New Andrew Jones MoFi SourcePoint 10 Concentric Loudspeakers

In July of 2021, the prominent loudspeaker designer Andrew Jones announced that he had ended his successful 6-year run at Elac, and had taken on a new, yet-to-be-revealed role designing loudspeakers elsewhere. Like many audiophiles, I was eager to know what his next creations would be. Celebrated for his high-value designs at Elac (and before that, at Pioneer), Jones also has high-end bonafides as the founding architect of TAD’s home audio division and the creator of TAD’s cost-no-object Reference One loudspeaker ($145,000/pair). At the Axpona audio show in April of 2022, Jones revealed that his new gig was designing a line of loudspeakers for MoFi Electronics, the hardware manufacturing division of the Mobile Fidelity family of companies. But that announcement only piqued my curiosity further, as no details were offered about the forthcoming speakers. Would they be affordable like the Elacs, or mega-expensive like the TADs? Most speculated that they’d fall somewhere in the middle. Just a few months later, the Mobile Fidelity brand took a big hit in the form of a scandal surrounding the revelation that the company’s lauded vinyl records aren’t “pure” analog; there’s a digitization step in the mastering process. As this debacle made headlines for weeks on end, the anticipation of MoFi-branded speakers naturally took a back seat for a while. But now that the MoFi vinyl dumpster fire has mostly fizzled out, MoFi Electronics has finally revealed its first loudspeakers, the fascinating SourcePoint 10 ($3,700/pair). I can only imagine that the company is glad to have something else for people to talk about, and these speakers do look special.

Jones says that MoFi essentially gave him carte blanche, and that the design brief only included a request for deep, powerful bass, and an aesthetic design that captured the kind of mid-century modern look that has caught on in recent years at companies like Wharfedale, JBL, KLH, and Mission. The request for this kind of physical design, which tends to have a wider front baffle than Jones has used recently, led him to investigate the use of bigger drivers. This in turn led him to design a 2-way speaker instead of his usual 3-way designs. Jones is known for 3-way speakers that feature a concentric driver array, in which the tweeter sits inside of the midrange driver. Concentric drivers offer advantages in time-domain performance and imaging, but there are downsides too. Minimizing these downsides is perhaps easier in a 3-way concentric design than in a 2-way concentric (such as the KEF LS50 and its variants). And that’s why Jones has tended to favor 3-way concentrics until now. When a tweeter is mounted in the center of another driver, the tweeter’s output suffers from distortion as a result of the motion of the larger driver surrounding it. One way to reduce that distortion is to limit the motion of the larger driver. Sending the lowest frequencies to a separate woofer reduces the amount of sound that must be reproduced by the midrange driver. Hence, Jones has always favored 3-way speakers, in which the bass frequencies are routed away from the concentric tweeter/midrange driver array. But there’s another way to reduce the amount of motion needed from a driver — just make it bigger. A larger driver can move the same amount of air with lower excursion (i.e. less movement) than a smaller driver. Because Jones had sufficient space to employ a big driver in this new wide-baffled speaker, he could design a 2-way concentric that maintained the low distortion that he demands. The result of this experimentation is the all-new 10-inch concentric driver array used in the MoFi SourcePoint 10.

Editorial Note about Driver Sensitivity by Gene DellaSala

The other often overlooked advantage of employing a larger driver is increased sensitivity. We finally see a concentric driver speaker design from Andrew Jones with a sensitivity rating of 91dB. Most of the concentric Elac speakers Andrew Jones designed in the past have had a mid 80dB sensitivity rating limiting just how loudly they could play without entering thermal compression. Seeing a high sensitivity design like the SourcePoint 10 is a very welcomed attribute.

In a technical white paper, Jones goes into more detail about the potential disadvantages of a 2-way concentric design compared to a 3-way, and the ways in which his new design circumvents these obstacles to deliver superior results: 

As the sound spreads away from the tweeter and up the cone, it encounters the woofer surround – typically, a half-roll shape that disrupts the wave propagation. It causes re-radiation that interferes with the direct sound from the tweeter to produce dips and peaks in the response, typically in the 10-20kHz region. The greater the required woofer excursion, the larger the surround needs to be — and, hence, the more the disruption. A second problem happens when the woofer cone is moving. Its location with respect to the tweeter changes from the extreme of being in front of the tweeter location to being behind it. This positional shift causes changes in the tweeter response, resulting in intermodulation distortion, decreased clarity, and added sonic harshness — particularly with vocals. Both issues can be fixed by limiting the motion of the woofer. We can now use a low-profile surround to minimize disruption of the wavefront. The reduced displacement greatly lessens the frequency-response variations of the tweeter due to cone position. By minimizing cone motion, however, we potentially reduce how much bass we can produce.

For every octave of restricted bass response, the required cone movement reduces four-fold — a significant amount. If we use the concentric driver just as a midrange driver and add a dedicated bass driver via suitable choice of crossover frequency, we drastically minimize cone movement. This arrangement makes for a very complex solution, however. Not only do we now have three drivers, but we need extra crossover components that tend to be bulky and expensive. The other approach is to simply increase the cone area. As previously explained, bass level is a combination of cone area multiplied by excursion. We can trade one for the other by using a large driver that allows us to stay with the simplicity of a two-way system. This approach is adopted in SourcePoint 10, where a 10-inch-diameter woofer is combined with a low-profile multi-roll surround. By its nature, it meets the goals of our original design brief.

