loudorren
Well-known Member
Hello Aludra,
Mike, The input impedance of the preamplifier will accommodate all cartridges from moving coil, moving magnet, moving iron, strain gage semiconductor, and photo pickup semiconductor.
The argument that I had with the Technics engineers went like this: When I had disclosed to JVC and Technics/Panasonic about the Phase Lock Loop technology that I had developed for the CD-4 system, we were in a negotiation phase for them to use the development. I had filed a patent application, which made it patent pending. When a patent is pending, no one can get a copy of it unless you are with the patent office or, the owner of the patent discloses it. I was prepared and eventually did disclose the information when the negotiations were completed (took 1.5 years). At that time the only semiconductor company making PLL chips was Signetics. So the engineers for JVC and Technics/Panasonic figured that they could get around my invention by using the NE565 PLL chip. What the did not know was that the PLL chip alone would not solve the problem. Then came the bailing wire, chewing gum, and band aids. First was AGC (Automatic Gain Control of the 30 KHz carrier). That didn't work. Then came high gain amplifiers for the carrier. That also did not work. Finally, they came up with carrier process control which consisted of carrier crosstalk nulling and manual carrier level control. This actually gave some performance to the Technics SH340 and the JVC 4DD5. This, however, was not the correct solution to the problem. The following is right out of installment III, soon to be available. "A PLL detector is just another FM detector. It's major advantage over discriminators, Ratio Detectors, and Quadrature Phase Detectors is that it is more linear (lower distortion) than the others. All of these detectors suffer from the same problem. They want a constant carrier level with no variations(incidental Amplitude Modulation)." The PLL is a little more robust, which is why the SH340 and the 4DD5 can give some CD-4 performance. The real answer is a very high gain 100dB limiting amplifier, which removes all amplitude variations of the 30 KHZ carrier. The small drop in carrier level from outer to inner diameter of the disc is insignificant and is never seen by the detector because of the limiter.
Hope this answers your question
Lou Dorren
Mike, The input impedance of the preamplifier will accommodate all cartridges from moving coil, moving magnet, moving iron, strain gage semiconductor, and photo pickup semiconductor.
The argument that I had with the Technics engineers went like this: When I had disclosed to JVC and Technics/Panasonic about the Phase Lock Loop technology that I had developed for the CD-4 system, we were in a negotiation phase for them to use the development. I had filed a patent application, which made it patent pending. When a patent is pending, no one can get a copy of it unless you are with the patent office or, the owner of the patent discloses it. I was prepared and eventually did disclose the information when the negotiations were completed (took 1.5 years). At that time the only semiconductor company making PLL chips was Signetics. So the engineers for JVC and Technics/Panasonic figured that they could get around my invention by using the NE565 PLL chip. What the did not know was that the PLL chip alone would not solve the problem. Then came the bailing wire, chewing gum, and band aids. First was AGC (Automatic Gain Control of the 30 KHz carrier). That didn't work. Then came high gain amplifiers for the carrier. That also did not work. Finally, they came up with carrier process control which consisted of carrier crosstalk nulling and manual carrier level control. This actually gave some performance to the Technics SH340 and the JVC 4DD5. This, however, was not the correct solution to the problem. The following is right out of installment III, soon to be available. "A PLL detector is just another FM detector. It's major advantage over discriminators, Ratio Detectors, and Quadrature Phase Detectors is that it is more linear (lower distortion) than the others. All of these detectors suffer from the same problem. They want a constant carrier level with no variations(incidental Amplitude Modulation)." The PLL is a little more robust, which is why the SH340 and the 4DD5 can give some CD-4 performance. The real answer is a very high gain 100dB limiting amplifier, which removes all amplitude variations of the 30 KHZ carrier. The small drop in carrier level from outer to inner diameter of the disc is insignificant and is never seen by the detector because of the limiter.
Hope this answers your question
Lou Dorren
