ENIGMAcoustics Sopranino Electrostatic Super Tweeter review

THE ENIGMAcoustics MYSTERY review

1. Getting to Know You

The ENIGMAcoustics Sopranino is a self-biasing electret driver loaded to a short horn. At the rear of the housing is an adjustable crossover (8, 10 and 12 kHz), and adjustable sensitivity (87, 90 dB).  The unit is driven in parallel by your system’s amplifier.  
Enigma recommends the Quad ESL as the ideal match for the Sopranino. While the Quad’s midrange is universally admired, designers have long been aware of the speaker’s diminished output in the treble.  Forty years ago, Mark Levinson chose the Quad as the midrange of his no-holds-barred system, but supplemented the treble with the Decca ribbon tweeter.  That’s why stacked Quads, held bottom to bottom in oak frames, have a small slot between speakers: the Decca goes there.

(It’s amusing to note that this system, complete with preamplifiers, active crossovers and six amplifiers, all cables, two enormous passive subwoofers, two pairs of Quads and two tweeters, cost about $130,000 in 2015 dollars.  The price was breathtaking, totally shocking.  Who could possibly afford such an assembly?  And now we have a number of turntables that cost more, and loudspeakers that expensive are thick on the ground.)

Other reviewers have placed a Sopranino on top of a single Quad 57.  To the best of my knowledge, Mono and Stereo presents the first report of an Enigma tweeter used with Quads stacked in Levinson stands.

A problem presented itself immediately: the Sopranino’s horn is about an inch taller than the aperture allowed by the Levinson stands.  This tweeter is quite handsome, but it’s too large to fit between Quads.

Enigma sent along a pair of stands.  These are simple devices that allow the user to adjust tweeter height from 36 to 48 inches off the ground.  The stands are neat, well-made, and easy to assemble; they are also two more pieces of gear in the listening room.  Oh, well.  If I had wanted a small loudspeaker, I should have chosen the Quad 11L, a very small box with built-in amplifiers.

In my 27x17x14 foot room, the Quad ESL tweeter panels are ten feet apart .  Per Enigma’s instructions, I placed the Sopraninos outside the Levinson stands, so they were thirteen feet apart, and thirteen feet from my listening seat.  I adjusted the platforms to place the units 43 inches off the ground, level with my ears in the listening chair.

I ran Anticable Level 3 speaker cable from my VAC Renaissance amplifier to the Sopranino’s WBT terminals.  This is simple, honest copper wire that doesn’t editorialize.  Let the Sopraninos speak for themselves, I reasoned. 

2. Soundings

The Sopraninos opened the soundstage considerably, with a deeper and wide image. The effect was not subtle.  Instrument placement was a bit more sharply defined, as well.  Focus was sharper, but without the chiseled, overly detailed effect that I’ve heard with some solid state amplifiers that nail down every detail, but also drive nails into the music.  The Sopraninos also avoided drawing attention to themselves, unlike some exotic tweeters.  The Sopraninos gave me specificity while preserving the delicacy of the performance.  Height did not change.  Since stacked Quads operate as a line source with a tweeter nearly two meters tall, this was not surprising.

It didn’t take long to notice that the tweeters’ output is directional.  In addition to the 3 dB gain switch, the listener can get more or less sound by adjusting the toe-in.  With the Enigma stands this is easy to do, and again, the results are easy to detect. There is no discernible break-in period.  What you hear in the first minutes is what you will hear months later.

When I was satisfied that I had matched the new tweeters to the rest of the system, I settled in for some serious listening.  

Color saturation and image density are two measures of how realistically a system portrays musical events.  The Sopraninos put flesh on the sonic bones.  Too often a speaker will suggest an instrument and allow the listener’s imagination to add shading and tone.  With the tweeters adjusted correctly, I heard more shading, the small but indispensable clues that musicians are in the listening room.  Put it the other way: when I removed the Sopraninos, the system was very good – just not as good as it was with them in place.

I did not expect the Sopraninos to improve the midrange.  If the unit’s lowest crossover frequency is 8 kHz, and the slope is 12 dB per octave, the tweeters should play 36 dB softer at 1 kHz and their contribution should be negligible.  That’s not what I heard.  Not only were the top registers of female voice and violins clearer and more articulate, so were the middle tones.  This was the first of my Enigma mysteries.  I welcomed the improvement, but couldn’t explain it.  

