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Thread: L100A brilliance and presence setting help

  1. #1
    Junior Member Viking's Avatar
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    L100A brilliance and presence setting help

    I used to have the L25 Prima way back - but was a fool to sell them when I had to move. 1 month ago I descided to get a second hand pair of the L25 since I kinda lost my interest in music and missed the good old JBL sound, but changed my mind when I red about the L100.

    Found a mint pair of L100A serial 294624 A and 298221 A, I think they are L100A "late" ?? Paid 500 USD less shipment.

    Now - how do I set the PRESENCE and BRILLIANCE settings to neutral ? Scale is from 0 to 10 on both - on all other L100 models I have seen the scale is from -5 to +5.

    By the way, they sound realy great and better than the L25 - my good old records are ALIVE again
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  2. #2
    RIP 2011 Zilch's Avatar
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    Tweak to taste:

    "Presence" is your mid-range control. "Brilliance" is the high frequency (tweeter) control. Tweak as desired to achieve the sound you like in your listening environment.

    Start with them both in the middle, perhaps, and adjust from there by listening. There's no way to ascertain "flat" without instrumentation to measure it....

  3. #3
    Senior Member Don C's Avatar
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    I think that JBL intended for them to be set in the center, which ends up with both dots at the left. I prefer to turn down the midrange a bit from there though. The early version had laboratory standard positions marked, but I dont think that the response was any flatter with those settings. I'd suggest to trust your ears, and set them to the position that sounds best to you.

  4. #4
    Junior Member Viking's Avatar
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    Thanks for the suggestions - sounds logical. Wonder why they changed the scale on my "lates" - anybody have some info on this story ?

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    According to George Augspurger, the mid control should be set to around 4, and the high control to about 7 for flat response, if I remember correctly.

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    I have a relatively early pair of L100a - and the "owner's manual" for same. The manual simply states that you should set the brilliance and presence controls to the "laboritory standard" (marked on the foil plate)and adjust from there to suit your listening environment. The manual even makes mention of the "clap test" which just goes to show that standard approaches to testing accoustics haven't changed much in 30 years. However, I agree with Don C that flat is probably as he suggests. I think that the settings he mentions were those specified for the 4310.
    I don't think there is a manual for the L100a anywhere on the Heritage site. I will submit one in the next week or so - can't do earlier as I am presently working away from home - then you can havea a look for yourself.

  7. #7
    Junior Member Viking's Avatar
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    But does it have the 0 to 10 scale ? There are no such marking on mine - just the scale from 0 to 10.

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    All I can tell you is what George Augspurger told me - and he designed the L100 crossover. He mentioned a method of setting the levels by ear which I thought was interesting:

    You can do this with pink noise, or music, as a signal source.

    With you seated in your normal listening position (and another person standing next to the speaker), start with both level controls turned fully off. Have the person start bringing up the mid control very slowly. At the point you hear the sound "change", tell the person to stop, and repeat the procedure with the treble control. Again, at the point you hear the sound "change", tell the person to stop. The system should now be set up pretty close to flat.

  9. #9
    Dang. Amateur speakerdave's Avatar
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    Or start with both controls turned down, source turned to FM, interstation noise, volume level set fairly low. Listening close to the speaker adjust the mid control until the sound seems to come from a point halfway between the woofer and the mid. Do the same thing with the mid and tweeter. Note the position of the controls and let this be your reference point. Do the other speaker.

    David

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    the scale 1-10

    Hi Viking
    Sorry - I don't have either the boxes or the book in front of me right now, and I cannot find any illustration on E-Bay that is good enough for me to advise you - but I think mine have a "reference" setting at the 12 o'clock position with +/- sttings either side of that. I'll have a look in about 12 hours time (don't know what the real time is in your part of the world, but it's sure to vary from Sydney Australia) and post something more then.
    Sorry - but some of the other posts will probably help you more than I can anyway!!
    Geoff S.

  11. #11
    Senior Member GordonW's Avatar
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    I tend to not like "brightness"... so the pet position I find for most L100A controls, is between 3 and 4 for the midrange, and between 5 and 6 for the tweeter. Seems to balance them right out.

    Of course, this is with the speaker ON A STAND (usually about 15" tall). If they're on the floor, the higher position recommended by Augspurger makes sense. The floor will reinforce the bass and midbass, and the mids and highs would need to be increased to compensate. But, I find, that the best balance of everything occurs on a 15" stand, with the above settings... it reduces the "boom" at 60-70 Hz, and results in a surprisingly neutral speaker...

    Regards,
    Gordon.

  12. #12
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    L100 Instruction Manual

    Hi Viking
    Attached as promised are two quick and dirty scans from the orignial JBL manual. I will submit the whole thing for upload in a week or so - don't have time just now, but maybe this will be interesting reading...if the whole upload thingo works. If not, I'll just have to get my act together and submit...
    Geoff S.

  13. #13
    Junior Member Viking's Avatar
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    Hello again

    Thank you for all the good advises and the enthusiasm. I did try a combination of both. For the mid I start to hear a change in the sound image at 2, at 3 the sound comes equally from the woofer and the mid. The tweeter is a little bit more difficult to adjust by ear - but I find that 3 is a good level. The setting now is at 3 and 3, which is what the speakers was set at when I got them a couple of weeks ago, and what I feel sound right to my ears.

    I will try to find a local audiophile with the right gear to come and take a look at my speakers, to see how far my ears are from the theoretical flat responce.

    They stand so far on top of the old speakers ( 48cm high ) till I find the right position. Placement is very critical so will experiment with this. However - they are really really good speakers, small adjustments to get it perfect is just part of the fun - they sound great in almost any position.

    Will go more close into the configuration when I have changed my amplifier, since the chain is no stronger than the weakest link. I use a Technics SU-610, specs. looks fine but I have the feeling that they drag the L100 down and that the settings could depend very much on the amplifier too, so will look for a more suitable amplifier.

    Any suggestions of a classic good quality amp for my speakers, should be soutable for a pair of L150A too, since my next project will be to add L150A to my collection. Output for speaker set A and B is a must. Thinking to find an old MARANTZ ?

    20 years ago with my JBL L25 I had a JBL Lansing pre-amplifier, the one with square white plastic buttons with build in light, and a alu. square pot as volume. As a fool I sold it, also used a JBL Lansing small amplifier, but it was not mine.


    I will keep you updated in the process.

  14. #14
    Member droh's Avatar
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    For what it's worth...

    At this point I think the good advice has already been dispensed asabout how to set the controls regardless of what the decals may reveal. But in case it's useful I'm posting pics of two different models that i have. I think these would be considered an L100A and an L100 Late? Anyway, they both have scales with a zero in the center and an indication of "Laboratory Standard"
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  15. #15
    Junior Member Viking's Avatar
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    So mine should then be "very late" version of the L100. Please check the large picture in my first post.

    Anybody know the story about the scales I have ? They are very different from all the former L100īs. My serial number starts with 29, yours with 23 so a long time in production between the two speakers.

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