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JERN14 ES Loudspeaker and REL T/5i Subwoofer

JERN14 ES Loudspeaker and REL T/5i Subwoofer

A week and a half before Christmas, I went down to my condo’s lobby to get the mail. As expected with the holidays coming up, a slew of packages were piled up on the floor, including one immoderately duct-taped box measuring 14″ x 3″ x 16″ with my name on it. I bent down to retrieve it with one hand: The box didn’t move. I tried next with two hands. It still didn’t move. It was then I knew that my latest TAS review assignment had arrived.

The JERN14 ES is a diminutive but hefty two-way loudspeaker with a distinctive rounded, one-piece cast-iron enclosure—“14” is the weight of the speaker in kilograms. It has limited low-frequency output and is intended for use with a subwoofer; JERN recommends the REL T/5i, a modest-sized almost-cube that the purchaser bolts to an iron damping plate (the item inside the package I found so challenging to wrangle in the lobby). There are, of course, many well-regarded speakers with cabinets made wholly or partially from aluminum. But iron? That’s a much more unusual choice. Before getting to the particulars, some background and a little metallurgy are in order.

Dansk Skalform A/S is a foundry located outside of Aars, a town on the Himmerland peninsula in northern Denmark. For more than 40 years, the firm has been producing metal parts for demanding clients, including many in the automotive realm—Porsche, Audi, and McLaren are customers. More recently, it ventured into the loudspeaker business with a subsidiary company called AudioForm. Though the design was promising, AudioForm’s cast-iron speaker was not a commercial success. Enter Ole Lund Christensen, an affable Dane with a long and wide-ranging career in audio that began during his days as an engineering student when he became the importer for KEF in Denmark. He subsequently developed several successful consumer audio brands, including Gamut, which he sold in 2004. Christensen designed one of Europe’s most sophisticated recording studios and has overseen the installation of cost-no-object music systems for wealthy audiophiles internationally. He was on the lookout for one more challenge when he encountered the AudioForm loudspeaker at a trade show. “When I knocked on the cabinet,” Christensen told me, “I immediately said, ‘This is genius!’ I told the owner of the company, Mr. [Soren] Dissing, that it was a brilliant idea. I was a bit ashamed that I didn’t come up with the idea myself because, somewhere in my memory banks, were my university books on metal technology. It’s well-known in the metal industry that if you want to reduce vibration, you use gray cast iron.” To revive the product, Dissing hired Christensen who made some significant changes that both improved the performance of the AudioForm speaker and reduced the production cost and selling price substantially. The brand was renamed JERN, Danish for “iron,” and Christensen moved from Copenhagen to Aars (population approximately 8000) to be close to the factory.

Cast iron is a family of iron/carbon alloys that have in common a low melting temperature that has obvious manufacturing utility. Disadvantages of cast iron, compared with aluminum, include low tensile strength and poor ductility—unlike aluminum, iron can’t be extruded or otherwise “worked.” Christensen’s specific mention of gray cast iron is significant: It’s the most common variety of cast iron, used to make machine-tool parts and automotive engine blocks. Slower cooling and the presence of silicon result in the formation of the graphite flakes characteristic of gray cast iron’s microstructure. In addition to lower cost, an advantage of gray cast iron over aluminum is its superior damping capacity, by a factor of several hundred. The large graphite flakes give gray CI the “constrained damping” characteristics of many more complexly engineered (and expensive) materials used for high-end loudspeaker cabinet construction.

The JERN14 ES is a distinctive-looking loudspeaker with the general form of a small sphere atop a larger one. More than one visitor saw a resemblance to the Schmoo creature from old L’il Abner comic strips (look it up). For me, the shape and heft of the JERN evokes a kettlebell at the gym—specifically, a kettlebell undergoing cell division. The enclosure is cast as a single piece and the inner surface is covered with small domes that serve to vary the thickness of the cabinet and reduce resonances (see photo). The standard finishes are a black, gray, or white “structured paint” that has a pleasantly textured feel and won’t show fingerprints or dust. There’s a high-gloss red alternative that’s very popular in JERN’s Asian market. Custom colors are available for an additional cost. JERN provides cloth covers for the two drivers that are held in place magnetically, though most users will surely leave them off for critical listening.

Two ScanSpeak drivers are utilized, a ¾” fabric dome tweeter that’s been in production for 45 years and a 5¼” glass-fiber woofer, available since 2009. Both are off-the-shelf units. The woofer performs quite well up to 9kHz, and the two drivers are crossed over at 4000Hz, an unusually high value for a two-way design. It’s the woofer’s broad functional range that allowed Christensen to implement a 6dB-per-octave crossover, instead of the fourth-order topology of the earlier AudioForm product, with just two high-quality (Mundorf) components, a coil and a single capacitor. Genuine sheep wool is placed in the center of the enclosure where it’s most helpful as a damping material, Christensen says, as air velocity is greatest away from the cabinet walls. The design positions the tweeter behind the plane of the woofer, assuring correct time alignment of the two drivers. Internal wiring is with vibration-resistant, Teflon-insulated, silver-coated copper cable. The rear of the enclosure sports a single pair of WBT 0703cu Nextgen binding posts.

