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Vandersteen Treos



What a coincidence. I recently reviewed the PS Audio Stellar Phono preamplifier and noted that the company was run by a single-minded owner from the USA. I find that audio products that come from single-minded owners are different and their sound quality can be exceptional as they do not have to keep the investors/venture company happy. The audio does not have to be ‘safe’. Safe audio is invariably competent but without any risks or anything to mark it out from the crowd. I am not saying major corporations can’t make great audio as they have the resources for great R&D and can make the audio more consistent, but for the real diamonds in the coal mine, they tend to come from single-minded owner/manufacturers.

The Vandersteen Treos in for review also come from a single-minded owner/manufacturer.  Richard Vandersteen is a Dutch émigré who started making loudspeakers in his workshop. Richard had a very clear idea of what makes a great loudspeaker. He demanded a natural-sounding loudspeaker with no parts of the frequency spectrum emphasised to add excitement to the sound. That emphasis can lead to audio fatigue after a few hours, despite initially sounding exciting. Richard Vandersteen found that if he wanted superb 3D sound then he had to reduce the size of the board that the speaker units were mounted on. He took it to the extreme and mounted the loudspeaker units on poles and found the sound was much improved. He also prefers gentler slope crossovers to maintain correct phase relationships. His loudspeakers use 6db/octave crossovers rather than steeper crossovers used in other speakers, with some monitor speakers using 24db/octave crossovers. These steep crossovers can cause phase problems. The penalty for using gentler crossovers is the speaker units have to be higher quality as they will still be operating past the crossover point but at a reduced level. If your speaker breaks up badly just past the crossover point then using gentler crossovers causes real issues.

Having established an overall approach Richard had the issue of the speakers/crossovers being on show with the speakers on poles. He then had a flash of inspiration and covered the speaker with a black ‘sock’ of audio transparent material. A little bit of luxury with a real wood top and base and the speaker was taking shape. As a bonus, to please his frugal Dutch origins, the speaker could be made at a more reasonable cost as they had no wooden boxes or expensive veneers to be paid for. Richard christened this speaker the Vandersteen 2 and took it to an audio show. It was a huge success and since then over 100,000 pairs have been sold. A wonderful success story and Richard went on to design many more speakers. I have seen and used the latest incarnation of the Vandersteen 2s and they are a good floor-stander, with 3 speaker units and a 10” active audio coupler and they still manage to sell for an amazing price of $5400.

Richard has since designed and built the follow-on speakers: the Model 1, Model 3a, Model 5 and Model 7. A straightforward naming convention! And of course, the Quatros (4 is an unlucky number in Asia). These speakers incorporate a powered sub-woofer with 2x12” aluminium woofers and an analogue bass signal frequency adjustment system. The Quatros use a crossover box between the pre and power amp to send the high frequencies to your amp. The Quatros deal with the bass. I have heard these speakers at various shows and they have a way of filling a large room that belies their reasonable size. Due to customer requests Richard also made a veneer version of the Quatro. It should have been straightforward but Richard reports it was a job and half requiring considerable redesign. Yes, it is more expensive but looks wonderful and disappears in most rooms as it has a narrow profile.  I mention them as the Treos here for review are considered to be a pair of Quatros without the active bass units.

As time marches on Richard has developed the speakers and the various speaker units used in them. The speakers have altered and changed but the overall sound characteristics have not but the sound quality is much better.

Richard is a very talented engineer and he has built and flown his own aircraft. Not many audio manufacturers have done that and he obviously, has great confidence in his engineering! And whilst building his aircraft he pondered on what he wanted from his aircraft and loudspeakers. Balsa is used extensively in aircraft as it is extremely stiff and very light. Richard wondered whether he could make a speaker using balsa for the driver cone. And off he went to try to make one. Many people can come up with great ideas but brilliant engineers convert the ideas into real products. Not only that he wanted to make his speakers behave like a perfect piston and not suffer break-up. If the cones were stiff enough the cone would move as a unit and not break up. But they had also to be light enough to behave as a perfect speaker cone. That was the promise of using balsa.

Richard was successful and then some.

Tweeters can also be a problem. Richard initially used metal dome tweeters and coated them with ceramic to improve their sound.  Looking for an improved tweeter he came up with the idea of using carbon fibre for the tweeter. After  a lot of R&D, he made a carbon tweeter that behaved much better than the previous metal domes. They sounded much better for it but unfortunately, they were more expensive as they take over 8 hours to make.



Richard incorporated these improvements (and others) into his speakers where he could. It is true to say that not only is Vandersteen a technology-led company but they have a significant number of patented ideas incorporated into all their speakers.

