PDA

View Full Version : L-100 Crossover design



dgorshe
03-03-2004, 07:59 PM
Anyone want to help me design a crossver for an orginal set of L-100's. the orginals are kinda cheesy and the cut off frequencies dont get the full potential out of the LE5-2 midrange. Any ideas would help, thinkin about crossing the midrange at 800 hz and keeping the tweeter the same at 5000hz.
Sorry about the newbie question.

boputnam
03-03-2004, 08:12 PM
Originally posted by dgorshe
...the orginals are kinda cheesy :yes:

Are you sure, sure, sure you want/need to do this? If you've got that kinda knowhow, there are better JBL endeavors that will reward your efforts much more richly (read: audibly). JMHO... :duck:

dgorshe
03-03-2004, 10:26 PM
Umm... i need ideas on the other endevors then. :confused:

4313B
03-04-2004, 06:42 AM
Use an L50 crossover and see if you like the results better.

4313B
03-04-2004, 06:43 AM
L50A

4313B
03-04-2004, 06:47 AM
If the lower midrange ends up sounding goofy, throw a 3.5 mH inductor with a DCR of 7.5 ohms across the LE5.

Also run an impedance curve on the L100 driver to get the conjugate/zobel in the N50 set right for it. In other words, the 36 uF capacitor might need to be adjusted somewhat for the L100 LF instead of the 127 LF.

dgorshe
03-04-2004, 06:49 AM
thanks for the info.

boputnam
03-04-2004, 07:30 AM
Originally posted by dgorshe
Umm... i need ideas on the other endevors then. :confused: Well, my only point was that particular assemblage of transducers is not the apogee of JBL design. If you got the know-how of network design, you might be more pleased with differently directed efforts.

But, I've been roundly criticised for my admittedly jaundiced view of the L100, so carry on... ;)

4313B
03-04-2004, 07:54 AM
Oh I get where you're coming from Bo. I'd personally just toss them off a third floor roof and see if they bounced, or donate them to Letterman so he could test if they floated, but if someone wants to play around with them more power to them :)

boputnam
03-04-2004, 08:17 AM
Originally posted by Giskard
Oh I get where you're coming from Bo. I'd personally just toss them off a third floor roof and see if they bounced, or donate them to Letterman so he could test if they floated, but if someone wants to play around with them more power to them :) :rotfl: Yea, exactly. I just love the WIDE-EYED response :shock: when a good set of ears (finally...) starts moving UP the JBL food chain. There is SO much up there... :yes:

dgorshe
03-04-2004, 10:50 AM
so are the 4312's a move up on th jbl chain or just the same old shizt. L-166's? or are they also cursed with the "L" syndrom? Remember im only in college so cash flow is at a minimal.

4313B
03-04-2004, 11:02 AM
If you have the L100's then play around with them. Don't worry about our constant maligning of the L100, it's fun. One thing is certain, you're starting out with more loudspeaker than I did.

boputnam
03-04-2004, 12:07 PM
Doug (it is Doug, isn't it...?)...

The 4312 is a modest upgrade from the L100 - the MF has less of the rising response character that "plagued" (my word) the LE5-2. Having said that, the L166 is certainly another step beyond, with the improved MF, better HF (although as Giskard has pointed out, it can be quite "strident"... ;) ), and it has a lo-pass / hi-cut filter on the LF which neither the L100 or 4312 have. Oh, and there certainly is no "avoid the L's" metality here - that is a fine lineage. :yes:

So, if your searching and have dough for one pair, there you are.

If you've got the L100's, follow Giskard's network suggestions, get a waterbed and a case of Heineken and you'll amaze your friends with your precise attention to period... :p

dgorshe
03-05-2004, 06:42 PM
well i have the L-100's at home and im away at school so they are bing used in my dads room right now, i have the 4312's right now and 2 sets of L-166's

Giskard, what are the cut off frequencies on the L-150?

Ian Mackenzie
03-05-2004, 07:22 PM
For the best and most amusing readings ever on the L100 search for Bo's ultimately triumphant L100 basher thread where he nearly got seared by the Hoards after being dunked then plucked masterfully by Macka and Don's billiant follow-up on the L100's history in the making...the full Monty...probably the best post on the Forums to date.

Damn Yankee

Ian:o

boputnam
03-05-2004, 10:03 PM
Originally posted by dgorshe
the L-100's are at home ... so they are being used in my dads room Perfect! As we age, our hearing fades. Surely he loves the L100's - as it should be... :rotfl:

You, sir, got the best of the lot. Only go home on holiday, for brief periods... :)

dgorshe
03-05-2004, 11:09 PM
lol:rotfl: :rotfl: :rotfl:

GordonW
03-07-2004, 07:08 PM
Here's another alternative crossover that might work. This is from the JBL S-70 Alpha, which except for having an LE20-1 (instead of an LE25, which is functionally equivalent to my ears and measurements despite the cosmetic differences), is the EXACT same drivers (123A, LE5-2, LE20-1/LE25) as an L100 .

The only problem I see, is that the difference in box volume, and therefore the difference in the bottom-end bass "curve shape" of the 123A in the smaller L100 box compared to the much larger S-70 Alpha (2 cubic feet as opposed to nearly 6!) box, may result in the bass-to-midbass/midrange/treble balance, becoming, well, a bit unbalanced. This may be reperable by tweaking mid and tweeter level controls, maybe, maybe not. If the L100s are used near a wall or on the floor, then I'd think the problem would be exacerbated- conversely, if they're on proper stands (say, 12 to 18 inches tall stands), a couple feet from the nearest wall or corner, they may work out pretty well with the S-70 crossover...

