JBL Synthesis 1400 Array BG loudspeaker Measurements

Sidebar 3: Measurements

Other than the in-room and nearfield measurements, for which I used an Earthworks QTC-40, the quasi-anechoic measurements of JBL's Synthesis 1400 Array BG were all performed using DRA Labs' MLSSA system and a calibrated DPA 4006 microphone. The JBL's specified sensitivity of 89dB/2.83V/m was confirmed by my measurement. While this is not as high as with some horn-loaded designs, it is still usefully above average. In addition, the 1400 Array is an easy load for the partnering amplifier to drive, with an impedance magnitude that remains between 6 and 8 ohms over almost all the range above 200Hz, with a low electrical phase angle (fig.1). However, a minimum value of 4.8 ohms at 103Hz and a combination of 6 ohms and –52° phase angle at 71Hz will mean that the amplifier needs to be comfortable driving a 4 ohm load.

Fig.1 JBL 1400 Array, electrical impedance (solid) and phase (dashed). (2 ohms/vertical div.)

The traces in fig.1 are mainly free from the wrinkles that would suggest the presence of cabinet resonance modes. However, the woofer enclosure sounded lively when rapped with a knuckle, and performing cumulative spectral-decay tests on the output of a simple plastic-tape accelerometer fastened to the enclosure's panels revealed that the small impedance wrinkle at 180Hz was associated with a resonant mode (fig.2). However, high-level modes at 250, 313, and 400Hz were also present on all surfaces, and I would have thought these would add some congestion to sounds rich in lower-midrange energy. However, while LG was aware of these resonances—he could feel them when he rested his fingertips on the cabinet while playing the half-step–spaced toneburst track from Editor's Choice (CD, Stereophile STPH016-2)—he couldn't hear any coloration that might be laid at their feet.

Fig.2 JBL 1400 Array, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of woofer-enclosure side panel (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).

Listening to pink noise from behind the cabinet with the horn section disconnected, I could hear a slight hollowness coloring the sound. However, this came not from the lively cabinet, but from some low-level peaks in the port's output at 400 and 600Hz (fig.3, red trace). The fact that the port faces to the speaker's rear will reduce their audibility with music. The saddle centered on 29Hz in the impedance-magnitude trace indicates that the flared, 4"-diameter port is tuned to this low frequency; its output does indeed peak between 20 and 50Hz, and the minimum-motion notch in the woofer's output (fig.3, blue trace) does lie at 29Hz. (This is the frequency where the back pressure from the port resonance holds the cone stationary.) The woofer rolls off smoothly before its crossover to the horn array at the specified 750Hz. Above the crossover frequency, it rolls off steeply.

Fig.3 JBL 1400 Array, acoustic crossover on tweeter axis at 50", corrected for microphone response, with nearfield responses of woofer (blue) and port (red), plotted below 350Hz and 800Hz, respectively.

The horn array (fig.3, green trace) has an equally steep rollout below 1kHz, and its response on the tweeter axis is basically flat (with subjectively inconsequential ripples) in the region covered by the midrange horn. A sharp but very narrow suckout is evident at the upper crossover frequency of 8kHz, and above that frequency the tweeter appears to be balanced a couple of dB too high in level. Above 300Hz, fig.4 shows the 1400 Array's response on the tweeter axis at 50"; below 300Hz, it shows the complex sum (taking into account both acoustic phase and the different distances of the woofer and port from a nominal farfield microphone position) of the woofer's and port's nearfield responses. Around half of the apparent boost in the bass region is an artifact of the nearfield measurement technique, but it does appear that the 1400 Array's low frequencies are generously balanced and well extended. As LG noted, the JBL's bass shook the air in his room "and rattled loose radiator panels." A slight depression in the midrange is followed by a flat low treble and, again, a touch too much energy in the region covered by the tweeter.

Fig.4 JBL 1400 Array, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with complex sum of nearfield responses plotted below 300Hz.

