Vote on LX-16 Retirement

[witoman]

I am continuing with my project to convert an pair of L200's into a pair of quasi-L300's. I now have 136A's in for the woofs and have plugged up one of the two ports. I have gotten a pair of 3110 crossovers so that the woofs only see 800 Hz and below signals. I want to replace the original LX16 crossovers with the 3110's.

I am now faced with an ethical dilemma, what to do with the LX16 "umbilical cord" that goes from the LX16 mounted on the rear of the L200 and internally goes to the HF attenuation control switch on the front of the speaker.

It would be easiest to just cut the umbilical cord and let it dangle inside the cab and not mess with removing the (now inactive) HF switch, but I would be left with a useless LX16 crossover. BTW, a pair of intact LX16's go on eBay for about $20 to $30.

The alternative would be to peel off the HF control's foil on the front of the speakers, unscrew the HF control switch, replace the (probably now damaged) foil over the hole left and then remove the intact LX16. The delimma is do I essentually destroy an vintage piece of JBL equipment for the ease of removal or do I bite the bullet and risk messing up the foil on the HF switch when I remove the switch?

Any thoughts or alternatives?

(yes, I still need to tie-in an 077 or 2405 UHF driver which I will do via a two-way external electronic crossover set at 7 KHz. I'm also stuck with keeping the H91 horn on the LE85 driver).

[Zilch]

Remove the foilcal and switch, plug the hole. Foilcal will come off neatly with a heat gun.

LX-16s are hardly worth listing for resale.

What's to be concerned about? They're not L200s anymore, and there's little likelihood of restoring them as same.

You're not stuck with H91, if you're willing poke the driver out the rear panel and seal or box it.

[I keep offering that as an option, but nobody seems willing to actually do it.... ]

[hjames]

Do a test - get a blow dryer and use it to heat up the entire foilcal - with luck the glue will soften and you can remove the foilcal in one piece and stick it to a piece of wax paper or something similar. If that works then you can try and remove the screws that hold the level control subpanel from the front baffleboard.

I'd recommend building a new subpanel - you can get a replacement level control pot from Parts Express. I found replacement T-nuts that matched the JBL screws at Home Depot and bought some plywood scraps there to make a new panel for the new high level adjuster.
Just use nice thick copper zipcord to make a newer cord - for my speakers the large gauge zipcord was fatter than the original stranded wire JBL used!

I turned my 4320s into quasi-4333s by building and installing a new crossover (Giskard specs) with a tethered new subpanel. If you are making L300s (the home version of my quasi-4333s)
they are 3-ways and you'll want mid level and hi-level adjustment pots, right? Or are you going to biAmp them?

I am continuing with my project to convert an pair of L200's into a pair of quasi-L300's. I now have 136A's in for the woofs and have plugged up one of the two ports. I have gotten a pair of 3110 crossovers so that the woofs only see 800 Hz and below signals. I want to replace the original LX16 crossovers with the 3110's.

I am now faced with an ethical dilemma, what to do with the LX16 "umbilical cord" that goes from the LX16 mounted on the rear of the L200 and internally goes to the HF attenuation control switch on the front of the speaker.

It would be easiest to just cut the umbilical cord and let it dangle inside the cab and not mess with removing the (now inactive) HF switch, but I would be left with a useless LX16 crossover. BTW, a pair of intact LX16's go on eBay for about $20 to $30.

The alternative would be to peel off the HF control's foil on the front of the speakers, unscrew the HF control switch, replace the (probably now damaged) foil over the hole left and then remove the intact LX16. The delimma is do I essentually destroy an vintage piece of JBL equipment for the ease of removal or do I bite the bullet and risk messing up the foil on the HF switch when I remove the switch?

Any thoughts or alternatives?

(yes, I still need to tie-in an 077 or 2405 UHF driver which I will do via a two-way external electronic crossover set at 7 KHz. I'm also stuck with keeping the H91 horn on the LE85 driver).

[toddalin]

I'm thinking that you want to make something like this.

When I got my L200 cabinets, they were in very bad shape and needed a major rebuild so I wasn't concerned about historic value. On one, the lower front molding was busted out and missing so I had to fabricate a new one and do lots of fill work. I also raised them 1-3/4" to clear my bricks. I just filled/smoothed the hole and painted the fronts in black.



More recently I built a new set of three crossovers (800 Hz/7,500Hz) (L,C,R) that are documented on this site. Zilch tested one and found it superior to the old, comparable JBL offerings.

[witoman]

Thanks everyone for some great advice. Like Larry the Lobster, the LX16 crossover will be saved by using a 1500 w blowdrier on the foilcal.

I will be bi-amping this quasi-L300 with a GAS Ampzilla for the q-L300 (feeding the 3110 7 Kz and below) and a GAS Grandson amp for the UHF driver from 7 Kz and above.

I will keep in mind the final stage, that of making a cutout in the back for the longer H92 horn, but I'm not too skilled at that sort of thing. I do have a single H92 that was being sold solo on eBay for a few bucks, so I can get the sizing right.

BTW, what issues do I face of having the LE85/H91/L91 being crossed over at 800 Hz from the 3110?

[Zilch]

BTW, what issues do I face of having the LE85/H91/L91 being crossed over at 800 Hz from the 3110?

