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SPEC
RSP-901EX
Real-Sound Processor

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Regular Price: €818.18

Special Price: Outside EU (excl. Tax): €495.87 Incl. Tax: €600.00

Availability: In stock

Quick Overview

  • Real-Musicality speaker impedance corrector
  • Especially effective for semiconductor based amplifiers
  • Compatible speaker impedance preferably 10 Ω or lower
  • Effective for amplifiers of up to 1 kW
  • Box made of real spruce tone wood
  • Comes as a set of 2 pieces
  • Weight 200 gram / 7 ounce
  • Dimension 117x47x100 mm / 4.6x1.8x3.94 inches

SPEC | RSP-901EX | Real-Sound Processor

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"Real-Sound" and far beyond musical expressions

You could discover an unexperienced "real sound", far beyond musical expressions of "past audio" with the 901EX, our latest "Real-Sound Processor". 

You could recognize at one hearing, 901EX is not only an audio accessory but also real audio gear for improving the sound quality of your system dramatically. The sound will be more clear and natural throughout the entire range with a 901EX. You could feel and experience more real sound with full musicality. In a word, you could be convinced that 901EX brings out the full potential of your audio system.

The function of the "Real-Sound Processor"
The operating principle of the "Real-Sound Processor" was published in the Japanese specialized magazine named MJ, "Audio Technology" by Mr.Yasui in 1971. He just brought out this concept as " impedance correction" for speakers. Yasui-san was a senior amateur researcher and a person of authority in the field of semiconductor linear amplifiers. At that time he got into the conclusion that only the pursuit of improving the static characteristics of power amplifiers could never bring the superior sound. He also noticed the importance of an amplifier’s dynamic characteristic including the actual movement of a speaker to get musical sound. But still right now, after more than 40 years, we regard his point of view as an excellent insight and still a relevant challenge for the present "audio technology". Sorry to say, we should recognize we only know the improving of the dynamic characteristics of the system consisting of amplifier and speaker might be an extremely important factor for getting superior sound quality, however we are not able to find an effective measuring method to express the dynamic behaviors and also expose the real relations between those characteristics and our hearing. We suppose, so many reasons might exist. But one of the major difficulties of analysis of the dynamic characteristics is the speaker itself. Needless to say, the speaker is the transducer which converts some electric energy to kinetic motion. But if we were to say frankly, this transducer would be a collectivity of imperfect characteristics for being driven by the amplifier. You know how fluctuant the impedance vs. frequency characteristic is. Yes, it might be quite simply the hard load of the amplifier. But also you should remind one more thing, the "Counter-electromotive Force" of your speakers. The motion of a speaker is started in the magnetic circuit or voice coil of the unit by the current flowing from the amplifier according to Fleming's left-hand rule and at the same time this motion raises up counter-electromotive force in the voice coil according to Fleming's right-hand rule. It is true that the amplifier drives the speaker, but it is a fact that the speaker also affects the amplifier by this counter-electromotive force. And this counter-electromotive current returns to the amp via the speaker cord, making it difficult to drive the speaker in accordance with the input signal. This current causes negative effects especially on the traditional semiconductor linear amplifier. Since the transfer function of semiconductors is poor in linearity compared to a tube, this type of amplifier inevitably needs to have the static characteristics corrected by the negative feedback circuitry incorporated. But this negative feedback makes the amplifier stage vulnerable to the counteraction, counter-electromotive current from the speaker, causing complicated phase delays inside of the amplifying stage. Needless to say, this physical phenomenon hurts the sound quality of the audio system consisting of amplifier and speaker.

The effect of "Real-Sound Processor" 

The "Real-Sound Processor" has two major functions, one is to reduce the fluctuations of the speaker’s impedance vs. frequency characteristic. The other is absorbing that counter-electromotive current from the speaker including its crossover network. Accordingly, the processor enables the amplifier to drive the speaker more faithfully according to the sound source, improving the sound resolution and dynamics, and it also reproduces natural harmonics. Above all you could find the deep, rich and fascinating tonal characters you have never experienced before and also agree that the amplifier can drive the speakers easily now.


The latest "Real-Sound Processor", RSP-901EX 
We constantly try to improve the sound quality of the "Real-Sound Processor" and learned that only the tonal- or sound quality of the parts, being resistors, inductors and capacitors, define the sound itself. You should recognize that the perfect resistor and capacitor has never existed. For example, a capacitor consists of mainly its capacitance, a small quantity of resistance and inductance. Also we should remind the matter of material’s physicality. Sometimes, when we do hearing tests for capacitors, we feel the unique tonal character of a dielectric material or electrode itself.
But fortunately early 2014, we learned to know some outstanding quality parts. It was the highest quality hermetic sealed oil filled capacitor, named "Green Cactus" series made in USA, by Arizona Capacitors, Inc. This type of capacitor enabled us to get the live and natural sound of the new "Real-Sound Processor". And in this summer we released the RSP-701 for our domestic market. And now thankfully, 701 is the successful product in the field of audio-accessories.
By the way, language above all Japanese is far away from European language.
They say that Japanese is a vowel sound and compared to this Japanese, major European languages are made of consonants. These consonants surely consist of a high frequency spectrum. So we supposed that European people may have more sensitive hearing for high frequencies than ordinary Japanese people and determined to change to another "Green Cactus", it reproduces much finer mid-to-high range. Also, we changed the resistor adopted in 701 to another one which has the smoother and more open air character.
As well, please pay attention to the appearance of RSP-901EX. It’s like a jewelry box made of real spruce from north America with string instrument’s color. The box is produced by the famous "Shirakawa Co., Ltd" at Hida-Takayama, a beautiful historic town. You will see also woodworking is the Japanese traditional handicrafts.

We firmly believe that RSP-901EX could bring out the full potential of your system and you could fully enjoy the "Real-Musicality" through "Real-Sound" of the 901EX!