R Swerdlow
Active Member
For anyone interested, I've attached a pdf file with full details, including photos and parts list, of the new crossover.
JBL L100's: Now I get it.
- Thread starter Jayrosc
- Start date
What I find to be the problem with the 70s Locanthi designs is already pushing the midrange too high up where its directivity decidedly shrinks - only to be immediately contrasted with a wide dispersion dome sitting in the middle of its sweet spot. The resulting image is peculiarly hourglass shaped from a frequency standpoint. Instruments that span both upper drivers exhibit a wide-narrow-wide again perspective. Fun house mirror effect.
The current LSR6332 with identically sized drivers solves the problem by using a 2.2k crossover to the tweeter. And lowers the woofer crossover to minimize directivity issues experienced at the top part of the woofer's range as well.
The LSR6328P w/ LSR6312SP IMO do one better with the 12" woofer in a separate cabinet with its own amp, ... my opinion anyway.
Jayrosc
Super Member
Boy oh boy! Thanks for all the input on these! NOW, I'm going to ask if some of you tech types can dumb things down for a sec: I've been running these for a couple days, currently using our local classic rock radio station's "Z to A" countdown of the greatest rock, etc. etc.. This morning I tried messing with the mid range and tweeter controls. First, let me say that they work. All the drivers produce sound and the mids and tweets respond when I turn the dials. BUT, and this is a big BUT, the mids and tweets do not turn completely off when I turn the knobs all the way down. Did JBL set these up so that there was always a smidgeon of sound coming from all the drivers? Or are the pots on these not working properly? I don't mind changing them, but would rather not.
Attachments
The trimmers adjust, but do not turn anything off.
With respect to the L100/4310/4311, my point was merely to observe that the choice of crossover frequency can significantly affect the overall sound quality of a speaker using identically sized drivers. Asking a 5" driver (4" piston) to deliver two and a quarter inch wavelengths will negatively impact directivity.
toxcrusadr
Omelette au Fromage
They are supposed to allow some range in the volume, but it is assumed the listener does want to shut off any segment of the music completely!
Jayrosc
Super Member
Yeah. "1983" is quite the trip. Of course, back when I was listening to it, it was through a pair of "acousti-phase" two ways, I think from Sears.
I had a pair of 88+12 to which I added some RTR ESR-6 modules and unhooked the midrange and tweeter...the result too good!Don't forget the L88 Plus 12 a.k.a. the L88P/M12!
Regards,
Gordon.
greatoldone
Member
My cousin has a pair of L100A's which he bought new in 1974 and still has them in use with a MacIntosh C28 and 2105! I had him over to my home to listen to a pair of JBL 640's I was selling. We listened to a CD of DSOTM. I had never heard that well-known recording sound so good! I told my cousin to sell the L100A's and buy the 640's. He declined and someone else bought the 640's. The newer JBL's sounded far better!
Jayrosc
Super Member
Well, Labor Day is coming to a close. Jethro Tull's Aqualung is blasting through these right now and I continue to enjoy them just as much as I did when I hooked them up a few days ago. But, since my listening habits are seasonal, I suspect they will go out of rotation soon as the nights cool and the leaves crisp and whither. Gone will be Blue Oyster Cult, Rush, Walsh, Purple and other rock legends. They will go to the back of the stack of music, making room for recordings like West Side Story, Carousel and La Boheme. My Allison Two's will go into service for this next phase of sonic pleasure, but I hope to soon find a pair of Bozak's that might up the game a bit.
BUT, for tonight, my JBL L100's shall rock rock rock.
BUT, for tonight, my JBL L100's shall rock rock rock.
sensei91
Active Member
I was that " hi fi nut " in 1973, when I auditioned a pair of L100s , listening to the Who play " Pure and Easy " . Paid $ 500.00 for them , and had them as my main speakers for around 27 years. I replaced them with a set of Def Tech 10B . I had to have a woofer reconed around that time.
Now I have them in a small spare room, for low volume listening , Rock and Jazz only and they still sound fantastic. Using a pair of 15 " subs for added bass . Source is a cheap KLH receiver , and an OPPO DVD/CD player. Every night the local NPR station plays Jazz, and they sound terrific. They also do very well as the mains for DVD audio and SACD on the same system. The KLH has a 6 channel amp.
I will never sell them. For serious listening I go upstairs for the Def Tech driven by a Mac MC 162.
rollcentre
Boom-tizzz
I've have had the l100A and still have the original l100. They sound quite a bit different to my ears. Both bone stock. The crossovers are different which has already been mentioned.. the original design does have inductors. Another difference is the porting. The originals have no port tube and the inside wall closest to the port has no rock wool. To me this is where the speakers sound different. Seem like jbl was trying to get big speaker sound in a small size. Doesn't work in all types of music, but when it does - it's great. Drums from older recorded rock music is the most fun to listen to with them. When I wanna hear Bonham banging drums, these are the speakers I wheel out.
The original l100s are also quite a bit different to 4310s to my ears... Even though they have the same drivers. The l100a and 4310 were closer matches, imho.
sensei91
Active Member
Nice set up !
After reading this thread I decided to revisit an older CD on the L100s.
Dean Peer " UCROSS "
This CD really brings out the best in these speakers.
wu6fiend
Well-Known Member
Tonight I hooked up my recently purchased pair of L100 Centurys for the first time. They are sitting on top of a pair of new stands from Deer Creek Audio (excellent quality, lightning fast shipping, definitely recommended). I've been going through a succession of old favourites (Elton John, Fleetwood Mac, Eagles, Boston, Journey, Joe Cocker, Pete Townsend, Sting) and thoroughly enjoying myself. Even my wife is tapping her foot. My plans are to re-oil the cabinets (picked up some Watco dark mahogany today), and switch the present orange grills (which are mint, and new) to a set of black ones (already ordered). The former owner already installed very nice modern binding posts. I really like these speakers, and they will be sticking around.
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wu6fiend
Well-Known Member
The speakers I normally use for 2 channel are the JBL Performance Series (PT800s docked with PS1400s). Today I connected them along with the L100s to my Sony N77/E77 combo, and alternated, back and forth, the same songs. The sound was very similar, although the vocals and midrange on the L100 were slightly more pronounced, and the bass on the L100 was "punchier". The PT800/PS1400s were smoother, and possibly over time would be less fatiguing. I would be surprised if the L100s out performed their 20 year newer, considerably more expensive brethren, as the retail price on the PT800s was around $3400/pair, and the PS1400s retailed for $1600/each. Even the orange grills on the L100s are (surprisingly) growing on me!
RobRoy
It's just stuff - but fun
When I sold them back in the 70's I had huge respect for them except I wanted more bass and thought they were just a bit overpriced. But I think a pair of those with a simple subwoofer would be a pretty killer vintage speaker setup.
Have no need for a sub with the L100’s or any of my speakers. Maybe using the 300 watt McIntosh MC2300 helps, but I had to move the L100’s away from the back wall as the bass was almost too much. Placement and quality amplification play a big role in how these speakers will sound, IMO. I love them.