— Andrew Jones

The 10-inch Concentric Driver

The all-new 10-inch concentric driver used in the SourcePoint 10 is said to be the result of an 18-month R&D effort, and MoFi promises both “stunning clarity and deep bass impact” from this custom design. The 10-inch paper-pulp cone reportedly produces large and dynamic sound with minimal excursion, thanks to a surface area that’s almost 2.5 times greater than that of a typical 6.5-inch bass driver. As Jones described above, this reduction in movement allows the woofer to serve as a more consistent waveguide around the tweeter, resulting in “the most coherent sound possible, with the least amount of distortion, and without sacrificing bass,” according to MoFi. The centrally-mounted tweeter uses a 1.25-inch soft dome with a wide-roll surround and large-diameter voice coil. The tweeter can play lower than most, crossing over at 1.6kHz, thanks to great power handling and minimal thermal compression. At the upper end, the tweeter delivers smooth response beyond 30kHz, according to MoFi. The heart of this concentric driver array is a new neodymium magnet system called Twin-Drive. As Jones explains, simply optimizing the frequency response of the woofer and tweeter won’t get you all the way to sonic nirvana. You must also minimize distortion in the motor structure of the drive unit, or else the motor distortion will generate new frequencies outside of the original signal. In an effort to reduce these distortions, the Twin-Drive system was created. This innovative design “creates a fully symmetrical magnetic field, eliminating flux modulation for extremely low intermodulation distortion (IMD),” according to MoFi. The company claims that this technical achievement is an important part of the SourcePoint 10’s pure and accurate sound.

Abiding by the requirement that the tweeter motor structure fit within the voice-coil diameter of the woofer, typical concentric driver designs feature tweeters with relatively low sensitivity. SourcePoint 10 uses a compound motor structure named Twin-Drive to solve this issue. The magnets of the woofer and tweeter motor deliberately couple together so that each aids the other in driving flux across both the woofer and tweeter gaps. The result: Greater flux density than either motor can achieve alone.

— Andrew Jones

The Cabinet

One of Jones’s claims to fame is that he doesn’t just design drivers; he also designs the crossovers and the cabinets. A 10-inch woofer requires a fairly large cabinet, and it had better be a heavy-duty affair that won’t add resonance. The SourcePoint 10 features 1-inch thick MDF panels on the top, bottom, and sides, with extensive internal bracing. The front baffle is made from a 2-inch thick MDF panel. (The front panel is painted in a smooth satin black, while the other surfaces are treated to real wood veneer.) Measuring 22.5 inches tall by 14.5 inches wide by 16 inches deep, each speaker weighs a substantial 46 pounds. According to Jones, the cabinet was designed to optimize both bass extension and overall system efficiency.

A large woofer requires a large cabinet. SourcePoint 10 has an internal cabinet volume of 50 liters, or almost two cubic feet. Because of the relationship between box size, low-frequency extension, and efficiency, this volume can be traded to gain both bass extension and efficiency. SourcePoint 10 has a sensitivity of 91dB, low-frequency point of 42Hz, and true 8-ohm impedance with a minimum of 6.4 ohms at 150Hz. This makes SourcePoint 10 very easy to drive and well-suited to a wide range of amplification.

— Andrew Jones

At Elac, Jones was not known for designing highly-sensitive, easy-to-drive speakers. When showing off a pair of $500 Elac Uni-Fi bookshelf speakers, Jones would often use high-powered amps costing multiple thousands. But thanks to its 91dB sensitivity (achieved in part by the use of a large cabinet and large 10" driver), the SourcePoint 10 can be driven to satisfying levels by a 30-watt amplifier, according to MoFi. Tube-lovers, take note. Jones also points out that the SourcePoint 10’s nominal impedance of 8 ohms is the real deal. Some other speakers have impedance specs listed as “compatible with 8 ohms,” but they’re really 4-ohm speakers across most of the audio band. According to Jones, the SourcePoint 10’s comparatively benign impedance curve means that you don’t need a high-current bruiser of an amp to make these speakers sing.

The most visually interesting element of the SoucePoint 10’s design is its multi-faceted front baffle. Some speakers, such as the aforementioned TADs and KEF LS50s, use curved front baffles to minimize diffraction. But curved lines don’t scream “mid-century modern,” so Jones instead designed a series of facets into the 2-inch thick front baffle.

The shape of the front baffle also matters. When mounting any driver in a cabinet, the cabinet edges will refract and reflect the sound that travels across the baffle to the cabinet edge. This radiation interferes with the direct radiation from the driver and causes high-frequency response irregularities that vary with listener location. This can be particularly troublesome with a concentric driver configuration. In SourcePoint 10, such diffraction is greatly reduced by sculpting the baffle to produce multiple facets. The varying distance from the driver to the edge smooths out the diffraction ripples; the sloping surfaces further minimize them. As the listener, you benefit by hearing only the smooth, even response of the driver — not the sound of the cabinet.”

— Andrew Jones

Rounding out the mid-century vibe is your choice of Satin Walnut or Satin Black Ash real wood veneer. These furniture-grade veneers are even book matched for mirror-imaged grain patterns on each pair of speakers. With the grilles off, the veneer peeks around the corner from the sides in the form of a picture frame that goes around the edge of the front baffle. Because the picture frame is set back from the drivers (thanks to that extra-thick baffle), it can add some style without introducing problematic reflections. MoFi suggests listening with the grilles off, but Jones says the grilles have been designed to have minimal effect on the sound of the speakers. The magnetically-attached grilles do retain the profile of the multi-faceted baffle, but the look is softened somewhat by the fabric. Dedicated stands will be available as an optional extra (price TBD). The first batch of SourcePoint 10 speakers is already sold out; the next batch has started to ship and the end of January, 2023. They can be purchased now from authorized dealers like our friends at Audio Advice.

Unless otherwise indicated, this is a preview article for the featured product. A formal review may or may not follow in the future.