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-   -   P Spice parameter for MC cartridges like Lyra and Audio Technica? (http://www.diyaudio.com/forums/analogue-source/155373-p-spice-parameter-mc-cartridges-like-lyra-audio-technica.html)

tiefbassuebertr 20th November 2009 09:10 AM

P Spice parameter for MC cartridges like Lyra and Audio Technica?
 
to develope by p-spice simulation nearly perfect head amps for low impedance moving coil cartridges, a modelling is actually necessary.

Unfortunately most engineers design from existing experience without any computer aided design. This is for me the main reason, why permanent very large audible differences by comparing of RIAA phono preamplifier are to observe, even by very expensive devices.

I have heard and read about great parasitic influences by very low output moving coil cartridges e. g. by the Lyra Dorian. See frequency response about
Lyra Dorian phono cartridge (English)
between 4 KHz und 18 KHz 7 db difference (!!!)

For me it is perfectly clear, that there are no possibility to compensate only with an appropriate load resistance. An equalizing is necessary for neutral and uncolored sound. CAD based no problem, but without CAD a very big problem.

Why there are no exactly CAD models for MC cartridges, even by the most expensive of the world?

h_a 20th November 2009 09:20 AM

Spice modeling of MM-cartridges is regularly done as coil resistance+inductance and manufacturer's recommended loading capacitance is usually known. What is not known, completely ignored and therefore what makes this simple Spice simulations worthless is the mechanical part of the cartridge that is not taken into account. It's an oscillating mechanical system with a large resonance and to ignore the most vital part can only give poor results.

Modeling the mechanical part may be done by deriving an equivalent electromechanical model from the frequency response, measured for the cartridge in question.

Not done in 5 minutes, though.

Have fun, Hannes


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