Merits of the RS Serires MC Cartridge
If we closely examine the face of a color television tube, we will find dots of the 3 primary colors, red, blue and green, laid out in a minute pattern. By mixing different amounts of these 3 colors, it is possible to produce the entire range of colors in the visible spectrum. We can only perceive the result of any such combination.
Considering sound; by using a microphone, the various sounds produced by any combination of musical instruments and voices are added together to produce a single electrical output. When this signal is played back through a loudspeaker system, we can easily distinguish each type of instrument and voice quite often, individual instruments and voices within the total sound. Furthermore, if any of the instruments' or voices' timing is correct, even very slightly, we can readily distinguish this. Our ears are thus sensitive to the components of the sound,
frequency, amplitude and time.
It is not unusual for two cartridges to have very closely matched frequency responses and distortion levels, and yet for their sounds to be quite different. Similary with speakers, amplifiers and other audio components. This is bacause the measurements are only made in the frequency domain and are usually steady state. This is a much simpler situation than occurs in real music. If measurements were to be made in the time domain, those components that looked similar in the frequency domain, would be found to be noticably diflerent. Again, time may be seen to be an important factor.
I will now discuss how important the time domain responce of a cartridge is and also how to carry out a simple test to determine how well a cartridge plays back this important "time information”. A stereo cartridge converts the modulation on the two groove walls into separate electrical signals. When this is happening, a number of dynamic effects occur within the generator system, and these effects vary with signal level. In addition these effects lead to the right and left channels sounding different to each other.
You can demonstrate this for yourself by playing any record that has a vocalist in the center of the stereo image and then listening to each channel separately, by turning the balance control from one extreme to the other. The right channel will have a bias towards brightness, with a harsh and metalic sound, and a lightness of bass. You may think that the singer has just become 10 years younger ! The left channel will have a bias towards the bass end, with a boomy and bim sound and a lack of top. The singer now will sound 10 years older! Neither channel sounds right.
You may wonder about the validity of the frequency response figures for your cartridge that showed both channels as being the same. This phenomenon arises from the "time information" and I refer to it as "time distortion".
The RS or "REAL STEREO" series MC cartridge, is the first cartridge in the world that can completely eliminate "time distortion" and play back a sound in both channels that is truly authentic to the original recording.
A. " REAL STEREO " Generator System
In order to eliminate the causes of " time distortion " in a cartridge's generator system, it is necessary to consider not only from the mechanical viewpoint, but also from the electrical viewpoint. After many years of development, I have found 13 points, attention to each of which is vital during the designing of a cartridge, if " time distortion "is to be avoided. For both MC and MM cartridges, 13 vital design points apply, however they are not the same in each case.
Only in the RS series have these points been correctly identified and attended to, and thus only the RS series can playback REAL STEREO. The 13 vital design points for a MC cartridge are as follows.
1. Magnetic pole direction
2. Coil winding direction
3. Coil winding method
4. Prevention of dynamic induced current in the coil bobbin
5. Prevention of dynamic induced current in the magnetic circuit
6. Method of prevention of dynamic induced current
7. Grounding of coil bobbin (yes or no and method therof)
8. Grounding of yokes (yes or no and method thereof)
9. Grounding of magnet (yes or no and method thereof)
10. Siting of output terminals
11. Case material (metallic or non-metallic)
12. Grounding of case (yes or no and method thereof)
13. Electrical connection between cartridge case and headshell
(presently 7 patents are pending)
Let us consider the coil winding method, item 3. The normal method used is shown in Fig. 1. It is mechanically symmetrical around a vertical axis, however electrically it is assymmetrical, as a vertical movement produces left and right channel signals that are in anti-phase. The method used in the RS series is shown in Fig. 2 and is far superior.
The winding is electrically symmetrical around the horizontal axis, as the signals in each channel are in-phase with each other. This symmetry is more easily understood if we consider how the two methods of winding would be connected for monaural. Conventional and RS series coils are shown monaurally connected in Fig. 3 and Fig. 4 respectively. Note with the RS series coil, how the wires do not cross over each other, thus avoiding any coupling effects.
