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Review: JBL 3 SERIES Monitors & Sub

JBL’s entry level 3 Series monitors have ridden the flagship M2 monitor’s waveguide right into the sweet spot.


21 August 2014

JBL’s development of its M2 Master Reference Monitor became like an in-house space program. Mimicking the trickledown effect of a concept car, the rest of JBL’s monitor range is slowly benefiting from the tech breakthroughs first built for its flagship; most noticeably, the waveguide.

The reverse pillow appearance of the M2’s Image Control waveguide is designed to give a sweet spot like no other. The sort of sweet spot you could park a car in, or more practically, move from rack to rack without losing the detail from either side. It’s odd to have that much freedom of movement. It feels intrinsically like you’d have to make a sacrifice somewhere else — say, precision panning — for it to work. But in practise, the imaging is precise, with the added benefit of not having to hold your head still like it’s clamped in a vice. 

The 3 Series is the first range to get the M2 touch up. They’re at the lower end of JBL’s monitor range, but you wouldn’t know by looking at them. The waveguide technology is on full display, with slight differences as the same equations are solved for different dimensions and hardware specs.

There are two monitor sizes in the range, a five-inch and an eight-inch — both two-way designs. The waveguides on the 3 Series have a rectangular form — as opposed to the square shape of the M2 — presumably to make the dispersion wider in the horizontal plane and render them more suitable to desk/console-top use. Also, the four uninterrupted surfaces of the M2’s waveguide have been broken up by central ridges on the 3 Series variation, which apparently helps the high frequencies stay on track. Undoubtedly, these monitors have the widest sweet spot of any I’ve heard, and the phantom centre, while wide, is always in the middle. Even the detented level knobs on the rear manage to give a very accurate balance between the two sides. Sometimes these are imbalanced depending on the quality of the rear volume pots, but the 3 Series had no such issues.


I had the LSR308 eight-inch, two-way monitors on review, as well as the companion LSR310S 10-inch powered sub. The 308s themselves are what you’d expect in size, but not weight. For an eight-inch monitor, they’re quite easy to handle — probably aided by the lighter-weight moulded plastic fascia. Both drivers are physically aligned, so you don’t get any odd phase discrepancies that have to be compensated for out of the box.

The 308 is biamped, with two 56W Class D amps giving plenty of oomph (112dB SPL, C-Weighted) and eliminating the need for a heat sink — which helps keep the cost down and the weight too. The 305 has a little less power, but still biamped with two 41W Class D amps.

Even without the sub, the 308s had a satisfying amount of low end. My first impressions of the speakers were that they tended to bring out the ambience in recordings more than my other monitors. I was listening back to some room Royer drum room mic recordings, and they sounded much more ambient than my Dynaudios, which seemed like a combination of good high-end detail with a wider sweet spot.

On kick drums, they had a much more instantly satisfying scooped sound, but compared to all my other speakers and headphones, they seemed to miss a bit of the low end shell resonance — it was mostly thump and click.


JBL 3 Series
Monitors & Sub

    JBL-LSR305: $249 each
    JBL-LSR308: $449 each
    JBL-LSR310S Sub: $649


    Jands: (02) 9582 0909 or info@jands.com.au

  • PROS

    • Huge sweet spot
    • Tonally consistent in the stereo field 
    • Plenty of power
    • Musical sub notes

  • CONS

    • A bit of upper-mid resonance
    • Would be nice to have a ‘sub defeat’ switch


    JBL’s 3 Series monitors have benefited from the flagship M2 reference series’ development. These two-ways may be down the price range, but get a lot of upper class tech. The sub is also a worthy addition to the range, and will be the secret sauce for some.


The ridged waveguide is obviously the looker on the front panel, but the subtle blue/white light and piano black woofer surround are nice touches that really give the 3 Series a lift.


On the rear, the 3 Series caters to both professional and recreational markets, with switchable input sensitivity between +4dBu and -10dBV; there are also XLR and ¼ -inch jack inputs; separate low frequency and high frequency trim with a range of -2dB/0/+2dB; and a detented volume knob. The port is rear facing, and has a double flange to reduce the turbulence of exiting air.


The LSR part of the model name stands for Linear Spatial Reference, which is JBL speak for ‘we take loads of measurements, from everywhere’. The purpose is to make sure you get consistent response characteristics from the speaker no matter where you’re standing in a room. Obviously it depends on how linear the response of your room is, but you’re not going to get massively inconsistent frequency spikes or drops if you happen to move across the soundstage.

And indeed, satisfying the LSR design criteria and delivering a super-wide sweet spot courtesy of the M2-inspired waveguides makes these very consistent monitors.

Tonally, there seemed to be an overall mid resonance centred around 800Hz that made things seem a little boxy at times. The frequency response is quoted as relatively flat, but if you put your finger on the front fascia you can feel minute vibrations in the plastic, which makes me wonder if it’s a mechanical effect rather than tuning preference. Again, I checked it against a number of other monitors and on a wide range of material, and it was obvious it was peculiar to the JBLs. The tonal effect was that snares lost a bit of woodiness as ringing was emphasised, and guitars were generally more present.


Adding subs to monitoring systems opens a can of worms. Control rooms and home studios aren’t often designed to handle sub frequencies very well, mainly because you have to invest a lot to adequately absorb them. That said, I fired up the LSR310S and found it to play nicely in my space. It’s not overpowering, and keeping the level dials consistent between monitors and sub seemed to be the right balance.

I’ve found other subs to be lacking in musicality; rendering little more than a badly tuned fart, or consistently the same note. The JBL was pleasantly musical, and gave that little extra extension. It’s nice to have, even just to hear if you’re in the ballpark or not.

You have three crossover settings in the sub that feed outputs to your left and right monitors: a standard crossover at 80Hz; an XLF (Extended Low Frequency) option, which boosts the output of the sub relative to the total output; and an External crossover setting, which also cuts the thru outputs to your monitors. The standard crossover was natural, but if you want to get a sensation of what your tunes are going to sound like pumped up in a club, a flick to XLF every so often wouldn’t hurt.

There’s also a 180° phase switch if you need a bit of leeway in positioning. One thing I would have loved though, would be a switch for dropping the sub in and out; allowing you to flick between sub-assisted and full-range monitor settings.

The 3 Series is a very capable entry- to mid-level monitor choice. They render detail and ambience well, and are tonally consistent across their enormous sweet spot and beyond. While you don’t need the sub — especially if you’re running the eight-inch two-way monitors — I enjoyed having that low end extension, and it is a musical addition.

These JBLs are worth considering if you’re in the market for some monitors, especially if you spend a lot of time away from a central position. Great for anyone that tracks in their control space and monitors through speakers.


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