ReProducer Epic 4

If you need a pair of portable and compact monitors, the Epic 4s have you covered!

It’s not a trivial task to conceive, engineer and bring to market a new range of active monitors, especially one that features an innovative and unusual industrial design philosophy, so ReProducer Audio Labs ought to be proud of their achievements so far. In previous reviews, I’ve looked at the company’s Epic 5 and Epic 55 active monitors and been decidedly impressed. The subject of this review is their most compact, entry‑level model.

At 24 x 16 x 17.5cm, ReProducer describe the Epic 4 as a nearfield monitor, but to my eyes it has a portable/location monitor kind of vibe, not least because the monitors ship in a smart zip‑up fabric shoulder bag. The Epic 4 enclosure follows the unusual skewed trapezoid form first established by the Epic 5, and uses the same classy construction materials. A CNC‑machined and paint‑finished aluminium front panel is attached to an MDF carcass finished with a faux brushed‑aluminium laminate.

The Epic 4s ship with a padded carry case.Around the back of the enclosure is a heatsink, connection and control panel that offers balance XLR and unbalanced phono inputs, an input gain knob, low‑ and high‑frequency shelf EQ knobs and a switch that engages and disengages the auto‑standby feature that legislation often requires. The two EQ knobs provide ±5dB of adjustment below 250Hz and above 2.5kHz. Downstream of its inputs, the Epic 4’s amplification comprises 50 Watts of Class‑D power each for the bass/mid driver and tweeter. The crossover between the drivers occurs at 3kHz, with symmetrical 24dB/octave filter slopes. The last rear‑panel feature of note is a pair of blind tapped holes intended for the attachment of mounting hardware — including ReProducer’s own soon‑to‑be‑introduced wall bracket. It seems to me that the rapid increase in multi‑channel monitoring installations means mounting bracket facilities have become almost obligatory on compact active monitors. ReProducer have probably made a smart decision to have that kind of practical need covered.

The front panel carries an 85mm‑diaphragm bass/mid driver and, behind a perforated grille, a 30mm‑dome tweeter. The bass/mid driver incorporates a copper pole‑piece cap and secondary magnet in its motor system aimed at reducing distortion and voice‑coil inductance modulation, and it features an aluminium diaphragm with a rubber half‑roll surround. The aluminium dome tweeter features a damped chamber behind its diaphragm that will serve both to lower its fundamental resonance and reduce the degree to which energy radiated from the rear of the diaphragm reflects forward and causes response and anomalies.

ABR

Like both the Epic 5 and Epic 55, the Epic 4 is reflex loaded courtesy of an auxiliary bass radiator located in the underside panel of the enclosure. The ABR is slightly larger than the bass/mid driver, at 110mm diameter, and employs an injection‑moulded polypropylene diaphragm. Using an ABR for reflex loading is more expensive and complex to implement than a simple port, but it can offer advantages. It side‑steps the compression and distortion mechanisms that ports can introduce — although ABRs also potentially have compression and distortion mechanisms of their own — and enables lower reflex tuning frequencies to be more easily achieved.

Having said that, the Epic 4’s reflex tuning frequency is at a relatively high 75Hz. This is mostly explained by the monitor’s diminutive dimensions and need to minimise bass/mid driver diaphragm displacement by having the ABR do the lion’s share of the work at a musically busy part of the audio band. Even with the help of its ABR loading, the Epic 4’s compact nature means it can’t avoid being relatively limited in low‑frequency bandwidth. ReProducer claim a ‑3dB cutoff point of 80Hz, which in my experience of similar‑sized speakers seems about right. A subwoofer seems the obvious next step for ReProducer Audio Labs, especially in the light of the Epic 4’s suitability for surround multi‑channel applications, and they confirmed to me that one is scheduled for launch in the first half of 2023.

One consequence of mounting the ABR on the underside is that when installed on a monitor shelf, the Epic 4 needs to be raised to give the radiator clearance to work. To that end, each Epic 4 ships with four screw‑in, blunt‑ended conical feet that lift the enclosure by 30mm. In addition to the feet, some small neoprene pads are also supplied to provide a little mechanical decoupling if desired. The use of four feet is fine if the surface on which the monitor is installed is perfectly flat, but if the surface is uneven, as is the repurposed scaffold plank that comprises my monitor shelf, a degree of rocking results. It is possible to accommodate some unevenness by unscrewing one of the feet slightly, but there’s no second nut provided that would enable such an adjustment to be locked. The Epic 5 overcame this problem by providing a central screw fixing point that optionally enabled three‑footed installation, but there isn’t space on the underside of the Epic 4 to allow such an arrangement. My solution was to use a coin beneath the raised foot to fix the potential for rocking, but it never felt quite right.

