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Re: Can you show me mathematically how it can be done.

Cheapjack, I need your info, before I can proceed. It is important to know how I can address you without making a major project out of this.
Now, you might want to know WHY I know so much about the Dyna? I owned and used one as my personal unit, for over 10 years, until I replaced it with a JC-2. However, I did not know of this real problem with the Dyna until I worked with Matti Otala to contibute to the paper on the measurement of TIM given at the AES in 1976. I helped write the spec for TIM, so I know a lot about it.
In 1977, I was asked to give a paper at an IEEE session on TIM at the IEEE Audio ... meeting in Tulsa, in 1978. I called my paper: 'Omitted Factors in Audio Design' where I expanded general measurement of TIM to REAL phono inputs that I actually measured. This is WHY knowing what cartridge you are using (in general) is very important.
For example, IF you are using an inexpensive Shure cartridge, you should be safe enough. The Shure can't slew its way out of a paper bag, BUT IF you are using a Grado, then we MIGHT have a problem. I have to look up my old paper that is almost 30 years old and compare the waveforms, in order to tell you more. An MC cartridge is usually too fast for a Dyna, AND I used an MC cartridge for 7 years with the Dyna. Why? How could I not know that something was amiss? Because the byproduct is 2'd harmonic, NOT higher order odd distortion or internal clipping of the signal. It just softens the sound, rather than makes it annoying or edgy.
The problem is: The 1-2 ma output current of a 12AX7 tube, can't properly charge the RIAA caps under high dV/dt (slew rate) conditions. Please remember the RIAA caps are connected from the output to the input. They MUST be charged and discharged by the output tube driving them.
Now, what about the Mac C22 or the Marantz 7 tube units? They USE a cathode follower at their outputs to DRIVE the RIAA caps. Dyna cheaped out! Still, it can be a pleasant preamp to listen to, and I enjoyed it for more than 10 years.

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