Review: JBL 4309 2-way Bookshelf Loudspeaker

Review: I like the JBL 4309 because of their shape and design. Although they don't play 100% neutral tonally, they sound complete

Retro hi-fi isn’t just limited to the use of tubes and room-filling horns. Some other loudspeakers – such as some models from JBL Synthesis – also bring back memories of the “golden age of hi-fi”. The youngest member of the Studio Monitors series, the JBL 4309 (2,000 euros/pair), also plays with the image of the good old days.

Mainly because of the walnut veneer supplied for the test (the 4309 is alternatively available with a black veneer), the baffle painted matt blue and the basic shape of the boxes in the wider-than-deep shoebox format, I almost feel like I’ve been transported back to the 1970s. Not that I actively remember that decade, but that’s pretty much how I imagine my hypothetical front end if I’d had hair on my chest back then. With the 4309, the designers at JBL obviously didn’t follow the call for a “slender foot”, and that’s a good thing – full broadside against the rumored beautiful living zeitgeist. This design is also very well suited for installation close to a wall, as it does not protrude so far into the room. JBL has thought along accordingly and placed the computer-optimized outlet openings of the bass reflex tubes – of which each 4309 has two pieces – on the front under the bass-midrange driver. Whether and how well this works in practice, we will hear and find out later.

Die JBL 4309 besitzt zwei Bassreflexöffnungen

Speaker enclosure

The JBL-4309 case features 18mm thick walls and is internally braced. That should be enough to keep resonances in check. After all, loud-speakers of this size class are not usually subject to brute force. At just under eleven kilograms, the JBL 4309 can still be carried and placed easily. The underside of the housing has an additional, one-centimetre-thick plastic plate that effectively prevents scratches in the veneer, but according to JBL it has no acoustic function.

Kunststoffplatte auf der Unterseite der JBL 4309

The blue baffle on the walnut version is protected from prying fingers and eyes by a dark blue fabric-on-plastic frame cover. The black veneered model comes with a black cover. You won’t find any magnetic holders, they’re plugged in the old-fashioned way. The corresponding plugs are made of plastic, but seem quite stable.

Two pairs of gold-plated binding posts per box are used to connect the speaker cables. If you have single-wiring cables, you will find the standard gold-plated bridges in the terminal – my tip, however, is to replace these with short pieces of cable or terminated cable bridges.

Bi-Wiring-Terminal der JBL 4309

Sound projector – the tweeter horn

The horizontally wide emitting tweeter horn is also not exactly the latest hi-fi optics standard, but a trademark of JBL loudspeakers and another reminiscence of the sixties and seventies of the last century. A small rotary control sits shamelessly underneath, with which the (super) high-frequency behavior can be influenced from 7000 Hertz with +/- 1 decibel in half-decibel steps. This does not correspond to the pure teaching of audiophile conservatism, but for many practical applications it is most likely more of an advantage than that the additional components and contacts do great harm.

The tweeter itself is a patented 25 mm compression driver with the unromantic designation “2410H-2”, which plays from a very low 1600 to a breezy 30000 Hertz (at -6 dB). It has a ring-shaped polymer membrane, which according to JBL is particularly light. The very stiff, V-shaped geometry of the annular membrane reduces distortion and standing waves in the membrane and eliminates phase errors, and dynamic compression is to be avoided at very high levels. Spoiler alert: This works great.

Das „High-Definition Imaging“-Hochtonhorn (HDI) der JBL 4309

According to JBL, the upstream horn is also patented under the name “High-Definition Imaging” (HDI). According to JBL, the HDI horn geometry should ensure more even radiation in the room – at angles of 100 degrees horizontally and 80 degrees vertically, the frequency response between 2 and 17 kilohertz would remain within a range of -6 decibels, based on the maximum level in this frequency band. By the way, anyone who reads horn and thinks high efficiency is wrong. JBL only states an average of 87 dB/2.83V/m for the 4309; converted to the nominal impedance of 4 ohms, the characteristic sound pressure is 84 dB.