It works, but does not sound as good as H92. L200B with H91 was crossed there. You might want to try your H92 sitting on top to hear the difference.

Consider crossing the 077 at 10 kHz instead of 7 kHz, or some place in between. L300 crossed the UHF at 8.5 kHz.

For extended bass, closing one of the L200 ports with a 4" plumbers' test plug gives ~28 Hz box tuning.

I don't remember offhand where L300 was tuned, but it's likely found in these forums somewhere.

With both ports open, L200 is tuned at ~37 Hz. I'm gonna go out on a limb here and suggest that's too high for 136A to sound "optimal"....

[witoman]

With both ports open, L200 is tuned at ~37 Hz. I'm gonna go out on a limb and suggest that's too high for 136A to sound "optimal"....

I guess that explains why the L200B had only one port with the 136A. Thanks!

[Anthony L100]

You're not stuck with H91, if you're willing poke the driver out the rear panel and seal or box it.

[I keep offering that as an option, but nobody seems willing to do it.... ]

Hey Zilch, I think i've even seen you describe this as a "mess", but if it solves the problem of H91 @ 800 it's gotta be better. How far would the LE85 protrude with H92?

[toddalin]

Hey Zilch, I think i've even seen you describe this as a "mess", but if it solves the problem of H91 @ 800 it's gotta be better. How far would the LE85 protrude with H92?

~3"

[Anthony L100]

Thanks Toddalin, when I finally get around to modding my 200As I will probably take that route. Only trouble is, I really like the character of the standard LE85 with ali diaphrams (probably originals), silky smooth with reasonable extension, I wouldn't want to lose that.

[Thom]

Of the 4 inch drivers are some preferable to others?

[Zilch]

Only trouble is, I really like the character of the standard LE85 with ali diaphrams (probably originals), silky smooth with reasonable extension, I wouldn't want to lose that.

Different horn takes the same driver. Not an issue.

Before I decided to start cutting, tho, I THINK I'd spend $30 on a pair of the El-Cheapo 1" PT Waveguides and thread-on adapters for my LE85s to try, as well.

LE85s with aluminum diaphragms have nice HF extension, but the horn/lens kills it with collapsing vertical dispersion (below). Gotta add a UHF driver if you keep the exponential horn.

The "mess" is more than wood chips; unless you delay the woofer, H92 creates even more of a time alignment problem than H91. Here's what gtimbers said about this issue in a different system:

The weak areas of that type of design are several. First, there is a large time off-set between the 10" driver and the HL92 horn. This shows up in both the on-axis response, the directivity pattern and the homogeneity of the driver blending.

Jim Thiel:

In real life, sound has harmonics that reach your ears at a specified time. If those harmonics are changed by distortion, it decreases the realism of the signal. Time alignment and first-order crossovers provide more realistic spatial realization and a greater clarity of the energy of time-and there's an intangible property of realism. There are significant sonic benefits that are provided by time coherence and phase coherence.

Kevin Voecks (Revel):

It is of critical importance that this response occur not only on-axis, but also far off-axis, since the off-axis responses make up the sonically critical first reflections and the power (reverberant) response. Very few loudspeakers perform well in this critical parameter.

[Zilch]

Of the 4 inch drivers are some preferable to others?

None in this thread (yet), Thom. Maybe start a new one....

[toddalin]

Thanks Toddalin, when I finally get around to modding my 200As I will probably take that route. Only trouble is, I really like the character of the standard LE85 with ali diaphrams (probably originals), silky smooth with reasonable extension, I wouldn't want to lose that.

There is an alternative to cutting the back and adding a box. You could actually move the baffleboard to the front of the cabinet and pick up the necessary space (ala L300). The side vents would need to be sealed.

As hard as this sounds to do, at least one person on this forum has done it. This would also add volume to the cabinet reducing the tuning frequency. There would be various ways to do the grills, either by raising them, or just leaving the front "flat" (rear mount or recess the speaker and attach the slant plate directly to the grill cloth).

Another alternative would be to make a 3" standoff to go on the existing baffleboard for the front of the horn and slant plate. In this case, the time alignment would be no worse than the H91 though it would sort of block the woofer.

[witoman]

Success! Last night I was able to use a hairdrier to heat one of the HF control switch's foilcal. It came off fairly easily and cleanly using just my fingers, but someone has suggested using a putty knife would work better.

All of this is best done with the woofer pulled so that you can look and reach around the interior of the cabinet. The 136A on this first speaker is out for reconing (that's a horror story) and was out already.

I have removed one of the LX16 crossovers intact and have plugged the switch's shaft hole from the inside with a chair leg "coaster" that you would stick on the bottom of a chair's leg to keep it from scratching the floor. Then I smoothed the foilcal back on the front of the baffle.

Back to the crossovers. I removed the rubber gasket from around the LX16's mounting flange and placed it on the 3110's flange, no problem. I then replaced the original wires going from the crossover to the woofer with 14 gauge speaker wire, leaving the HF driver's original wires in place. Finally, I mounted the 3110 on the speaker (a perfect fit) and hooked all of the driver wires up. It all looks great. I won't be able to test it all out until I get the 136A back from reconing.

I'll do the other speaker tonight. Thanks again to everyone.