MC cartridge loading: still baffled

@mijostyn thanks for the reply!

Concerning the anti-skate setting, using music as my test (not a test record), I get no right channel distortion even with the anti skate turned off!  Turntable is absolutely level.  Using the run-out  area test, sure, the arm skates when lowered into this area but tracks fine when allowed to enter the run-out groove at the end of a record.  I finally settled on an anti-skate setting ~ 0.5 just to have some counter force but using test records with atypical modulations might be overkill.  If I hear any break up coming from the right channel (outer groove wall distortion then I will adjust it higher but for now, I am quite content using this lower setting.

I should also add that I do not see any deflection of the cantilever when the arm is lowered into a groove.  However, the cantilever is not very compliant so this may be a factor.  I am comfortable using real music as a test and listening for possible break up if the antiskate setting needs to be adjusted higher.  I acknowledge the possibility that I might be wearing the stylus or inner groove unevenly.

Mijo forgot to mention that your empirical finding that you need much less AS force, in terms of grams, than VTF is absolutely to be expected.  The notion that if VTF = 1.5, then AS = 1.5 is antiquated.  Setting AS = VTF will nearly always result in an excess of AS, which you can hear in the form of L channel distortion. So, you did good.
Likewise for the choice of resistive loading.  First, as Mijo said, you are always well advised to go along with a manufacturer recommendation, and second because loading is for the phono stage more than for the cartridge.  You might want to search the long and contentious thread on cartridge loading for posts by Atmasphere, who explains this well.  I too have found that 47K sounds more "open" for me, using an Atmasphere MP1 phono section with one or two of my LOMC cartridges.

Anti-skating force depends on the stylus profile too, with advanced profiles it's never equal to the tracking force, normally lower. I remember VdH interview and his thought about it. 

Regarding the loading just buy a phono stage with optional loading and use what you like, do not listen to anyone. 

Back to the loading question:  is the proper loading more a function of the phono pre or the cartridge itself?

Ayre made their recommendation to you on account of the fact that they did the proper homework in their design of their phono section.


There is another thread active on this forum that relates to this topic. So I am repeating myself here:  The loading resistor is primarily for the benefit of the phono section, not the cartridge (although decreasing the load resistor value will decrease the compliance of the cantilever). The cartridge has an inductance and the tone arm cable (and to a certain extent, also the input of the phono section) has a capacitance. They are in parallel. Anytime you find an inductance and a capacitance in parallel you have a tuned circuit, also known as a 'tank circuit' (as it stores AC energy) which resonates at a certain frequency. BTW an inductance in parallel with a capacitance is the means used to tune a radio to a station.

Since the inductance of a moving coil is usually slight and capacitance of the cable is also low (or should be) the resonant frequency is rather high and can be anywhere from several 100KHz to several MHz. This resonance is a peak and can be as much as 30dB! When the peak is at resonance, the term for this is 'excitation'. The energy of the cartridge itself is enough to drive the tank circuit into excitation.


Essentially as far as the phono preamp is concerned this energy is RFI (Radio Frequency Interference) and is injected directly into the input of the phono section! It can overload the input of the phono section and this can result in a tick or a pop. So to avoid this problem the input of the phono section should be designed with plenty of headroom.


The loading resistor suggested is in parallel with the tank circuit. It acts to detune the tank circuit and prevent resonance. Since a cartridge manufacturer has no idea of how competent the phono section to which the cartridge is connected will be, they often recommend a low loading value to allow that phono section to operate correctly. Its well-known that RFI causes audio electronics to not sound right (often brighter)!


But if the phono section is RFI immune and has good overload margins, the loading resistor simply isn't needed. This allows the cartridge greater compliance and can result in better tracking performance, depending to some extent on the tone arm. Right about here things get a bit complex, but as a general rule of thumb most cartridges are designed to drive 47Kohms, despite the 100 ohm loading recommendation.

The bottom line is try it both ways and see.