L100, L100A, L100T, L100T3 crossovers compared

[pierce]

I was going over crossovers and stuff for my L100T, and compiled this in a email discussion with a friend who used to do pro audio in the 60s/70s... Seemed interesting enough to include here. These crossovers are cribbed from the tech specs of each speaker system...

the -original- L100 Century model used this crossover...
http://hogranch.com/files/Bitmaps/xover/lx12-10.jpg
and claimed 2500Hz / 7500Hz (!!) crossover frequencies. WTF, thats pretty high for a 12" woofer, isn't it??


late model (cheapified?) L100A used...
http://hogranch.com/files/Bitmaps/xover/n100.jpg
(look ma, no chokes!) and 1500Hz / 6000Hz crossovers (with essentially the same three drivers, a 123A woofer, a LE5 mid, and a LE25 tweet). Geez, those are just inlow highpass capacitors, is that 3dB/octave or something??


now, my much later model L100T uses this crossover...
http://hogranch.com/files/Bitmaps/xover/n100t.jpg
which is significantly more complex, and claims 800Hz/4500Hz crossover frequencies, using the 2214H woofer, 104H-2 mid (an updated LE5), and 035Ti titanium dome tweeter. The L100T datasheet claims 12dB/octave, while the earlier ones don't specify this.

Finally, the L100T3, which as many have stated, has a modified crossover,
http://hogranch.com/files/Bitmaps/xover/n100t3.jpg
same basic circuit, speaker datasheet gives same 800/4500Hz crossover points, same 12dB/octave, so whats different other than the component values?!? The T3's speakers are only cosmetically different by most accounts (2214H-1, 104H-3, and 035TiA).

I wish I remembered more of my analog electronics and filter theory, sadly thats all faded into the distant past, as I've pretty much only done digital electronics (eg, computer stuff) the past 30+ years.

[TonyM]

The first thing that stuck out to me was the difference in value for the padding resistor used on the tweeter between the 100T and T3. I don't know if they were trying to recountour the sound of the speaker or compensate for different driver sensitivity. I have a pair of 100t and I hear a lot of people talking about the T3 crossover.

[4313B]

I don't know if they were trying to recountour the sound of the speaker or compensate for different driver sensitivity.They were trying to make the entire t3 Series sound "less irritating". Evidently it worked. JBL networks were tuned empirically.

[jbl_daddy]

Does the 4310, 11, 12 run full range to the LF driver???:blink:
I wonder???

[TonyM]

I think the intention was to rely on the natural roll off of the woofer and midrange drivers. Obviously it works, they sold millions of them.