As the JERN14 ES is a sealed-box design, bass falls off at a rate of 12dB per octave below 100Hz; for any real-world scenario, low frequency augmentation is going to be needed. JERN, as yet, doesn’t make a subwoofer and suggests the REL, a compact (10.5″ x 12.5″ x 12.7″), non-ported design with a single down-firing 8″ driver. This sub provides a –6dB in-room response down to 32Hz, which doesn’t represent pant-leg-flapping bass in the lowest octave but is appropriately scaled to the dynamic capabilities of the 14 ES. The T/5i has a 125-watt Class AB amplifier onboard that will accept a line-level signal from a preamplifier, but REL and JERN—and yours truly—strongly recommend using the high-level input, which takes signal from the same amplifier(s) powering the main speakers. REL supplies a 10-meter interconnect with bare wires at one end to connect to the positive terminals of the right and left channels of your power amplifier(s) and a Neutrik speakON plug that connects to the subwoofer. With this option, the amplification for the sub, obviously, is identical in character to that provided to the JERNs, and the integration of sub and satellites is very effective. In comparison, running the REL as an active subwoofer via a long RCA-to-RCA cable from a preamp’s “.1” output resulted in the all-too-familiar sound of limited LF main speakers paired with a boomy sub. Actually, Christensen doesn’t want us to think of the JERN/REL combination as a satellite/subwoofer system but, rather, as a three-way loudspeaker in which the bass driver, shared by both channels, happens to be in another cabinet.


On the T/5i’s rear panel are controls for adjusting level and phase, as well as the crossover frequency, from 30 to 120Hz. Christensen suggests beginning with the filter set at 120Hz. At that value, low male vocals were slightly colored; a setting of around 95Hz proved to be ideal. JERN’s 23kg cast-iron damping plate (it weighs nearly twice as much as the REL itself) significantly enhances the performance of the T/5i. The iron base is secured to the T/5i with four long screws that are inserted through the undersurface of the plate and through the REL’s four aluminum feet to the subwoofer. The T/5i has a price of $749; JERN’s damping plate adds another $499 but the improvement in bass articulation and control is well worth it.

There are a surprising number of options for installing a pair of JERN14 ES’s in a domestic setting. A significant expanse of the loudspeaker’s bottom surface is flat and the 14 ES can simply sit on a piece of furniture, up close to the front edge of its top surface. This is how I first heard the speakers at RMAF 2017, and they certainly made a good impression. However, JERN now includes with each 14 ES a hard solid-rubber ring, 6″ in diameter, on which the speaker is placed. This better couples the JERN to the surface it’s on, both acoustically and mechanically, and allows for minute adjustments in toe-in and front-to-back tilt. In my experience, there’s no other speaker with which such adjustments can be made so easily—think of the last time you wrestled with a heavy spiked speaker to optimize imaging or tonal balance. For this evaluation, JERN supplied 36″ Pangea Audio LS300 steel speaker stands ($250/pair, though Audio Advisor is selling them for $100/pair as I’m writing this) which have a 6″ top plate on which the rubber ring fits perfectly. The LS300s were spiked and two of the three hollow supports filled with sand, in audiophile-approved fashion. But Christensen doesn’t feel that’s necessary—any unwanted vibrational energy has already been dissipated into the rubber ring, long before it can make its way to the spikes and floor, he told me. The one caveat about this arrangement is that it could be unacceptable in homes with toddlers: one investigational tug on a speaker cable could bring the cannonball-like JERN hurtling downwards.

JERN also manufactures metal stands, 95 cm (37.4″) or 115 cm (45.3″) in height. A hollow iron tube screws into the bottom of the 14 ES and attaches at the other end to a 50-pound base. Finally, there are JERN tripods—three wooden legs connected to a cast iron plate that is secured to the bottom of the speaker. Two sizes are available. One is intended to rest on a piece of furniture and the other attaches at the floor to a wooden ring. The JERN stands and tripods are relatively costly ($239 to $599) but are safer alternatives, if there are curious children (or rambunctious pets) around.

I was interested to hear the JERN14 ES loudspeakers in both a stereo and multichannel context. Christensen (and his U.S. distributor, Steve French of Apopka, Florida) obliged with five, plus the requisite Pangea stands. Music came from digital sources only—an Oppo 103 to play discs and a Baetis Reference 2 media computer to handle files. For stereo, the DAC was a T+A DAC 8 DSD; for multichannel, my Anthem D2v processor. To provide stereo amplification, I mostly used a pair of Pass Labs XA60.8 monoblocks, though a Parasound HCA 2200II (with a cost more in line with the JERN14 ES’s $3498-per-pair price) saw some service. For surround, a third XA60.8 powered the center channel and a Pass Aleph 0s drove the back speakers. Analog cables were Transparent Audio Generation 5; digital wires included Revelation Audio Labs (AES/EBU), Apogee (coaxial), and Transparent (HDMI) models.

The primary listening position was the same for both stereo and multichannel. The front left and right JERNs were 110″ from that location with the center channel 113″ away. The left surround was 83″ from my ears and the right surround 74″. (Asymmetries were addressed electronically with the Anthem’s DSP room correction software.) The subwoofer began in a corner but integration with JERNs was sub-optimal. Moving the T/5i to immediately in front of the center channel produced consistently good results.

In tonal accuracy and balance, the JERN/REL combination performed stunningly well—after two important adjustments were made. The first, as noted above, was reducing the sub’s crossover frequency from 120Hz to about 90–95Hz and the second was carefully adjusting the tilt of the JERNs so that the woofers were aimed at my ears. “The whole system has been aligned for the woofer to point to your ears precisely,” said Christensen. He explained that the dispersion characteristics for the tweeter are excellent, and those small drivers can be aimed over the head of a seated listener. However, at the 4000Hz crossover point of the larger driver, the dispersion isn’t great—thus the recommendation. When those two requirements were met, the tonal naturalness of the JERNs was as good as I’ve heard. Thomas Quasthoff’s baritone had just the correct blend of resonance and texture that makes his voice—or the voice of any great male singer—instantly identifiable. Likewise, the JERNs passed the “Old Italian Violin Test” with flying colors: The differences between Stradivarius and Guarneri del Gesù instruments were obvious.

Musical detail was superb. The opening movement of Mahler’s Symphony No. 4 has a lot going on simultaneously and listening to Michael Tilson Thomas leading the San Francisco Symphony was like having the score open in front of me. Toto’s classic rock staple “Africa” was engrossing, the myriad percussion elements, voicing of the synthesizers, and nuances of the rich vocal harmonies registering with unforced clarity. In the 1950s and 60s, the great jazz saxophonists were often recorded quite immediately, and the JERNs facilitated parsing the different embouchure approaches of, say, Lester Young and Sonny Rollins.


Though dynamics are quite good for a small speaker, with exuberant choral and symphonic music, you must be careful not to push the JERNs beyond their limits, as some stridency can develop. A related metric is scale. As the volume increases, powerful instrumental combinations—for example, the brass section in a Tchaikovsky symphony—will not necessarily scale up realistically. The lesson is this: Don’t play these things louder than they are meant to be played. Believe me, at a point well before the gain setting will start to adversely effect dynamic ease and scaling, you’ll be hearing from the neighbors. That will be plenty loud to thoroughly enjoy your favorite “power music,” whether it’s the 1970s-vintage Chicago Symphony Orchestra or Lyle Lovett and his Large Band.

The same goes for bass. If your expectations are reasonable, the JERN/REL system provides satisfactory LF support for all musical styles. The terrifying descending organ pedal line in the “Le Verbe” movement of Olivier Messiaen’s La Nativité won’t rearrange the china but it may still have you reconsidering your religious convictions. The T/5i provides satisfactory orchestral weight and tuneful bottom-end support for pop music, when it’s on the recording—for example, David Patton’s percolating bass part on Elton John’s “Nikita.” One should resist the temptation to turn up the bass level on the REL as, with many older non-classical recordings, “bass” is often actually midbass that can quickly become slow and undifferentiated. Above-average bass slam and extension is a lot to ask of one 8″ woofer, and a possible remedy could be to use two T/5i’s, placing one in each front corner of the room. Alternatively, one can decide to accept a lighter bass presentation, consistent with the JERN’s tonal character and dynamic potential.

Spatiality is excellent. On the orchestral track I’ve used dozens of times to assess this audio parameter, Bernard Haitink’s live recording of the Shostakovich Symphony No. 15 with the Concertgebouw, the layering of orchestral sections from front to back is completely believable. Soloists—glockenspiel, bassoon, flute, trumpet, violin—are precisely localized, but not artificially so. On Todd Rundgren’s anthemic “Just One Victory,” which closes his 1973 album A Wizard, A True Star, there are easily eight or nine Todds overdubbed for the final choruses, singing in groups or individually at different depths in the soundfield. This wasn’t the greatest recording to begin with but, with the HDtracks 24/192 download played through the JERNs, Rundgren’s boundless imagination and studio legerdemain come through loud and clear.

