ENIGMAcoustics Sopranino Super-Tweeter

A QUAD’s Best Friend

Equipment report
ENIGMAcoustics Sopranino Electrostatic Supertweeter
ENIGMAcoustics Sopranino Super-Tweeter

What is not so simple is the task of integrating the Sopranino into an existing system. Lacking a volume control (save for its -3dB switch), there’s the practical problem of gain-matching the Sopranino to a range of speakers of varying sensitivity. It turned out that this is not as serious an issue as it sounds, since an indirect adjustment of volume level is possible by use of the toe-in angle. The fact that output level falls off with angle, though not as dramatically as is the case for a large flat panel, can be put to good use in controlling the tonal balance at the listening seat. The most serious set-up complication arises from potential interference between the super-tweeter and the main speaker’s tweeter. The latter is not rolled off by an external crossover network and depending on its relative distance from the super-tweeter, response dips and peaks may result in a frequency overlap region. Granted that with two level settings and three crossover frequencies, there is fair amount of flexibility built-in for experimentation, far more than is offered by other add-on tweeters, but that of course is no guarantee of success.

When the review project was arranged it was agreed that the Sopranino should be evaluated in one specific context. The framework chosen for this review involved mating the Sopranino with the QUAD-57 ESL. The rationale was based on three factors. First, the QUAD needs help in the treble. Second, it made sense to extend the response of an ESL with another electrostatic driver. And third, since there are over 60,000 QUAD ESLs out there, this coupling would be of interest to a large audience. There is already an established history of extending the QUAD-57’s treble response via the use of an add-on tweeter. The JansZen Z-130, Decca Ribbon, and even the Dukane Ionovac plasma tweeter have been used for this purpose. I recall Bob Graham describing such a setup many years ago, where he used a Dukane Ionovac tweeter crossed over at about 8kHz to very good effect.

Stands were provided by EnigmAcoustics to allow positioning of the tweeter behind and a few inches above the top of the QUAD, the bottom of the stand being at about 39 inches off the floor. The stands were machined out of high-grade acrylic stock and were beautifully finished. Optimal placement is with the Sopranino centered behind the QUAD’s treble panel. As you might have expected, level-matching the 83dB-sensitive QUAD necessitated use of the Sopranino’s -3dB gain setting. In order to obtain a natural brightness level, it was also necessary to toe in the Sopranino such that the tweeter axes intersected in front of the listening seat. To be a bit more precise, a toe-in angle between 5 and 10 degrees (with zero degrees being straight out) should do the trick. A side benefit of such a toe-in angle was an apparent increase in soundstage width.

It turned out that the best way to hone in on the optimal crossover frequency was to focus on female soprano voice. It’s easy to be seduced by an overabundance of presence region energy. Initially, I was wowed by an 8kHz crossover setting, but it quickly became clear that tonal colors just weren’t right, being too hot, while the treble range developed some rough spots texturally. It has been said that if something measures good but sounds bad, you’re measuring the wrong thing. But this was a case of measuring bad and sounding bad. There were severe interference effects measured at the 8kHz setting, fewer with the crossover shifted to 10kHz. Moving the measurement mike several inches vertically also resulted in significant response dips. The most synergistic and stable blend was observed at the 12kHz/-3dB settings, and all subsequent listening tests were conducted with these settings dialed in.

If ever a speaker needed a super-tweeter, the QUAD is it. It is a prime example of British sound, being laid-back and a bit polite though the midband. Well, with the Sopranino in the system, the presentation was fundamentally transformed. Imagine, if you can, a QUAD that is much more neutral in character, whereby instruments are brought a bit more forward in the mix. Where the QUAD sounded somewhat muffled and lacking immediacy playing solo, the Sopranino enhanced transient clarity and soundstage transparency. There was now a genuine sense of treble air, and, most importantly, tonal color saturation improved significantly, especially when it came to soprano voice and violin timbres. It was hard to believe that a driver that outputs such a small fraction of the total acoustic energy could have such a dramatic impact on the perceived sonic impression. But that, ladies and gentlemen, was what happened. I also noted a consistent improvement in image focus. Image outlines coalesced into palpable organic wholes that made for much more secure spatial resolution of complex orchestral passages.

There’s no doubt in my mind that the QUAD and the EnigmAcoustics Sopranino are soul-mates. Despite my initial reservations about driver blending, the Sopranino proceeded to strikingly refresh and extend the QUAD’s performance. Once experienced, there’s no going back. I can’t imagine enjoying the QUADs in the future without the Sopranino super-tweeters. It’s fair to say that performance-wise the Sopranino catapults the venerable QUAD-57 into the 21st century. If you’re a QUAD owner, be sure to check out the Sopranino—it’s a QUAD’s best friend!


Frequency response: 8-40kHz (+/-3dB)
Nominal impedance: 4 ohms
Sensitivity: 90dB (1m/2.83V), with 0/-3dB switch
Weight: 6 lbs.
Dimensions: 7.13" x 7.60" x 8.15"
Price: $3690/pr.

11 Chrysler
Irvine, CA 92618
(949) 340-7590

Associated Equipment
PrimaLuna Dialogue Premium and JWN 807 amplifiers, Yoshino-EAR DAC, April Music Stello U3 digital converter, Sony XA-5400 SACD player with ModWright Truth modification; Kuzma Reference turntable; Kuzma Stogi Reference 313 VTA tonearm; Clearaudio Da Vinci V2 MC phono cartridge; Pass Labs XP-25 phono stage; Pass Labs XP-30 line preamplifier; FMS Nexus-2, Wire World, and Kimber KCAG interconnects; Acoustic Zen Hologram speaker cable; Sound Application power line conditioners

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