Whether this top-octave boost will be heard as such will depend on the speaker's radiation pattern in the same region. The 1400 Array's horizontal dispersion, normalized to the response on the tweeter axis, is shown in fig.5. Other than some discontinuities at the top of the passband of the vertically oriented midrange horn, it is remarkably even and well controlled. It appears as if the large-diameter woofer's fairly narrow dispersion in the midrange is beautifully maintained through the lower treble by the midrange horn's own pattern. And while the speaker becomes more directional in the top octaves, its dispersion is very even with frequency, and doesn't show the usual narrowing above 20kHz. In the vertical plane (fig.6), the 1400 Array's response, again normalized to the tweeter-axis response, doesn't change over quite a wide listening window, other than the discontinuities at the top of the midrange unit's bandpass. This is just as well, given that the tweeter is a high 46" from the floor.

Fig.5 JBL 1400 Array, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.

Fig.6 JBL 1400 Array, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 15–5° above axis, reference response, differences in response 5–15° below axis.

Whether or not the JBL will sound as if it has too much high-treble energy will depend on the size of the listener's room and the absorptivity of its furnishings. LG did comment on "terrific treble extension." I performed my usual spatially averaged response in LG's room; the result is shown in fig.7. (To generate this graph, I took and averaged twenty 1/6-octave smoothed responses for each speaker individually, in a rectangular grid measuring 36" by 18" and centered on the positions of Larry's ears in his listening chair.) The broad boost in the mid- and upper bass is due both to the residual room effects and to the 1400 Array's own generous output in this region. Note also that the JBLs are generating full output down to 25Hz. But, good grief! Look at the in-room response above 200Hz: It is extraordinarily flat and even, falling within superb ±1dB limits other than a very slight boost at 2kHz. The fact that the in-room balance remains flat above 5kHz, despite the increasing absorptivity of the room furnishings, does mean that the JBL's highs will sound "airy," if not exactly "hot." Compare this graph, for example, with fig.8 in the measurements, taken in the same room, accompanying LG's review of the Revel Ultima Salon2. The Revel is close to being perfectly neutrally balanced above 5kHz, and sounds that way. But the JBL's overall achievement is still remarkable.

Fig.7 JBL 1400 Array, spatially averaged, 1/6-octave response in LG's listening room.

Fig.8 JBL 1400 Array, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).

In the time domain, the 1400 Array's step response on the tweeter axis (fig.8) indicates that all three drive-units are connected with positive acoustic polarity, and that the tweeter output arrives at the microphone half a millisecond before that of the midrange, which in turn arrives half a millisecond before that of the woofer. This is definitely not a time-coincident design, though the fact that the ear/brain does integrate arrivals over a longer period than 1ms should mean that this won't matter much. LG was impressed by the stability and accuracy of the JBLs' imaging, which you'd think might be adversely affected by the lack of time coincidence. But as far as the lower-frequency units are concerned, the 1400 Array's step response is at least time-coherent, in that the overshoot of the midrange unit's step smoothly leads into the woofer's step. This suggests an optimal crossover implementation.

Finally, the JBL 1400 Array's cumulative spectral-decay plot (fig.9) is not as clean as I would have liked to see, presumably due to reflections of the driver outputs from the edges of the horns. Nevertheless, LG found the JBL's treble to sound smooth and grain-free.

Fig.9 JBL 1400 Array, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).

I have been a fan of the 1400 Array's designer, Greg Timbers, ever since I met him and listened to prototypes of his JBL 250 on a visit to the company's Northridge, CA, factory in 1981. (Sadly, as I wrote these words, it was announced that while research and design will remain in Southern California, the manufacture of JBL and other Harman Group loudspeakers will move to the company's maquiladora factory in Mexico.) So while I'm suspicious of horn-loaded designs, I'm not surprised that the Synthesis 1400 Array BG offers both superb speaker engineering and superb measured performance. I keep returning to that remarkably flat and even in-room response: Good grief!—John Atkinson

JBL Consumer Products
1718 W. Mishawaka Road
Elkhart, IN 46517
(516) 594-0300

Jimmy_G's picture

It would be interesting to compare how much of Project Array's magic that Mr. Timbers was able to distil into his curious Studio 5 series as both designs feature large bi-radial horns and trapezoidal cabinets.  

