muRata's Amazing ES103A Super Tweeter Review By Dick Olsher

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October 2004

muRata's Amazing ES103A Super Tweeter
Review By Dick Olsher
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The muRata super tweeter is a high-tech product spun off the company's on-going R&D program in piezoelectric ceramics. Those of you who followed my Consumer Electronics Show reports for the past couple of years may recall the attention I lavished on this particular technology. At the core of the tweeter is a spherical piezoelectric ceramic membrane with excellent pistonic motion and dispersion characteristics, and featuring frequency extension well beyond the range of human hearing into the ultrasonic range. You must, I am sure, be wondering at this point about the utility of pushing the response of a tweeter into the auditory range of dogs and bats.

While ultrasonics can't be heard in the conventional sense, such energy can couple directly to the brain and be perceived. There is in fact scientific evidence (including PET scans) that demonstrates cerebral blood flow activity in response to ultrasonic energy. Of course, these findings are irrelevant to music reproduction in the home since the program material is severely bandwidth limited. For example, the standard CD format is confined by a 20kHz hard limit. Yet despite the program bandwidth limitations, in my experience, the higher the tweeter's upper frequency limit, the faster it sounds. But there is more to it than that. As you will discover very shortly, a super tweeter's impact can extent well below its active bandwidth.

The ES103A is housed in an aluminum cylindrical enclosure that is attached to a cast base. It comes in two flavors, A and B, which account for cosmetic finish differences, and in addition the B version includes an adapter for mounting the base to a microphone stand. The tweeter is intended to be placed directly on top of an existing speaker cabinet, or placed next to the main speaker either using a speaker or microphone stand. The super tweeter incorporates the required high-pass filter, so all you have to do is connect it to the amplifier. That may be done by running wire from the main speaker terminals, or by connecting it directly to the amplifier output terminals. In either case, be sure to maintain the correct signal polarity. The super tweeter's short-term power rating is 300 watts, so it may be safely connected to even high-power amplifiers.

The average SPL rating is 90dB/W/m. In my experience, as long as the main speaker's tweeter is rated within about ±3dB of the ES103A, the super tweeter should integrate well with the main system. In addition to the flagship ES103A, a slightly less expensive version (ES105) was recently released, which is said to offer similar performance and features an integrated enclosure-pedestal design.

The Sound

There was a time, many years ago, when I viewed the frequency extremes with prejudice, as merely an audiophile obsession with bass and treble. High-fidelity then was being defined and promoted by the industry on the basis of lower distortion and frequency bandwidth. The resultant perception was that a legitimate pathway forward from low toward high fidelity lay in extending a system's frequency extension. This notion gave birth to two new product categories: subwoofers and add-on tweeters. And the rest is history; G-d only know how many such zillions of add-on products have been sold over the years. As my personal priorities had to do with midrange quality and tonal balance, I rejected the zero to daylight bandwidth approach then as nothing more than either an effort to sugar-coat failures in the critical mids or as a doomed attempt to fix bass balance problems. To this day, I still hold a dim view of subwoofers. Tragically, many audio dollars get sucked up in a subwoofer purchase, typically in an attempt to fix a small two-way speaker's bass balance. For various technical reasons, this will not work, the most obvious one being that complaints about bass balance usually have to do with lack of bass in the upper bass region, spanning the octave from 120Hz to 240Hz. And that is a frequency range that is not addressed by the addition of a subwoofer.

Ironically, as I have aged and my own auditory system's high-frequency extension has diminished, my appreciation of a super tweeter's role in a speaker system has in fact increased. Take, for example, the Spendor BC1 loudspeaker. Here is a British classic from the 1970s that in its day was routinely winning magazine-sponsored blind listening tests, and for years had captivated the hearts of music lovers with its sweet midrange tone. Its driver complement consisted of a small woofer, a tweeter, and a super tweeter. I had wondered back then as to why Spendor had opted for a three-way design where two of the drivers are tweeters. My argument was that engineering logic dictates that the driver complement for a three-way should include a midrange driver. Years later, I have come to realize that the BC1 should be viewed as a two-way design with an added super tweeter. And that part of its enduring appeal, a critical design factor that elevated its sonics above the competition, can be traced to the use of the Coles 4001 super tweeter.

If Spendor was so successful in its implementation of a super tweeter, then taking the Spendor BC1 lessons-learned knowledge forward, the obvious question becomes: is it possible to improve the sound of a good two or three-way speaker by adding-on a super tweeter? In the case of the muRata ES103A, the answer is a resounding yes! Though the nature of the sonic improvements will surprise you. Given the range of the ES103A's frequency response, from 15kHz to 100kHz, most listeners would merely be looking for added transient speed and treble transparency from their loudspeaker system. And while the upper octaves did gain air and definition with the ES103A in the system, the main benefit turned out to be in the midrange. The music's drama and microdynamics were intensified. Harmonic textures were more vibrant and in focus - as if a giant search light were illuminating the soundstage, resolving more of the color and energy of the musical tapestry. The rhythmic underpinnings of the music flowed with greater flair and conviction. The overall effect was to nudge the sound closer to the essence of the real thing, namely live music.

