View Full Version : L100A brilliance and presence setting help

01-31-2005, 08:10 AM
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 :rockon1:

01-31-2005, 10:11 AM
"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....

Don C
01-31-2005, 10:15 AM
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.

01-31-2005, 11:43 AM
Thanks for the suggestions - sounds logical. Wonder why they changed the scale on my "lates" - anybody have some info on this story ?

Harvey Gerst
01-31-2005, 12:00 PM
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.

02-01-2005, 03:12 PM
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. :)

02-01-2005, 04:22 PM
But does it have the 0 to 10 scale ? There are no such marking on mine - just the scale from 0 to 10.:blink:

Harvey Gerst
02-01-2005, 06:41 PM
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.

02-01-2005, 07:07 PM
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.


02-02-2005, 03:59 PM
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.

02-02-2005, 09:07 PM
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...


02-03-2005, 03:32 AM
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.

02-03-2005, 04:22 AM
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.

02-03-2005, 06:48 AM
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"

02-03-2005, 10:17 AM
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 L100s. My serial number starts with 29, yours with 23 so a long time in production between the two speakers.

Don C
02-03-2005, 10:25 AM
JBL reserves the right to change specifications without notice. Your foilcal looks the same as the ones on the raffle speakers. There was an even later version that had the 123A-3 woofer.

02-03-2005, 10:40 AM
How can I verify which woofer I have without opening the cabinet ? I thaught I had the 123A-3 woofer :blink:

02-04-2005, 01:47 AM
Hello Viking, I think you have to take out the woofer to see which model you have... but i am akmost sure that you have the "123A-3" woofer...



02-04-2005, 02:41 PM
Was about to take some close up pictures of the speaker and inside, when my semi-new Powershot A40 refuse to work :banghead:, ask for new batteries all the time, cant even take pictures with USB connected - a HW or SW problem, better dump it south. So did order a Casio Z55, expected arrival during nex week :bouncy:

Seems the whole world gets digitized and equipment work or dosnt work, and you cant repair it. Former Mercedes E class had plenty of electrical problems too - fault in material used for the cabling, software and computer problems - seats begins to move without asking for it - sprinklers puts whater on the windscreen when not commanded - gearshift randomly - in the old days you could repair the stuff your self - now you have to return the whole product back to the manufaturer and wait and hope.

Glad to receive a pair of L100 close to 30 years old, and still working. If something breaks I can repair it my self.

Bill H.
02-04-2005, 03:21 PM
Bought one 3 months ago, neat but you still get no instruction manual!!!!!!

Mr. Widget
02-06-2005, 02:14 AM
You L100 fans might get a kick out of this. It shows a response plot of one of my L100 Centuries. Take a look at post #3.



02-18-2005, 11:14 AM
Hello all, Im back. Finaly got the new camera to take some pictures - changed my mind so got the casio S100 instead.

Here is a photo of the front panel so you can see the controls. I did promise to take some pictures of the inside - this has to wait a few weeks I take the family to Havana on Tuesady.

Quality is quite OK for such a small camera.

02-18-2005, 11:21 AM
Bought one 3 months ago, neat but you still get no instruction manual!!!!!!

Changed my mind and got the S100 instead - ver very slim, takes good pictures too if you give it the light it needs.

Manual is on CD ROM and huge so thats why its only on CD, it would fill more than the full camera packing if on paper. I suppose this is the way manuals will be in the future, we better get used to it.

02-20-2005, 07:48 AM
Wish I could take as good close-up pics!!!:banghead:

My Olympus D-370 doesn't do good on close-ups!

02-20-2005, 09:13 AM
Even in macro mode?

02-20-2005, 10:18 AM
My Olympus D-370 doesn't do good on close-ups!Out of curiosity, I just checked. The D-370 does have a macro function allowing for sharp focus from 9.84 - 23.62 in. Not the closest, but better than none. Check the instruction manual for how to turn the macro function on and you should be able to get pretty good closeups, at least down to about 10".


02-20-2005, 12:12 PM


Now if I cood figger out this hosting/posting stuff...doh! :homer:

Me and compuketers are...


02-20-2005, 04:37 PM
I have the same foilcal on my L100A as in Vikings photo. Woofer is 123A-3. I still have the Instruction manual that came with the speakers.

I Quote "The controls are calibrated in terms of a laboratory standard reference level, indicated by a "5" on the instruction plate. When both the Presence and Brilliance controls are set at this level, the loudspeaker system will be adjusted for balanced performance characteristics in a reverberation-free environment. Since most listening rooms possess varying degrees of high frequency absorption and reflection, some adjustment of the controls is usually preferred."

The manual then goes on to explain how to arrive at specific settings. If anyone wants more I'll try to get the manual scaned.

02-20-2005, 05:06 PM
It would be nice to get the L100A Owner's Manual

Here's one version -


12-11-2007, 01:24 AM
My L100 Century's are moving to a new place in the house, specifically on some built in book shelves. Is there any harm laying them on their side so the Woofer, tweeter are about ear level. Esthetically speaking they would look better, But I would sacrifice if it meant keeping the awesome sound intact. The lowest shelf/top of lower cabinet is about ear level The whole wall is about 18 feet wide, built ins to the ceiling split by a fireplace. What would the maximum lateral spacing be. Any suggestions would be appreciated

12-11-2007, 07:18 AM
I trust you realize how old this thread is?!

Judging from the foilcal on the later L100, sideways is preferred on a shelf. That's the typical position for the 4412A monitors, too, which are similar in layout and size, and intended for shelf mount. Outboard or inboard placement of the tweeters will depend on room size and separation distance.

Mr. Widget
12-11-2007, 10:15 AM
My L100 Century's are moving to a new place in the house, specifically on some built in book shelves. Is there any harm laying them on their side so the Woofer, tweeter are about ear level.Harm?

They will certainly sound different. You might like them even better or you might be disappointed. There is only one way to find out.

This type of placement was certainly anticipated by the designers as it was the preferred look back in the '70s, that said I don't think they were particularly optimized for either horizontal or vertical placement, or free standing vs. stuck in a cabinet.