Jones-Scanlon Baby Reds

Speaker-building is an established art, but occasionally it can still yield surprises — such as the strange and wonderful Baby Reds.

Monitors often tend somewhat towards the formulaic, but occasionally I get to play with something that's a little off-piste. My SOS colleague Bob Thomas reviewed the larger Jones-Scanlon monitors back in the SOS August 2019 issue and was somewhat blown away by them, so I was fascinated to spend some time with the smaller and significantly less expensive model. I should add that, though cheaper than their previous model, the Baby Red is still priced some distance from the entry-level bracket.

The top panel houses the input connections and DSP controls.The Baby Red really is, in quite a few respects, out of the ordinary. The first and most obvious difference is the colour. I've complained a few times about the continual procession of black boxes that take up station either side of my DAW screen over the years, so you'd imagine I'd be happy with the gloss red of the Baby Red, but I'm not really sold on it (fickle, I know). If it had been painted Fender Surf Green, or Lake Placid Blue, I'd have been waxing lyrical — but there is a happy ending to this paragraph because, as they are built to order, Jones-Scanlon say you can have a pair of Baby Reds in pretty much any colour you like (and, of course, you may absolutely adore the red!).

Though the Baby Red is a relatively large baby and not the lightest monitor in the world, thanks mostly to the 19mm-thick MDF of its reassuringly dead-sounding enclosure, it still probably falls into most folks' definition of 'nearfield' in terms of size and weight. The front panel is home to a nominally 6.5-inch (16.5cm) bass/mid driver, a horn-loaded compression tweeter, and twin small-diameter reflex ports. I've never thought twin ports were preferable to a single larger one because, all else being equal, smaller ports become non-linear earlier than larger ones, but I can see why the decision was made on the Baby Red: front-panel space is limited. The front-panel edges are softened to reduce diffraction, yet the port exits are completely un-flared, which, it seems to me, is likely to result in some airflow noise and port compression.

Around the back of the cabinet is found, as usual, the amplifier heatsink but, in a further sign of idiosyncrasy, the connection and switch panel is located on the top surface of the monitor. On the one hand it's actually quite refreshing not to have to reach around the back of a pair of monitors to access the sockets and switches, but on the other hand, the connection panel is rotated 90 degrees so that its socket and switch legends read from front to back rather than from left to right.

Innards

Internal signal flow is all-digital, courtesy of a custom DSP module that operates at 192kHz sample rate. The crossover frequency is at 2.4kHz with decidedly steep (eighth-order, or 48dB/octave) slopes. Downstream of the DSP, the Baby Red amplification is an OEM Class-D module from Pascal of Denmark rated at 500 Watts for the bass/mid driver and just 150 Watts for the tweeter. The difference between the power available for the bass/mid driver and the tweeter reflects partly that the bass/mid amp needs spare headroom for equalisation (see the next paragraph), and partly that the compression tweeter is inherently around 20dB more sensitive than the bass/mid driver.

Back on the connection and switch panel, the Baby Red provides a switched IEC mains input, balanced analogue and digital S/PDIF signal inputs, a 'service only' USB socket, and an additional S/PDIF output on one monitor of the pair. For the purposes of the digital input, a switch on each monitor defines its right-channel or left-channel role. Along with the channel switch there are two three-position switches that optionally select a 40Hz high-pass filter and a 98Hz boost of 6.45dB. The other two switch positions are currently unused, but there are plans to offer further EQ functionality in the future (the USB socket will enable the necessary firmware update).

The purpose of the 40Hz high-pass option is to offer some driver protection when played very loud (when bypassed, the speaker is specified as being -10dB at 28Hz). The intention of the 98Hz boost option is a little more unusual. The idea is to provide approximate correction for what Jones-Scanlon feel is one of the most commonly found LF room acoustics issues. I was a bit sceptical about the idea until I fired up Sonarworks to correct the Baby Reds in my room and was reminded that the first major response suckout is just under 100Hz. Maybe the 98Hz boost is not such a bad idea? Running Sonarworks in the context of this review was not done simply out of curiosity: Baby Reds are shipped as standard with a copy of Sonarworks Reference 4 Studio Edition (including the XREF20 calibration microphone). This seems to me a great idea, although it potentially leaves the 98Hz EQ option a solution without a problem.

