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Thread: Anyone tried the Troels Gravesen L112 upgraded crossovers ?

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    Senior Member andresohc's Avatar
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    Anyone tried the Troels Gravesen L112 upgraded crossovers ?

    I just read Troels Gravesen articles on modifying the L112 crossovers (http://www.troelsgravesen.dk/JBL-L112.htm), to clean up the midrange lobbing and muddling of the mids by the woofers and tweeters. I couldnt find any discussion of this on Lansing Heritage and wondered if anyone has taken the jump and how did it go? Worth the effort?

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    Well, I haven't built anything of his but I do have huge respect for Troels Gravesen and all of his efforts .

    His latest ( tip-of-the hat ) tribute to the 4345 is really quite inspired ( & very much an acknowledgement to JBL's prowess in it's 4-way designs ).

    So, with all that glowing praise I would certainly try one ( or two ) of his mods on JBL's legacy products ( if I owned any ).


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    Senior Member andresohc's Avatar
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    Great rep in DIY speaker circles

    Quote Originally Posted by Earl K View Post
    Well, I haven't built anything of his but I do have huge respect for Troels Gravesen and all of his efforts .

    His latest ( tip-of-the hat ) tribute to the 4345 is really quite inspired ( & very much an acknowledgement to JBL's prowess in it's 4-way designs ).

    So, with all that glowing praise I would certainly try one ( or two ) of his mods on JBL's legacy products ( if I owned any ).

    Yeah, his 43XX project looks delectable. In the L112 mods he basically redesigns the filters to decrease the overlap of the elements and decrease the lobes in the mids. Serious mods that no doubt cost quite a bit for new caps. He reports it sharpens up the midrange, makes it more discreet so that the imaging isnt so muddled. He also suggests building new front baffles with the elements aligned vertically. He has no love for the 044 tweeter which I have grown fond of. I grew up with JBLs on this site and was hoping to defer to the expertise here. Or maybe other suggestions a little less radical as an alternative. Maybe replacing the inductors with larger air core coils, newer midline caps etc.

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    Senior Member BMWCCA's Avatar
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    I've owned my L112s for about 37 years and have never heard anyone complain about the "defects" Troels mentions.

    I also happen to like the 044. Apparently JBL did, too, since they updated it for the 250ti.

    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."óGreg Timbers

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    Senior Member 1audiohack's Avatar
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    I noticed on Troels choices page he says over and over that functionally he cant know what you like and he wont hear the same as you will hear.

    You couldnít possibly know if you would like them more or less with his crossover networks unless you directly compared them.

    That said, I am glad you like them as is, honest.

    Barry.
    If we knew what the hell we were doing, we wouldn't call it research would we.

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    Administrator Robh3606's Avatar
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    I also happen to like the 044. Apparently JBL did, too, since they updated it for the 250ti.
    Well what condition are his in?? After how many years who knows?? They don't look right based on his measurements. Do these have a foam pad as well or did they consider the phenolic self dampening and not need one??

    Rob
    "I could be arguing in my spare time"

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    Quote Originally Posted by 1audiohack View Post
    I noticed on Troels choices page he says over and over that functionally he cant know what you like and he wont hear the same as you will hear.

    You couldnít possibly know if you would like them more or less with his crossover networks unless you directly compared them.

    That said, I am glad you like them as is, honest.

    Barry.
    True all that!

    Troels mentions that he he likes the voicing of the L112 but wanted to improve it's imaging abilities ( which he did > from his perspective ).

    If better imaging is one's goal then try his mods ( if one has the money ) or reverse engineer his efforts ( fwiw, all the necessary info is actually on that page for those who have the talent and inclination ).

    Quote Originally Posted by Rob
    Well what condition are his in?? After how many years who knows?? They don't look right based on his measurements. Do these have a foam pad as well or did they consider the phenolic self dampening and not need one??


    Troels consistently shows he has great respect for JBL's transducer designs ( he likely hasn't had enough of them pass through his fingers to create an opinion on JBL's QC abilities ) .

    He's also the first ( serious ) speaker designer to offer up some very public shout-outs for the le20 ,le25 & le26 tweeters.

    "Imaging" isn't for everyone ( & the lack of it in many of JBL's middlin home products hasn't really hurt JBL's sales in past decades ).