Pulp Nonfiction – the low-midrange speaker

In addition to this extroverted construct, the 16.5 centimeter low-midrange driver seems almost homely at first glance. It takes the signal from the tweeter with an acoustic slope steepness of a full 24 dB/octave, which in turn is limited downwards with an even steeper 36 dB/octave. Speaking of the crossover – JBL claims to have donated high-quality components to it: Air-core coils, wire-wound resistors and metalized film capacitors are intended to carry out the signal split as smoothly as possible.

Die Membran des 6,5-Zoll-Tiefmitteltöners der JBL 4309

The basket of the driver is made of cast iron, and JBL calls the membrane very fancy “Pure Pulp Cone”. The cone consists of pure cellulose, also known as: paper. I really like paper cones and have been disappointed more often than enthusiastic by other cone materials, especially polypropylene, especially in the midrange. Of course, as always, there are exceptions to the rule, but I think I can say that the voices and overtones of string and wind instruments with good cardboard usually seem most natural to me.

Be that as it may, according to JBL, the engineers attached great importance to distortion-free reproduction at high levels with the woofer, which is why they gave it some of the tried-and-tested JBL technologies: a long-excursion voice coil, a drive with a particularly symmetrical magnetic field, a stabilization ring for an even magnetic flux and a copper short-circuit ring should contribute to the achievement of the goal. The light, stiff membrane of the Pure Pulp cone with its multiple concentric ridges is also intended to prevent partial vibrations and ensure a piston-like movement. But enough of the theory. Let’s let the little beasts off the leash.

JBL 4309: sound test and comparisons

In my listening room, the JBL Synthesis 4309 find their place on the solid steel SS6 stands at almost exactly the recommended height of just over 60 centimeters and a base distance of exactly 2 meters. The attempt to place the speakers as close as possible to the rear wall fails: with just under 10 centimeters of air in the back, the bass doesn’t sound too fat, but it is unround and unbalanced. At a distance of 30 centimeters, we come to a warm-green range in terms of tonality. But it is only at almost 50 centimeters that the powerful upper bass is joined by an elastically resilient, audible low bass.

JBL 4309 im Hörraum

Punchy bass

The full-bodied characteristics with a bass that is surprisingly powerful, substantial and physically perceptible at high volumes for the size is not entirely unexpected. But I am surprised by the quality of the implementation: I did not expect the JBL 4309 to play so precisely, dryly and agilely in the bass. Ironically, with the intro to the TV series Seinfeld – dominated by a funky slap bass that grooves very fast pitch slides – I also noticed that the JBL reproduce the bass range exceptionally “tunefully”. With the JBL 4309, every beat of the thumb is reproduced precisely and “in time” by the bass and tweeter on the eardrums, I have rarely been able to understand the tone sequences of the bass so simply and clearly – not even with the very disciplined ones Sehring M801 (2,000 euros). The Berlin cubes play a little more tonally neutral in the bass – in the upper bass and fundamental tone, the JBL 4309, depending on the setup, are sometimes more, sometimes less, more muscular or fuller. For example, they give Tools ‘ unbelievable epic “Invincible” (album: Fear Inoculum) a comparably punchy … no, downright lustful drive in the bass. Please keep this thought in the back of your mind for a moment, I will come back to it later.

The lower end of the frequency range that the JBL 4309 transmit is also significantly lower than one would expect given their physique. Okay, the deep bass rumbling in the sofa doesn’t really come from the two 16s and the four bass reflex tubes , but acoustically I hardly miss anything.

Likeable figure – fundamental and middle tone

The JBL 4309 don’t really play hyper-neutral in the fundamental and midrange either, but that’s okay. Kurt Wagner sounds great in Who Can Resist from Rodrigo Leão ‘s phenomenal album A Estranha Beleza da Vida a little fuller than the Sehring M801 or the ATC SCM11 (1,900 euros). The Brits from ATC also reveal the upper midrange slightly more transparently, while the Sehring M800 remain more factual and neutral overall – the JBL, on the other hand, appear sympathetically jovial, less academic, even if this word doesn’t really apply to either the ATC or the Sehring. Perhaps this is partly due to the fact that neither one nor the other box is able to keep up with the dynamic weightlessness, looseness and the effortless start of the 4309 in the vocal range – even starting from very high basic volumes. If you value clean maximum dynamics in the mids, the JBL 4309 is the best choice – and the best in this three-pack.

