PURE AUDIO PROJECT DUET 15 - REVIEW

PURE AUDIO PROJECT DUET 15

I never could make sense of supposedly full range single driver loudspeakers. They have no bottom to speak of, they roll off at about 4 to 7 kilohertz, and all their energy is concentrated in the midband. Table radios are great for informing you of local politics and weather, but they are anything but hi–fi. If anything, single driver speakers are dark and shouty to a greater or less degree, and thin where they shouldn’t be. You can add a sub and super–tweeter, but then you no longer have a single driver. What’s a mother to do?


The answer? Find a better driver. To a German full ranger, the guys at Pure Audio Project, Ze’ev Schlikand his stateside compatriot Thomas Sulentic, add a nice, simple second order Mundorf crossover‡ and 15" driver in an open baffle arrangement employing your choice of a high-density fibreboard, wood or bamboo baffle. The mid–HF driver is Voxativ’s “entry level” AC-1.6, an 8" widebander equipped with a translucent Japanese paper cone and large whizzer, driven by a ferrite magnet via an underhung voice coil to reduce distortion. Optionally, another Voxativ is available as a voicing alternative. About that, Schlik told me that “…In general, the AC-1.6 is a superb performer in (the) Duet15 and we don't feel there are any sonic compromises with this configuration.

“The (alternative Voxativ) AC-PiFe features a unique wooden cone and therefore the sonic signature is just a bit different, with an extremely realistic feeling of sonic mass mainly in the midrange, overall clarity, and bass definition.” A custom 15" Eminence woofer is tasked with the lower-mid and low-frequency duties. There’s a crucial detail in that last sentence; a direct radiator for the low midrange and bass. The larger woofer takes up the slack for the smaller woofer’s lack of bass production. Because the Pure Audio Project Duet15 is of the open baffle persuasion, it radiates long wavelength energy impartially into space, resulting in less room interaction. No enclosure means no internal standing waves and reflections, making for a small (pun intended) more open sound. It’s true, though…open baffle speakers do sound different and more unencumbered than most speakers in boxes.

So now you can see that the Duet15 is a two–way design. The aforementioned whizzer cone should narrowcast high frequencies, but does it? Is the Duet15 as dark as I’ve come to expect from a full range transducer? Well, yes and no. It doesn’t immediately telegraph “darkness” and it’s not noticeably beamy, but it certainly is rolled off at higher frequencies. In my room, things start to head toward the south pole at around 17kHz, and are down 3dB by 18k. That is still significantly more high frequency energy than another single driver full range model I had in the house until last week. It was the epitome of veiled highs, bleached bass and clamorous midrange. Then again, that creature employed a Chi–fi full ranger, also 8", and it just wasn’t high fidelity. Even modern “smart speakers,” the ones the size of a cantaloupe, put one over in many ways on that particularly poor example. Sulentic explained that “Because the (Voxativ) cone is made of wood, it has more mass behind it, leading to a more tonally rich mid/bass and midrange, and some more texture in the highs. It is a full range after all…It might seem to be more forward, but it’s not—it’s just a bit more in focus. These little changes add up to a noticeable, palpable feeling of energy.” That Chinese equivalent I mentioned also employs an attractive wood pulp cone and whizzer used in a less expensive Euro open baffle. From the front, the budget competition looks remarkably similar to the Duet15 and costs about $2K less than what PureAudioProject sells. When it comes to sound quality, however, there is no comparison. The Asian–anchored unit has all those aspects I steer away from: a ragged mid–forward response that forces me to dislike most entry level full range loudspeakers.

My Duet15 demo arrived in four cartons: two reusable, mostly paperboard and plywood cases with cloth straps and two much smaller cardboard boxes with the base and crossover already joined. The entire front baffle, with drivers installed, was contained in the bigger container. Because there is no enclosure, I could easily wrangle the two pieces out of their packages. Four hex screws was all it took to marry the base to the baffle. The crossover was pre–wired, so after that it was a simple matter to clip each set of “internal” leads onto the corresponding spring–loaded binding posts for each driver, and away I went. For a civilian purchasing the product, everything arrives flat–packed in five cartons. The customer mates the base to the baffle, mounts the drivers and crossover, then connects the drivers to the crossover with pre–dressed included cabling. As supplied to a customer, this process is quite a bit easier than assembling an Ikea bookshelf.

