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David V. Webber
03-25-2010, 12:16 PM
I have a pair of " Bookshelf " Speakers I made using JBL components .
LE85 Mid / High , [ Potato Masher Lens ; will accept gift of Slant - Plate
Lens , ] LE14 Woofer with LX7 crossover . Just saved - up the $ 600
to replace the two blown LE85 diapragms . Woofers just re - foamed .

If I were to add a JBL Slot Radiator to the " mix " , what sort of a
" High - Pass " would I need ? Just a Cap , or a coil also ? I am 75 , so
if it is a little brighter , skipping any Resistor would probably be Okay .

The diagram of the original LX7 is on this site . However , Mr. Greg Timbers sent me a complete set of parts to build a new pair , FREE , with a pair of GIGANTIC Air Coils ! His " new " LX7 is " modern " , and perhaps differs slightly from the original . If you need that info , I can send you a
picture of that diagram .

Just missed a pair of Slot Radiators on Ebay ; ( but , perhaps , they had been " stressed " !!?? )

DAVID V. WEBBER

610 - 793 - 1129

jcrobso
03-25-2010, 12:26 PM
I have a pair of " Bookshelf " Speakers I made using JBL components .
LE85 Mid / High , [ Potato Masher Lens ; will accept gift of Slant - Plate
Lens , ] LE14 Woofer with LX7 crossover . Just saved - up the $ 600
to replace the two blown LE85 diapragms . Woofers just re - foamed .

If I were to add a JBL Slot Radiator to the " mix " , what sort of a
" High - Pass " would I need ? Just a Cap , or a coil also ? I am 75 , so
if it is a little brighter , skipping any Resistor would probably be Okay .

The diagram of the original LX7 is on this site . However , Mr. Greg Timbers sent me a complete set of parts to build a new pair , FREE , with a pair of GIGANTIC Air Coils ! His " new " LX7 is " modern " , and perhaps differs slightly from the original . If you need that info , I can send you a
picture of that diagram .

Just missed a pair of Slot Radiators on Ebay ; ( but , perhaps , they had been " stressed " !!?? )

DAVID V. WEBBER

610 - 793 - 1129
This way we can see what your doing.

David V. Webber
03-25-2010, 08:39 PM
I scanned all the stuff from Greg Timbers . The scanner sent it all to the Computer . I've looked through hundreds and hundres of Documents /
Pictures with no luck . I DO have a FAX . OR , [ I am in no rush , I have two crossovers to build ! ] , I can slip them in an envelope and send them " Snai Mail " .

My E - Mail address is :

DaveSail - at - AOL . Com

cosmos
03-25-2010, 09:01 PM
Best would be to use a 3105 (N7000 7000 Hz crossover) or 3106 (N8000 8000 Hz crossover) for the 2405/077 slot ring radiator.

You can download both the 3105 ( N7000 ) & the 3106 ( N8000 ) schematics from JBL at crossover schematics (http://www.jblproservice.com/navigation/Network%20Schematics.html) .

That said, the LE85 goes up high enough that most would say they don't need a tweeter. It's a great driver. Further, At 75, if you can hear higher than a LE85 goes, I want to have your hearing and I am only 52...

Also, a little recommendation would be to go back and erase your e-mail address. It will get picked up by programs scouring the web in search of e-mail addresses and the amount of junk e-mails you get will go up.. You can safely say that your email address is "DaveSail - at - AOL.com" and humans will interpret it correctly..

Best regards.

David V. Webber
03-25-2010, 10:00 PM
Thank you for the proper crossovers . Are any still made , or would I have to build my own ?

I don't listen to loud rock with " Thumpers " in my car trunk , so my ears are pretty good . At one of those , ( actually , two , ) Speaker Builder
meetings in Virginia , one guy had a device that played a sampling of all the frequencies up to and well beyond 20,000 Hz. Of course , it is a matter of volume and distance from the source ; ( fades as the square of the distance . ) I was sitting in the front row , and I'm certain I could hear at least the 22,000 Hz . [ My left ear is a BIT off from the right , due to terminating a Deer out front who used a Mercedes to commit suicide . I used my Colt Python , with a .357 Magnum round , and NO ear - plugs or muffs ! That rang for awhile ! David V. Webber

Mr. Widget
03-25-2010, 11:49 PM
I don't listen to loud rock with " Thumpers " in my car trunk , so my ears are pretty good . At one of those , ( actually , two , ) Speaker Builder meetings in Virginia , one guy had a device that played a sampling of all the frequencies up to and well beyond 20,000 Hz. Of course , it is a matter of volume and distance from the source ; ( fades as the square of the distance . ) I was sitting in the front row , and I'm certain I could hear at least the 22,000 Hz .That puts you firmly in the freak of nature category... congratulations. Even in High School, I topped out around 18KHz... and don't even get close to that today. :(

Assuming you are hearing above 15KHz, you owe it to your fine hearing to definitely use a pair of proper tweeters. 077/2405s would be my choice if sticking with vintage JBL.


Widget

RKLee
03-26-2010, 01:45 AM
.
.
I used my Colt Python , with a .357 Magnum round , and NO ear - plugs or muffs ! That rang for awhile ! David V. WebberWow, that is loud really loud even with ear muffs and a foam plugs together.

Personally, I would add a super tweeter to the mix because I like the sound better. I think JBL's factory passive crossover for the 077 was at 7KHz.

Doc Mark
03-26-2010, 08:41 AM
Wow, that is loud really loud even with ear muffs and a foam plugs together.