    I kind of doubt that GT will come here to explain JBLs' reasoning behind releasing so many speaker systems into the market with muddled imaging ( & I suspect it's a subject that many of the JBL faithful don't really want to hear ).


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    I only know Troels Gravesen based on his L100 century filters which have been very popular here in Denmark.
    Having had 4 pairs of L-100 myself, restoring and showcasing them for friends and on forums i have heard more times that i like to, that "If you want them to sound better - make the Troels Gravesen filter".
    While i do admire the filter Troels Gravesen makes and his way of working, the sound of the filters aren't for me - it takes away some of what i like about JBL. It might not be a "Theoretically correct" sound in terms of modern loudspeaker designs, and you can throw better crossover charts at me all day, but that doesn't change the fact that, in my mind, it takes away what i like about the sound. which leads me to my critique, because there is something I just simply cannot fathom in the approach:
    If you don't like the sound of your speaker - why not buy a different speaker?


    I love my JBL's for how they sound - with good and bad. There are a lot of people who love their original JBL's as well, and who has a hard time getting a pair that is still original, and in good condition.
    Instead of modding or tricking out your speaker to become something else, why not sell it to someone who wants exactly that, and look for something that kills the itch? (Or buy all the components and build a clone )

    and of course, i know it is fun to tinker, and that you don't necessarily harm any part of the speaker, trying a new crossover (As long as you take care with foilcals taking out the filter screws and keep the L-pads mounted since the new filter doesn't use them) - but still?
    I often compare vintage audio with vintage cars - it seems counter-productive to make your old mustang into a vintage jaguar

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    Quote Originally Posted by santashooter View Post
    I only know Troels Gravesen based on his L100 century filters which have been very popular here in Denmark.
    Having had 4 pairs of L-100 myself, restoring and showcasing them for friends and on forums i have heard more times that i like to, that "If you want them to sound better - make the Troels Gravesen filter".
    While i do admire the filter Troels Gravesen makes and his way of working, the sound of the filters aren't for me - it takes away some of what i like about JBL. It might not be a "Theoretically correct" sound in terms of modern loudspeaker designs, and you can throw better crossover charts at me all day, but that doesn't change the fact that, in my mind, it takes away what i like about the sound. which leads me to my critique, because there is something I just simply cannot fathom in the approach:
    If you don't like the sound of your speaker - why not buy a different speaker?


    I love my JBL's for how they sound - with good and bad. There are a lot of people who love their original JBL's as well, and who has a hard time getting a pair that is still original, and in good condition.
    Instead of modding or tricking out your speaker to become something else, why not sell it to someone who wants exactly that, and look for something that kills the itch? (Or buy all the components and build a clone )

    and of course, i know it is fun to tinker, and that you don't necessarily harm any part of the speaker, trying a new crossover (As long as you take care with foilcals taking out the filter screws and keep the L-pads mounted since the new filter doesn't use them) - but still?
    I often compare vintage audio with vintage cars - it seems counter-productive to make your old mustang into a vintage jaguar
    Those are all good points ( & I believe they are well made ).

    IME, the pursuit of imaging in my own projects can lead to sacrifices in "Tone" that are very hard to quantify ( & harder to rectify ).

    I find it does end up being a balance between the two ( when not willing to just chuck the components and look for some that are less dynamic > or smoother sounding ).

    In a nut-shell, I find that as one sharpens the image then one is also sharpening possible transient related audible annoyances that will also need some attention. It's truly a double-edged sword. So, many times it's just easier to soften the focus to retain the tone ( which I speculate JBL used to do ).

    BTW, my budds original 4310's still sound great in their original form ( with great tone et al ).


  10. #10
    Senior Member Ian Mackenzie's Avatar
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    My impression is it was a consumer sound Jbl wanted to portray at the time.
    Therefore it is (was) what it is.

    I actual recall hearing the L112’s. They were a Impressive bookshelf loudspeaker which was a popular category at the time but well above my budget.

    The competition were Avid 103’s, ESS Tempest and the like in the West Coast Sound space to name a few. I mentioned the 103’s because l ended up with the Avid 102’s which were to my taste and budget at the time.

    If today you compare an AR3 to an L100 or an L112 you will find the AR3 needs a lot more power.

    In contrast Jbl Pro was exploiting the new bi radial monitors which were a true monitor if the dates in the L112 article are correct.

