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Jbl l100 and 4311 imaging (or lack thereof)

PROJECT 2501

PROJECT 2501

Active Member
For such a regarded speaker youd think they would perform excellent in soundstage and imaging. Now, if others have been able to produce a stereoscopic audio image with these speakers id like to know how they did it because ive failed to get even the slightest imaging out of them no matter the placement.
Which brings me to this question. Why did they choose to switch from the vertically aligned baffle to the offsetting formation? I could only imagine the vertically aligned speakers had much better performance in imaging like almost every other quality loudspeaker designed in that way. I am aware that other baffle arrangements can produce an imaging effect and ive managed to get a coherent stereo image from a pair of pioneer cs-66a speakers so i know the jbls driver placement isnt the sole cause of its lack of imaging...
So what gives?

They are truly well crafted speakers, some of, if not the best made speakers i own. The highest quality drivers and beautifully constructed cabinets. But completely overrated in performance in my opinion.
Its a love hate thing..
 
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PROJECT 2501 said:
For such a regarded speaker youd think they would perform excellent in soundstage and imaging. Now, if others have been able to produce a stereoscopic audio image with these speakers id like to know how they did it because ive failed to get even the slightest imaging out of them no matter the placement.
Click to expand...
The reason is JBL's simple crossover allowed the woofer and the mid-range to work without an upper frequency limit. As the frequency goes up the dispersion of drivers drops off. That 12" woofer can deliver sound at frequencies well above 500-600 Hz, but only directly on-axis. Off-axis there is little sound output. Same for the mid-range at frequencies above 2 to 2.5 kHz. These drivers beam sound in a narrow pattern. With two speakers in stereo, you get a very narrow sweet spot. I found, with my L100As, the imaging seemed a bit better at high volume. At low volumes, there was little if any.
PROJECT 2501 said:
Which brings me to this question. Why did they choose to switch from the vertically aligned baffle to the offsetting formation? I could only imagine the vertically aligned speakers had much better performance in imaging like almost every other quality loudspeaker designed in that way. I am aware that other baffle arrangements can produce an imaging effect and ive managed to get a coherent stereo image from a pair of pioneer cs-66a speakers so i know the jbls driver placement isnt the sole cause of its lack of imaging...
So what gives?
Click to expand...
In the 70s, many people kept bookshelf speakers on their sides instead of standing up. That non-vertical arrangement of the 3 drivers worked better at allowing either way of placing the cabinet. Now most people place cabinets upright so the drivers are arranged in a vertical line.

JBL chose to use a minimal crossover that allowed the woofer and mid-range to operate at frequencies too high for wide dispersion. The crossover had a single capacitor and a variable L pad for the mid-range and another set for the tweeter. They had high-pass filters, but no low pass filters that could define an upper limit. The woofer had no crossover filters at all. Wide dispersion of sound that would allow a better stereo image and sound stage apparently wasn't a major concern.

Crossover design software, as we've known it in the last 25-30 years, didn't exist then.
PROJECT 2501 said:
They are truly well crafted speakers, some of, if not the best made speakers i own. The highest quality drivers and beautifully constructed cabinets. But completely overrated in performance in my opinion.
Its a love hate thing..
Click to expand...
I experienced the same as you. In 2006, I had new crossovers designed for these speakers. They made a remarkable difference. For details, see the attached PDF file, or the below link

http://www.audioheritage.org/vbulle...05-New-crossover-design-for-L-100A&highlight=
 

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R Swerdlow said:
The reason is JBL's simple crossover allowed the woofer and the mid-range to work without an upper frequency limit. As the frequency goes up the dispersion of drivers drops off. That 12" woofer can deliver sound at frequencies well above 500-600 Hz, but only directly on-axis. Off-axis there is little sound output. Same for the mid-range at frequencies above 2 to 2.5 kHz. These drivers beam sound in a narrow pattern. With two speakers in stereo, you get a very narrow sweet spot. I found, with my L100As, the imaging seemed a bit better at high volume. At low volumes, there was little if any.
In the 70s, many people kept bookshelf speakers on their sides instead of standing up. That non-vertical arrangement of the 3 drivers worked better at allowing either way of placing the cabinet. Now most people place cabinets upright so the drivers are arranged in a vertical line.

JBL chose to use a minimal crossover that allowed the woofer and mid-range to operate at frequencies too high for wide dispersion. The crossover had a single capacitor and a variable L pad for the mid-range and another set for the tweeter. They had high-pass filters, but no low pass filters that could define an upper limit. The woofer had no crossover filters at all. Wide dispersion of sound that would allow a better stereo image and sound stage apparently wasn't a major concern.

Crossover design software, as we've known it in the last 25-30 years, didn't exist then.
I experienced the same as you. In 2006, I had new crossovers designed for these speakers. They made a remarkable difference. For details, see the attached PDF file, or the below link

http://www.audioheritage.org/vbulle...05-New-crossover-design-for-L-100A&highlight=
Click to expand...

Great info man! Thanks
 
PROJECT 2501 said:
For such a regarded speaker youd think they would perform excellent in soundstage and imaging. Now, if others have been able to produce a stereoscopic audio image with these speakers id like to know how they did it because ive failed to get even the slightest imaging out of them no matter the placement.
Which brings me to this question. Why did they choose to switch from the vertically aligned baffle to the offsetting formation? I could only imagine the vertically aligned speakers had much better performance in imaging like almost every other quality loudspeaker designed in that way. I am aware that other baffle arrangements can produce an imaging effect and ive managed to get a coherent stereo image from a pair of pioneer cs-66a speakers so i know the jbls driver placement isnt the sole cause of its lack of imaging...
So what gives?

