JBL Crossover Question:

wallacefl said:
I think you should give it a go in one speaker and compare it to the other unmodified....
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I'm with Wallace - I'd have to at least try the "upgrade" crossovers just for the curiosity factor. You can't hurt anything, and you will then have the answer to your question: "Will it sound good?"

By the way, is this entire exercise about curiosity, or are your stock crossovers bad?

GeeDeeEmm
 
GeeDeeEmm

This is strictly curiosity and ignorance. I bought the crossovers off of ebay not realising there was a L100A vs L100T difference. I am a noob for sure with too much disposable income and an ear for clean beautiful music. The curiosity came after the ignorance. I can't send the crossovers back. So I thought I would ask and learn the differences. My L100A's sound great. I have a Kenwood 600 Supreme being refurbished and so I thought I should improve the speakers before that AMP is done. Now I am just scratching my head. Because the Kenwood KA-5500 I have isn't going to sound like the 600 Supreme anyway. So testing would be learning but not headed towards my end goal. Yep I am a confused noob but addicted to the old stuff. I must say it's fun though!!!
 
Try a temporary hook up of 1 speaker. Run wire through the front port, to each driver, then to the L100T crossover. Hook up the new crossover to your receiver, and test it. Just be sure not to short the crossover board against any metal surfaces. Now, you can compare the 2 different speakers against each other. Determine if the new crossover is better or just different?
 
AMFADAVE said:
GeeDeeEmm

I have a Kenwood 600 Supreme . . . Yep I am a confused noob but addicted to the old stuff. I must say it's fun though!!!
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Can there be a better combination than retirement, lots of disposable income, and a love for the "old stuff?" That's an enviable situation. I hope you will keep us informed as you make your journey of discovery. You are at the right place to gather lots of information on gear you may be considering, and that information (mixed with a large number of subjective opinions, of course ;)) can help you avoid the usual rabbit holes that folks new to the hobby inevitably find themselves in.

I wasn't familiar with the Kenwood Supreme 600, so had to search for it. That's a very impressive integrated amplifier - and apparently rather rare to find. ( http://www.thevintageknob.org/kenwood-Model_600.html )
598113-kenwood_supreme_600_stereo_amplifier_the_legend.jpg


GeeDeeEmm
 

Attachments

tarior said:
This is what should be in the L100A. Very different from that of the L100T, Murphy's, or Gravesen's designs.
5916-JBL_L100A_ts.jpg
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The good news is that the cross-over frequencies are known. If you would like to put a steeper slope (like 12db per octave) you could add some coils to the mid and hf drivers, but this will change the phase relationship and the outcome would be a guess and by golly.

One "goof" that the L100(A) had in its simple design was that the midrange was not "boxed in" at its top end. However, the good news is that the midrange driver dropped off rather naturally, even tho some musical content is being produced by both drivers (too much, IMO), that smears the upper midrange.

In my opinion, I would leave the design alone and concentrate more on the adjustments of the driver levels, balancing them out as best as possible. I also think the L100s benefit from being placed high off the floor (tweeter not at ear level) as I remember mine seemed to beam the HF a little too much. A graphic EQ may (and I mean may) help tame the mid to hf transition. The EQ can be a dangerous weapon in the wrong hands, benefits are usually small deviations from flat. The sound of the L100 can also be easily changed by their room position in regards to walls/floors, but also by toe-in angle and distance apart.

Anyway, do as you see fit. I wish I still had mine......:)
 
Similar but different model JBL, I have a pair of JBL Aquarius 1 (AKA S-105) that I bought in 1971 in Okinawa. the speaker components are being reconed and magnets re-energized. one of the crossovers needs a potentiometer, I would like to upgrade both ... any suggestions..
sincerely, Byron
 

These were on ebay. This is what the seller said about them:

They are very easy to replace. Each wire will be labeled which driver it connects to and with +/- tag also.

You just need to solder the wires to the drivers.

What you should know is that these crossovers i build are essentially the same crossover as the original, only with higher grade parts and an impedance stabilizer network to replace the level controls with level taps for improved sound quality.

This is not a completely new topology of changing of the speakers character. Just want to make sure you understand what you are purchasing.
You will experience sound quality improvement, but it will not transform your speakers into some other sound.


So I guess they are essentially the same as original, just new parts. Would they be an improvement over the original 45 year old components?
I did originally use a Lasen Peak EQ with the L100's and a Marantz 2270 which I am about to get refurbished. Looking to get the system up and
running like it was back in the 70's. Also, would the EQ need any work or just a good cleaning?
 
Dennis G said:

These were on ebay. This is what the seller said about them:

They are very easy to replace. Each wire will be labeled which driver it connects to and with +/- tag also.

