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View Full Version : Looking for some tech help. Possibly building using JBL 2470 horn and 123A drivers



Theonetruegreg
11-06-2013, 08:30 AM
So, I'm brand new here and was directed via another forum of which I have been a longtime member.

First off, give you some background. I have a spare set of L100's (not L100a). I also have recently acquired a nice pair of 2470 compression drivers in 2345 radial horns.
I am very much thinking that maybe I should replace the somewhat lacking LE5-2 midrange driver in the L100's with the horns, along with improving the speakers overall.

Much talk has been paid attention to about building a larger, well braced and damped cabinet for the 123a, and limiting it's upper frequencies as JBL left them to run uncontrolled at full-range.

Where I'm at is, not a terribly technically proficient engineer. So, if this is a feasible project, I will need extensive help with crossover design. I am a furniture builder, so, am equipped to handle building complex cabinets, no problem. And, I keep my system simple, so no DCX, multiple amps, or crazy components or EQ. Just an integrated KT88 based tube amp.

You guys know these drivers. What they do and what they don't. How they work together. Looking forward to hearing your opinions!

(I am sure there are better suited compression drivers to this task that could replace the tweeter as well and run all the way up to 20khz+, but I am of somewhat limited means, so seeing what can be done with the raw components on hand)

grumpy
11-06-2013, 08:52 AM
Seems like it would be worthwhile to decide whether to base a proposed system on the 123A or on the compression driver.
Revisiting the L100 crossover has proponents (with instructions and measurements) here somewhere.

The 2470 can be a nice mid driver, but really won't cover the top octave... and that horn (2345) has a good home
in a 4560 PA box (where it's sensitivity and throw pattern are better matched), and looks nice/retro,
but will make for a difficult setup indoors.

Can you describe what you mean by the LE5-2 being lacking? I think you might be the first person I've
heard describe the L100 as being lacking in the mids... the crossover and controls are working?

ivica
11-06-2013, 08:58 AM
So, I'm brand new here and was directed via another forum of which I have been a longtime member.

First off, give you some background. I have a spare set of L100's (not L100a). I also have recently acquired a nice pair of 2470 compression drivers in 2345 radial horns.
I am very much thinking that maybe I should replace the somewhat lacking LE5-2 midrange driver in the L100's with the horns, along with improving the speakers overall.

Much talk has been paid attention to about building a larger, well braced and damped cabinet for the 123a, and limiting it's upper frequencies as JBL left them to run uncontrolled at full-range.

Where I'm at is, not a terribly technically proficient engineer. So, if this is a feasible project, I will need extensive help with crossover design. I am a furniture builder, so, am equipped to handle building complex cabinets, no problem. And, I keep my system simple, so no DCX, multiple amps, or crazy components or EQ. Just an integrated KT88 based tube amp.

You guys know these drivers. What they do and what they don't. How they work together. Looking forward to hearing your opinions!

(I am sure there are better suited compression drivers to this task that could replace the tweeter as well and run all the way up to 20khz+, but I am of somewhat limited means, so seeing what can be done with the raw components on hand)

Hi Theonetruegreg,

Welcome to the 'club'. I think You can find a lot of interesting projects here base on JBL drivers.
I would suggest You, to put-a-side 2470+2345 until You can get other drivers (say 2405, 2123 and 2235/45) and then make larger box.
I think that L100 box with their drivers has to remain together and used as they are.

Reagrds
Ivica

Theonetruegreg
11-06-2013, 09:35 AM
Seems like it would be worthwhile to decide whether to base a proposed system on the 123A or on the compression driver.
Revisiting the L100 crossover has proponents (with instructions and measurements) here somewhere.

The 2470 can be a nice mid driver, but really won't cover the top octave... and that horn (2345) has a good home
in a 4560 PA box (where it's sensitivity and throw pattern are better matched), and looks nice/retro,
but will make for a difficult setup indoors.

Can you describe what you mean by the LE5-2 being lacking? I think you might be the first person I've
heard describe the L100 as being lacking in the mids... the crossover and controls are working?


Tested and measured, they are working correctly. The LE5-2 in the original series 1970 L100 is rolled in at 2500 hz, the whole setup doesn't sound quite as well-rounded as the L100a that most people are using. I'm sure a simple reworking of the crossover would be tremendously beneficial, but that ain't my forte.

Seems in the current situation, may be better to sell off the horns and focus on a reworking of the L100 (there is a ton of info out there on redoing them, but it's all based on the L100a that uses the LE25 tweeter, not the LE20-1 that I have). Too bad, horns look impressive, and the home-built sets I've heard have impressive dynamics and don't seem to change much off-axis (and a touch of vanity in saying "look at these amazing things I built" is always nice).

I really do appreciate you fellas quick and informed responses. So, should I be making a new thread about how to go about designing an updated crossover



on a related note, when I was pulling the horn from the driver, I found one very angry and highly poisonous brown recluse spider taking up residence in the throat! It was quite exciting!
https://scontent-b-dfw.xx.fbcdn.net/hphotos-frc3/1454638_10151707369367927_1485757020_n.jpg

badman
11-13-2013, 03:19 PM
https://scontent-b-dfw.xx.fbcdn.net/hphotos-frc3/1454638_10151707369367927_1485757020_n.jpg

Wow, that's a recluse? Good thing you didn't stick your finger down there and antagonize it :)