MM cartridges and capacitance


Can someone explain to me why an MM cartridge would "want" to see more than the minimum possible level of capacitance loading?

This question is provoked by a lot of commentary on "that" "MMs are great" thread, and a question someone just asked, and the fact that I have two phono stages (granted, older Japanese stages) which have multiple capacitance settings and I have never gotten a "better" result from being at the high end rather than the low end. In many cases, it doesn't seem to make a difference, but so far I have not gotten an improvement from raising the capacitance setting.
t_bone

Showing 4 responses by t_bone

Al,
From the things I have read, and the cart designer I have talked to on the subject of that resonant peak in frequency response, that peak is waaaaaaay outside the audible band. However, the problem is that it is so large, that just like a really big earthquake, it can cause problems a long distance away, and so can stress phono stages at levels within their reach (which would still be outside the audible band), which causes performance issues inside the phono stage.

The numbers I have seen of that resonant peak would suggest that it is like no earthly peak in comparison but magnitudes higher in comparison from the sea level starting point of the audible band. As I understand what you are saying, cart designers are effectively moving to the foothills of Mordor (and raising it ever higher) in order to make their badly insulated houses warmer.

Then again, I may be misunderstanding this...
Al,
Thanks for the link to the Hagerman calculator. I'd actually read that page a few times but until now had never tried the calculator myself, AND more importantly I had mistaken the range of resonant frequency peak by at least one power of ten on MM carts. If the inductance estimates are correct, it means one wants to have capacitance as low as possible in order to preserve the harmonics 'air' which extend beyond the audible band. It would be difficult to imagine why one would want to bring that mountain closer to the audible frequency.

As an aside, I am looking at the formula just above the MM FrR calculator and I don't understand how a high SQRT(LxC) in the denominator would lower any ratio with a 1 in the numerator. Could you explain ResonantFrequencyCalculations for Dummies?
Al,
Thanks.
With regard to the fraction... My math is OK. I misspoke.
I see frequency as being a number X greater than one. I see a higher frequency as being a number greater than X which is greater than 1. If I take one cycle, it's frequency (stated as a fraction) is a number Y less than one and greater frequency is an even lower number.

I expect it is the case that I do not understand where the decimal place is and how sqrt(faradsxhenrys) changes to frequency.
Al,
You are a scholar and a gentleman.
Thank you very much for that explanation.