3. Changing partners

It’s very safe to say that the Sopraninos are a complete success with stacked Quads.  But how do they perform with other loudspeakers?

I tried them with Silverline 17.5s.  These are simple two-way vented box enclosures with Dynaudio drivers.  Sopraninos made this very pleasant speaker more articulate and more incisive.  The Enigma perched comfortably on the cabinets, so the small footprint and modest visual impact of the Silverline were preserved.

Next came a pair of Sonic Precision speakers.  Since they use the ScanSpeak 2904 tweeter – rated out to 40 kHz, just like the Sopranino – I wondered if the electret tweeter would make an audible difference.  The answer was simple, and arrived as soon as I plugged the Sopranino into the system: yes, it did.  With the crossover set at 12 kHz and sensitivity at 90 dB, there was more air and improved sense of space.  

This raised a couple of questions.  Shouldn’t these two tweeters, separated by several multiples of a 20 kHz signal wavelength, interfere with each other?  They should, but don’t.  No one who came to that trial could hear cancellation or augmentation effects.  Shouldn’t the tweeters, with different radiating areas, confuse the imaging?  No again.  

My last test pulled the Edgar Slimline horns into the room.  The Slimlines use a Fostex tweeter that fades out around 15 kHz.  Here the Enigma effect wasn’t so pronounced.  I suspect this relates to the Edgars’ 100 dB sensitivity.  The Sopraninos can’t come close to that output level.  

I was left with a greater mystery.  How can reviewers – no matter how well trained and experienced their ears – hear the Sopraninos?  Here’s a hearing acuity chart from The Internet Journal of Otorhinolaryngology.  

Even young adults lose some high frequency acuity; but older ears lose more, and far more in the upper octave.  To state it bluntly, people over 50 shouldn’t need tweeters at all.  This is the ENIGMAcoustics enigma: either we are all deluded, or we are hearing something that we can’t measure.

4. What You Can’t Hear Can Hurt You

For a very long time, it has been an article of our faith that human hearing extends only so high as 20 kHz. I’ve been puzzled by the success of extended bandwidth products such as the MuRata tweeter, which is said to reproduce signals as high as 100 kHz, and Spectral amplifiers, which claim to reach out to 1 MHz.  Even if we could hear that high, what is there to hear?  Neither digital nor analogue formats promise anything more than 20 kHz.  And yet I’m not alone in reporting that the difference is audible.

Professor Milind Kunchur at the University of South Carolina has worked on these phenomena.  Some of Professor Kunchur’s research is summarized here:


There’s also an article published in Journal of Neurophysiology, “Inaudible High-Frequency Sounds Affect Brain Activity: Hypersonic Effect”:


This is the piece that everyone on audio blogs and discussion circles talks about.  Near the end of the abstract I read, “These results suggest the existence of a previously unrecognized response to complex sound containing particular types of high frequencies above the audible range.”

Hmm.  Maybe our brains can respond to very high frequency information; but where does the information come from?  Not from phonograph cartridges, nor from compact disc players with brick wall filters, nor through our aging ears.

There’s an old proverb about evidence: a surgeon should believe what he sees, not see what he believes.  That applies equally well to audio.  We can debate the theories, but we shouldn’t disregard what we hear.

5. A Matter of Values

As I write this, a pair of Sopraninos costs almost $4,000 dollars.  A pair of stands costs $600.  That’s a lot of compact discs, an impressive new DA converter, or a respectable turntable.  You’ve got a pair of loudspeakers.  You like them.  They sound quite good. Does the improvement justify the expense?

I think this misses the entire point of our hobby.  We may be neurotic, but we can tell the difference between two components, and we definitely prefer one to the other.  We spend thousands of dollars – more than a pair of these tweeters – on interconnects, line conditioners and isolation platforms to achieve much smaller improvements.

I recently spent a very pleasant weekend listening to a system out of the 1960s: an AR turntable, Shure cartridge, Dynaco preamp, amplifier and speakers, with 18 gauge lamp cord.  The most modern part of the system was a Nakamichi compact disc player from the late 1980s.  After I became accustomed to the sound, it was quite acceptable.  Yes, I had to suspend my disbelief at the limitations of the assembly, but that’s what we always do: I have yet to hear a home system of any cost that sounds like a performance in Avery Fischer Hall in New York or the Musikverein in Vienna. 
Yes, they’re expensive, but the Sopraninos can take us another step closer to our goal.

Text: H. Richard Weiner