You may have noticed that there's no mention of analogue input sensitivity adjustment, and that's because there is none. I didn't have a problem with the fixed input sensitivity, and to be honest, I mostly find with active monitors that include adjustment that none is necessary, but, again continuing the off-piste vibe, the omission is unusual.

Surround Sound

So, on to the drivers. I'll start with the bass/mid unit, which features a surround component almost certainly unlike anything else you will have seen before. Before I get on to explaining that surround, however, a bit of background is in order.

The Baby Reds employ a 6.5-inch Purifi driver for the low end, and an Italian-made Faital tweeter for the highs.Unlike the majority of speaker and monitor manufacturers, Jones-Scanlon do usually make their own drivers, but chose the Purifi one for the Baby Reds as Wayne Jones explains: "This is the closest we could find to our own drivers.  We didn’t want to spend another two years developing our own 6.5” driver."

The bass/mid driver for the Baby Red comes from a Danish start-up company called Purifi, and the co-founder of Purifi is one Bruno Putzeys. That name may ring bells, but if it doesn't, or they don't ring loudly enough, Putzeys is renowned for his development of the Hypex nCore Class‑D amplifier technology, and perhaps closer to monitoring home, his conception and development of the Kii Three monitor. Putzeys' philosophy as an engineer, it seems to me, is very much one of working from first principles to address fundamental problems. That philosophy led him to ask why it is that large-diameter drivers often seem to have a subjective quality, a sense of dynamic ease and clarity, that small-diameter drivers struggle to match. Putzeys' belief is that this originates in the distortion resulting from smaller driver diaphragms having to move much further than larger driver diaphragms to generate the same volume level. So the Purifi driver is designed to minimise distortion due to diaphragm (and voice-coil) displacement, and it employs a number of innovative techniques to achieve that end. Most of the techniques are hidden behind the diaphragm, within the magnet and voice-coil architecture, but the odd-looking surround component, designed to minimise a specific distortion mechanism, is anything but hidden, so I'll do my best in the next paragraph to explain its appearance.

It might not be apparent at first glance but, according to Putzeys, the typical rubber-roll surrounds found on compact bass and bass/mid drivers are a significant source of distortion at high volume levels because they deform unequally on diaphragm inward and outward displacement. This is less of a problem on large drivers because the surround contributes only a small proportion of the total diaphragm radiating area, but with a compact driver it can be significant. A quick diaphragm area calculation on a typical, conventional 6.5-inch driver bears this out: the radiating area of the surround contributes over 25 percent of the total. So the surround on the Purifi driver is designed to minimise distortion by behaving equally on in-stroke and out-stroke, while simultaneously performing the other required functions of allowing freedom of low-frequency linear displacement and dissipating the mid-range energy that travels outward through the diaphragm. Its unusual form is entirely driven by meeting those three requirements.

Another significant difference between the Purifi driver and many more conventional compact units is that it is designed to retain its low distortion characteristics over much greater diaphragm displacement than is usual. A conventional driver will allow maximum linear displacement of around ±5mm. The Purifi driver doubles that to be linear over ±10mm. It would, after all, make little sense to design a driver specifically to minimise displacement distortion, and then not maximise the advantage by making sure it was capable of extreme displacement. If you're intrigued by the Purifi driver and displacement distortion mechanisms and would like to know more than I can say in a couple of paragraphs, there's an interesting blog post on the Purifi website.

Sound The Horns

Moving on from the bass/mid driver, the Baby Red's tweeter is also an interesting choice. It's an Italian-made Faital FD371 horn-loaded compression driver that would normally be found in live-sound applications, and as such it is far more sensitive (dB per Watt) and capable of far higher volume levels than needed for nearfield monitoring. It's also, similarly, far more sensitive and capable of far higher volume levels than the bass/mid driver. The traditional 'price' of the high sensitivity and volume level capability in horn-loaded compression tweeters is increased distortion and narrower dispersion, but undoubtedly in the first case, the tweeter in its Baby Red application is going to be used at a fraction of its intended volume level so distortion will be inherently low. The tweeter will also likely be all but immune from thermal compression (or risk of thermal damage) because so little heat will be dissipated in its voice coil. So if it turns out that the Faital FD371 fundamentally performs well, its use may well turn out to be an inspired decision.

