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What is "Dreams" Wideband AMT Driver?

 

In order to meet the critical specifications for Mark & Daniel speaker systems, a wideband driver capable of covering the audio frequency band from 800Hz-20KHz with satisfactory performance was required. These drivers needed to be of reasonable size and of modularized design, so that they could easily complement different speaker systems in the future.


After reviewing all possible solutions, we decided to develop our Dreams (Directly Responding Emitter by Air Motion Structure) wideband driver, based on the AMT (Air Motion Transformer) principle invented by Dr. Oscar Heil in the 1970s.

 

 

Dreams (the modified AMT) wideband driver with pleated ribbon diaphragm structure, along with other types of ribbon tweeters, all belong to a branch of speaker design best described as the planar-magnetic technology.

Although in operation their method of sound reproduction is simple, almost all high quality ribbon drivers are very costly and difficult to assemble, producing low product yields. Because there has been no way to manufacture these unique drivers in commercial quantities, they are considered to be exotic or unconventional designs. Hence only a few speaker manufacturers in the world provide these products. However, these superior designs are prized by high-end audiophiles for their incomparable accuracy of reproduction, transparency, low distortion and stunning resolution of subtle signal details and harmonic texture. Ribbon drivers have already become the preferred choice for high-end audiophiles for normal tweeter applications above 1.5 KHz.

 


 

Planar ribbon tweeters (Quinsy-Ribbon tweeters, more precisely) have an aluminum circuitry etched onto a planar substrate. The weight of the diaphragm cannot be too heavy to degrade the High Frequency response; yet the diaphragm cannot be too small to avoid too narrow an operating bandwidth. There are physical contradictions between the two parameters, somewhat similar to the inherent design contradictions common to conventional dome tweeters.

However, our Dreams AMT driver, with the pleated ribbon diaphragm design, is a superior sound driver compared to the planar ribbon tweeters and conventional dome tweeters, whether one considers operational theory or practical reality!

The Dreams AMT driver has a much larger diaphragm compared to planar ribbon tweeters, yet each of our pleated micro ribbons is very light in moving mass, only about 6% to 20% compared to a typical 1¡± dome tweeter.

These pleated ribbons are completely sunk into a strong magnetic field; this unifies all the micro ribbons to directly drive a certain amount of air volume to get a high acoustic output with low distortion. Since the micro ribbons have such low mass, they respond with excellent transient response and provide high-resolution texture to music; on the other hand, the large total diaphragm size assures a high SPL output with low FMD pollution. The diaphragm¡¯s movement is completely controlled by the magnetic field with even forces applied to all ribbon surfaces.

The Dreams AMT driver is also a more efficient driver because the air mass (air movement) generated by squeezing is 5 times larger, and the velocity of the air particles travels 5 times faster than that produced by the pushing and pulling of a diaphragm to conventional tweeters; there is also no diaphragm¡¯s beak-up¡± distortion anywhere in the entire audio frequency band, thereby adding less coloration to the audio signal while remaining pure to the original source.

Another major feature of the Dreams AMT driver is that it is a wideband high-resolution driver rather than simply a High Frequency tweeter. Since the air motion driver in operation has a sharp directivity in natural, once the pleated diaphragm becomes too large (at a certain width limit), it becomes necessary to shape the diaphragm and magnetic structure into a curved shape through very sophisticated modifications in order to achieve better dispersion characteristics. Additionally, the efficiency of electro-magnets is low; therefore, a great many expensive NdFeB magnets must be assembled together to obtain satisfactory efficiency. After numerous mock-up tests and failures, the DM-1 Dreams driver eventually achieved the extraordinary performance targets we originally envisioned
.

 

The Dreams AMT driver inherited all the advantages of the planar ribbon driver such as light weight, low moving mass, excellent transient response, high resolution, coherently resistive impedance, and high power handling. Furthermore, these outstanding characteristics are achieved over 5 full octaves in wideband operation, with even dispersion, lower Frequency Modulation Distortion, and higher Sound Pressure Level output.

Imagine --- now all the musical information above 800Hz can reach your ears through one single emitter, without any delay, without phase variations, without interference between different drivers, without an additional LC compensation network. This depth, width of spatiality, accuracy and high natural resolution ensures the Dreams AMT driver has established a new standard for true Hi-Fi reproduction!!

 

 

 

  
  
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