I started my listening with my default lineup of gear: Parasound’s princely JC 5 power amplifier, driving the speakers via ANTICABLES’ down-to-earth Level 3.1 “red” single conductor cables. Conversion was supplied via Audio Mirror’s Tubadour IV and Mytek’s Liberty II DAC. The Duet15 includes a magnetically attached speaker grill for the mid/woofer only. During their visit in my living room, the grills were set aside. As usual, I surfed through my Qobuz accounts with the help of Amarra Luxe, cherry-picking from my rock, jazz, Americana and classical playlists. Here were some standouts found during my listening: Penguin Cafe Orchestra’s Galahad from the 2023 release Rain Before Seven…a reverb–dipped chamber rock piece that trots through prog and classical territory on its way to settling into a space of its own [Qobuz 96k Erased Tapes]. Never shrill or aggressive, the Duet15 felt solid, rich, and simply there; an unexpected delight for the full range uninitiated.

This year’s re–release of J.M.’s Dream Doll from Mal/2 [Qobuz 192k Craft Recordings] is a gem from Mal Waldron’s often overlooked œuvre. With Rudy Van Gelder obsessively at the controls and the crack transfer and mastering team† of Grey and Blakemore, this old skool track dips the listener into the cooling jazz waters of this 1957 recording. Bandleader Waldron’s understated keys, Arthur Taylor’s percussion and Julian Euell’s double bass underpin the track, while the holy horn trio of Jackie McLean, Bill Hardman and Saint John (Coltrane) take a sultry swing for the bleachers. The Duet15 is perfectly suited to this piece, lending a relaxed and smooth sound that embraces the listener like an intimate smoke–filled nightclub.

Continuing in the genre, Noah Haidu’s 2011 debut Slipstream [Qobuz 44.1k Posi-Tone Records], with Jeremy “Yourpeltness” Pelt and Jon Irabagon, heralded a lyric and original force on the jazz scene. The sixth cut, Take Your Time, showcases what these frisky felines are all about, and the Duet15 proffered a slice of tobacco- and cannabis–laden hep cats jamming that had me listening (gasp) to the whole album. One of my all-time favourite pop tunes is Steely Dan’s Rikki Don’t Lose That Number, and the Dan’s Pretzel Logic has been added to Qobuz in hi–res [192k Geffen]. For this round of sessions, it was big Roger Nichols at the controls and Gary Katz riding herd over a team of crack studio personnel. Listening through the Duet15s, I was transported to planet Fagen–Becker, seamlessly enveloped in their quirky blend of jazz, pop and blues…fantastic! At that moment, I was not aware of any shortcomings in the loudspeakers. I could not have asked for more or less.

Another new release, the Warner Classics album Mendelssohn: The Hebrides, Symphonies Nos. 3 "Scottish" & 4 "Italian" - Weber: Overtures with Otto Klemperer conducting [Qobuz 192k], highlights what some may consider the Duet15’s shortcomings. With the massed power of an orchestra, the Duet15 grows a touch congested. That midrange bark that seems to be part and parcel of all full range drivers also makes its presence known. I must stress, however, that these are minor shortcomings in an overall offering that delivers musical truth and sonic beauty. As an aside, I will confess that I’m not afraid of superior EQ, and a tasteful amount of quality equalization transformed the Duet15s from very tasty to quite scrumptious.

In case someone tells you “Open baffles can’t possibly do bass,” you can easily disabuse them of this fallacy with the help of the folks at PureAudioProject. Take, for example,

Montreal-based DJ and artist Debbie Tebbs, whose album Origine was released this year on Quartier Général. The track Vitamin D is a typical dance confection, with what is now an obligatory bandpassed intro and synth kick and bass lines behind D–Track’s deadpan rap…turn that sucka up and wave your hands in the air! Through the Duet15s, there is no lack of an appropriately solid bottom. In my room, the low frequency response started to roll significantly at 42 Hertz while still providing usable response down to 34Hz.

Earlier this year, the world lost a right good musician. Back in pre–COVID times, Marty Scorcese released The Irishman, with a cut off Robbie Robertson’s album Sinematic. The track, I Hear You Paint Houses [Qobuz 88.2k UME Direct 2019], features the late great Robertson singing with Sir George Ivan “Van” Morrison about a contract killing. The Duet15s disentangle the two artists’ voices while Robertson’s guitar and the rhythm provided by the percussive Jim Keltner lent a pleasantly syncopated sizzle. There’s a lot going on in that track, but the PureAudio apparatus transmits Gavin Lurssen’s careful mastering of Martin “Smokey” Pradler’s mix without blur or peaky annoyances.

My audio friend Gene came by while the Duet15s were in place. He was interested in hearing the Tubadour IV while I had it, so I was able to A/B for him between the Audio Mirror and Mytek’s Liberty DAC II. At twice the price, he preferred the R-2R Tubadour but, while I had him captive, I asked about the speakers. Gene opined that he wished for ”…more snap in the bottom end,” more toward a tighter, acoustic suspension or transmission line style of step response. That said, he found nothing offensive, which he immediately qualified as being a compliment. “They play loud without an ‘edge,’” he said, emphasizing edge with air quotes, adding that they were also timbrally well balanced. Except for the form factor, which must always be taken into consideration with an open baffle design, he enjoyed the Duet15 very much, adding that the combination of Tubadour IV and Duet15 assuredly conveyed the emotion of the music.

