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sE Munro Egg 150 Monitoring System

My favorite song as a confused teenager was “Substitute” by The Who.

My favorite song as a confused teenager was “Substitute” by The Who. “The simple things you see are all complicated” became an anthem for my realization that acoustics is, superficially, a very straightforward science and yet what we hear and interpret as audio is incredibly complex. Some 40 years later, I feel I have a sufficiently deep understanding of the subject to justify the unusual lengths taken to optimize the Egg monitor system.

The shape of the Egg is a product of natural evolution and the properties of strength, rigidity and smoothness all translate directly into physical parameters that can be justified from an acoustic standpoint. The diffraction effects are practically zero, and that means the frequency response is much more linear, especially off axis, and that affects all the energy radiating into a room. The internal geometry is less well documented, but the absence of parallel planes reduces the wave coherence and results in a more homogeneous output at low frequencies and less coloration from back pressure on the bass driver. The pressure zone (very near-field) frequency response between driver and port at low frequencies is the best I ever measured in any system, with less than +/-1 dB variation between 50 Hz and 500 Hz.

There is a great deal of debate about the bass response of monitors and all too often the LF output is extended at the expense of distortion and transient response. The other extreme is closed box (NS10) type construction, but this can result in too little real bass to qualify as a reference monitor, although useful in other ways as a tool of the trade. Quality is more important than quantity, so that is what we have strived to achieve.

The lack of diffraction and internal resonances gives a transparency that must be complimented by electronics that blend the driver and port response into a single wavefront. This is where physical timing errors and general filter delays can slur the audible spectrum and interfere with transient response. The Egg has a dedicated control unit that incorporates a relatively simple but very accurate analog network with some subtle EQ incorporated for hard, neutral or soft mid-band response. The bass and HF roll-offs are there for optimizing any given room position, but this leads to an important point.

The Egg operates best into open space, and the more it is given, the more the sound will be free of specular and spatial artifacts. The same goes for listening axis and angle of inclusion to the ears. In a big room with large monitors, these issues are governed by acoustics and directivity of drivers. In the near-field, as might be expected, the immediate surroundings are paramount. Even adjacent speakers will react and resonate in sympathy with the one being listened to. Less is more in this respect, and the difference between well installed, axially aligned Eggs and the average desktop speaker is spectacular— and that’s a promise!

Wireframe image revealing the interior structure of the sE Munro Egg 150The final link in the monitor chain is the power amp and cable interface. It was agreed with sE at the beginning that all the amplifiers needed to be external so that we could build decent power supplies and hardware without compromising the internal geometry of the Egg shell. It also means the controls—even the power switch—can be accessed without leaving your seat. That gives the engineer the luxury of listening to the speaker at the same time as switching the EQ! The four power amps are individually driven, and they are the cleanest, high-specification modules we could buy. Expense has not been spared with the electronics.

All in all, it’s the production that brings a product to market, and we at Munro Acoustics have been working closely with sE to make all the ideas work in large-scale manufacture. The materials used for the egg itself and the molding technique to strengthen the outer skin are more akin to Formula One monocoque cars than the usual folded chipboard factory output. To be fair, some makers use very heavy wooden cabs with reinforcement and bracing, but they are still boxes at the end of the day.

The final judgment always belongs to the ears of the beholder and the subsequent mix that comes from that process. We have spent two years developing the Egg concept, and there will be other models to follow. I have spent 20 years working with professional monitors, with Dynaudio and our own custom systems for large control rooms and film post production. I can honestly say the Eggs have something special about them—a synergy, where all the ideas arrive in synchronization. Judge for yourselves!

Andy Munro is an acoustician, designer and consultant and a partner in sE Munro.

Munro Acoustics

sE Electronics