You just need to solder the wires to the drivers.

What you should know is that these crossovers i build are essentially the same crossover as the original, only with higher grade parts and an impedance stabilizer network to replace the level controls with level taps for improved sound quality.

This is not a completely new topology of changing of the speakers character. Just want to make sure you understand what you are purchasing.
You will experience sound quality improvement, but it will not transform your speakers into some other sound.


So I guess they are essentially the same as original, just new parts. Would they be an improvement over the original 45 year old components?
I did originally use a Lasen Peak EQ with the L100's and a Marantz 2270 which I am about to get refurbished. Looking to get the system up and
running like it was back in the 70's. Also, would the EQ need any work or just a good cleaning?
Click to expand...
Dennis G said:

These were on ebay. This is what the seller said about them:

They are very easy to replace. Each wire will be labeled which driver it connects to and with +/- tag also.

You just need to solder the wires to the drivers.

What you should know is that these crossovers i build are essentially the same crossover as the original, only with higher grade parts and an impedance stabilizer network to replace the level controls with level taps for improved sound quality.

This is not a completely new topology of changing of the speakers character. Just want to make sure you understand what you are purchasing.
You will experience sound quality improvement, but it will not transform your speakers into some other sound.


So I guess they are essentially the same as original, just new parts. Would they be an improvement over the original 45 year old components?
I did originally use a Lasen Peak EQ with the L100's and a Marantz 2270 which I am about to get refurbished. Looking to get the system up and
running like it was back in the 70's. Also, would the EQ need any work or just a good cleaning?
Click to expand...
 
Dennis G said:
These were on ebay…

So I guess they are essentially the same as original, just new parts. Would they be an improvement over the original 45 year old components?
Click to expand...
Asking price was $158 per pair :eek:! As of now, they are no longer available. IMO, that's a good thing.

They would not offer any better performance than the original 45 year old components, despite using some parts said to be better quality. And that is their major problem. That original design has major flaws that are correctable. Replacing the original caps with film type caps doesn't address those problems at all. Its like putting lipstick on a pig. In a pinch, I might pay $10 or $15 for them, but not $158.

There is one minor improvement, the variable L-pads were replaced by some fixed value resistors. Variable L-pads all get oxidized, noisy, and eventually fail. You're better off without them. But getting rid of noise prone L-pads still does not fix the original crossover design.
 
@ Dennis G. Here is a write-up on changing the L100 to sound like a modern speaker. The writer is talented and has a very methodical approach.
The crossover he built will work for your L100A, but you will have to build and install it yourself. He includes a link to Jantzen for a DIY kit.
Or you can buy the parts yourself from Parts Express.

http://www.troelsgravesen.dk/JBL_L100.htm
 
tarior said:
@ Dennis G. Here is a write-up on changing the L100 to sound like a modern speaker. The writer is talented and has a very methodical approach.
The crossover he built will work for your L100A, but you will have to build and install it yourself. He includes a link to Jantzen for a DIY kit.
Or you can buy the parts yourself from Parts Express.

http://www.troelsgravesen.dk/JBL_L100.htm
Click to expand...
Thanks tarior. I've never done anything like that before but may give it a try.
 
@Dennis G and @tarior

The last I heard, Parts Express no longer sells that L100A crossover kit. It may still be available in Europe, but not in the USA. And you can't build it with parts you buy separately because that website doesn't reveal what those individual parts are.

I've never heard that crossover, but from what I've read about them, they seem to be good. The designer, a guy in Denmark, Troels Gravensen appears to know his stuff. His web site is full of info and DIY designs that look very interesting. But you have to buy his kit to build it.

That leaves only one re-designed crossover for the L100A that people can build for themselves. The schematic diagram and parts list is available for no cost. (See post #28 in this thread where I attached those documents.) I'm the guy who first built them, and you can ask all the questions you want. The crossover designer, Dennis Murphy, may also be available for questions, but he is busy with other projects, and he usually leaves those questions to me.

Dennis Murphy has quite a reputation in the USA. He is an accomplished DIY speaker designer, and has long been closely associated as a designer for Salk Sound, and more recently for his own small company, Philharmonic Audio.

I only know of one web page that does compare the sound of both the Troels Gravensen and Dennis Murphy crossovers for the L100A http://audionostalgia.co.uk/jbl-l100-crossover-upgrade/. Unfortunately, the writer seems to prefer the sound of the original crossover to either of the new designs. I've owned a pair of L100As since 1973 and I certainly disagree with him. I guess, there's enough preferences in this world for everyone to have their own.
 
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A guy can easily make his own kit, since the values of all the components are listed. Just takes a few extra minutes.
 
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