For me, the combination of the Mytek’s enhanced detail substantially compensated for the full ranger’s rolled last octave response. As I mentioned, the Duet15 is not a subjectively dark speaker, but it doesn’t have the sparkle and air that a well–integrated tweeter can provide. What it does have is an admirable naturalness, a “feels right” way of conveying a wholistic picture of a performance, the essence of the music sometimes hidden in a recording. That ability to reveal the blood and guts of an artist’s interpretation is, for me, missing from many very expensive “high end” loudspeakers, ones that impress with their size, weight and complexity but lack vitality—what my mastering engineer colleague David Glasser refers to as “bleached.” If I had to pick a single adjective to describe Ze’ev’s speakers, I’d have to say…organic. For fussy classical fans, these may not be my first choice…not enough air, not enough snap, blah blah blah. For the rest of us, these are loudspeakers that combine a genuine lack of aural artifice with room–filling energy that kept me immersed in my music. If you can get past their, ahem, dominating physical presence, you owe it to yourself to take a listen.

‡ — When asked about crossover specifics, Schlik said that for the “…Duet15 with AC-1.6 we designed a straightforward second order crossover that is manufactured to our specs by Mundorf and features audiophile MCAP grade caps, VS140 Coils and Hi-Res resistors.”

† — Multiple award–winning audio engineer Paul Blakemore is head of mastering for Concord [Concord Jazz, Concord Records, CRAFT Recordings, Fania, Fantasy, Fearless, Loma Vista, Original Jazz Classics, Rounder, Specialty & STAX]. When I asked in an email what was his approach to the remaster, he replied, “Mal is one of the albums that CRAFT is reissuing on both vinyl and HD digital. The vinyl is usually cut directly from the original analog reels by Kevin Grey. At the same time he cuts, he runs a 192-24 flat backup of each side’s cutting master reel. He then sends these flat transfers to me. They all require different things for HD digital reissue. I’m very respectful of the original full dynamic range, so I don’t compress. I do use some limiting because frequently there are a handful (like fewer than 10) of individual peaks that hold the average level down if they are allowed to extend to their unprocessed levels. I let the limiter catch these peaks by between 1-4dB depending on the nature of the program and what is causing the peaks. If the peaks are all percussion hits and very short duration, I’ll allow a tad more aggressive limiting, whereas if the peaks are caused by asymmetrical waveforms like trumpet or other conical brass instruments, I’ll be more gentle with them.

“Occasionally there is a need for some broad EQ. Often, the flat transfers, particularly in some musical styles like salsa/latin-jazz, are bass shy. I will do a broad LF shelf or very broad parametric (Q less than 1) to boost to a more pleasing balance. Top end EQ is rarely required. The Mal remaster has no EQ, just limiting.

“Mal does have numerous dropout fixes. Unfortunately, because of the purist approach to analog, these tape dropouts are cut on the lacquers because it isn’t possible to fix them and stay analog. For the HD digital release, I fix or improve as many as possible. Mal’s tapes had a lot of dropouts. In stereo masters, I either fix by doing surgical edits using a very small clone of the same music that occurs elsewhere in the song, or by using a spectral editor in a hard crossfade mode…When the original recording is from full-track mono, Kevin uses a stereo 2-track repro head. I also do mono transfers with a 2-track head rather than full track because it allows azimuth optimization for each song. Frequently, these albums were recorded in several sessions over several months, so there are azimuth differences in every song. Using a 2-track repro head, you can see the azimuth differences clearly on an oscilloscope and adjust for best reproduction. This technique also allows fixing dropouts by switching between the L-R tracks and using one or the other but not both. The oxide damage is often only in one area of the surface of the tape, so you can pick either the upper or lower track to avoid the oxide damage.

“CRAFT usually issues all these in only 192-24 HD but occasionally there will also be a standard res 44.1-16 bit eAlbum version. For these, I convert the 192 complete fixed album using Pyramix SRC with the apodizing filter rather than linear phase or minimum phase. The apodizing filter yields lower res files that retain more of the fidelity of the 192k to my ear.”

THE COMPANY

PURE AUDIO PROJECT

info@pureaudioproject.com
US: (646) 797 3147, (877) 927 2233
Europe: +49 69 29917675
Global: Tel, SMS, WhatsApp:
+972 54 258 4258