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View Full Version : New guy with a few questions....



RussinOhio
01-25-2008, 06:22 PM
Hi everyone. I've always been a huge fan of JBL's classic L-300 system. Although I do not own a pair I've spent some time here reading about them. Can someone please explain exactly what an acoustical lens actually does? Why are they (on the L-300 for example) angled down towards the woofer? As a matter of fact all acoustical lens are angled down from what I've seen. I'm guessing that the driver behind the lens is VERY directional and the lens "Sqeezes" the sound waves to spread them around in all directions.....much like sqeezing a garden hose with your thumb. I'm only guessing mind you. I feel I'm in a room full of technicians:)......so please excuse my ignorance! FWIW....I do own Altec 19 speakers with an 811b sectoral horn. So, whats the functional differance between an acoustical lens and a sectoral horn?

Russ

clmrt
01-25-2008, 06:56 PM
http://www.lansingheritage.org/html/jbl/reference/technical/lens.htm

:D

RKLee
01-25-2008, 08:38 PM
Discussion of Altec sectoral/multi-cell horns and JBL horn/lenses:
http://www.lansingheritage.org/images/altec/plans/1960's-lf-design/page06.jpg

RussinOhio
01-25-2008, 09:08 PM
http://www.lansingheritage.org/html/jbl/reference/technical/lens.htm

:D

Interesting stuff, thanks.

clmrt
01-26-2008, 03:07 AM
Sounds like Altec was trying to pick a fight.

spkrman57
01-26-2008, 06:13 AM
Always nice to see another Ohio audiophile in the flock!

I pass by Westlake sometimes when I visit family in Fairview Park.

Regards, Ron

fporfidio@opton
01-26-2008, 07:34 PM
russinohio, it's actually called a diffraction or diffusion lens (which explains it a little better) in short, to use your water hose analogy- if you put your hand over the hose but did'nt seal it and it came shooting out all360 degrees that would kinda be a lens in short it makes the pattern wider...frank

Gary L
02-04-2008, 06:45 AM
Good question Russ and lots of good info here.

I know how you love your 19s so it will be interesting if you find a set of L 300s and do the comparison between both.

Back in the days I picked the 19s over the L 300s. Partly because of price and partly because I felt back then the 19s had that chest pounding bass I loved.

Now I am sure I would go for the L 300s as long as I could still keep my 19s! They each have their merrits but I do believe the JBLs produce a sweeter mid and HF sound you will find pleasing.

If I can describe it I would say the 19s would be my speaker of choice when I want to crank it up and the 300s would be for when I want to sit and listen.

Gary

jcrobso
11-03-2008, 02:20 PM
Works like a wide angle lens on a slide projector. John