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PureAudioProject Trio15 Horn1 Speaker Review

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PureAudioProject Horn1 (picture courtesy of the company)

It figures, the one category of speaker I thought I could safely ignore through the years is the one I should have been paying closer attention to. I had concluded through listening events at shows, dealers and audiophile friends’ homes that lower power and high efficiency speakers were not the way to go to attain SOTA. What was I thinking? That higher power equals superiority? Likely. That nothing tops an electrostatic when it comes to cleanness and detail? Most assuredly. That low power/HE is ancient technology and inevitably the newer designs have surpassed it? No doubt. That horns are problematic, too finicky? Of course.

All wrong. These perceptions were all wrong, obliterated by the experience of hearing the PureAudioProject Trio15 Horn1. I have been pinching and kicking myself for the past several weeks as I have been romancing the Horn1; pinching myself to be sure this is not an illusion, that the experience is as magical as I’m hearing, and kicking myself because I have been a reviewer for more than 12 years and only now I’m relishing a lower power/HE (lower powered amp with higher efficiency speakers) combination in a big way. The truth is that I likely would not have trod the low power/HE path had I not been engaged in the series of reviews of the Trio15 variants from PureAudioProject. I have several iterations with the Horn1 still to explore, but already the few configurations I have assembled would qualify as most ardent audiophiles’ end game masterpiece. The previous versions of the speaker have led me to this, the Horn1, a transducer that, if I were pushed to choose, I would select over most panel speakers you care to name.

Now that’s heresy, declaring a horn hybrid to be more pure than an electrostatic speaker! Impossible! Well, not really, since I have gotten my hands on a fair number of panel speakers of both magnetic planar and electrostatic variety, and the Horn1 presents an experience as compelling or more compelling as all but the most expensive ones, namely the two best electrostatic speakers I have reviewed, the Kingsound King III, which I own, and the Sound Lab Ultimate 545 (reviewed as the U-4iA or “Euphoria,” the name at the time). What does it say to the discriminating audiophile when an affordable speaker such as the Horn1 presents as compelling an experience as some big panels? It says you had better pay attention to this review!


Strolling down memory lane

This article is not a dismissal of the previous reviews I have written about PureAudioProject’s variants of the Trio15 design. However, the company has outdone itself this time, presenting a sea change in performance for this speaker. I think back to the first model with the Tang Band driver – quite pleasant. The Voxativ was more nuanced, but much the same in terms of framework of performance. After all, they were both full range dynamic drivers. Not the Horn1; it is a departure both in terms of the driver and the experience, a reworking from the foundation on up of what the Trio15 can do. At this point, as I work through the nearly 200 vocal tracks for reviewing, I’m beginning to wonder, “What genre of music can’t it do well?” I haven’t found one yet.

I will answer the first money question that already, prior to publication, people are asking: Which of the three would be the best option for the person who is considering one of the three versions, but sees the escalation in price of the Horn1 as significant? The answer is easy; in terms of performance proportionate to cost the Horn1 is the best, no question about it. It is head and shoulders above the others. Buy the others only if you cannot afford the Horn1. I will answer the second money question – is it “worth it” in an absolute sense – as I work through the review, giving the reader a clear sense of the value I see in the Horn1.

As to the general sonic attributes of the Trio15 design and build, as well as PureAudioProject’s philosophy of speaker manufacturing, I direct the reader to the aforementioned reviews here at All of the variants of the Trio15 are proprietary designs manufactured in Spain.


Cursory glance at the Horn1

PureAudioProject has introduced a new, curvy frame while retaining the simple assembly advantages of a high-end “kit” speaker. Though the company offers a variety of baffle materials, including Baltic Birch, German Oak, Plyboo (bamboo), and High Density regular and colored MDF, the glossy piano finish White seems to be the default finish for the Horn1, a suitable foil to the auburn-toned wood horn.

Much about the Horn1 is hush-hush, such as the “experienced horn designer,” now retired and unnamed by PureAudioProject. I was told by Ze’ev Schlik, the founder of PureAudioProject, and Thomas Sulentic, U.S. Operations Manager, that this designer “holds a list of designs that are classics and awarded their companies numerous ‘best product’ etc. at most prestigious magazines…” My guess is the name will become common knowledge in time, but I seldom recommend purchase of a product simply because a name is associated with it. Having handled enough products with high profile names associated with them I have learned to largely disassociate the name from the performance of any given product in for review because, often enough, the name doesn’t necessarily equate to performance. I struggle to think whether I have ever bought a piece of gear because it was made by a certain designer/manufacturer. It seems upon recollection that performance has always been the arbiter of worth, so finding the name of the designer might be interesting, but it wouldn’t change my assessment.