    I agree with Earl in that tone wins over attempts to image. I recently heard a few live jazz sessions in Scotland and it’s about tone, instrumental clarity and vocal definition. That may sound like a line out of the 4343B brochure but that’s the real deal 15-20 feet from stage.

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    I recently heard a few live jazz sessions in Scotland and it’s about tone, instrumental clarity and vocal definition. That may sound like a line out of the 4343B brochure but that’s the real deal 15-20 feet from stage.
    Hello Ian

    Couldn't agree more, a couple weekends back had a trumpet player start playing at the back of the crowd about 30-40 ft behind me and walk up through the center of the crowd until he ended up on stage right in front of me. It was like it was a a real life surround sound demo! His trumpet cut through everything the clarity and tone was simply amazing!

    Rob
    "I could be arguing in my spare time"

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    I'm going to play a little Devil's advocate here. I think you will improve the performance of your speakers with a new set of crossovers, plus someone who knows what they're doing designed it for you. The quality of film/foil capacitors available today for audio is amazing. Check out the cap test page at Humble Hifi.
    http://www.humblehomemadehifi.com/Cap.html
    Quote Originally Posted by Ian Mackenzie View Post
    ....I agree with Earl in that tone wins over attempts to image. I recently heard a few live jazz sessions in Scotland and itís about tone, instrumental clarity and vocal definition.....
    I don't know why we'd assume a loss of tonal qualities or timbre. They are good drivers (though dated), as stated in the article. The adjustment he made to the crossover points and slopes are minimal, and the use of high quality capacitors (and possibly bypass capacitors) will likely improve the tonality of the speakers.

    In their configuration those speakers probably create a good center image but are never going to recreate a 3 dimensional vision of a live musical event. I recognize that no monitors I'm aware of, and few home speakers of that era do either, but imaging and particularly imaging specificity are critical attributes of a high quality home system, imho.

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by rusty jefferson View Post
    In their configuration those speakers probably create a good center image but are never going to recreate a 3 dimensional vision of a live musical event.
    Please help those of us without your experience and talent understand why this must be the case!
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."óGreg Timbers

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    Senior Member Ian Mackenzie's Avatar
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    Hi Rusty

    I think you misinterpreted my comments

    Taken in context of Earls second post and the reality of actually hearing live un amplified jazz the notion of imaging is not what the focus is on. It’s the tone.

    As l said in my post :

    “My impression is it was a consumer sound Jbl wanted to portray at the time.
    Therefore it is (was) what it is.”

    My post did not make specific reference to the article per say. But l support Earl’s comments in that if one takes an
    empirical approach to obtaining the right “tone” the design ideology behind approach’s to create the illusion of imaging become less important.

    If you look at Dave Wilson’s (RIP) top designs he adjusts the “X” “Y” dimensional location of individual drivers at installation relative to the listeners ears for the image properties. He also selects and or arranges custom drivers for tonal and other characteristics and carefully blends them with other drivers as a system. But you are talking about systems up to US$685,000 here.

    Other attempts to create a loudspeaker that image well may sound like a clock radio compared to a large system that can really bring the tone of musical instruments to life.

    Back to JBL we look at the 4313B that design was all about making an accurate loudspeaker and Jbl states this.

    I personally find going to an event and listening a good leveller or reality check in terms of what matters most.

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    Hey Ian,
    I get what you guys are saying. Clearly these speakers weren't made for recreating a soundstage. I think the author is probably describing better focus of the image with his adjusted crossover and that probably will have a minor tonal change. I'm just suspecting overall performance would be better with the more modern network. They are good drivers, and with modern network components would likely improve. Plus, it's a fun project. Not too expensive, and a good learning experience. Once built, the OP could experiment with different types of capacitors to voice them.

    Quote Originally Posted by Ian Mackenzie View Post
    ....Other attempts to create a loudspeaker that image well may sound like a clock radio compared to a large system that can really bring the tone of musical instruments to life....
    Agreed, and pertinent to Phil's question. The argument that the "ideal" speaker would be a point source in a sphere that's got flat response from 20hz-20khz and hangs rigidly in space. Though that speaker is unlikely to materialize in our lifetime, low diffraction speaker designs and dipole/bipole speakers for the home can do a good job creating the original event and still have good tonality. Again, speakers of this era just weren't designed with both in mind. No flames intended.

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