The JBL LSR6332 monitors are the best-equipped, and at the same time the oddest, members of an old acquaintance of ours, the LSR63XX family. We know them because we had the chance to read in these pages a test Ramon Sendra did on the LSR6328P and LSR6325P, and I even reviewed the new LSR43XX series for ISP, putting the LSR4328P through its paces.
Just a reminder that LSR, or Linear Spatial Reference, is a JBL technology used to build monitors that deliver a flat response at the mixing position within a window of ±15° vertically and ±30° horizontally, and not just on the monitor’s axis.
Best equipped, at first glance, because these are 3-way passive monitors with a 12" woofer (no small thing...), a 5" midrange cone and a 1" high-frequency driver. And odd because within this family they are the only speakers that need external amplification, with everything that implies, which is no small matter. Let’s talk briefly about all of that before we analyze these cabinets.
Active vs. passive monitors
Active monitoring systems are those in which the frequency split for the different drivers is done through active filters, that is, filters that divide the signal while it is still at line level and then amplify it for each transducer. In the case of nearfield monitors, the size of all the electronics allows them to be fitted (amplifiers included) inside the cabinet, which makes them the paradigm of portability and economy of resources, since all you do is buy them, plug them in and go. These are self-powered active monitors.
It is common in mid- to high-end systems for the rear panel of a monitor like this to have switches and buttons for modifying, to a certain degree, the operating characteristics of the electronics so they suit the room. In some cases the electronics are so advanced that they include DSP, which analyzes the level and frequency response of our system at the listening position and calibrates all the monitors so that what we hear is flat and balanced (for example, JBL’s RMC, which we have described before). From all of this follow the:
Immediate advantages, namely
| The amplifiers, being built (or at least designed) by the cabinet manufacturers themselves, are perfectly matched to drive them. | |
| Since the filtering is done on the signal and not on the load, power consumption is lower and the amplifier for each transducer works only with the range of frequencies it is going to reproduce. Greater efficiency. | |
| We don’t have to set aside any space or special room to house the amplifiers, which dissipate large amounts of heat and, if the cooling is active (fans), a not inconsiderable amount of noise. We all know what saving space means in any studio and, above all, “saving” noise. | |
| We can tune the system to our room without resorting to additional electronics and in a simple way. | |
| You don’t need to know anything about impedance or power to set up an active self-powered system. In other words, it opens the doors of the home studio world to quality monitoring. This isn’t an apology for ignorance... it’s a fact. |
What is also obvious is that the size of the enclosure, which has to house the amplifiers and electronics as well as the speakers, limits the size of the components that can be used and increases their level of integration. In large systems the electronics are kept separate, in racks that are usually located in “machine” rooms. And above all, it limits the freedom to choose the amplifiers to be used. A good speaker manufacturer is not necessarily also a good manufacturer of amplifiers and/or processors.
Passive monitors are characterized by incorporating passive filters, in which the frequency split for the different drivers is done on the amplified signal, with much poorer efficiency because of the energy lost as heat in the crossovers. They are much more common in the audiophile world, among people who like to choose every component of the chain separately and who don’t like the signal to be “processed” at any point.
In detail
The LSR6332 monitors, which are designed for use between nearfield and midfield, look formidable. They are bulky, as you’d expect, given that they house three cones, one of which is nothing less than 12" (300 mm). They are heavy (20.4 kg) and very sturdy, giving the impression that they will hardly move or vibrate from the sound they themselves produce. The rubberized matte finish makes them both elegant and secure to handle. Although they have no handles, they are easy to move, since the surface is non-slip. The front carries the three drivers mentioned: a 12" (300 mm) woofer, a 5" (125 mm) midrange and a 1" (25 mm) high-frequency driver. The whole assembly is magnetically shielded so it can be placed near video monitors.