Full disclosure, my own curiosity got the better of me last January and I purchased the 530s for my smaller 2 channel system and I haven't found reason to take them out yet. I figured that anyone implementing a compression driver mated to a horn, and sensitivity isn't the goal, has a design that certainly warrants a listen.  

I haven't had the opportunity to listen to any of the Synthesis Project systems yet so I've always been left wondering.  

Brodie_McChoad's picture

This is a little late, but since your comment was also way after the 1400 array review, I figured I'd leave this here for posterity.

I recently had a set of long-term Studio 590s, the largest in the Studio series. I also recently acquired a pair of the US-made Project Array 1400s which I have connected in the same system that once powered the Studio 590s.

I can tell you that there are similarities and of course differences. JBL has made so many different horn loaded loudspeakers and compression driver units over the recent years and not all of them were designed by Timbers and Moro. For example the Synthesis LS40/60/80s were designed by a different team and IMHO they were inferior to the Timbers/Moro designs. Of course I'm sure that some members of the engineering teams were shared among these projects, but I'm going off of what I've been told and what I've read at places like Lansing Heritage. In any case, onto the similarities:

The Studio 5xx series, having the 1" compression driver in the bi-radial horn performs very well on voices - specifically female voices, with a great sense of presence and holographic imaging whereby the voice seems to be in the room with you. Also, on the larger 5xx series, namely the 580 and 590, the bass is strong but controlled - as is the case with the Array 1400s. Without taking room acoustics or OCD placement issues into account, the bass can be felt in the chest sitting directly in front of the speakers, no matter how far they are away from a wall. There is also the same upper high end "sparkle" or "sizzle" in the Studio 5xx speakers as there is in the Project Arrays. This was NOT the case with the Synthesis LSxx previously mentioned. They sounded veiled. Also, as with the Arrays, the 580s/590s seem to be able to accept an unlimited amount of clean amplifier power. There is almost zero compression in any frequency range at extremely high listening volumes - for example voices and higher range percussion instruments sound as pronounced and airy, but louder, as they do at lower volumes. The Arrays obviously have greater extension and air, however - and are less fatiguing, even though the Studio series is far from fatiguing even during long listening sessions.

The differences/drawbacks of the Studio 5xx compared to the Project array are largely in the compression drivers and crossovers. The Arrays are just so relaxed, natural and capable across the entire midrange - treble frequency band. The 590s were pretty good, but this is another level. Also, the Arrays image much better and have a much deeper soundstage with greater separation and precision of individual instruments - at all volumes. Bass is very similar, due to the similar surface area comprised by the two systems' woofers, but the Arrays, with the 14" professional grade woofer, simply move more air more efficiently. I should note that the driver quality on the 590s is very good, almost professional actually. The magnets, voicecoils and baskets are substantial, and the 590s are about 3dB more efficient than the Array 1400s, so the differences in bass are not that noticeable in most listening rooms and moderate volumes.

However, the Studio 580s/590s are constructed of thinner MDF and as a result, the cabinets are susceptible to more vibration/coloration. Given the size of the 590s, though, it's a VERY slight difference and once again very difficult to make out on most material.

Finally, the perceived weaknesses of each speaker: lower midrange performance. In some respects the 590s had a more satisfying tone, where the 1400 Arrays are more neutral and natural. But it's like there's a slight chunk of the spectrum missing in both speakers, moreso with the Array 1400s. It's hardly perceivable. In fact, in general, as the price difference would obviously indicate, the build quality in the Studio line is much lower than in the near-flagship Project Arrays. The Studio series build quality - thickness of materials, finish, etc. - may not matter as much on smaller units like the Studio 530s, but when you have a set of speakers the size of the 590s in your living room, they better look damn good or they'd be better suited to a teenager's garage apartment or fraternity house dancefloor.