Crossover options

There are three crossover options for the Horn1, two of which are passive and one active. As with all the options on Trio15 speakers, the owner can choose to explore or ignore. In my assessment, the ultimate judgment of the value of a speaker is not determined by how it sounds when optimally tuned, but rather how it innately sounds. Persons shy of all the adjusting should not avoid a speaker simply because it has the capacity for tuning.

There is a more involved passive crossover for the Horn1, built by Mundoft of Germany. Description of the features of this crossover are listed on the website as:

  • Audiophile-grade two way XO, made by Mundorf in Germany
  • No notch filters
  • Bi-amping option available
  • Main Capacitor (in serial to the horn) is interchangeable
  • Horn SPL is adjustable by gold plated jumper selecting four high resolution audiophile-grade resistors


The diminutive red jumper with gold plated contacts having four settings varies the resistance through selection of a series of resistors (collectively called a serial component) going to the full range driver. This crossover also has four speaker posts providing another red jumper between the sets of posts to select between single-wired and bi-wired operation.

There is a tremendous amount of flexibility afforded the owner through these two jumpers. While this crossover is somewhat less pristine as than the alternative, the Leonidas crossover, it is more adaptable to a wide variety of audio systems. The four settings that vary resistance massage the sense of power nearly as though one were upping or lowering the wattage of an amplifier. The sense of how “alive” a speaker is – or if you prefer how much “jump factor” it has – is influenced strongly by these jumper settings. In this way the speakers can be matched up very well to high or low power amps, tubes or solid state. This is a case of fine-tuning a speaker, so experimentation is encouraged. With a change of component or cables I recommend stepping through the four options again. The effect is not unlike tube rolling an amp.

The other jumper is just as important, for opting to use the bi-wire capability of this crossover allows the addition of a second amplifier. I will speak more about this below as I discuss the particular systems I built for this review. As a unique feature of this review I will take you through some of my process in assessing reviewed items, a process which centers on building a lot of variants of systems. Along the way you will see the cumulative effect of using the jumpers for moving from single-wired to bi-wired, and from a single amp to a pair of amps.

10 Responses to PureAudioProject Trio15 Horn1 Speaker Review

  1. Jeff C says:

    Thank you for the interesting and thorough review. A few questions come to mind. Since you are interested in DIY projects, have you ever heard or built a Troels Gravesen design such as the large Illuminator 4 or 5 or some of his open baffle designs ? I am wondering how they stack up against the Horn1. Also, since I know you think very highly of the Legacy Aeris and V Series, could you compare and contrast them to the Horn1?

  2. Dan says:

    Nice review. How would you compare these to your Legacy V? Or for us with the Legacy Focus SE with Wavelet?

  3. Shahed says:

    Thanks for your wonderful review Doug! I’ve ordered a horn1 to upgrade from my voxativ.

    I was hoping you’d write a bit more on the amplifier horn1 pairing. Did you try any tube amp/single ended/high and low power SS/Class D? I’d be very interested to hear your opinion on which amp you thought was the best match for horn1.

    Now regarding simplified vs default crossover – I’m going to use my existing voxativ crossover with the caps/resistor changes. You mention it’s purer. Which crossover do you think is more suitable more modern music rock/pop that are not the greatest in sound quality. This is assuming that I do not see myself biamping the horn1. But from your review it seems biamping provides a clear improvement. Instead of biamping, if I just bi-wire would that be a clear improvement as well?

    Congratulations on a very detailed and interesting review!


  4. Gentlemen,
    God’s Joy,

    Thank you all for your positive feedback on the article; it is gratifying that you found the article useful.

    Jeff, I was previously unaware of that DIY site. I have not done DIY myself, and restricts articles to retail speakers. I considered trying DIY many years ago, but thought that the time and equipment costs to do it properly would be prodigious. I think it would nearly have to be a second hobby to make it worthwhile if the goal was a fine speaker. Those designs look much more demanding than a weekend warrior just starting out could accomplish. So, no, I have no comparisons to other actual DIY designs.

    Dan, like Jeff, you also were curious about the comparison to Legacy products. A simple basis of understanding would be that the PAP Horn 1 is most like the Focus SE in terms of its ability to present the scale of the music. The chief difference between them all is the presence of a cabinet versus the PAP being open baffle. The presence of a ribbon tweeter also is a big departure in these other designs.