Along with ensuring that the ABR is able to work properly, the height of the Epic 4 in use is significant in a further respect. This is that the acoustic integration of its drivers defines a prime listening axis not, as you might expect, perpendicular to its back‑tilted front panel but parallel to the horizontal. This puts the listener slightly off‑axis of the tweeter. Vertical listening position might seem a minor consideration but when I came to make some acoustic measurements of the Epic 4 it did seem relatively sensitive to microphone position in the vertical plane.

Measuring Up

Diagram 1: The Epic 4’s axial frequency response, with the EQ set flat (red trace) and at +3dB (green).

Diagram 1 shows an axial frequency response of the Epic 4, with the measuring mic aligned midway between the two drivers, leaving the path length from the tweeter slightly longer than that from the bass/mid driver. There’s three things to note. Firstly, the basic linearity of the response curve is impressive. Secondly, the tweeter level seems somewhat attenuated compared to that of the bass/mid driver. Thirdly, the response displays a noticeable suck‑out in the crossover region around 3kHz. The green overlay curve of Diagram 1 illustrates the effect of using the HF EQ to raise its tweeter level by 3dB. It flattens the overall balance (before measuring the Epic 4 I’d already concluded that its subjective balance was somewhat shy at the top end of the band), but also makes the 3kHz suck‑out a little more apparent.

Diagram 2: The Epic 4’s on‑axis response (red), and as measured 10 degrees above and below (blue and green traces, respectively).

Diagram 2 investigates the 3kHz suck‑out a little further with a couple of vertical off‑axis measurements: one 10 degrees upwards and one 10 degrees downwards. I was expecting one of these measuring positions to identify a sweet spot where the drivers integrate more seamlessly, but neither quite did the trick. The flatter response came from the downward measuring position, but of course that listening position is the less likely one. However, I don’t feel that the suck‑out is a deal breaker — it’s more an unexpected quirk, but it will colour the Epic 4’s subjective tonal balance, and its presence is slightly surprising considering that the closely spaced drivers and relatively steep active filter slopes ought to result in more seamless integration.

My final electro‑acoustic investigation was very close (under 1cm) microphone measurements of the output of the bass/mid driver and the ABR. Diagram 3 shows very clearly the drop in output (and diaphragm displacement) just where the ABR output reaches its peak, around 75Hz. Also revealed is the suitably clean decay of the ABR above its resonant peak — there are no obvious resonant features that would point to midrange energy escaping from the enclosure.

Diagram 3: Close‑mic measurements of the bass driver (green) and the ABR (purple).

In Use

I’ve already mentioned that I initially felt the Epic 4 tonal balance was a little dull and needed some help from its rear‑panel EQ, but of course there’s much more to any monitor than just tonal balance. In a monitoring context, the Epic 4 can’t really avoid being defined by its size. It’s small so, try as it might, it can’t play deep bass. What bass the Epic 4 can play, though, it manages well, with a good level of pitch accuracy and dynamic detail. I’d be reasonably confident of judging, for example, a kick drum and bass guitar balance with it (though anything happening much below about 70Hz would be a closed book). The Epic 4 also manages to retain its usefully informative bass up to surprisingly high volume levels.

While the fundamental midrange quality of the Epic 4 is good — in that it’s well able to reveal a high level of useful midrange detail and create well‑focused stereo images — the upper‑midrange frequency response quirk identified in the measurements does, I think, impact on its subjective performance. There’s a mild extra degree of warmth and a slight softness of impact to higher‑pitched voices and instruments. Snare drums, too, lack a bit of snap. This kind of tonal fingerprint is, of course, something that almost all monitors possess to some degree, and, as is the case with the Epic 4, where it’s not associated with a significant resonance phenomenon it can be learned and factored into mix judgments.

The tweeter fitted to the Epic 4 is the same as that employed in the Epic 5 and Epic 55 and, as in those two monitors, it performs to a very high subjective standard in achieving a good balance between overt clarity and natural ease of presentation. It doesn’t scream for attention but just gets on with the job. In fact, the combination of the Epic 4’s recessed upper midrange balance and high‑quality tweeter makes for a particularly relaxing listen. I can imagine long mix sessions with the Epic 4 without suffering listening fatigue.

If I found myself working away from home and needed some accomplished yet diminutive monitors that happened to come in their own padded shoulder bag, a pair of Epic 4s would exactly fit the bill.

Once I’d reached around the back of the Epic 4 and used its EQ to turn the tweeter up a little, things snapped into focus, and it revealed itself to be a highly capable little monitor. It has that mild tonal quirk in the midrange, and, given its dimensions and consequently limited low‑frequency bandwidth, it will never cause any earthquakes in the studio — but it does an extremely competent job of compact, portable monitoring. If I found myself working away from home and needed some accomplished yet diminutive monitors that happened to come in their own padded shoulder bag, a pair of Epic 4s would exactly fit the bill. They’re pretty cool to look at, too.