Personally, I would add a super tweeter to the mix because I like the sound better. I think JBL's factory passive crossover for the 077 was at 7KHz.

Morning,

Yes, JBL did use a 7khz crossover point for the 077, but I must add that the 077/2405 sounds a bit harsh when crossed over that low. That wonderful tweeter really comes into it's own when crossed a bit higher. I'd go no lower than 8khz, and might even go up higher, say to 10khz, for best results. My first 2405 came with the JBL 3105 crossover, which is set for 7khz. To my ears, the tweeter sounded a bit harsh, brittle, and edgy with that crossover. Later, I experimented with higher crossover points, using my old Crown VFX-2A electronic crossover, and I was very impressed by how the 077/2405 opened up and smoothed out it's performance. For what it's worth.... Take care, and God Bless!

Every Good Wish,
Doc

Mannermusic
03-26-2010, 10:10 AM
Morning,

Yes, JBL did use a 7khz crossover point for the 077, but I must add that the 077/2405 sounds a bit harsh when crossed over that low. That wonderful tweeter really comes into it's own when crossed a bit higher. I'd go no lower than 8khz, and might even go up higher, say to 10khz, for best results. My first 2405 came with the JBL 3105 crossover, which is set for 7khz. To my ears, the tweeter sounded a bit harsh, brittle, and edgy with that crossover. Later, I experimented with higher crossover points, using my old Crown VFX-2A electronic crossover, and I was very impressed by how the 077/2405 opened up and smoothed out it's performance. For what it's worth.... Take care, and God Bless!

Every Good Wish,
Doc

Hi Doc - Yes, on the money, been there done that. And, if you look at the JBL schematics, you will see that the 3105 actually crosses (LF= -3db, HF= -3db) at 5kHz! As Doc says, too low for the 077; sounds harsh, etc. It's the 3106 that is more reasonable for the 077 crossing at 7kHz. Plus, it has a 20 ohm pad on the low frequency horn which is usually desirable. But, what I, and I'm sure others, did is wire up my own version of the 3106 and tweak per my ear/room, et al. Always seem to end up with a 1 mF cap and .3 mH coil plus L pad adjusted as necessary (I wire it up fixed). And, of course, it never ends!:bs:

David V. Webber
03-26-2010, 11:14 AM
Is the Cap in series on the " + " side and the coil across , ( before or after the Cap ) ? David V. Webber

robertbartsch
03-26-2010, 11:57 AM
I ran the 077 slots with the n7000 crossovers in a home system for about 25 years and I never thought they were edgie or harsh but crossing these higher is probably not a bad idea.

If you are considering this I would look at the JBL 2405 slots in ceramic motors since they are a lot less expensive than the 077 or 2405 alnico drivers. ...just make sure you are using JBL OEM diaphragms.

Avoid e-bay, if possible.

toddalin
03-26-2010, 12:31 PM
As a better alternative to the simple 1.5 mfd cap/0.3 mH coil in the 3106. You may find that the circuit used in the 4433 to sound better. It retains the same cap/coil as the 3106 on the mid but adds a 1 mfd cap before the coil and the coil is reduced to 0.16 mH on the tweeter.

The 075 and its variants have a dip in the 8-9kHz range to varying degrees, and best I can figure, the second cap creates a peak that is to fill this dip in the 2405/077.

Ruediger
03-26-2010, 02:06 PM
..., one guy had a device that played a sampling of all the frequencies up to and well beyond 20,000 Hz. Of course , it is a matter of volume and distance from the source ; ( fades as the square of the distance . ) I was sitting in the front row , and I'm certain I could hear at least the 22,000 Hz .

One would need to know how the guy sampled the signals and how he played them back before one could explain what has happened.

If the sampling frequency is too low for the signal beeing sampled (if the Shannon theorem is violated) You will not sample and play back silence but rather some audible artifacts. Your ears will hear ***something*** but that will not be 22 kHz.

Ruediger

Mannermusic
03-26-2010, 02:35 PM
Is the Cap in series on the " + " side and the coil across , ( before or after the Cap ) ? David V. Webber

Yep, the cap is in series "+", coil parallel. You can also try the cap alone (first order filter) as you mentioned above and then "clip in" the coil (after the cap) with alligators soldered to the coil leads. Basically follow the JBL schematic. An old text I like is, Hi-Fi Loudspeakers and Enclosures by A.B. Cohen. It's an oldie based on fundamental math and physics - excellent basic learning tool for hobbists. Lots of examples. Remember, "One test is worth 1000 expert opinions!" Have fun.

David V. Webber
03-26-2010, 02:55 PM
I ran the 077 slots with the n7000 crossovers in a home system for about 25 years and I never thought they were edgie or harsh but crossing these higher is probably not a bad idea.

If you are considering this I would look at the JBL 2405 slots in ceramic motors since they are a lot less expensive than the 077 or 2405 alnico drivers. ...just make sure you are using JBL OEM diaphragms.

Avoid e-bay, if possible.

Who sells the Ceramic ones ? Is the sound different in any way from theAlnico ? Or the Power Handling , etc. ?

louped garouv
03-26-2010, 03:30 PM
to my understanding; none are sold new anymore, possibly NOS could be found...

the ceramic motors are reportedly functional equivelents of the earlier alnicos


you can spot the difference pretty easily...

http://www.usspeaker.com/jbl-2405h-size120.gif
ferrite/ceramic

and

alnico
http://www.audioheritage.org/photopost/data//517/jbl-077_s-dos.jpg