The carbon tweeters and balsa were incorporated into the 7s, 5s, Quatros and gave a big jump in sound quality.  The speakers gained a far more natural sound. But what about the 3a? Carbon tweeters are expensive so it would have to be a carefully considered choice. The 3a is a larger version of the 2s and also uses audio socks. Customers would be slightly wary of an audio sock design if the price was high. So, Richard decided to design a veneered version of the 3a based on the Quatros but without the powered double bass units. As it was a redesign it got a new name, the Treo was born


The Treo is essentially a passive version of the original Quatro Wood, sharing the same driver complement sans the powered-bass system. It is offered in an array of wood finishes in a strikingly attractive form factor. But the Treo is also a modern take on the legendary Model 2, a paragon of cost-effective performance that's made in the USA, with an elegant outer package.

Vandersteen uses a reflection-free midrange and avoids this time-domain distortion by using an open back with a cylindrical magnet structure that allows the back wave to be broken up and diffused inside the speaker cabinet so it doesn’t smear the signal reaching the listener’s ears.

Vandersteen speakers are developed in house with extensive listening guiding the progress of their evolutionary and sometimes revolutionary design decisions. A good sign in that they listen and that drives the development of the speaker as well as the measurements.   




Another salient feature of the Treo CT is its ‘cabinet in a cabinet’ construction. The inner cabinet is separated from the outer shell with a viscous membrane designed to dampen vibration and resonance. The resulting wave dampening trapezoid shape of the speaker creates a striking and attractive cabinet available in a variety of wood veneer choices. Located inside are the Carbon tweeter covering 5kHz to 30kHz, a 115mm midrange from 600Hz to 5kHz, a 165mm woofer at 35Hz to 600Hz, and a passive radiating 200mm woofer covering 35Hz to 55Hz. The enclosure is ported on the bottom and uses phase-coherent, first-order (6dB/octave) crossover slopes throughout. There are bi-wireable spade connections along the barrier strip. Three spikes act as feet with the rear spike being height adjustable via a supplied set of washers to provide the appropriate tilt to match the tweeter to the listening distance and ear level. The spikes also provide enough ground clearance for the downward-firing woofer port.

The Treos were delivered to chez George and I set them up away from the sidewalls and about 1 metre from the back wall. I used the excellent manual and followed the process described. It was straightforward with only minor tweaks needed for domestic acceptability. I checked the frequency response and there were no significant issues in my 30’x20’ room. Toe-in was small. ARC and Vandersteen are often found at various audio shows so my ARC Ref 5 and Ref 110 was pressed into service. The speaker’s sensitivity is low at 85db/watt so I would need all those lovely 100w/channel. I fed the amps with an Audionote DAC4.1x and a Chord Qutest (+sBooster 12V supply) and a dCS Bridge via a Melco N10. For CDs, I used an AN 4T Transport and for vinyl a Voyd 0.5 Ref TT, SME V and an AN IO II cartridge. The tiny vinyl signal went through an AN SUT and my new PS Audio Stellar phono stage. I used Transparent Audio and Cut Loose silver ribbon cables throughout. To connect to the speakers, with their strip connectors, I borrowed some Audioquest cables from the distributor.



I ran the speakers for a day or so before listening. They were the personal pair of the distributor, Signature Audio Systems, so were already run in, but to be sure. 

And what a listening experience. The first obvious thing was they imaged superbly well especially with ARC amplifiers. The large soundstage was very solid and did not ‘wander’ as happens with some speakers. On the right recordings (Beethoven 5th Piano Concerto recorded in St Martins in the Field) the soundstage was huge and very reminiscent of when I was at the recording. Interestingly, the soundstage reduced significantly when playing some modern recordings. Yes, it was there when it was on the recording and not an artefact of the speakers/amplifiers. On a lot of studio recordings, individual instruments were easy to hear as separate entities without the sound being pulled apart. And a 100’ soundstage with 50’ pianos were not a mark of this speaker. A great start.

The overall frequency response was very flat with no part of the frequency being emphasised. Some newer speakers emphasise the higher frequencies to make the speaker more exciting. But it is wearing with prolonged listening. It was great to hear all the instruments and no pumped-up bass and high frequencies. I have seen comments on Vandersteen speakers saying they can sound as though the top end has been gently rolled off. Can’t say I have heard that and the Treos most certainly have real sparkle to the top end. No, they are not aggressive. But you can hear that cymbals are a metallic instrument, not steam escaping. And some drummers can play the cymbals with great subtlety as opposed to a bright sound in the background.

Onto my audio test lists.

