The Secrets Team has reviewed many electrostatic speakers in the past.

This review takes a look at the first portable Bluetooth electrostatic speaker system.

BenQ treVolo Review


BenQ treVolo Wireless Bluetooth Portable Electrostatic Speakers

  • Unconventionally designed Ben Q electrostatic diaphragm technology
  • Quad amplified design
  • Dual bass drivers and passive radiators
  • CD quality aptX Bluetooth transmission
  • Selectable built-in equalizer modes
  • Speakerphone convenience
  • USB transmission through Micro USB connection
  • 12 hours battery life

BenQ is a firm that is known for a world class line of professional DLP video projectors, monitors and digital signage. The Ben Q treVolo is the world’s first portable Bluetooth electrostatic speaker system. When the Secrets Team told me they were sending the world’s first Bluetooth electrostatic speaker system for me to review I was truly intrigued. Many years ago I had owned a cherished pair of Acoustat Model 4 electrostatic loudspeakers. I fondly remember their clarity of sound and their size. Visitors to my home would jokingly ask me if I had the monoliths from 2001 a Space Odyssey. When the package arrived my wife asked if the box contained the speakers I was expecting. When I said yes, she responded with “they’re tiny”. I opened the box to see if BenQ had produced a small miracle and at the same time kept their corporate vision of “Bringing Enjoyment ‘N’ Quality to Life”.

Frequency response:

60 Hz – 20 kHz



Bluetooth® 4.1

Input Types:

3.5 mm Stereo Input, USB Audio

aptX Support:


Playing time:

12 Hours (dependence on user scenario)


Key definition:

Power Key, Volume Key (+-), Sound Mode Key (end call), Play/Pause(talk), BT Pairing Key

LED indicator:

Red LED x 1 ; Blue LED x 1; Green LED x 1

Other information


Built-in Rechargeable Lithium-ion Battery

Other Features:

Built-in Microphone for Speakerphone Function


AC/DC Charger, Quick Start Guide

IO port

Micro USB x1 ; Line-in x1 ; Line-out x1 , Power Jack x1

Input Power Rating:

DC 12V 2A

Temperature Range for Use:

0~40º C


7″ H x 3.1″ W x 5.3″ D Closed)


2.5 Pounds


treVolo Music


BenQ, treVolo, Wireless Bluetooth, Electrostatic Speaker, Portable Speaker

BenQ treVolo Review


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What’s an electrostat you say? Simply put, an electrostatic speaker is made of a thin membrane that is sandwiched between two perforated conductive plates. The plates are called stators and when a high voltage charge is applied to the system, the membrane will vibrate. The vibration creates magic, because music is re-created through the system. I can always use a little magic in my life so I was excited to see and hear the treVolo.

BenQ treVolo Review

Carefully pulling the small treVolo from the box I immediately liked its clean un-boxy look. From the outset the treVolo looked and felt like a quality high-tech device. The jewel-like unit has angled lines and rounded edges, giving it a stealthy look, and the metal outer sheath gives it a substantial feel. On the top and the back are the controls of the unit. A large round button on top is the power on and off. In front of the button are a set of four smaller ones: the phone answer and disconnect line (yes, while you stream from your phone you can answer and use the device for a call) and the volume up and down buttons.

BenQ treVolo Review

The two phone buttons also double as the music mode (the treVolo has three user selectable equalization modes) button and the pause/ play buttons. At the bottom of the back plate are the AC power in, line out, line in, and micro – USB inputs.

BenQ treVolo Review

Behind the beautifully sculpted front plate are two woofer units. After admiring the outside I then carefully opened its wings, or rather the electrostatic panels that open out from the front of the unit. To me it was almost butterfly-like. Revealed behind each panel was an oval sub bass radiator unit. The treVolo features an internal quad amp that drives the electrostatic panels and the bass units. I couldn’t wait to plug in the included charger.

The experience of having an electrostatic loudspeaker brought fond memories of long ago for me. At one time I was the proud owner of a pair of Acoustat Model Fours. These were really large full range electrostatic speakers. I loved the detail and the clarity of these (at the time) state of the art speakers. Now one of the quirks of electrostatic speakers is that they are not as dynamic as cone or horn speakers. However, they are fantastic at reproducing solo or chamber music. They do this so well that you feel like you can reach out and touch the musicians. Another quirk is that, because of the large radiating surface, most electrostats tend to have a very tight optimum listening window. That is because the radiating pattern of the high frequencies is very narrow. What that means is that they tend to beam the sound towards you. I remember that when listening to the Acoustats I could change the sound of what I heard simply by moving my head slightly from side to side. When I did this the placement of the musicians on the stereo plane would shift. Modern electrostats have generally improved in this area. Martin Logan is one manufacturer that curves the panel to increase the dispersion pattern of the sound. In addition, Martin Logan and other manufactures have added cone speakers like subwoofers to complement the sound of their speakers so that they are more dynamic and have added bass. The treVolo also uses dynamic cone subs and passive radiators. (Please see the next picture.) Now as I prepared to listen to the treVolo, I wondered what I would hear from this new design.