Regards,
Gordon.

GordonW
03-07-2004, 07:11 PM
Oops, I just noticed- center tapped inductor on the HF section, Giskard, shouldn't a pair of .125 mH inductors wired in series, with the junction between the inductors acting as the center tap, work as a substitute? Or is there a significant resistance in that inductor as well (as in, some resistors needed in series with both inductors)?

Regards,
Gordon.

4313B
03-08-2004, 03:00 AM
That's the wrong LX30 - that newer LX30 is for the S21 system (124A/H, LE5-2/LE5H, 077)

I've posted the old LX30 schematic in this thread:

http://audioheritage.csdco.com/vbulletin/showthread.php?s=&postid=6323&highlight=c533#post6323

The old LX30 is the original network for the C533 custom loudspeaker system designed for Bob Fine. That system morphed into the L100 and 4310.


*****


http://www.audioheritage.org/vbulletin/showthread.php?s=&postid=705&highlight=lx30#post705


http://audioheritage.csdco.com/vbulletin/showthread.php?s=&postid=5725&highlight=lx30#post5725

GordonW
03-08-2004, 09:39 PM
I guess that JBL screwed up on the S70 Alpha III technical manual then... since the schematic I posted, came DIRECTLY from there. In that, they, specifically, specify the 123A-1, LE5-2 and LE20 as the active drivers...

Regards,
Gordon.

4313B
03-09-2004, 05:20 AM
Yes, it is wrong. The LX30 shown on the tech sheet is the LCS component series LX30 designed for the 124A/124H, LE5-2/LE5H, and 077. The original LX30 should be the one on the tech sheet. Easy enough mistake. I show all the differences in the links posted above.

Harvey Gerst
03-13-2004, 05:51 PM
Well, George Augspurger designed the x-over for the L-100, so go bitch at him. Ed did the x-over for the 4310, but in Ed's home system, he didn't use any inductors whatsoever in the x-overs - just some capacitors to roll off the bottom end on the mids and tweeters, and some L-pads. I still have that handbuilt system (out of Ed's house) when Edna insisted he "get rid of that monstrosity".

4313B
06-03-2004, 08:33 AM
"Well, George Augspurger designed the x-over for the L-100, so go bitch at him."

Hmmm, I can't imagine anyone wanting to go bitch at G.A. about a system designed 33 years ago that ended up being pretty successful and spawned a whole series of follow-ups. :p

"Anyone want to help me design a crossver for an orginal set of L-100's. the orginals are kinda cheesy and the cut off frequencies dont get the full potential out of the LE5-2 midrange."

If a person has looked at an L100 network next to say an L112 network I can see where "cheesy" might come into play. JBL did get pretty fancy with their various network mounting schemes and purpose-built pcb network boards, "cans", etc. Even back then some people might say an L100 network looked "cheesy" compared with something like an LX4-2 "can" from the later versions of Lancer 77's.

"Ed did the x-over for the 4310, but in Ed's home system, he didn't use any inductors whatsoever in the x-overs - just some capacitors to roll off the bottom end on the mids and tweeters, and some L-pads."

So Ed's home system network became the basis for the network that was used in the later L100A, 4310 (late), 4311, etc. The "story" continues to fill in. :)

How does the C533 designed for Bob Fine fit in then? I was told the C533 started this whole thing but it apparently used the LX-30 filter (NOT the LCS version for the S21 system) which looks identical to the "newer" 3111 filter used in the 4310 (late).

Here's what I have on the L100/4310. Bo has since worked out all the "polarity" issues with the various LF drivers.

Thanks Harvey!

Robh3606
06-03-2004, 09:03 AM
Hello Giskard

Great table but the Le-25's had to cut in there somewhere.

Rob:)

4313B
06-03-2004, 09:19 AM
Yep, you're right. It was used in the later L100's. The chart needs to reflect what Bo has found with the polarity debacle as well.

Harvey Gerst
06-03-2004, 09:42 AM
I can't fill in much beyond my previous post since I left JBL right around that time (i.e., the introduction of the 4310 and L100). As I recall, George's recommended settings for flat response out of the L100 or 4310 were about 3 (about 9:00 o'clock) on the midrange pot and 7 (about 2 or 3:00 o'clock) on the tweeter, but my memory ain't what it use to be, so those numbers ain't carved in stone.

I think Ed's mission was to get close to the sound of an Altec A7 with the knobs straight up (hyped mids and slightly lowered high end), while George's settings would get you into the flat ballpark.

Hope this helps a little.

boputnam
06-03-2004, 09:57 AM
Originally posted by Giskard
The chart needs to reflect what Bo has found with the polarity debacle as well. :yes: Yup.

I'm just too buried in research right now to Search for that particular post. I will do so, later...

4313B
06-03-2004, 10:03 AM
Yeah, that's a problem with all this. Revisions get buried with originals and not in the same place. Someone could easily run across erroneous information. Oh well, kind of like reading genuine JBL literature right? :p

Anyway, I'm sorry I got happy with the ctrl-c and ctrl-v keys in the original Rob. :rotfl: