This is a review of the “Retro 15 Neo Be” speaker. It’s a drop-dead gorgeous horn-loaded and hand-made speaker by Frank Fazzalari, founder of Coherent Audio, a small Canadian speaker manufacturer operating out of Stoney Creek, Ontario. The speaker measures 22″ long x 13″ deep x 34″ high. They sit on small stands which raise them 7″ off the ground. This places the tweeter at approximately ear height for seated listeners. On the rear of the cabinet there are two ports. Rear wave resonances are tamed by lattice slats inside the cabinet rather than the more commonly seen polyfill insulation. The front baffle sounds solid when you knock on it. The sides sound less solid. And the top sounds hollow. I believe Frank has tuned the cabinet by using panels of different thicknesses. Like Audio Note speakers, these cabinets are designed to resonate. This philosophy of cabinet design contrasts with the current craze to make cabinets as inert as possible by using multiple layers of composite materials or, in some cases, aluminum enclosures.

The speakers probably weigh close to eighty pounds–one person can move them, but with difficulty. The level of woodworking, from how the terminal posts are inset into the cabinet to how the model name is stamped into the cabinet, is superb. I think of these speakers as a piece of fine furniture that happens to convert electrical into sound energy. Size and finish wise, they bear a physical resemblance to the DeVore Orangutan O/96, another lovely and well-regarded speaker.

This is the demo pair from Coherent Audio’s booth at the 2017 Toronto Audio Visual Entertainment Show, otherwise known as “TAVES.” There they were powered by a Triode Amps 2A3 setup, a captivating combination of a lower power tube amplifier with a high efficiency speaker. Since there were no local dealers, I travelled to Toronto to have a listen. Also on the listening list at TAVES were the JBL Synthesis K2 ($80,000), the GoldenEar Triton Reference ($11,000), and various speakers by PMC. PMC champions transmission line cabinets where the rear wave of the speaker goes through a tuned labyrinth. They claim that this results in deeper and more integrated bass than either sealed or ported designs. I find this approach fascinating and wanted to have a listen. The GoldenEar Triton References were appealing because their low-end has been compared to that of the legendary Mirage M3s, a speaker I lived with and enjoyed for many years. They could produce subterranean bass that energizes the room. To be able to charge up a room is great fun. And the JBL I wanted to hear because JBL is a legend and the K2 was there attempt at a state-of-the-art horn design. Unlike the speakers by Coherent, GoldenEar, and PMC, I was not planning on buying the K2s. At $80,000 it was listening only! In the end, I purchased the Coherent Retro 15 Neo Be demo pair from Frank for $11,165 (CAD), shipping included. They were 3 months old, so they were pretty much new. At the time of writing this review, I’ve enjoyed the speaker for a year. This last year I moved, so I’ve also experienced how they perform in different settings.

At the heart of the Coherent Audio Retro 15 is a modified Radian 5215 15″ Neo Coaxial Speaker. These bad boys are designed for commercial applications, boast a 700 watt AES power handling capacity (!), and retail for $1200 (CAD) each. A 3″ horn loaded driver handling the frequencies above 800 Hz is built into the dustcap of the 15″ treated paper woofer, hence the “coaxial” designation. The advantage of coaxial designs is that the low and high frequency drivers are time-aligned. Conventional speakers that have separate woofers and tweeters mounted on a panel are not time-aligned: the different frequencies arrive at the ear fractions of a second apart, smearing the presentation. Heroic crossover design can ameliorate this, but with a coaxial speaker, time alignment happens automatically. The Radian 5215s combine two great technologies. They are time-aligned. And they are, above 800 Hz, horn loaded, which makes them super efficient. With one or two watts of power, they will fill most rooms with concert hall levels of sound. On a side note, Radian is the last manufacturer who still builds and assembles all their drivers in the USA.

What modifications has Frank done to the Radian 5215? He took off the dustcap so you can see the high-frequency horn in the centre of the speaker (no grilles come with the speaker). And he discarded the Radian designed crossover with an autoformer of his own devising. You see, the 5200 series Radian drivers were designed for punishing commercial use. The crossover was designed to protect the speakers, not for audiophile sound. Sound wise, it’s like a horse-blanket. Frank’s genius was to recognize that, if he could come up with an audiophile crossover, the Radian 5215 could be the centrepiece of a world-class home loudspeaker. Traditional crossovers use resistors to match different sensitivities of low- mid, and high-frequency drivers. Autoformers match drivers of different sensitivities by multiplying impedances. Autoformers are much more expensive than resistors. They are, however, much more efficient than resistors, which dissipate the power produced by the amplifier as heat. With autoformers, the amp never has to produce this extra power since the driver appears to the amp as a higher impedance device. The “first watt” crowd will love the autoformer concept: musical purity favours simpler, lower power designs. Klipsch is another manufacturer that combines high-efficiency horns with autoformers, at least in their “Heritage” line.

Horn loudspeakers are the holy grail to me. Horns are efficient. Two or three watts of power is sufficient. No need for half-kilowatt monster amps. You have your choice of any amplifier. Single-ended triode?–check. Output transformerless OTLs?–check. Class A tube or transistor?–check. Huge Krells?–you could use these too. The horn colouration, if anything is an advantage. Commercial speakers, because efficiency is important, are invariably horn loaded. As a result, we naturally associate the sound of horns with live music. Though horns can play loud, they sound extremely pleasing at low volumes. This is true of the Coherent Retro 15s as well as the Klipsch LaScala, another horn I lived with happily for many years. They are a great late night speaker. Horns are quite different than Magnepan panels in this regard. I have owned the MG-II and, more recently, the 3.7i. I love them, but you always are reaching for the volume to turn them higher, and they just soak up the power. Not so with horns. Late night listening sessions are possible with horns. Horns take you closer to the music, as they project more direct sound towards the listener.

While both the Coherent Retro 15s and the Klipsch La Scala use horns, the sound from the Retro 15s is more refined. The La Scalas, on the other hand, tend to grab you more viscerally. Another difference between the two is that the bass driver on the La Scala is a folded horn (a type of compact horn). The bass (and low midrange) handled by the 15″ woofer on the Retro 15s is not horn loaded. As a result, the cabinet size of the Retro 15s is about half the size of the La Scala, which is massive. Both speakers seem to put out a ton of bass. But it’s different bass than the bass from the latest ported speaker designs with multiple low-end drivers such as the Mirage M3 or the GoldenEar Triton References. Those speakers can convulse rooms. The bass from the Retro 15s and the La Scalas is more airy. And since many owners of horn speakers will be using low powered tube amps based on 300B or 2A3 tubes, the bass will have the bloomy tube sound. I’ve had tubes in the past, having built single ended 300B and OTL kits (I build speakers too, which is great fun). But right now, the Coherent Retro 15s are being powered by a Devialet 120 amplifier. It’s an all-in-one design, perfect for condo living: built into one box the size of a bathroom scale is a class A/D amp, a digital-analog converter (DAC), a world-class digital preamp, and a wireless function where you stream music from your computer. No more unsightly box and wire clutter from preamps, amps, transports, and D/A converters. Yay!

Frank expressed surprise when I told him I was going to be using the Devialet with his speaker. He’s built and tuned his speaker to work with tubes. At the show, he demoed the speaker with a 2A3 tube amp. What I love about the Devialet, however, is that it is dead quiet. It is dead quiet, dead accurate, and like horn speakers, it is–being a class A/D amp–efficient. At its hottest the chassis gets up to 45 Celsius. I’ve had tube amps I could fry eggs on. You know, the ones that input 100 watts of power and deliver 2 watts to the speakers. Who needs such inefficiency anymore? I love the Devialet’s analytic and revealing sound. Tubes are fun, but their euphonic characters sometimes add a pleasant bloom to the sound that isn’t there. This bloom masks subtle sonic cues and emphasizes others. Devialets are all about control and efficiency. And yes, you can use them with horns. My Devialet 120 started off as a Devialet 110 five years ago (purchased in 2013 sight unseen). It became a 120 from a free firmware upgrade. We’ll see more and more audio manufacturers take this route in the future. This is as good as Tesla owners who wake up one morning to find they have the new ‘ludicrous’ mode update.

How to the Coherent Retro 15s compare to other horns? Just as they were more refined than the La Scalas (a speaker I’d very happily purchase again), the JBL Synthesis K2s were that much more “airy” in the top end than the Retro 15s. But whereas the Synthesis K2s are a three-way design, the Retro 15s are a time-coherent two-way design. As I get older, I favour simplicity. Two-way rules! Then there are the Tannoy Ardens, another 15″ dual concentric speaker. The Retro 15s, however, blow this legendary speaker out of the water. I auditioned a used pair (with new surrounds in great condition) driven by McIntosh electronics. Like the Retro 15s, they had a big, big, lifelike sound. Perhaps even bigger than the Retro 15s, which have a laser focus to their presentation. But the bass from the Ardens was absolutely out of control. Bloated, big, and flabby. Some may like their gigantic presentation. But, to me, they’re out of control. I’ve also heard the Avantgarde Duos, but it’s been too long to draw comparisons. I do remember that I loved the sound of these beautiful art-pieces and that the powered DSP bass was module was a great idea. They must be going for close to $25,000 (CAD) these days, so they’re out of my price range. At least right now. Maybe one day down the line though. The Avantgarde Solo was in my price range, but they sounded congested.

Here’s one feature of horns that I find very interesting. I used to live in a New York style loft condo: the upstairs is open to the downstairs. One thing that horns do that no other speaker does is that they sound very lifelike from the next room. The speakers were downstairs, and I had a home gym upstairs. When working out, when the horns were playing, it would sound like a real band was playing downstairs. When I had box speakers, it would never sound that real. And the Magnepans sounded downright wrong. It must have something to do with the radiation pattern of the sound?

Now another interesting thing about all these high-efficiency horn speakers (the Retro 15s, La Scalas, Ardens, and K2s) is that, while they seem to pump prodigious bass out of huge boxes, they don’t actually go that deep. The lot of these speakers go down to the low 40s before dropping off. Considering that conventional ported box speakers with 8 or 12 inch drivers can routinely get down to 35 Hz or lower, this doesn’t seem so impressive. Of course, conventional box speakers are much less sensitive and need to be paired with big amps to achieve this. So low bass must be one of the tradeoffs of a horn design. Here’s how the Retro 15s measured from my listening chair (roughly 12′ from the speakers). Measurements taken with Galaxy Audio Checkmate CM-140 SPL meter:

• 20Hz 59dB (-17dB)
• 25Hz 59dB (-17dB)
• 31.5Hz 64dB (-12dB)
• 40Hz 66dB (-10dB)
• 50Hz 68dB (-8dB)
• 63Hz 66dB (-10dB)
• 80Hz 76dB (0dB)
• 100Hz 75dB (-1dB)
• 125Hz 79dB (+3dB)
• 160Hz 77dB (+1dB)
• 200Hz 78dB (+2dB)
• 250Hz 80dB (+2dB)

The Retro 15s measured similarly in my previous condo:

• 20Hz 60dB (-24dB)
• 25Hz 61dB (-23dB)
• 31.5Hz 69dB (-15dB)
• 40Hz 73dB (-11dB)
• 50Hz 81dB (-3dB)
• 63Hz 87dB (+3dB)
• 80Hz 84dB (0dB)
• 100 81dB (-3dB)
• 125 79dB (-4dB)
• 160 86dB (+2dB)
• 200 84dB (0dB)
• 250 84dB (0dB)

They’re fairly flat from 50Hz and up. The 50Hz (-8dB) and 63Hz (-10dB) dips at my current place have more to do with the room than the speaker. They drop off fairly sharply in the 40s and have useable bass down to the low 30s. One thing that’s been illuminating from measuring speakers: a “big” sound isn’t the same as deep bass. A lot of box speakers (such as the Mirage M3s and the Golden Ear Triton Reference) go lower, but the horns sound much bigger. Instruments and voices sound more solid, like they occupy a real space. Box speakers have a leaner, smoother presentation. Horns are raw and elemental. One of my friends, a jazz singer, commented that these were the first speakers she could make out subtle changes in pitch and timbre in her favourite vocal recordings.

To fill in the bottom octave, I went out searching for a subwoofer. Like many of you, I’ve had subs in the past. There was a Yamaha, a B&W, and Hsu. The Hsu ULS-15, a sealed 15″, was actually quite nice. And a good deal. I’ve never been able to perfectly mate the sub to the mains, though. The ULS-15 (with wireless option!) was probably the best of the bunch (the B&W was 12″, too small), but they were matched with the Magnepan 3.7i, a brilliant and exceedingly frustrating speaker. After much research, I ordered a Rythmik FV15HP. It’s a 15″ aluminum cone self-powered dual-ported sub. It is big and it plays at -2dB at 17Hz or -6dB at 12Hz. That’s pretty impressive. I use it with one port plugged. After months of hair-pulling tuning, fidgeting with knobs and controls, and moving things around, here are the frequency measurements with the sub at the listening chair:

• 20Hz 77dB (+1dB)
• 25Hz 70dB (-6dB)
• 31.5Hz 71dB (-5dB)
• 40Hz 80dB (+4dB)
• 50Hz 77dB (+1dB)
• 63Hz 75dB (-1dB)
• 80Hz 76dB (0dB)
• 100Hz 73dB (-3dB)
• 125Hz 75dB (-1dB)
• 160Hz 81dB (+5dB)
• 200Hz 77dB (+1dB)
• 250Hz 82dB (+6dB)

Not bad! +/- 6dB across the board! Purists will inevitably poo-poo adding a sub to such a brilliant time-coherent speaker, but purists be damned! The big sub is big fun. And, every once in a while, when a recording has deep bass (Bach organ music, Andy Stott, Portishead), one is rewarded. The sub also does a good job of bringing out bass guitar lines in rock music, say Springsteen. On most music, the effect of the sub is quite subtle, certainly more subtle than the measurements suggest. Unless I were doing A/B comparisons or listening to electronic music with room shaking bass, I probably couldn’t tell if the sub were on or off. The sub is positioned in a corner behind the right speaker. The left and right speakers are placed about 4′ from back wall (measured from front baffle), so that’s just enough room to fit the sub there. The right speaker almost conceals the sub. Almost. Did I say that the sub is big? And for those of you wondering: “Why not a sealed sub?” the answer is that at my old loft-style place the sub had to energize a 15,000 cubic foot space (30’x20’x25′). Although sealed subs may be more musical, a vented sub puts out power. At my new place, it’s quite overkill. It’s coasting along at maybe 10% of its capacity. Nothing wrong with that. Power in reserve.

How do the Coherent Retro 15s compare to the Magnepan Magneplanar 3.7i? With the Coherent speakers, you’re sitting in first row, like it or not. And with the Magnepan speakers, you’re sitting 20 rows back, like it or not. With the Coherent speakers, the treble is crisp. With the Magnepan speakers, the treble is silky smooth and extends into the air. With the Coherent speakers, you can hear where the left and right speakers are. The centre image is stable and focussed. The soundstage is contained between the speakers. With the Magnepan speakers, it’s harder to heard exactly where the left and right speakers are. The centre image is diffuse. The soundstage extends far beyond the edges of the left and right speakers, and the depth is awe-inspiring. The Coherent speakers are ever-present. The Magnepan speakers are ever-distant. With the Coherent speakers, the midrange is detailed and palpable. With the Magnepan speakers, the midrange is detailed and recessed. With the Coherent speakers (without the sub), the bass is articulate and light on its feet. With the Magnepan speakers, the bass is, well, different. The Retro 15s will play all types of music: from heavy metal to Lieder and from Bruckner’s symphonies to Woody Guthrie, they will perform. Despite what some aficionados say, the Maggies do not like Motorhead. I found that, with the Maggies, I would listen more to choral and symphonic works. The Maggies are good at recreating the empty space around the instruments such as the interior space of a cathedral. But their ability to do this comes at the expense of recreating the exciting and visceral punch of rock music. With the Coherent Retro 15s, I found myself tapping my feet more often. With the 3.7i, I found myself cranking up the volume and closing my eyes more often.

Frank hasn’t been the only audiophile interested in the Radian coaxial drivers. Live Act Audio out of Germany uses the same driver in their Emotion and Reference Series of speakers. The Emotion Series employs one coaxial driver in a ported box. The Reference Series employs a single coaxial driver with multiple bass drivers. Their Live Act Series 115 (LAS 115) is the closest model to the top of the line Retro 15 from Coherent. Front instead of dual rear ports. Similar size. Full floorstander, as opposed to the Retro 15, which sits on a compact 7″ stand. But while the Retro 15 retails for $11,165 (demo model, includes delivery), the LAS 115 retails for 29,990 Euros ($45,000 CAD). I don’t even want to know how much Live Act Audio’s top of the line Live Act Series 512 costs: it employs four 12″ bass drivers with a single 12″ Radian coaxial driver in a 2 – 1 – 2 configuration. I’m sure it sounds great. And I’m sure it goes for six-figures.

Though Coherent Audio is a small Canadian company run by what seems like a husband and wife team, local audiophiles seem to have heard of their speakers. The reason may be that there is a huge (well, huge by audiophile standards) following for Tannoy dual concentric speakers. The offerings from Coherent Audio offer a very viable and attractive alternative to purchasing used Tannoy speakers. The pair of Ardens I auditioned, for example, must have been 40+ years old. They had new surrounds put in at Sound Hounds. The cabinets had been reveneered and in great shape, but nothing like the beautiful fine furniture finish Coherent offers. For example, the Ardens have wood veneer sides, but sport a plain black front baffle. The Ardens were going for $3000. I offered $2800, but the owner wanted $3000 firm. And I’m sure he got it. In a way, I’m glad he didn’t accept my offer. Now I have the mighty Coherent Retro 15s. But if he had accepted my offer, it wouldn’t have been all that bad. The nice thing about vintage is that you can enjoy the speakers for a few years, and turn around and sell them for the same price. Rob at Q-Electronic has also heard about Coherent Audio and the Radian drivers. He’s going to come by for a listen one day. And if he likes them, he’s going to build a pair for his own use at home. Radian drivers are a hidden gem in the audio world.

Here’s a photo of the speakers in the listening room:

These speakers sound great and look great. Frank is superb to deal with. My biggest worry was the shipping. But it turns out my fears were misplaced. They were professionally packaged in a box within another box. Both speakers were attached onto a single pallet and shrink wrapped. It was a joy to unpack them, as much though had gone into protecting them on their journey across Canada. I’m glad I went to TAVES 2017 to hear these speakers. Although they’re slightly off the beaten path, Frank exhibits regularly and it’s easy to find him. I’m a very satisfied customer.

Until next time, I’m Edwin Wong, and I’m doing Melpomene’s work.