. 



Front of woofer.



Rear of woofer - no, a Peerless SDS will not drop in, I already checked



Front of tweeter.



Rear of tweeter

Crossover.

Hope you enjoyed this tear down etc. I have them packed up now, they will live with the on-board sound of my work-supplied Dell laptop and will be powered by Lepai. 

If you want any further information, let me know and I will see if I have time - I killed most of the night playing with these, I think wifey is upset a little bit LOL

On edit, I discovered how this forum software handles images is confusing and even a bit annoying - it adds them as "inserted" if you use the dialog box method from the top of the screen. It bypasses that if you drag directly into the post. Weird. Annoying because I tried deleting after using the insertion method to no avail. 

Anyways, hope this works.  

JasonP

Looking at the suckout in your measurements between 200 and 1000 hz, I bet these were intended to be placed against or very near a back wall. How do they sound? All of the monitor type speakers I've heard from JBL have sounded pretty good to me. Nothing to blow one away, but solid speakers.

I'm about to build a new sub and replacement amp for a broken Klipsch ProMedia THX 2.1 speaker set (I really like these and how they sound). I should tear them down too and post it up here.

jr@mac

They have a keyhole mount, so I imagine they were anticipating wall mounting, yes. 

They sound... ok. I will probably EQ them to something better at the office, though.

greywarden

Do you plan on "fixing" them?

jr@mac

Nope. Sitting on my work desk will fatten em up a bit and some simple eq will finish it.