Avantgarde Acoustic Duo loudspeaker Page 2

Avantgarde says that current-production woofer enclosures have factory-fitted inserts for floor spikes. In addition, longer auto-switching "on" times are defined for the woofer electronics, plus a continually on switch. Future iterations of the Duo will also have an additional control providing an adjustment of +6, 0, –6dB centered on 25Hz. This will help the speaker cope with home-theater power requirements.

No one should have to make allowances for a horn design. Rather, it should be judged on its overall merit; then its balance of favorable qualities, assuming them to be sufficient, can be weighed in its favor. Previous encounters with horns had left me concerned about their characteristic colorations, but I needn't have worried. The Duo was comparatively low in coloration; it sounded different from a conventional speaker, yes, but no more colored than many a fine, reference-grade conventional loudspeaker.

No, this horn speaker didn't sound like a trumpet, nor did it have megaphonic projection. In fact, it was surprisingly unobtrusive in acoustic terms, though it was hard to weigh how that dramatic up-front appearance influences one's aural judgment.

First impressions were of a powerfully wide frequency range, of an evenly balanced design with an exceptional dynamic range. Audiophiles speak of very big amplifiers (ie, over 250Wpc) as sounding "effortlessly dynamic" with a given speaker. However, a firm distinction needs to be made between that kind of dynamic range, which involves raw amplifier power and correspondingly high peak currents flowing through the speaker's voice-coil, and that produced by a loudspeaker possessing genuinely high efficiency. The Duo requires very little current, and its dynamics are of a genuinely different kind (footnote 1).

The Duo offered excellent microdynamics; I was made aware of a tactile quality more closely associated with live musical instruments than with heavy speaker diaphragms. Electrostatics can suggest this through sheer transient purity and accuracy, but somehow don't sound this immediate. With the Duo, transient-rich percussion reached out in a most appealing way.

Second, the Duo had a breathtaking dynamic range, second in my experience only to that of the Wilson X-1/Grand SLAMM, and then only in the bass. In fact, the Duo probably outreached the SLAMM in the mid and treble. Big orchestral climaxes were truly thrilling—all-encompassing, concert hall–like sensual assaults. There was no hint of compression or failure of clarity at high levels.

The Duo was highly sensitive. Not only did a variety of different amplifiers drive it with ease, very little power was required to drive it at all! For a joke, I connected the speakers to a stereo portable radio with a couple of clean watts per channel and got genuinely high volume levels. Avantgarde told me that when used in some German discotheques, 20W power amps had proved ample!

Putting aside those sound-quality aspects specific to horn technology, I tried to view this speaker dispassionately and put it in the context of other similarly priced systems in the $10k–20k range. That includes (among many others) a number of important examples, from the Wilson WITT Series II and WATT/Puppy 5 to the Avalon Ascent, the MartinLogan ReQuest, the EgglestonWorks Andra, and the Audio Physic Caldera 2.

The Duo's trump card is its midrange, that single horn covering 170Hz to 2kHz in a single pass. So much goes on in this region, and the Duo rewards its owner with excellent linearity, clarity, detail, separation of instrumental lines, immediacy, and natural attack. Here the Duo reached beyond its peers. Moreover, allied to a harmonically pure, comparably resolved and transparent SET amplifier, that feeling of an aurally distortionless, tactile, and transient immediacy was significantly enhanced.

If these were the Duo's strong points, its weaknesses were all moderate in degree. However, they were apparent in direct comparisons with other high-performance loudspeakers. Presumably aided by its direct-coupled power amplifier, the Duo's bass was pretty good by subwoofer standards, and will satisfy many listeners. However, it didn't wholly integrate with that lightning-fast midrange, sounding a little displaced in time and agility. In critical comparison with the best freestanding speakers, the Duo showed some shortfall in tune-playing clarity and crisp control.

For whatever reason, the high-frequency horn was not quite as aurally successful as the glorious midrange unit. The treble stuck out a little compared with the best direct-radiators, sounding forward of the mid and presence ranges. This lead to some additional vocal breathiness and exaggerated the airstream sounds of woodwind instruments. The balance was also lifted in the high treble, sometimes achieving an attractive airiness and sparkle, but at other times adding noticeable "tizz" and "zing."

The high treble occasionally emphasized tracking and similar jitter-related distortion, suggesting some mild resonance or roughness at the edge of audibility, this less noticeable with tube than with solid-state amplification. Despite this, the treble was notably smooth, with good violin timbre and pure, unstressed vocal sibilants.

