Can You Design Me a Crossover That:

[toddalin]

Can better integrate the 2235 with the LE175 on an HL-91 with an 075.

Changing out the 130As to 2235's left a "hole" in the area between 500 - 1,000Hz. To me, this is perceived as a muffling of peoples voices.

I am currently using an N1200/N8000. I would like to crossover the woofer to the horn at about 800 Hz. This should be high enough to let the horn operate within its range while reducing the size of the "hole." A two-way that retains the N8000 would work fine. All components are 8 ohm.

Thanks

[speakerdave]

You might be able to build one yourself. You could begin by looking at this thread about the 3133, the crossover for the 4333/L300. Your list of equipment is similar, although there are differences.

http://www.audioheritage.org/vbullet...highlight=3133

I'm not sure if there is a free crossover designing service available here. I think there probably would be help available if someone started out on his own and ran into some glitches, but that's just my guess. Our new forum is called DIY, not DIFM.

David

[John]

Our new forum is called DIY, not DIFM.

David

[toddalin]

Thanks for the link. I should be able to adapt the L300 network.

There are limits to DIY and I would still be physically building the crossovers. I just figured that if the design was out there, why reinvent the wheel? Even with the L300 design, I would probably just use the two-way section and still retain the N8000s just to fill in the hole in the back of the cabinets.

[edgewound]

Todd...

You should probably look for LE85/2420 or 2425/6 if you want the midrange to be clean and trouble free to work with a network such as for an L300. I'm afraid you'll find the LE175 won't be up to the task...it was meant to work with 130A or D130. Just my opinion...might save some future headaches.

[speakerdave]

Todd...

You should probably look for LE85/2420 or 2425/6 if you want the midrange to be clean and trouble free to work with a network such as for an L300. I'm afraid you'll find the LE175 won't be up to the task...it was meant to work with 130A or D130. Just my opinion...might save some future headaches.

The 130A and the D130 both have much higher output than the LE15 or 2235. The sensitivies of the 175 and the 85 are listed as identical. The differences would be in UHF extenstion. Either is adequate when crossed over to a supertweeter.

David

[edgewound]

The 130A and the D130 both have much higher output than the LE15 or 2235. The sensitivies of the 175 and the 85 are listed as identical. The differences would be in UHF extenstion. Either is adequate when crossed over to a supertweeter.

David

I understand...but my thinking is that the bigger motor will better handle the lower crossover point and the transients that go with home theater sound tracks. Like I said...just my opinion. Also 2425's are still reasonable on ebay, etc.

[speakerdave]

. . . . my thinking is that the bigger motor will better handle the lower crossover point and the transients that go with home theater sound tracks.

Could be true.

Either driver will be better off with the longer horn at 800 Hz.

David

[speakerdave]

I just figured that if the design was out there, why reinvent the wheel?

Indeed. My wisecrack was a little out of line, but I couldn't resist. I should talk, anyway. The whole crossover thing has given me the hesitation blues.

Even with the L300 design, I would probably just use the two-way section and still retain the N8000s just to fill in the hole in the back of the cabinets.

It seems to me Ian has suggested that cascading crossovers, although apparently JBL-recommended practice in the past with prebuilt units, can involve unnecessary compromises when building from scratch. In the old charts ('70's) JBL treats the 175 and 85 compression drivers as interchangeable vis-a-vis horns and crossovers for HF and the 075 and 077 also when used for UHF. It might be better to go for the whole 3133, either using the charge-coupled or bypassed version. (And then pay for the parts by selling the N8000's on ebay.) Anyway, that would be a specific question I would post for the filter wizards.

David

[toddalin]

Edge, it's certainly a future possibility, but three nice LE85's don't come cheap and and HL92's are scarce. (Wasn't easy to get wife to go for $1,050 just to redo the four woofers. )

I assume that I can use higher wattage resistors than indicated (e.g., substitue a 25 for a 20 watt resistor) so long as I retain the proper resistance.

