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David V. Webber
05-05-2003, 07:42 PM
I am using Radio Shack 2000 Hz crossovers between my LE 14As and my LE 85s, while Mr. Greg Timbers is gathering components for me to build a pair of LX7 replacements. Only a Cap in the circuit. No resistors or attenuation of any sort. Crossover should be 500 Hz. While I was at work this past Sunday, my younger brother was playing some CDs on my system. ( Hafler SE 120, 60 WPC Mosfet Amp. ) He had the volume up high, ( 3/4 ? ). Now, one LE 85 doesn't make any sound at all, and the other makes a scratchy sound. Do I need new diaphragms, or just a pair of new Caps ? If the diapragms ARE blown, are they available ? If so, at what cost ?
Thank You, David V. Webber

David V. Webber
05-06-2003, 05:49 AM
The original LX7 crossovers are in Northridge. I'm in Pennsylvania. Greg has found SOME autoformers, however, the taps are the wrong value. He is correcting this with a resistor. All the caps are either blown or leaking badly. He is collecting the Autoformers / resistors, some nice Air - Coils, some SOLEN Metalized Polypropylene caps, etc, so that I can build myself a new pair of LX7 replacements. ( I will leave the top / front of the crossover in place, to seal the cabinet and provide terminals. )
The current problem is that one LE85 makes no sound, and the other just scratchy sound. I wonder if they might be damaged ? Or, are the cheap ( $ 12 ) Radio Shack caps blown? The folder which came with them, says that they can handle 100 Watts. The amplifier is a 60 Watt per Channel, Hafler SE 120 Mosfet. If my brother had the amp up to even the 2/3 level, ( 40 Watts, ) then a large portion of that would go to the Woofer, and a lesser portion to the LE85. However, the proper crossover has a 25 Ohm 75 Watt resistor and a 20 Ohm 11 Watt resistor in parallel with the LE85, as well as some attenuation in the autoformer itself. The Radio Shack crossover has nothing except the one cheap cap. So, I'm wondering if the LE85s might be damaged in some fashion ? Coils burned out ? Diaphragms blown ? How much do new diaphragms cost ? Do the original aluminum ones sound better than the new ones ? David V. Webber

David V. Webber
05-06-2003, 09:13 AM
It looks like my brother owes me $ 1000 plus shipping !!
Sadly, he has no job, no money, and owes others many, many thousands ! I only have $ 740 per month from Social Security, of which $ 440 are fixed bills, leaving me around $ 300 per month for
" Speaker Repairs " !! Looks like I'll have to save - up for 3 or 4 months just to fix the LE 85s, AND my LE14As need re - foaming
if not complete re - coning ! So, there will be no hurry to build my new LX7s !!! Is suicide the answer ? DVW

Rolf
05-06-2003, 09:20 AM
Hi.

I would strongly recommend to use crossover frq at 800Hz on this driver. Witch horn do you use? I guess Rober G agree??

Rolf

David V. Webber
05-06-2003, 01:22 PM
Greg is drawing up a new wiring diagram, and supplying all the components. He knows the volume, ( 1.7 ft. cubed, ) and the port
dimensions, ( 4 1/4" x 7 1/2", ) and the two drivers, ( LE14A and LE85 ); plus, he knows I want to build them, someday, into " Baby
Summits / L - 300s ", [ Who better ? He designed the Summit !! ]
He also knows my Amp, ( Hafler SE 120, ) and Pre - Amp, ( Parasound P / HP - 850 ). So, if 800 Hz is now preferred over
the original 500 Hz, I'm sure he's aware of it! Isn't he sort of, THE
crossover Guru ??? I'm near " Price - Stevenson ", JBL Service Center, Downingtown, PA. I'm not to sure of their competence, as they tested both my LX7s, and said they were fine; while, in fact, one was just about dead, and other had all the caps leaking.
However, they were so impressed with my Rosewood Veneered,
" Super " Bookshelf Speakers, that they offered to Re - Cone them for just the $ 350 price of the two kits ! I wrote Greg and asked for a sketch of the physical layout, as some air - coils must be a certain distance apart, and at right - angles to each other in two axes. Also, I wonder whether I should add one of those little, " Raychem " resettable fuses in the LE85 circuit ? DAVID

David V. Webber
05-06-2003, 01:36 PM
I forgot, as I didn't print - out your note. The horn is the 1217 - 1290, S.N. : 24237. Mr. Widget says I should switch to the H91
horn, and the slant - plate lens. ( Would have to be put on with Velcro, only with the grill off. ) In my cabinet, the LE85 1217 - 1290 combination has the magnet - end almost against the rear wall, and the face of the " Potato Masher " just behind the cloth. He says to use a burned - out 2405, and buy new diaphragms, as that would be cheaper than an 077. In any case, it will be quite awhile before I can afford to make them into 14" L - 300s !! David V. Webber

Mike Caldwell
05-06-2003, 02:19 PM
Hello
If your using a "potato masher" or in the future using a
H91 horn your 500hz crossover is too. Both of those horns
only have driver loading down to about 1200hz.

Using a single cap for a crossover only give you a 6db per octave
cut off that may have been a factor in blowing your diaphragms.
The 6db per octave cut has it's advantages but you will
have to move the crossover frequency higher to still give the driver protection for excess low frequency or go with a 12db
crossover network.

Mike Caldwell

David V. Webber
05-06-2003, 04:41 PM
Well, Mr. Greg Timbers has drawn the new crossover diagram, and mailed me the components today. I don't know enough to be able to tell the " order " or crossover point just by looking at the wiring diagram. I could E - Mail Greg, but for now, I think I've bothered him enough !!! David V. Webber

dmtp
06-16-2006, 06:13 AM
I realize this thread is ~3 yrs. old, but I am embarking on a similar journey and would be VERY interested in a diagram of the crossover you ended up with. Any chance of posting it? or PM me?

David V. Webber
06-16-2006, 07:08 AM
My scanner doesn't work . I will be glad to Xerox it for you , and mail it !
Just need an address . PS : I haven't built them yet , as I am still looking for a pair of the GOOD diaphragms for my LE - 85s ! David

You can " E - Mail " me at : DaveSail@AOL.Com
or phone at : 610 - 793 - 1129
or write : P. O. Box 97 , Chadds Ford PA , 19317