So, starting with more audio centred music I tried the theme tune from His Dark Materials by Lorne Balfe. The soundstage opened up with a large orchestra playing the theme tune which builds up in the short 1:58. The sound was natural, sumptuous. And the tonal dynamic range was large with warm bass and brighter percussion.

I followed this with The Games of Thrones Medley by 2 Cellos. The rasp of the cellos was natural, not over smoothed making it difficult to identify them as Cellos or overdone and thin sounding. The speaker built up the tension by subtle changes in timing that gets released slightly as the track finishes leaving you in expectation of what was to come; a dramatic TV programme.

Onto the electronic sounds of Ember playing ember. The electronic effects were easy to hear and place in the soundstage. Unlike some other speakers, it was not the artificial ultra-sharp placement that just sounds wrong. The music simply flows as does the bass with the bass not sounding staccato. Great. If I want to be critical (it is my job!) then there was a small lack of ultra-deep bass.  But foot tapping and head bobbing was there aplenty.  

Surprisingly Led Zeppelin playing Dazed and Confused (not the best recording) sounded dynamic and powerful with Percy Plant letting it rip. This was a raw and unrefined Led Zep on their first album recorded in a very short time. No, it was not a ragged sound but it was raw and a letting it rip Led Zep. The track went at a great pace and Page’s guitar solo cut through the air and gave us all a taste of what was to come from the lads.

Tom Jones on Did Trouble Me allowed his closely miked voice to shine through. This cut back recording supplemented his singing and his voice was superbly rendered. In contrast, Rhiannon Giddens recording of Birmingham Sunday starts with gentle country-tinged sound but as the track develops the dark subject emerges and the speakers allowed the emotional contact between her and the listener over the murder of these black people. Wow, powerful and easy to hear and connect with through the Treos.

Opium from Dead Can Dance has a lot of percussion and drum sounds recorded with varying amounts of reverb. All came through clearly with a naturally recorded voice. A great track that builds up with a large soundstage made up of many layers. It certainly kept my attention.

On to some bombastic cinematic music from Hand Zimmer. Why So Serious from the Batman film. This is a mixture of an orchestra and special effects to give a huge powerful sound with an enormous soundstage. And that is what I heard. Big, powerful, dynamic and also delicate during the quieter parts. Yes, some of the bass power was not as dramatic as other speakers as the speakers’ bass response goes down to the low 20s. But that did not stop this music from being dramatic and powerful. Kevin Akam from Signature Audio mentioned that the bass can be ‘helped’ by mounting the speakers on a granite plinth to help the downward-facing port and of course there is always a bass sub. Despite this music made an unaware wife jump in her seat when the bass effects came crashing in.

I then started to forget all this reviewing lark and went into enjoyment mode and just listened to what I fancied at the time. The Treos opened the window onto what was recorded and was informative and musically enjoyable.  I was having fun and enjoying my music.

So in conclusion, the Treos are a well-made innovative speaker that just plays music. Yes, there is a lot of speaker technology but if it had not sounded so informative and musical it would have been for nought. It was a great speaker with a very modern dynamic sound. Given the construction and all that is involved with this speaker then £14K is not unreasonable. In fact, it is difficult to think of a competitor that can do all this speaker does for the price. Yes £14K is a lot of money but this is a lot of speaker and there are always the other Vandersteen speakers in the range. If you like a dynamic speaker with a brilliant soundstage and a natural sound (and have the money) then get to listen to this speaker. It would be worth your while.

Boy, the distributor of these speakers was sure glad to get them back from me! Me less so.

Distributed by Signature Audio Systems.

Treo Specifications



1” Exclusive Dual-Chamber, Transmission-Line Loaded, Ceramic-Coated Alloy Dome with Ferrofluid Voice-Coil Cooling 


4.5” Reflection-Free Tri-Woven Composite Cone with Die-Cast Aerodynamic Basket and Magnet System with Ferrofluid Voice-Coil Cooling 


6.5” Woven-Fibre Cone and Precision-Formed Magnet Assembly Copper Faraday Ring 


8” Carbon-Loaded Cellulose Flat-Cone Woofer with Ultra-Long-Throw Motor Assembly with Down-firing port in QB3 Alignment

Recommended Amplification

40-160 watts per channel into 8 ohms

Frequency Response

36Hz – 30kHz +/- 3dB


85 dB, 1 meter/2.83 volt input


6 ohms +/- 3 ohms


First Order, All Drivers in Positive Acoustic and Electrical Phase


First order/6dB per octave, 80Hz, 900Hz, 5kHz

Input Terminals

Barrier strips, 7/16" max width

Dimensions (WHD)

10” x 43” x 15”


80 lbs. Net

Country of Manufacture

Made in the USA

Edited by George 47
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