There was a trace of horn character in the midrange best described as a hint of "echo," though not so much as to obscure the inherent clarity or to shift tonal balance. In the upper mids, some percussion (eg, woodblock) was emphasized, but not to the point of oppressive ringing or hardness (see the measurement results on the midrange horn). No coloration as such could be reliably ascribed to the structure of the horns themselves, or to the bass cabinets.

Stereo image focus was fairly good, the phantom center image wider than usual but not unduly so. In general, I obtained good image depth and transparency from the Duo. Image stability was very good, and notably unaffected by sound level. I heard less room-excited ambience; the sound was clearly more directed (as horn theory teaches us) toward the listener, with less room contribution than usual in the mid and treble. This kind of room drive took a little getting used to; I consider it a significant component of the "difference" felt to exist between the horn and direct-radiator technologies. Of course, in some rooms with awkward, asymmetrical dimensions and acoustics, the horn speaker will provide a more consistent and more accurate sound at the listening position because of its controlled directional behavior.

You might suppose that a horn system would favor some instrumental sounds more than others, but I didn't find this to be so. Orchestral brass sounded very good, but the Duo also proved surprisingly evenhanded on solo piano. Likewise, large-scale choral music was impressive, with excellent separation of solo voices from the chorus. Orchestral stages were well laid out, with satisfying reach to subtle low-level percussion playing at the back of the band.

Those magnificent dynamics and free-sounding percussive transients helped give this speaker a lively, upbeat quality suited to rock and classical music. Pace and rhythm were pretty good when adjusted for an optimized "dry" setting for the chosen alignment of subwoofer and room location.

Bass reached to a solid 30–35Hz, nearer to 40Hz when driven hard—worthy, but not in true subwoofer class. The speaker could be driven to truly high sound levels without premature collapse of the active bass; the designers have got the matching power envelope more or less right.

Finally, there's the Duo's appearance, which some listeners felt approached engineering expressed as art, while others found the horns too large and threatening a presence to blend into a domestic setting. It speaks to me of modern loft-apartment living, places with large windows and expansive views.

To appreciate the qualities of Avantgarde's Duo, it's necessary to discard your prejudices, holding back from the analytical view that all must be in perfect balance. The Avantgarde Duo certainly is not perfectly "balanced" in performance, and maybe a high-efficiency horn can never be when compared with well-optimized, lower-efficiency, direct-radiator speakers. Yet it also argues well that balance isn't everything.

There's true sonic value in that majestically broad, dynamic midrange, in the obvious microdynamic delicacy and accuracy, the near-zero distortion, the potential for very high sound levels, the easy amplifier loading, and this speaker's compatibility with low-powered purist triode amplifiers. And make no mistake, the rest of it's pretty good too—though you'll need to listen for yourself to really appreciate the quality of the entire creation. It will work with any good amplification, but truly sings with small zero-feedback triode amps—surely a match made in heaven? For me, the Avantgarde Duo proved to be neither a review reference nor a monitor speaker, but I shall not forget my time with it in a hurry.

Footnote 1: I've found that a simplified view of distortion behavior and dynamic range in moving-coil speakers can be directly related to the required input current, without specific consideration of either electrical power or sound level. From this standpoint, which hinges on the inherent nonlinearity of the conventional electrodynamic transducer, the design that requires the least current is potentially the most linear and most dynamic. My measurements reveal that the Duo attains a high 110dB SPL on an input current of 0.7A RMS; most of the bigger three-way direct-radiating speakers (4 ohms impedance/86–88dBW sensitivity) will require some 6.5A to achieve this same loudness.
Avantgarde Acoustic GmbH
US distributor: American Sound of Canada Inc.
Richmond Hill, Ontario L4E 3M7

dc_bruce's picture

driven by an all-tube BAT electronics chain, including phonostage. The bass was a mess, perhaps because the person who set the system up didn't take a lot of time to dial the bass system in. On the other hand, the rendering of Ella Fitzgerald's voice was simply extraordinary in its realism and palpability. So much so, that I forgot to even listen for audiophile things like imaging, soundstage depth and so on.

Even in today's dollars, these are out of my reach financially; and, obviously they visually dominate any normal-sized room. But, if I did have the room and the $$$, these sure would be tempting, especially if a good digital LF room correction system were applied to the box woofer.

FWIW, I have heard Klipschorns in multiple settings, driven by a variety of electronics; and they never tempted me in the least.