The woofer is based on JBL’s Differential Drive® technology, which, using a neodymium magnet structure and a dual-coil motor, aims to keep to a minimum the loss of power transfer between the amplifier and the speaker caused by the increase in coil resistance as temperature rises with use. On top of this it adds a third coil that acts as a dynamic brake to reduce the excess cone excursion that occurs at high levels, avoiding audible distortion. The cone is made of a graphite and polypropylene composite, supported by a soft rubber surround. The impedance, like that of the other transducers, is 4 ohms.
The midrange driver has a neodymium magnet structure with a woven Kevlar cone. The aim was to make it an especially powerful transducer to withstand the low crossover frequency it shares with the woofer, which is set at 250 Hz.
The high-frequency cone is made of a titanium composite with a ceramic material responsible for the magnet structure. It sits inside an elliptical waveguide (Elliptical Oblate Spheroidal) which, together with the chosen crossover points, ensures the directivity and spatial response of the whole system.
On the same plate as the midrange and high-frequency drivers is the bass reflex port, which has an elongated design intended to reduce turbulence and the phase and compression problems that could arise. This entire plate can be rotated 90° so the cabinets can be installed vertically or horizontally without compromising sound quality. These monitors come in right and left versions, marked with an L and an R at the end of the model number. The assembly features crossovers with impedance compensation at 250 Hz and 2,200 Hz, 4th-order (24 dB/octave) with -6 dB at the crossover point. According to the manufacturer, it covers 60 Hz to 22 kHz at +1 dB/-1.5 dB. It extends to 54 Hz at -3 dB and down to 35 Hz at -10 dB. The internal resonance frequency is 33 Hz.
On the back of the cabinet there are only the speaker cable connections, which have the particular feature of allowing bi-wiring. All this does is increase the cross-section of the cable carrying the load, and it is a nod to the high-end hi-fi world, where it is a very fashionable feature, without adding any special virtue you couldn’t get with a cable of twice the gauge. A bi-amp-capable design would have been more important, since that really does add versatility to the system. There is also a selector that lets you attenuate by 1 dB from 2.5 kHz to 20 kHz. In addition, there is a screw system for mounting the cabinets on standard stands.
Put to the test
The first thing we had to do was choose which power amp to use for the tests, so, to have some basis for comparison, we brought two CROWN models up to the studio: a Macro-Tech 602, which delivers 300 W per channel at 4 ohms, and a CE1000, which delivers 450 W at the same impedance. The manufacturer recommends using amps with output power between 150 W and 1,000 W, since the cabinets can handle 200 W continuous RMS and peaks of 800 W. Initially, because of the Macro-Tech’s superior quality, that was the amp we chose.
Once everything was set up and wired, we started testing with a pair of self-powered Dynaudioacoustic BM15A monitors as the reference (a two-way cabinet with 8" and 1" drivers). First I picked material I had recorded and mixed myself, mainly because I know it perfectly and because it was recorded and mixed on the reference monitors we use. The initial impression couldn’t have been better. The monitors delivered a clarity, definition and detail I hadn’t heard on my own monitors. It wasn’t a matter of whether they were brighter or more “midrangey”; it wasn’t about tonal color. I felt as though I had moved up to a different division. The stereo image was spectacular, and the placement of the instruments in space seemed 3-D. I’m not exaggerating when I say my head was already starting to run the numbers...
However, after a while of evaluating only that, and once the initial surprise had passed, I realized something wasn’t as it should be. The highs and upper mids were almost perfect, the low mids were very good, although at this point some of those present at the test would have preferred to attenuate them a little. But... there was little bass. You read that right: the low end was so understated that it felt like a live show when the subwoofer amps haven’t been brought up, as if very little was reaching the cabinets below 100 Hz.
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Conclusion
In the world of nearfield active monitors, where there is electronics that lets you correct the speakers’ response, adapting them to the quirks of rooms and making up for acoustic shortcomings that couldn’t be addressed for lack of means. Where there is no need to add complexity to a studio setup and you can buy off the rack. Where every euro we spend has to give us the maximum possible satisfaction as quickly as possible. In that world, passive monitors, which have no added value other than the sound they produce, simply have to be excellent. And the units I tested come close to that excellence. Only the sluggishness with which the bass began to show up keeps them from earning a higher score.