JohnBlue JB4 Mk2

We loved JohnBlue’s miniature JB3 monitors, so we were looking forward to experiencing the JB4 Mk2s. Thankfully the same ethos was followed — high quality construction with simple components, and no complicated crossovers or dampening — and the end result is speakers that sound spectacular at all but the highest volumes.

The JB4 Mk2 speakers are beautifully constructed. Instead of the glossy black lustre of the entry-level JB3 speakers, the JB4 Mk2s have a mottled cherry veneer that’s polished to a satin sheen. Constructed of one-inch thick MDF, the speakers feel very solid; the trade-off is that they weigh six kilograms each. The cherry wood veneer is quite realistic, while the copper-plated posts on the back of the enclosure are of equally high quality.

Each JB4 Mk2 uses a single four-inch full-range driver, placed in the centre of the speaker’s fascia. The maximum rated power is a seemingly measly 30 Watts, but this figure is deceptive. With a sensitivity of 89dB, the JB4 Mk2s are able to pump out high volumes from low-powered sources, making them a perfect fit for amplifiers like the KingRex T20.

The only other accompaniment to the full-range driver on the face of the JB4 Mk2 is a low, thin port cut at the base of the enclosure. It’s designed to radiate sound from the enclosure’s edge, amplifying audio while no doubt increasing bass response.

The idea behind an enclosure with a single full-range driver is to cut out complex crossovers and interference from the signal path. Whatever the trickery, we don’t care — because the end result is a speaker with amazing clarity and depth. Like we did with their smaller siblings, we hooked the JB4 Mk2s up to a KingRex T20 and UD-01 playing lossless FLAC audio files.

It’s no secret that we loved the JB3’s expansive nature — their ability to fill a room with sound despite being so tiny — and naturally we were keen to test whether these speakers could equal the feat. Of course, they did. At low to moderate volumes, the soundstage between the speakers is immense. The impression is given that you’re listening to much larger speakers that are positioned farther apart than in reality. This rich soundstage creates a large ‘sweet spot’ in which music sounds best.

Treble from the JB4 Mk2s is very rich — ‘syrupy’, even! There’s still plenty of detail audible, but it’s reproduced with a bias towards musicality and liveliness rather than bit-perfect accuracy. The omission of a dedicated tweeter means that all notes sound very linear and equal, so there’s no emphasis towards high frequencies to be found here. This has the advantage of ensuring there is no painful harshness at higher volumes.

Mid-range is, in a word, engaging. There seems to be slightly more detail evident here than higher up in frequency ranges (maybe a function of the full-range driver’s physical preference towards middle frequencies). It’s possible to distinguish individual guitar strings and hear every nuance within a singer’s vocals.

Bass is more evident than on the JB3s, thanks in part to a larger driver and the forward-firing port at the base of the enclosure. There’s certainly no trace of the boominess or overpowering volume you’d expect from a dedicated subwoofer; but there is a distinctive kick that permeates lower frequencies. Bass is tight and rolls off quickly, so if you’re looking for floor-shaking thumps that last for hours you’re out of luck.

The JB4 Mk2s are not completely suitable for the desktop due to their more traditional bookshelf size, but there’s very little we can otherwise fault them for. If you can find somewhere to set them up with appropriate accompanying equipment there’s a very good chance you’ll fall in love with them.