Anton's picture

Modern "high end" is a full decimal place to right in the wrong direction.

I know, shut up and get back to my Silver Bullets in my single wide.

thatguy's picture

I wonder as the price goes up what the point is where the high price actually becomes a good factor for a certain type of well off shopper.
I'm sure there are those that don't want it if it is at all affordable. The crazy high price adds to the uniqueness and lowers the chance that anyone that visits them will have the same.

dc_bruce's picture

By "today's dollars," I meant the purchase price reported in Collums' review, as adjusted. $80,000? That's truly insane.

Glotz's picture

LMAO... You funny.

I just bought a case of PBR and I'll be over in 10 minutes!

partain's picture

What is meant by a "dry" chosen alignment of subwoofer and room location ?

tonykaz's picture

Some Bicycle Box cardboard, a razor knife, a glue gun and some Scans Drivers will provide anyone with super performance at Schiit Level Prices.

Avant is selling Artistic and Active Sculpture Art to wealthy or near wealthy Socials.

apparently only comparable to Wilsons.

This reads like prospective Marketing copy.

Tony in Venice

JHL's picture

...there you go again.

Does the inherent corruption of material currency ever weigh just too heavily on the socially deeply, deeply virtuous? Must be exhausting.

tonykaz's picture

Are we discussing DIY or something else ?

What is "inherent corruption of material currency" , are you referring to $80,000 Horn Loudspeakers?

Tony in Venice.

JHL's picture

...what we're "discussing". I thought the context was the review but apparently it's really the unsavory dollar and how it comports with your next social formulations on acceptability.

tonykaz's picture

Are you objecting to an opinion?

Nearly everything is this Publication is solidly Opinion Based. ( Mr. JA1's measurements are not )

Of course you have your opinions, don't you? Maybe you aren't allowed to voice your points of view, except to mention mine.

I don't mind you making acidic comments, they would probably be useful if they were probative.

Every single reader of Stereophile has thier own unique opinions and points of view, based on their personal Life experiences .

Bon Vivant

Tony in Venice

JHL's picture

...on the nature of opinions before.

First, they are not a right because opinions and rights are in different domains. There's no conflation of opinion and *speech* insofar that the opinion, as I once said, that I can walk into a speeding bus unscathed is obvious nonsense. I may claim a right to say so, but it remains rubbish.

Second, the right to speech is a construct of structural contract in the west and obviously has no bearing on the comments section in Stereophile - different domains here again. Whether you can make claims about audio tantamount to walking into busses and defend them as tacit rights is also crap.

Third, therefore these abstracts, as you stretch them about, don't give you cover. We're not talking about rights and we're not restricting yours. You making vague references to oppression as some *further* moral slight is just as illogical.

The heart of your inferences hereabouts are commonly that a large price tag carries all this social baggage that somehow involuntarily induces your negative value judgements on others as if such were some cosmic pronouncement. Some universal truth.

You can hold and say whatever dumb opinion you wish but that doesn't validate it. Speaker parts in bicycle boxes is only a tortured commentary on the manufacturer in the review above in your own odd compulsion. The rest of us don't care. I know I don't.

Which is my opinion. Here's another opinion. Let the reviewer have his.

tonykaz's picture

I'm reviewing the reviewers. ( journalists ) ( I love Stereophile and admire the writers and thier work, for the most part )


you don't have the right to limit others points of view. Do you?

Of course, I can understand that you have anxieties that you need to present but I have no obligation to honour you or negatively respond to you trolling and I won't !

You certainly write an interesting complaint.

Mr.HR suggests that the people that buy this super expensive stuff don't actually read Stereophile. Do you own Avantguard ? or horns in general ? Hmm.

I've owned horns ( klisph ) and built horns.

Tony in Venice

JHL's picture

Reviewing the reviewers - if that's what you're doing when you divine the supposed intersection of price, social class, and the character of others - has nothing to do with this "right" you've just introduced.

As I just noted, obviously rights lie elsewhere entirely. Rights also fail your formulation when you challenge mine, such as they are, to note your using these threads to comment like you do. How has anyone abused a right somehow "limited" your remarks? I began with *there you go again* because there you go again.

This isn't trolling, Tony. It's challenging the *anxious* compulsion to use a hifi magazine to launch off-topic critiques not supported by evidence.

Social warriors overlook the affronts they commit correcting a world whose imagined affronts they can't take.