Interestingly enough, the rumor from inside has it that Timbers was working on a successor series to the Studio 5 line before he was laid off. The Studio 5xx series is a damn fine approximation to the class-leading sound of the Project Arrays, which themselves are a very nice approximation to the Project Everests (I have not heard the K2). Then there's price - including on the used market. IF I'm looking at spending about $1-2K on a set of floorstanders and I am a fan of the JBL sound or compression drivers, then I strongly consider the 580s/590s over JBL products like the LS60/80 or even the s3900s and s4700s, which will set you back at least $3K more per pair - used. You get most of the best parts of the high-end JBL sound in the Studio 5xx series, and the Project Array/K2/Everest, IMHO, represents the only logical step up (not considering the actual "home studio monitor" line of the 4365/4367 etc.) from the Studio 5xx series. I just don't think you're getting your money's worth "upgrading" from the Timbers/Moro designed Studio 5xx speakers to the other synthesis products that aren't the "Project _____" or studio monitor series.

Hope this helps, even if it's a bit behind. I love the sound of both the 590s and the Array 1400s, and both have that "it" factor with the upper sizzle and lower kick that gets you tapping your foot and occasionally gives you goosebumps. The same CANNOT be said for the other synthesis speakers I've heard.

Reciprocal's picture

You have accurately described the legacy JBL Sound, speaker colorations, uneven frequency response, speaker resonances. The new JBL is the sound of a speaker with no "it factor," no sound of its own, no special upper sizzle nor lower kick. Dr. Floyd Toole's research has proven in double blind listening that speakers targeting flat, even response, spatially, temporally and time aligned, according to the JBL anechoic testing rather than by a designer or committee, and confirmed with consistent wins in double blind listening, hence Revel Salon, JBL M2, 708P/I. The LS80 Synthesis designed by Charles Sprinkle, credited by Dr. Floyd Toole as one of the architects of the M2, is designed with modern criteria, that the best speaker has no inherent sound signature of it's own, no "it factor." It contains the more powerful 176ND two inch pure titanium diamond patterned diaphragm compression driver with neodymium motor and ferrofluid-cooled rectangular edge wound aluminum voice coil that operates beyond its resonance limit yet does not launch into your awareness with any kind of "sizzle" not present in the source. The other drivers are similarly spec'd of higher quality than Studio 590 series including the crossover network, drivers and cabinet; speaker weighs 85 lbs compared to 32 lbs for Studio 590 which is actually quite larger.

So don't let your bias drive luddite rhetoric. In professional reviews, the LS80 have been acclaimed subjectively and tested well objectively. If you were able to properly audition in JBL's spin-o-rama double blind listening chamber, automated random shuffling among speakers with neither you nor the tester knowing what's playing, it's been proven that neutral speakers win the challenge. Few get that opportunity, not you and not the Lansing Heritage Forum group either. I know, I was one of the luddites amply endowed with enough JBL sparkle and kick to punt the 590's out of the end zone. The Modern JBL speaker doesn't have the nostalgia of the old butt kickers but they are better because the sound you get doesn't include speaker colorations. Win for Floyd Toole and Charles Sprinkle, as well recording engineers, studio mixers and masters, live pro sound, commercial and home theatre, and audiophile enthusiasts.

Brodie_McChoad's picture

But Greg Timbers and Jerry Moro designed the Studio 590 (and its drivers) and the former is on record stating that the speakers were "something special"....in fact it is rumored that they were working on a successor "Studio" series at the time that Harman was acquired by Samsung and their division was moved to New York.

The LS line is in no way comparable to the M2 monitor which costs well over $10K/pair and requires bi-amplification and/or extensive in-room equalization to sound as intended. What I didn't mention in my previous review is that I also have a pair of Project Array 1400s and access to a pair of Project Everest 6700s which I have also compared to the 590s and LS60s. I can tell you that the Arrays and Eversests have more in common with the sound profile of the Studio 590 than they do with the LS series. I have no idea why but it's true. And the frequency response of the 590 is very flat, actually. See the test results here:


It is not correct to refer to one driver as "more powerful" than another. Of course the lower of the two high frequency drivers has a larger diaphragm than the single compression driver found on the Studio 5XX line, but the "super tweeter" simply cannot keep up and does not project the frequencies above 11kHz into the room adequately. All magnets are neodymium now (unless they are AlNiCo in the older JBLs) and the titanium diaphragm is not inherently superior to the "Teonex" film used in the 590's compression driver, in fact titanium breaks up much sooner than aluminum if I remember correctly. All have ferrofluid as well. So the driver technology and construction in the LS80's lower tweeter is not inherently different from or superior to the compression driver in the 590. That's right I said "lower" as the LS80 actually uses a small polyester film driver for the true high frequency reproduction. It's not very good at its job.