The only slight negatives I have on the tweeter are firstly that, to my aesthetic eye, it would have looked more comfortable if it were oriented so that its edges were vertical/horizontal, and secondly that its fit in the front-panel rebate is not particularly accurate. The rebate fit perhaps falls into the nit-picking category, but then again, Baby Red is not inexpensive. And on the tweeter orientation, it seems to me that rotating it 45 degrees would have allowed it to be mounted closer to the bass/mid driver. This would slightly improve vertical dispersion consistency and might also have provided space for port exit flaring.

Measuring Up

On the subject of port exit flaring, when I opened Sonarworks and ran a sine wave sweep, it seemed to reveal a low-frequency chuffing noise from the ports, so the first thing I did on firing up Fuzzmeasure to make a few Baby Red measurements was to investigate a little further. In doing that I discovered that some of the noise was caused by minor air leaks through the XLR input sockets on both speakers. Air leaks through connectors is not an unknown phenomenon on active speakers but, again, at the not insignificant price ticket of the Baby Red, finding one is a little disappointing (see the 'Ports & Leaks' box for more information). My drawing attention to the leak begs the question of its real-world audibility and significance — and the good news is that most of the time it won't be audible, and I don't think it is significant enough to affect the fundamental electro-acoustics. However there might be specific occasions when it becomes audible. For example, I dug out an old DI recording of my Steinberger electric upright bass and its low E, played at admittedly a very high level, did the trick.

It has enormous authority and clarity and displays all the subjective qualities of a much larger monitor working well within its limits.

Back on the subject of reflex ports, however, my old bass recording also made some Baby Red port chuffing audible. Now, the Baby Red is not by any means alone in having ports that make unintended noises when driven hard. All reflex ports become turbulent and eventually noisy, but generously flared ends will buy you a few more dB of headroom before it happens.

Diagram 1: The Baby Red's frequency response, measured on axis (green), and ±10 degrees off axis vertically (orange = above, red = below).

Along with doing the Fuzzmeasure analysis of the Baby Red port behaviour (see the graphs in the online version of this article), I also checked the system's basic frequency response from 300Hz upwards. Diagram 1 illustrates the response at 0.7m distance on the tweeter axis and at 15 degrees off-axis vertically above and below. The axial response is reasonably flat but with a rising tendency at high frequencies, and the off-axis response, as expected, shows the relatively directional nature of the horn-loaded tweeter. The above-axis curve demonstrates a narrow suck-out around the crossover region caused by the destructive interference between the two drivers as their path lengths to the microphone change. This is slightly unusual, because the vertical-axis crossover suck-out on a conventionally arranged two-way speaker (ie. tweeter above bass/mid driver) usually occurs below the perpendicular axis rather than above. I suspect things are different with the Baby Red because the effective source of the tweeter is located some distance behind the bass/mid driver. An 'upside down' configuration for the Baby Red might have been worth trying because it would direct the suck-out downward towards the desk and potentially suppress the first reflection.

Listening In

Now comes the part where I attempt to put into words the experience of listening to and using a pair of Baby Reds. The first thing I noticed on switching them on was some background hiss. It's not unusual — listening at only a metre or two asks a lot of nearfield monitor electronics — but it is slightly distracting.

The second thing I noticed is that Baby Reds really don't sound much like a typical pair of nearfield monitors. It was almost as if somebody had removed the wall behind my DAW display and installed a pair of traditional, horn-loaded main monitors a couple of metres away. The Baby Red, despite or perhaps because of its unusual design, plays a remarkable trick of sounding huge. It's also able to play at levels way beyond the needs of nearfield monitoring, without showing signs of strain or apparently changing the slightest in character. It has enormous authority and clarity and displays all the subjective qualities of a much larger monitor working well within its limits. The underlying sense of messy distortion that's sometimes the signature of small drivers working hard is all but absent. Reverb tails, compression artifacts and imaging qualities are all startlingly clear. I can't recall ever before hearing quite so clearly the effect of the phase versus latency options that Sonarworks provides, for example.

