Brent -- Regarding using a 47K load, iirc correctly even the estimable Harry Pearson (founder of "The Absolute Sound") wrote many years ago of preferring the sound of some particular mc cartridge when loaded (or perhaps I should say "unloaded") with 47K! But as Axel indicates, that would be optimal only for a small minority of mc's.
Basically, what the typical lower value load does is to dampen what would otherwise be a large high frequency (usually ultrasonic) resonant peak. You can find an explanation of that here:
http://www.hagtech.com/loading.html
The degree to which that peak would produce adverse audible consequences, such as brittleness or edginess, would depend on its amplitude, its frequency, the bandwidth of the rest of the system, and the intermodulation and other effects that may be produced in the rest of the system by ultrasonic or very high frequency spectral components, as well as on the mechanical damping provided in the cartridge itself, as Axel points out.
Axel & Saudio -- Thank you for your comments. I don't question your experienced-based comments, and I think we all agree that mc cartridge matching necessitates that listening be the final arbiter even more so than with the rest of an audio system.
I haven't seen any good explanations of why use of a step-up transformer would typically call for heavier loading than would be the case if a high gain phono stage or head amp were used. After giving it some thought, I've developed the following theory:
A real-world transformer can be modeled as an ideal transformer in parallel with an inductor on the primary side, representing "magnetizing inductance," as well as other resistive and inductive elements representing loss mechanisms. See the diagram around the middle of this page:
http://en.wikipedia.org/wiki/Transformer
Referring to that diagram, if we assume that the series leakage inductance Xp is relatively insignificant compared to the cartridge's inductance, then by Thevenin's Theorem the magnetizing inductance Xm can be considered as combining in parallel with the cartridge inductance. That will result in a lower total inductance, and therefore an ultrasonic resonant peak which is higher in amplitude if a heavier load is not applied to damp it.
Although the peak will be higher in frequency as well, and it will also be affected by the bandwidth limitations of the transformer, all of which sufficiently muddles the situation such that, again, listening would seem to be the only way reach any meaningful conclusions.
Regards,
-- Al
Basically, what the typical lower value load does is to dampen what would otherwise be a large high frequency (usually ultrasonic) resonant peak. You can find an explanation of that here:
http://www.hagtech.com/loading.html
The degree to which that peak would produce adverse audible consequences, such as brittleness or edginess, would depend on its amplitude, its frequency, the bandwidth of the rest of the system, and the intermodulation and other effects that may be produced in the rest of the system by ultrasonic or very high frequency spectral components, as well as on the mechanical damping provided in the cartridge itself, as Axel points out.
Axel & Saudio -- Thank you for your comments. I don't question your experienced-based comments, and I think we all agree that mc cartridge matching necessitates that listening be the final arbiter even more so than with the rest of an audio system.
I haven't seen any good explanations of why use of a step-up transformer would typically call for heavier loading than would be the case if a high gain phono stage or head amp were used. After giving it some thought, I've developed the following theory:
A real-world transformer can be modeled as an ideal transformer in parallel with an inductor on the primary side, representing "magnetizing inductance," as well as other resistive and inductive elements representing loss mechanisms. See the diagram around the middle of this page:
http://en.wikipedia.org/wiki/Transformer
Referring to that diagram, if we assume that the series leakage inductance Xp is relatively insignificant compared to the cartridge's inductance, then by Thevenin's Theorem the magnetizing inductance Xm can be considered as combining in parallel with the cartridge inductance. That will result in a lower total inductance, and therefore an ultrasonic resonant peak which is higher in amplitude if a heavier load is not applied to damp it.
Although the peak will be higher in frequency as well, and it will also be affected by the bandwidth limitations of the transformer, all of which sufficiently muddles the situation such that, again, listening would seem to be the only way reach any meaningful conclusions.
Regards,
-- Al