[speakerdave]

. . . and HL92's are scarce.

I have a pair of H92's sitting in my garage, black, crinkle paint, nice and clean; one of the foilcals has gone missing. I'm afraid I have $175 into them, but they're yours for that plus transportation if you want them.

David

[edgewound]

Todd...

Following Giskards recommendation and doing a little searching through my service lit...the L200B uses the HL91 crossed over at 800Hz but uses the LE85 driver with a 136A woofer. The L200A also used an LE85 & LE15B driver crossed at 1200Hz with the same horn. So Giskard seems to know that the LE175 will be fine with the HL91 at 800Hz so go for it. Personally I'd opt to cross the LE175 at 1000Hz just for a margin of safety at higher power levels and transients with home theater sound tracks. Besides that...the 4430 (2235H) crossover is at 1000Hz and that seems to sound pretty good. Theres plenty of software available at Parts Express to design that crossover for you...and they have the parts too. Have at it!!!

[Paul Joppa]

...
Changing out the 130As to 2235's left a "hole" in the area between 500 - 1,000Hz. To me, this is perceived as a muffling of peoples voices.

I am currently using an N1200/N8000. I would like to crossover the woofer to the horn at about 800 Hz. This should be high enough to let the horn operate within its range while reducing the size of the "hole." A two-way that retains the N8000 would work fine. All components are 8 ohm.

Thanks

First, the "hole" as others have noted may just be the reduced woofer sensitivity. The N1200 won't adjust the horn down far enough to match. It's also possible the different woofer HF rolloff changes its effective time delay, and a phase reversal of the woofer might help fill in.

OK, then here's my perspective on the technical history.

Originally, the LE-15/LE175 (S-7) crossed at 500Hz. My perspective - that was to keep the phase difference small enough to run the drivers in phase. (Plus, the LE-15 crapped out above 500Hz.) The 130A/175 combo at 1200Hz has a phase difference close to a wavelength so the drivers can be in phase at crossover.

The first monitor (4420?) upped it to 800Hz, probably to protect the 175 from damage. But the phase difference at 800Hz is about 1/2 wave length (assuming the woofer phase origin is some 4" behind the front panel). I don't know if they reversed the woofer phase for that or not. The longer H92 at 800Hz came closer to matching the 1200Hz crossover with the H91 horn, again allowing the woofer phase to be the same as the HF.

The crossovers, N500 and N1200, are pretty straightforward and easily adjusted to an 800Hz crossover - or just use the 4420 design, with the reversed phase as necessary. But do the calculations to get the sensitivity matched!

[Zilch]

Paul: S7 was LE-85, and you mean 4320, not 4420, I would assume....

Can you design me a crossover that can better integrate the 2235 with the LE175 on an HL-91 with an 075?

http://www.lansingheritage.org/image...omp/page08.jpg

[Paul Joppa]

Paul: S7 was LE-85, and you mean 4320, not 4420, I would assume....

http://www.lansingheritage.org/image...omp/page08.jpg

Shouldn't trust memory at my age!

Anyhow, the LX5 was specified for LE175, LE85, and 375 in the earlier versions; in fact before the 4320 with LX13 at 800Hz, the studio monitor used the LX5 at 500Hz. All of these were specified for use with the LE175/HL91 at one time or another, though in later years the minimum crossover for the LE175 drifted up to 800, 100, 1200, and eventually 1500Hz in the "potato masher" horn. I always assumed that was because amps got bigger and people were blowing out the drivers.

Sounds like several classic crossovers could be adapted, and a few were actually meant for the 2235. AFAIK, anything that used the LE85 will work fine with an LE175, losing mostly a litle HF extension. The big problem is always the tapped inductor/autoformer in the crossover, so an original JBL on the used market would be a lot easier than a new scratch-built crossover.

Always wondered if there was much market for suitable tapped inductors. It should not be that hard to get some made up, if one could amprtize the design and tooling costs (and if JBL did not object!)