    The V is in an altogether different class of sound due not only to its size, but also its dynamic capacity. While the Horn 1 is “shy” on Midrange presence the V maximizes it, and somewhat less so on down through the Aeris and Focus SE. The bass generated by the Legacy models is typically more pistonic and “pops” with force, versus the Horn 1, which does not pop the bass, but rolls it out with less carving of the note. Finally, the Horn 1 is shorter and without elevating it this sinks the soundstage more so than these other, taller speakers. The Focus SE and Horn 1 would be the closest in terms of overall performance capability, albeit with very different sonic signatures.

    Shahed, I think you will very much enjoy the Horn 1 variant of the speaker. I have tried a variety of solid state amps with the speaker, including a pair of 25wpc First Watt J2 amps, an older Belles Theatrix stereo amp, and two other amps in for review which I do not care to divulge just yet. The Horn 1 responds readily to power structure improvement. While it sings pretty when the J2 amps are used, it takes on a more forceful, powerful character with higher power. The Red Dragon S500 Class D Amps were superb with the speaker as well. I did not have tube amps on hand at the moment, but given the cleanness of the speaker and ease of driving it, you would have no problems associating the Horn 1 with such an amp.

    By all means, bi-wiring and bi-amping are both efficacious. If you can only afford bi-wiring, do it!
    You should very much enjoy the revised Voxativ crossover. If you like super-clean rock music, it should suit you well. You must decide which is more important, a certain degree more transparency in the Voxativ crossover, or the several more adjustments to the sound offered by the standard crossover. Both have their merits and perform well.

    Douglas Schroeder

    • doug s. says:

      to raise the soundstage, simply swap the the horn for the upper woofer; w/all the tweaks you tried, i am surprised this one has eluded you (so far). ;~)

      i heard the tang-band iteration of the trio at this past weekend’s caf; extremely impressive sound in a very large room, for <$4k delivered.

      doug s.

  5. Bill says:

    Mundorf makes three versions of oil filled capacitors. One is with Aluminum, the other two with silver and a silver-gold metal. Which of these three did you use ?
    Regarding the construction of the speaker; everything looks well made. The placement of the crossover very close to the speaker is asking for resonance. I would not mount it there.
    Good luck! Looking forward to your further experiments with the Horn1.

  6. Bill says:

    VH Audio has a good selection of hook up wire, some with silver and copper wires.
    It would be interesting to see how ribbon wire works with horn drivers.

  7. doug s., BILL,
    God’s Joy to you,

    Well, in regard to swapping the horn with the bass, it’s not possible as the baffle pieces the drivers are mounted to and the mounting holes for the frame are not symmetrical. The Bass baffle pieces are approximately 50% wider than the horn baffle. If they were symmetrical you can bet I would have tried.

    Bill, the Madisound invoice says the following about the capacitors “Supreme EVO oil 33mfd”. I apologize that I do not have time to run this down further for you. I suggest that if that is not specific enough, you call Madisound. The name associated with the billing was Brian Kane 608-831-3771

    Doug Schroeder

  8. Paul Letteri says:

    I have voiced capacitors well over 15 years and when running a Hifi store when not selling
    We did resistor capacitor mods the Black Supreme I find are still their best even though
    Their new Evo Supreme are out ,they slightly elevate the upper treble region
    The White evo oil are their least expensive and least good of the 3 and have the Aluminum oil
    I believe .these even as a bypass are slightly tipped up in scale in absolute terms .
    Cost per dollar the Obbligatto Gold have a warmer balance and very good .
    My latest what I call a breakthrough for value quality – high end the New Clarity CSA- c is for a Copper lattice on the ends. In the Leonitus it has a Big 68 uf cap 250v and get them pr matched I did to within .2uf use the Mundorf Supreme solder which the cuircuit board has.
    The Fostex Copper foil,Tin foil cap 2.2 uf using their unique dialectric .a great cap used here as a blend. And does not change anything in the circuit design. The Fostex very limited on sizes due to made for their Full range drivers this mixed with the CSA Clarity cap is open warm and very good layering of instruments it cost me $250 for them at Madisound.i did these in several different speakers for friends all were elated . If you want the Absolute best in resistors the $$30 a pop Path Audio
    They tested in 12 pair every one was under 1% total variation .duelund not even close their best 5%
    Which is a 10 % variance . I may be compulsive with my audio but results are well worth the effort.

  9. Paul,
    Joyous Thanksgiving to you,

    Thank you for the thorough workup on caps and resistors!
    Now, you’re discussing use with the Voxativ, correct?

    Douglas Schroeder

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