Nick Gowan, of True Sound, the US distributor, offers the following synopsis, with which I concur: "Given the name 'Super Tweeters,' many people are misled into thinking that the addition of this component will repair deficiencies in the high-frequency range of their systems. The contribution of the Super Tweeters to a high-end system is a much more pervasive one. The Super-Tweeters affect all frequencies, not just the high frequencies. Once the listener stops focusing on hearing a high-frequency effect, the true nature of the Super-Tweeters is clearly evident. Music has the shimmer of life, and everything sounds more intensely ‘real.' In that sense, the Super-Tweeters do not ‘add' high frequencies. Whether the music being reproduced is an aria or a symphony, the musical presence is more substantial and compelling."

Gowan also reports that the super tweeter effect is dependant on the quality of the main speaker system. A high-resolution speaker is said to offer the greatest scope for improvement, while speakers lacking in clarity may totally obscure the effect. Thus, the ES103A should not be viewed as a panacea that may transform a bad speaker into a superior performer. However, as my listening tests showed, in the context of a good-sounding system, the muRata super tweeters deliver the goods. My listening tests involved the BassZilla Platinum Edition and the Samadhi Acoustics Natalia loudspeakers. In the case of the BassZilla, the ES103A was positioned on top of the woofer box, adjacent to the open baffle. Despite its somewhat "awkward" placement, the super tweeter appeared to integrate well with the BassZilla's driver complement, which includes the Aurum Cantus G2Si ribbon tweeter. I was very curious to see how the ES103A would perform in the context of speaker whose frequency response is already extended to 40kHz, and to be honest I had my doubts. But the proof was in the listening. The upper-octave power response was changed due to the ES103A's wider dispersion relative to the controlled dispersion of the ribbon tweeter. The effect was to widen the listening seat sweet spot. But as I mentioned earlier, what really won me over were the gains in harmonic vibrancy and the intensified dramatic flair of the midrange. And this was true for both CD and vinyl playback.

With the Samadhi Acoustics Natalia, a four-driver, three-way conventional speaker system, which is used in my home theater system, it was possible to place the ES103A directly on top of the enclosure, and in vertical alignment with the existing tweeter. Note that for all of the listening tests, the super tweeter was wired in parallel with the main speaker terminals. I did not experiment with bi-wiring or bi-amplifying, which are the two other connection possibilities. Once again, even with a different speaker in a different room, and this time driven by solid-state electronics, the ES103A made for an audible improvement in midrange vitality.

It is important to note that at no time did the addition of the ES103A super tweeter brighten or etch the sound. These effects would typically represent tweeter artifacts in the form of dissonant distortion products or undamped resonances. At the top of my short list of awful super tweeters are horn-loaded inexpensive piezoelectrics. A popular modification to the vintage Dahlquist DQ-10 loudspeakers was to disconnect the piezo tweeters and breath a sigh of relief. Some of the Infinity speakers of years past also featured a relentless upper-octave balance caused by a beamy quasi-ribbon tweeter array. Taping over some of the Infinity tweeters proved to be an effective fix. In contrast, the ES103A was always so well behaved and pure sounding that it proved to be extremely easy to embrace even after a prolonged listening session.

Conclusion

Warning: the muRata super tweeter effect is addictive and can positively become habit forming. It helps bridge the gap between live and reproduced music. Disconnect the super tweeters, and it feels like someone turned off the lights: the presentation becomes darker and less present; to put it bluntly - boring. Once experienced, it's definitely hard to live without them. Their auditory system impact goes well beyond refining the upper octaves. If your high-end system is ready for a dose of Viagra, be sure to check out the muRata ES103A or its slightly less expensive brother, the ES105. In either case, your listening enjoyment is likely to catapult considerably closer to the live experience.

Specifications

Type: Super tweeter

Frequency Range: 15kHz to 100kHz (internal mechanical network)

Average SPL: 90 dB/W/m

Resonant Frequency: 103kHz

Rated Impedance: 8 ohms

Maximum Continuous Power: 50 W (pink noise)

Directivity: on-axis ± 45 degrees

Dimensions: 65 mm (diameter) x 110 mm (length)
(2.6" diameter x 4.3" length)

Weight: 1.1 kg (2.4 lb) each

Price information:
ES-103A $2,250 per pair
ES-103B $2,950 per pair
ES-105 $1,825 per pair