It was almost as if somebody had removed the wall behind my DAW display and installed a pair of traditional, horn-loaded main monitors a couple of metres away. The Baby Red, despite or perhaps because of its unusual design, plays a remarkable trick of sounding huge.

And speaking of Sonarworks, I used the Baby Reds with and without correction and, while I preferred them with, the difference was relatively subtle (I'm lucky that my room is reasonably free of major vices beyond the usual low-frequency standing waves). One thing Sonarworks did very effectively, however, was to tame the otherwise slightly over-enthusiastic high-frequency balance (although listening slightly off-axis does that too). Without correction, the HF balance was a touch overcooked for my taste. With Sonarworks the balance was warmer and the tweeter a little less conspicuous. And while I'm on the subject of the tweeter, my initial doubts about the use of a PA driver turned out to be unfounded. There were a couple of moments where I felt the Faital driver lacked absolute finesse in handling sibilance, but it made up for that in its detail and dynamics and the way its explicit character dovetails with that of the bass/mid driver.

The low-frequency bandwidth is extended and subjectively relatively free of port vices. Bass is informative and without obvious overhang or pitch uncertainty. I wonder if the remarkable performance of the bass/mid driver so dominates things that the fundamental port issues that all reflex speakers have are made less significant. Having said that, I'd love to hear a Baby Red that has a more sophisticated port solution, or perhaps employs Purifi's bass/mid driver-matching ABR (auxiliary bass radiator) instead.

So how on earth do I tie all that together in a concluding paragraph? When I began testing the Baby Red I was a little sceptical of some of its design choices and idiosyncrasies. Then I started listening and the doubts fell away. All that mattered was playing the next familiar old favourite to see what it sounded like and what forgotten details I might hear anew. Reviewing the monitor had come a distant second to listening for entertainment, which perhaps is all you need to know. The Baby Red is unique, and impossible not to love.

Port Behaviour

Even before non-laminar airflow becomes noisy, all ports tend to behave sub-optimally as volume level increases, so I used the Baby Red and Fuzzmeasure to try and illustrate the phenomenon. The curves of Diagrams 2a, 2b and 2c show the 10Hz to 300Hz output of a microphone placed closely adjacent to one of the Baby Red ports with the monitor driven at volume levels 10dB apart. The lower level corresponded to around 80dB (from one speaker) at my nearfield listening position, so the upper level was quite loud, but not unfeasibly so. Before making these measurements I'd sealed the Baby Red air leak around the XLR socket with Blu Tack.

Diagram 2a.

On Diagram 2a I've normalised the frequency response curves to 0dB on the graph. Above about 50Hz, where the airflow through the port is beginning to reduce (maximum airflow will be at the 40Hz port tuning frequency) the two curves are pretty much identical, but below that, the difference between them illustrates port compression. The airflow in the port has become turbulent and its acoustic output is 2dB lower than it should be.

Diagram 2b.

Diagram 2b illustrates the same phenomenon in the time domain. The curves show the step response of the port output (the ringing of the decay roughly corresponds to the port tuning frequency). The difference between the peak level of the curves shows again the reduction in output level when the port is working harder, but there's two other subtle differences that point to the port resonance Q having reduced. Firstly, the ringing of the blue curve is over more quickly, and secondly its wavelength is slightly stretched compared to the orange curve, showing that the port tuning frequency has dropped slightly. Both of these phenomena betray the increased port resonance damping that typically results from non-laminar airflow.

Diagram 2c.

Finally, Diagram 2c shows the percentage second- and third-harmonic distortion captured by the port microphone at the two different volume levels, and it reveals significantly lower levels of distortion at the quieter drive level. Increased harmonic distortion is typically of port turbulence.

My use of the Baby Red as a port compression guinea-pig was sparked by its use of twin non-flared ports, but I can't emphasise enough that the majority of port-loaded speakers will display similar characteristics to some degree (and it's not as if closed box speakers don't have their own set of low-frequency compression and distortion issues, because their drivers have to work harder). I guess the mild frustration on the Baby Red is that the choice of a bass/mid driver specifically designed to reduce distortion at high volume levels hasn't been mirrored in the design of the reflex ports.