They are truly well crafted speakers, some of, if not the best made speakers i own. The highest quality drivers and beautifully constructed cabinets. But completely overrated in performance in my opinion.
Its a love hate thing..
Click to expand...

Having owned L100s, they are IMNSHO poor at imaging. Just about any speaker is better. That said, they are well made and have the, as Zilch would say, the boom and tiz that a lot of folks seem to like. Personally, I feel it's a matter of nostalgia and not sound. On the up side, they have increased in value lately.
 
bhunter said:
Having owned L100s, they are IMNSHO poor at imaging. Just about any speaker is better. That said, they are well made and have the, as Zilch would say, the boom and tiz that a lot of folks seem to like. Personally, I feel it's a matter of nostalgia and not sound. On the up side, they have increased in value lately.
Click to expand...

The only reason I like them.. and I like them A LOT is because of the aesthetics and build quality. I love looking at them and touching them more than listening to them
 
I found that about 8 inches off the back wall, about 10" off the floor and the backs parallel to the back wall gave some image. Strangely the amp has something to do with image too, as well as source material.
 
Why would a monitor designed for near field listening be expected to image well? just wondering
 
Not too surprising ...
The L100's come from an era when the concept of imaging wasn't much talked about .. and it wasn't a design concern in many if any speakers ..
Most speakers then were wide baffle arrangements with serious diffraction issues . designing for imaging, diffraction, and time alignment evolved through the 80's ..
It was trickling around the high end in the 70's but wasn't yet a concern in mainstream speaker design ..
 
Akustic said:
Not too surprising ...
The L100's come from an era when the concept of imaging wasn't much talked about .. and it wasn't a design concern in many if any speakers ..
Most speakers then were wide baffle arrangements with serious diffraction issues . designing for imaging, diffraction, and time alignment evolved through the 80's ..
It was trickling around the high end in the 70's but wasn't yet a concern in mainstream speaker design ..
Click to expand...
Yes Infinity wanted to compete and match and better the 4311 design and succeeded remarkable with the Infinity Monitor Jr. Same size 3 way and images quite nicely enough to obtain the coveted Stereophile class C rating. I think they stated that it is like row M in the concerthall! It even has the rare transmission line loading, where the neighbors 3 houses away will complain about the bass, and you will also hear the bass.
 
backmd said:
Yes Infinity wanted to compete and match and better the 4311 design and succeeded remarkable with the Infinity Monitor Jr. Same size 3 way and images quite nicely enough to obtain the coveted Stereophile class C rating. I think they stated that it is like row M in the concerthall! It even has the rare transmission line loading, where the neighbors 3 houses away will complain about the bass, and you will also hear the bass.
Click to expand...

To my knowledge Infinity never made a true transmission line cabinet ..
They and a lot of other companies at the time were touting "Transmission loaded" systems that were basically ported boxes..
True transmission lines have a very complicated internal structure with a lot of baffles which are difficult and expensive to produce ..

I always thought that Infinity came into it's own with their EMIM & EMIT products.
That said they came out of the box competing even in the 70's ..and they succeeded.
 
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Actually can't say that I ever liked the sound of the L-100 ...

It was a notably inaccurate speaker with a boosted lower and upper bump that appealed to the rest of the college age Rock and Roll boomers .. ( I was one)..
They had a similar sized speaker that was available at the time .. L-76 maybe ?? that was to my ear a much more accurate sounding speaker ..
It was and maybe is the best Rock and Roll speaker but, in my opinion, JBL has made a lot of better speakers.

One of the things that I don't hear much about anymore is how abuse-able the L-100 was ..
You could crank that thing to ear bleed levels and it would just keep playing .. other company's tweeters were dead and gone long before ..

Maybe it should get The Party Speaker award ..
Some large percentage of the Baby Boomers must have been to at least one party where a pair was sitting there cranking ..
And some large, but incalculable number of Boomlet members were conceived under the influence of a pair playing ..
It's definitely an icon ..
 
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Akustic said:
To my knowledge Infinity never made a true transmission line cabinet ..
They and a lot of other companies at the time were touting "Transmission loaded" systems that were basically ported boxes..
True transmission lines have a very complicated internal structure with a lot of baffles which are difficult and expensive to produce ..

I always thought that Infinity came into it's own with their EMIM & EMIT products.
That said they came out of the box competing even in the 70's ..and they succeeded.
Click to expand...
Actually they were more than ported boxes. The cotton stuffing inside the long elongated port was crucial to the transmission line and without the stuffing exactly placed along with the stuffing inside the box was crucial for the transmission line execution.
 
backmd said:
Actually they were more than ported boxes. The cotton stuffing inside the long elongated port was crucial to the transmission line and without the stuffing exactly placed along with the stuffing inside the box was crucial for the transmission line execution.
Click to expand...

Yes .. but definitely less than a transmission line ..

Who was the first to come up with that long stuffing business ??
I remember that a number of speaker manufacturers were touting it for a while ..
The concept came from tuned ports .. well graduated from an open hole to tuned lengths, and then stuffing the port ..
Better than a chuffing port, but compared to Acoustic Suspension or a pair of Freid's, they still sounded like ported boxes to me.

My recollection is that Freid was manufacturing the closest thing to a real transmission line at the time and the bass lines from a pair of Freid's was delicious,
but he wasn't so good when it came to the top end .. at least that was my experience.

Transmission tuned ports ??
 
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