AJ's picture

Some Bicycle Box cardboard, a razor knife, a glue gun and some Scans Drivers will provide anyone with super performance at Schiit Level Prices.

Send me the plans so I can build it Tony, I have all those ingredients. I have tons of Amazon cardboard these days! Is that of audiophile quality like "Bicycle box"?



tonykaz's picture

Bike Shops have plenty of large double thickness Boxes for FREE.

Experiment with design, copy Avant but with 8 sides or copy Klipsch.

The Horn importance comes from it's inherent 9 db gain, driver coupling to the horn can be easily worked out.

Large Bicycle Boxes are nearly inert but they can be doubled up with glue-on added mass patches in places where you discover sympathetic resonances.

It's great fun and you may become one of the great loudspeaker manufacturers.

The drivers are the singing voice, the horn is mechanical amplification.

Tony in Venice

ps. you might also invest in a bicycle and become completely Solar Powered ( like we were 200 years ago ), my bike gets 10miles to the Cheeseburger.

Cooking Man's picture

I owned a pair of Duo’s from 2001 to 2017. These had the next generation subs from Martin’s review pair. If I recall correctly the Duos (or was it the Unos?) were Stereophile Speaker of the Year one year in the early noughties.
I loved the Duo’s for their slam,dynamics,visceral presence and sheer joie de vivre.
However as the years rolled by their Achilles heal become more and more troubling. In my system in my room with my music the crossover between the glorious midrange horn and the treble horn was the problem. I tried numerous amps over the years (Quicksilver,Pass Aleph,Mark Levinson,Graff,First Watt and latterly Mactone), performed the factory Omega upgrade and around 5 years ago spent a small fortune on a custom cross over with silver Dueland components. All enhanced the great qualities BUT only served to emphasise the Achilles heal.
I endlessly fiddled with positioning,tilt,footers,cables blah blah. Sometimes that was fun. Increasingly it was frustrating. In the end I threw in the towel. I borrowed in home loan a pair of active ATC SCM100’s and they never went back.
I did love the Duo’s but at times I hated them and in the end a clean break divorce was the best outcome. I miss their seat of the pants thrill ride of aural delight. I don’t missed the screeching treble,vicious sibilants and endless head scratching.

Jack L's picture


So you cook up the wrong way ! Sorry you went thru so much frustration before you finally gave up the huge horns.

In the demo of the Trio+huge Basshorn in Vantgarde showroom years back, my quality-oriented ears just could not handle the huge
yet clinical sound, I had to call for time-out after only 10 minutes. So from sublime to ridiculous, we swiched to a pair of
BBC monitor Rogers type compact standspeakers, nothing else chanaged.

I enjoyed the demo for 2 hours!

ATC England supplies 5-star ranked loudspeakers for recording studios & for home. Are your classical or tower or professional model ?? Excellent choice, my friend !

Listening is believing

Jack L

Cooking Man's picture

Thanks Jack but please don’t get me wrong. I had many years of pleasure with the Duo’s. As the review noted in some areas they were revelatory. And still would be. I believe my room at 19x20x9 feet was too small to allow the horns to integrate better. I couldn’t sit more than 12 feet from them. That why I said,my room,my music and,I should have added,my ears. All speakers in a room are compromised-it’s just a question of where those compromises and weaknesses are and how they affect the emotional response of the listener.
I bought the Classic ATC SCM100’s and a pair of Track Audio Reference stands. Hooked up to subsequently bought CH Precision L1/Xi and Ypsilon VPS100 phono stage my music delivers thrills and enormous pleasure. I’m very fortunate and grateful to be able to own such extraordinary equipment.

Jack L's picture



A 'horn' loudspeaker is built of a compressor driver with narrow beam-like directivity & a horn-shaped diffuser to spread out the dispersion.

Sitting too close we listen mainly the beaming from the centre compressor driver, sharp like cutting our heads off: sorta torture!

Sitting too far away we will virtually perceive much larger than life-size imaging of the instruments & the performers. An oboe will look like a bass bassoon. An soprano's mouth will look larger than her head !!

Two audio fans invited me to check out their Alec/JBL horns on 15" woofer boxes. Frankly, I was not impressed at all: plenty of sound, pretty shy in music delicacy & emotional feeling

Listening is believing

Jack L

denesdr's picture

That's not true at all. A compression driver have very wide dispersion on it's own and mainly the attached horn/waveguide sets the desired radiation pattern/directivity. True that there are sharp sounding compression drivers but there are right sounding compression drivers aswell, as with any type of tweeters.