However, the orientation of the loudspeakers towards the listening position is important for the tonality of the JBL. Because even if the tweeter radiates broadly and evenly, the mids – most of which fall within the working range of the woofer – can be more strongly influenced by the angle. That means: If the JBL are angled too much, the tonality changes and a subtle restraint in the mid-midrange may push the very slight fullness of the lower midrange a tad too far into the limelight. A slight angling towards the listening position ensures better linearity and incidentally improves the spatial imaging – more on that later.

Stereopaar JBL 4309 auf Stativen im Hörraum

Dash and boldness – the highs

The lively but not overemphasized presence and treble range of the JBL 4309 shoots out of the compression drivers extremely quickly, precisely and certainly not with false (!) restraint. The ATC SCM11 looks comparatively more settled, darker, and the correct-factual Sehring M801 also does not achieve the liveliness and radiance of the JBL tweeter – it almost reminds me of the super-swift upper room of the Grandinote Mach 2R (6,600 euros) with its super tweeter. The bell-like metal percussion on How Fortunate the Man with None from the amazing Dead Can Dance album Live from Orpheum Theateris very succinct and realistic – one wonders whether classic tweeter domes, especially those with textile membranes, do not add a more or less generous dose of fabric softener in 98% of cases.

For comparison, I have to reach up to the comparison shelf: The group colleagues Revel Performa 328Be (18,000 euros) with their beryllium domes can also achieve this effortless realism of the transient response in the treble. And of course, they do this even more convincingly, because they are finer and more articulated at the same time and with more air in the super treble – for nine times the money.

JBL 4309 mit Copland-Verstärker im Hintergrund

My ATC SCM50PSL (14,580 euros) also play silkier and more detailed, with more subtle shading on distinguished pieces than the JBL 4309. But the (not exaggerated!) metallic shine, the sparkling liveliness that the compression drivers of the JBL 4309 give to the metal percussion, seems to me, depending on the piece and genre, even more appealing from time to time.

Of course, I tried to elicit annoying tones from the JBL, because such a bluntly jagged conciseness in the treble is often accompanied by a certain risk of listening stress. But I was able to enjoy even long, loud listening sessions with quite exhausting material like Wiedegood’s mega-album There’s Always Blood at the End of the Road (not due out until January 2022, but I was allowed to preview it for review purposes) without any problems. The clarity of the Americans is not at the expense of long-term suitability, because the tweeter does not play too dominantly or loudly, but is dynamically superior, lively and very clean. Nevertheless: Rather bright playing amps like a Technics SU-R1000I would rather not recommend pairing in the sense of a good sound balance.

Space thing

As already indicated, a little care should be taken when setting up the JBL 4309. Also, to optimally adjust the spatial image, because if the angle is too strong, the room looks a bit narrower and unnecessarily constricted, without any real advantages in terms of image precision and outline sharpness becoming apparent. But if everything is correct – that means at a distance of almost 3 meters and a base width of 2 meters about 10 degrees inwards, starting from the parallel setup – then the JBL will display sufficiently three-dimensionally, sharp-edged and relatively precisely on or slightly in front of the box base; However, it doesn’t really go that far behind and if it does, then with spatially emphasized deep recorded music material. The Sehring M801 and the ATC SCM11 certainly score points here, but I’m not afraid to say

… the best comes last

I’ll be right on target: the JBL 4309 are incredibly fun, especially if you listen much louder with them than the ear doctor and property manager recommend. It’s best to treat the little jacks of all trades to a stable amp with an output of around 150 watts at 4 ohms and leave them alone for three minutes on a workday morning with the staccato guitar middle part from Tools “Invincible” starting at around 7:58 minutes to fly …