BenQ treVolo Review

In Use

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My guess is that BenQ is aiming this life style speaker for those young folks who want a portable, fuss free connection to a phone or mobile device for superior sound. As an aging boomer, I may not quite fit their profile, but I found that the set up was easy and quick. The top of the treVolo has a large round button that you press and hold down when you want to turn on the unit. It will make a little beeping sound (it’s alive and awake) and then you set your phone or device on discoverable mode from the Bluetooth setting. The treVolo appeared almost immediately on my I-phone 6 + and I selected it. Once linked I opened its electrostatic wings and I selected my music. I initially listened to I-tunes radio, but as Apple owners know the company has introduced its Apple Music to its customers. Most of my critical listening was done with the new Apple Music.

BenQ treVolo Review

My initial reaction was pleasant surprise. The treVolo’s sounded full and bigger than their tiny size. A feature of electrostatic speakers is that they radiate sound in two directions, to the front and to the rear. So not only do listeners hear the initial wave of sound, but there is a back wave as well. This is something common to all planar speakers including electrostatics. The front and back radiation of sound produces a more life- like sound to many listeners. In my room the little treVolo’s simply disappeared and sound seemed to float in the air.

Cat Stevens

Cat Stevens “Teaser and the Firecat”

I found one of my all-time favorite recordings, Cat Stevens Teaser and the Firecat album on Apple music. The first track, The Wind is a simple arrangement featuring Cat Stevens and his guitar. On this intimate track the treVolo gave a sweet rendition of the guitar strings as they were picked. Cat Steven’s voice was open and reproduced with appropriate weight. Beautiful song and beautiful reproduction was what I wrote down on my notes. I next moved on to Morning Has Broken and once again I heard great guitar and vocal presentation, both very clear and airy. The piano had good definition through the middle range, with enough low end to give satisfactory fullness to the sound.

Cat Stevens

Cat Stevens “Tea for the Tillerman”

Continuing on my listening journey with Cat Stevens I found Tea for the Tillerman. On the Where do the Children Play? track I was surprised by the clarity of the electric piano, it was very well defined. When the bass came in I thought the sound was very tuneful. The strum of the pick on the strings was very well rendered as you could hear each string resonate after being struck by the pick, very realistic. The drums were clear, though not as impactful as in reality or with much larger speakers. On the track Father and Son I simply wrote beautiful, beautiful song rendered beautifully. I noted that I could hear the individual brushes on the drum skin so much so that I could hear the brushes being lifted off the drum head. When the backing vocals came in, everything remained clear and musically involving.

Florence and the Machine

Florence and the Machine “Ceremonials”

I decided to try something a little heavier, so I dialed in Florence and the Machine. On the song Only if for a Night I noted again clear vocals, clear piano, clear percussion. If there was not enough low end punch for this music there was good mid-range punch and excellent rhythm. Moving on to the track Leave My Body I noted that there was good re-creation of the atmospheric sound scape. The churning drum work was also well defined by the treVolo.

Anderson and Roe

Anderson and Roe “The Art of Bach”

Next I tried some classical favorites. I found The Art of Bach by the delightful piano duo of Anderson and Roe and the recording provided lovely tone from the pianos. The scale of the piano was miniaturized by comparison to much larger speaker systems but the sound was smooth and clear through the mid-range. The wonderful, musical interplay between the artists was well preserved by the treVolo.

Academy of St. Martin in the Fields

Academy of St. Martin in the Fields “The Bach Brandenburg Concertos”

The Bach Brandenburg Concertos by the Academy of St. Martin in the Fields provided some of the best listening experiences for me during this this review period. The sound was glorious. The sound of the harpsichord, horns, and strings were kept clear throughout the recording. Notably, the treVolo was able to preserve the acoustic sound of the hall. The sound of the strings was especially enjoyable. I could listen forever to the beauty of the sound of the treVolo on this recording.

Sarah Vaughn

Sarah Vaughn “Golden Hits”

I took a listen to the incomparable Sarah Vaughn on her Golden Hits off the Mercury label. On the Misty track, I heard stunning, soaring vocals. The sax solo was well done and the mid-range had magic. The pure tone of Sarah Vaughn’s voice was wonderfully reproduced. When I listened to Moonlight in Vermont I stopped writing notes. The song and the sound just blew me away. I couldn’t believe I was listening to such a small blue tooth speaker.

ZZ Top

ZZ Top “Greatest Hits”

The treVolo did very well with acoustic music, but how about some rock and roll. I dialed up ZZ Top and listened to La Grange and Tush. The boys from Houston sounded pretty good over the treVolo. The limits of a small speaker kept me from going party mode, but the treVolo had nice fullness. In addition, I could hear good definition of the drum sticks, as well as good tonality on guitar, bass and drums. What the treVolo lacked in loudness and slam, it more than made up in rhythmic drive and nimble layering of the sound.


BenQ treVolo Review

With the treVolo, BenQ has produced an impressive package of portability, technology, and fun. While the small treVolo could fill a larger room with a healthy amount of sound, it also avoided the beaming electrostatic sound I have heard in older designs.


  • Very cool, high tech design
  • Excellent sound quality
  • Easy to use
Would Like To See
  • Larger, more powerful model

While this unit will not be the loudest small Bluetooth speaker or the most bass heavy, it may well be the most musically satisfying for listeners that favor natural acoustic music. Finally, the treVolo made such an impression on my wife that she said; “Just buy it already! It’s cute!” Thank you, Ben Q!

P.S. I used the treVolo as our sound system for my wedding reception at our church hall this past weekend. My son is giving a speech while my wife and I are seated at our table. You can see the treVolo on the white gift table next to us. The treVolo did a great job.

BenQ treVolo Review