There is no need to pretend you're some kind of audio genius if you enjoy the sound of the LS60/LS80, but my ears and the ears of numerous other comments thread participants do not lie. The LS60/80 is a good speaker for tamer music like classical but it cannot reach the dynamic heights of the Studio 5XX series. I don't think you know what the term "luddite" means, so please think twice about using it in the future.

https://www.whathifi.com/jbl/studio-580/review (same speaker, but smaller)

There are plenty of reviews to back me up. Timbers himself has stated that the driver quality in the Studio 5XX was top notch and that they should last a very long time. The only area where the LS60/80 is superior is in cabinet construction. But this was a mass market speaker as well, sold primarily in Japan and Europe and available in the U.S. on clearance for about $300/pair (yes, that's the LS80 - do some research and you'll see I'm correct). Again, though, I trust my EARS and 40 years of listening to high fidelity audio systems over the



In Post #86 Greg Timbers replies to a question about the Studio 5XX series:

"Other than being a face only a Mother could love, the Studio series is really great sounding stuff. The little compression driver is amazing and Jerry Moro did a great job on the woofers. We had them made in China, but the supplier implemented Jerry's design. We had a jerk for an Industrial Designer at the time and his taste was all in his mouth. I did what I could to salvage the acoustics of the design and fortunately, they work as well as stuff costing 2 or 3 times the money. The fit and finish isn't so great but buy them for the sound. They use really good components so they should last a very long time."

You said: "...speaker weighs 85 lbs compared to 32 lbs for Studio 590 which is actually quite larger."
Wrong. The 590 is bigger than the LS80 and it weighs approximately 70 lbs compared to about 84lbs for the LS80. There is not a substantial difference in the dimensions or weight.

You also said: "So don't let your bias drive luddite rhetoric. In professional reviews, the LS80 have been acclaimed subjectively and tested well objectively."

OK, then please back that up with some examples of professional reviews of the LS60 or LS80. I would love to see some links.

P.S. I also think you're not being truthful in your claim that you've been able to audition the 590s vs. the LS series in a blind anechoic chamber. LOL you're full of it. The LS60/LS80 is just not a very "fun" speaker to listen to. The high end is veiled and it does not convey energy into the listening room as effectively as the Studio 580/590 from my own personal and other peoples' anecdotal experience in the real world - which is what matters. Again, please stop using the word luddite if you don't understand its meaning.

Finally, you neglected to discuss the Array 1400s I mentioned. What do you make of the fact that the 1400s have more in common with the sound of the 590s than they do with the LS80? I think we can agree that the Project Array 1400 uses superior drivers to both, can we not?

Brodie_McChoad's picture

Or that they were unreasonably "hot" in the treble region. But they are a better rock'n roll and jazz speaker than the LS60/80 is. I use the words "sparkle" and "sizzle" only to describe program material that I already KNOW has a pronounced treble band - cymbals, air, bells, etc. The Studio 590 and the Array 1400s both sound better on that music than the LS80.

Also please note, as I mentioned above, the LS series makes use of the compression driver more as a midrange than a tweeter with a small polyester film diaphragm being responsible for the high end. I found that this driver was not capable of projecting the treble into the room either on- or off-axis as effectively as the compression drivers in the 590 or Array 1400s. You conveniently neglected to mention that particular driver, which I am almost positive is not of the same quality as the compression driver in the 590 and is not used in any other JBL high end speaker systems that I can think of.

P.S. Floyd Toole worked with Greg Timbers and Jerry Moro it appears. I wonder if he'd agree with you.