Like many well-engineered loudspeakers, the JERN14 ES’s don’t require gold-star electronics to show their strengths but will shine their brightest with top-notch amplification. Listening with the Parasound HCA 2200II driving the JERNs was very pleasurable and with more power, mighty orchestral climaxes actually crested more gracefully. But switching back to the Pass amplifiers kicked the experience up several notches, in detail, tonal neutrality, bass control, and dimensionality.

I had high hopes for the JERN/REL multichannel setup because of the benefits of using five identical loudspeakers for the main channels, configured with a geometry that approximates the ITU standard. Additionally, amplification was provided by a single brand. A fault with this configuration was that only the front right and left speakers were functioning as full-range transducers, as signal from their respective amps also made it to the REL. This was ameliorated by designating the center and two surround speakers as “small” in the Anthem’s bass management menu, which sent low-frequency information to front left and right JERNs, and thus to the subwoofer.

I was not disappointed. With rock, pop, and world music surround mixes engineered to create a vast soundspace—Roxy Music’s Avalon, James Taylor’s Hourglass, or Mickey Hart’s Over the Edge and Back, as examples—the effect was mesmerizing, if not to a “the-walls-of-my-room-are gone” degree, as can sometimes be achieved with my reference multichannel system of six Magico S Series speakers. The unraveling of complexities in elaborately engineered mixes, such as James Guthrie’s 5.1 treatment of Pink Floyd’s Wish You Were Here, was gratifying. With large-scale classical music, a sense of a specific venue was communicated, including recordings of the symphonic ensemble and room I’m most familiar with, the Philadelphia Orchestra in the Kimmel Center’s Verizon Hall. With small groups—the Hagen Quartet playing Beethoven’s Op. 18, No. 5 or Jazz at the Pawnshop—the dimensionality of the musicians’ deployment on an imagined stage went a long way towards providing a generous dollop of realism. In short, the JERN/REL system delivered on multichannel’s democratizing promise—to create a spatially compelling and dynamic presentation in a modest-sized room, with smaller loudspeakers, at lower volumes.

The JERNs are a fascinating product, but the brand may not have yet fully shown us what it’s capable of doing. The basic platform is indeed, as Ole Lund Christensen recognized when he first encountered it, “brilliant”—an enclosure that provides the kind of freedom from vibration, audible resonance, and coloration that the manufacturers of loudspeakers with aluminum or complex resin enclosures must go to considerably greater trouble to achieve. JERN sells a less expensive model, the 14 DS, which utilizes the exact same cast-iron enclosure and drivers as the 14 ES but substitutes a synthetic damping material for the real sheep wool and less exalted internal wiring. Might a deluxe version be a consideration, with custom-designed drivers to suit the one-of-a-kind cabinet, especially a more modern tweeter? What would a subwoofer made specifically to pair with the JERN14 ES be like? And could Christensen get around iron’s unfavorable strength-to-weight ratio to produce a larger, floorstanding JERN that wouldn’t be too heavy to appeal to the market? Time will tell.

In the meantime, any shortcomings in bass performance notwithstanding, the combination of two JERN14 ES’s and a single REL T/5i is as good a stereo loudspeaker system as I’ve heard for $5000. If you are interested in multichannel music, an additional three JERNs brings the total up to about $10k, an amount far lower than what you’d need to invest to realize a surround-sound loudspeaker system with Wilsons, Magicos, YGs, Rockports, or other transducers with heroically massive enclosures. The JERN/REL combination could provide long-term listening satisfaction, whether your musical tastes run to late-Romantic orchestral blockbusters, small group jazz, or—dare I say it?—heavy metal?

Specs & Pricing

Type: Two-way, closed box
Driver complement: One ¾” fabric dome tweeter; one 5¼” glass fiber woofer
Frequency response: 90Hz–20kHz
Impedance: 8 ohms
Sensitivity: 88dB
Recommended amplifier requirements: 20–200 watts
Approximate maximum dimensions: 8″ x 12″ x 7″
Weight: 30.9 lbs.
Price: $1749 per speaker

REL T/5i
Type: Closed-box, down-firing active subwoofer
Driver: 8″ long-throw FibreAlloy woofer
Lower frequency response: –6dB at 32Hz
Amplifier: Class AB, 125 watts (RMS)
Dimensions: 10.5″ x 12.5″ x 12.7″
Weight: 26.5 lbs.
Price: $749

JERN damping plate for REL T/5i
Dimensions: 11.5″ x 2.625″ x 14.25″
Weight: 50.7 lbs. (23 kg)
Price: $499

Birkevej 59
9600 Aars
+45 96981775

6022 Ardele Court
Apopka, FL 32703
[email protected]

North Road, Bridgend Industrial Estate
Bridgend, CF31 3TP
United Kingdom
+44 (0)1 656 768 777

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