B. The most Advanced Mechanical Parts
1. Pure Damper Material
When using the REAL STEREO generator system, it is found that the damper material must be absolutely pure and contain no powder filler. Normally, several types of filler are added in order to control sound balance. If a damper made from such a material is used in the RS series cartridge, it is possible to hear a rustling or clattering noise as a consequence.
2. Air Response Damper Mechanism
Individual damper units are used in the RS series and are arranged so that restoration forces acting in one plane are not coupled to the other plane. This gives the cartridge an extremely fast response and its characteristic clear sound images.
3. Extremely Powerful Magnetic Material
By using an extremely powerful magnetic material, it is possible to greatly reduced the size and thus the weight of the magnetic circuit. This makes the RS series cartridge suitable for use in any type of tonearm.
4. Pure Copper Wire Generator Coils
Recently, several method of producing very pure copper wire having a highly regular crystal construction have developed. The RS series uses 6-nine wire produced by one of these processes, in order to achive an even sound balance across the entire audible range.
5. Double Structure Body
By combining aluminum and plastic materials in the construction of the body, the resonance occuring on the body's surface is exduded from influencing the generator system. An additional advantage is that this method of construction is both light and rigid.
6. Cartridge Case For REAL STEREO
Item 11,12 and 13 of the vital design points make very complex demand of the body's electrical properties. The double structured body is necessary in order to achieve these properties, and to prevent external disturbances from influencing the generator system and also, it prevents eddy currents in the case from effecting the generator output signal.
7. Stylus
The styli used in the RS series have the edges of the diamond shank set parralel to the sides of the cantilever. Using this type of stylus, the hardest axis of the crystal is aligned to act as the contact point with the record groove. This gives stable and smooth tracing and produces a very refined sound, with the additional benefit of giving the stylus an extended life. The stylus is of the RS-30 is of the Micro-ridge type, which was originally developed in Japan and offers the highest performance. The life of this stylus is in excess of 1000 hours. It is recommended that the Micro-ridge stylus be used with brand new records; the line-contact stylus (RS-20) with records that have already been played, but are in good condition, and the elliptical stylus (RS-10) with worn records. However, the ultimate choice rests with the user.
TECHNICAL DATA / RS-10 / RS-10H / RS-20 / RS-20H* / RS-30 / RS-30H*Type / Moving Coil (Dynamic)
“REAL STEREO” Generator system
Output Voltage / 0.24mV (0.48mV) [3.54cm/sec, 1kHz]
Frequency Response
+/- 1dB / 10 Hz – 40 kHz
20 Hz – 20 kHz / 10 Hz – 55kHz
20 Hz – 20 kHz / 10 Hz – 75 kHz
20 Hz – 20 kHz
Channel Separation / > 25dB(1kHz) / > 30dB(1kHz) / > 30dB(1kHz)
Channel Balance / < 0.5dB [1kHz]
Recommended
Tracking Force / 1.8g [20 oC – 25 oC]
Tracking Force Range / 1.5gm – 2.0gm
Horizontal Compliance : / 15 x 10-6cm/dyne
Vertical Compliance : / 12 x 10-6cm/dyne
Trackability / > 80 m m/1.8gm
Internal Impedance / 4 W (8 W)
Recommended
Load Impedance / > 100 W
Cantilever Material / ALMg5 tube f0.38/f0.3 / Sapphire tube f0.33/f0.26 / Boron tube f0.3
Stylus / Elliptical Solid Diamond / Line-contact Solid Diamond / Micro-ridge Solid Diamond
Contact Radius / 8 m m X 15 m m / 6 m m X 35 m m / 3 m m X 60 m m
Output Terminals / f 1.25mm gold plated [EIA]
Net Weight / 4.2gm
· () : in case of H (High Output) model