In the majority of cases, for people who have already heard various other compact loudspeakers, this will go something like this with the JBL 4309: The electric guitar begins to play the staccato motif. You turn the volume up to the usual maximum because it already sounds pretty full. Then Maynard enters James Keenan with the vocoder. You notice that even now nothing is distorting or hurting and add some more juice. A smile. Then the percussion kicks in and it still feels like there could be more. The adrenaline rush slowly increases, because you know what is about to happen to you and the loudspeakers. Nevertheless, you give more material, after all, you only live once.tool can be unleashed so efficiently driving. And action! Because you can, make it even louder. And then, for ten, twenty, thirty seconds on the sonic high, you close your eyes, shake your head in disbelief, feel the goosebumps, and maybe you’ll think, “Why haven’t I listened to music like this for so long and had so much fun had with you?

The thing is: The JBL 4309 hold together the pressure and the concentrated energy of the band even at these almost brutal volumes for a compact box equipped with a 16-piece speaker. Nothing frays or compresses, the image isn’t flatter, and the treble isn’t tugging or annoying in the least. Grandiose sound pressure cinema.

JBL 4309 in Schwarz- und Walnuss-Furnier

Conclusion JBL 4309

I like the JBL 4309 because of their shape and design. Although they don’t play 100% neutral tonally, they sound complete, earthy, substantial and bluntly lively at the same time in a very charming way. Apart from the necessary care during installation, they are also quite easy to use. They didn’t reveal any real weaknesses to me in a good four-week test period. When listening to music in my almost 25 square meters, I don’t miss either (deep) bass, treble resolution, dynamics or limit levels without direct comparison to more voluminous speakers. The JBL 4309 shines in the last two subjects in particular, appearing effortless, unbridled and also clean and composed.

Lovers of deep stages will find boxes that better suit this requirement, as will high-frequency phobics or mid-range transparency fetishists. When it comes to electronics and cables, tonally neutral, preferably high-resolution and fast equipment in the three-digit performance range certainly fits best. Emphatically warm amps could perhaps place too much emphasis on the earthy, powerful bass and fundamental tone, and with very bright-sounding electronics, the balance in the treble could well tip over.

Fans of wind instruments, percussion, rock, funk, drums and any music with strong impulses and transients will find it difficult to find a less compromise-prone speaker for rooms between 15 and 30 square meters in this price range. And when it comes to party levels, not anyway.

The JBL 4309…

  • can play unbelievably loud and outrageously full-blown in terms of gross dynamics, without appearing strained. The fact that you only have to make a few compromises in terms of tonality and virtually no compromises in terms of coherence is quite unique in this price range.
  • need a lot of power for high levels – the efficiency of the 4309 is average despite the tweeter horn.
  • have a very deep, well controlled, crisp and powerful bass range that is a touch stronger than neutral.
  • appealing with an earthy, grippy base tone.
  • play the charmer card with a minimally heated midrange and leave maximum transparency in this area to other loudspeakers.
  • let the adrenaline level rise just as quickly as the mood of the listener with their open, fast, concisely sparkling and yet never annoying high tone.
  • are almost monkey-like fast and just as strong in impulses as in transients.
  • form on and just in front of the box base – depth gradation is only possible with material that has been recorded spatially.
  • adequately satisfy the demands of a three-dimensional projection for their price range, but also grow in this respect with very good electronics.
  • can be adjusted in the treble.


  • Model: JBL 4309
  • Concept: passive two-way compact speaker with bass reflex housing and horn tweeter
  • Price: 2,000 euros/pair
  • Dimensions & Weight: 419mm x 260mm x 227mm (HxWxD), 11kg/each
  • Efficiency: 87dB/2.83V/1m
  • Nominal Impedance: 4 ohms
  • Versions: walnut with dark blue covering, black with black covering
  • Miscellaneous: bi-wiring terminal, adjustable tweeter horn
  • Guarantee: 5 years