mc cartridge loading


I currently load an Audio Technica ART9 at 90 ohms, the load 'inherited' from another cartridge, am pleased with the sound but recognize the manufacturer's recommendation that at least 100 ohms be used.  Changing load requires opening the phono-amplifier case, somewhat tedious.   Is increasing the resistance (decreasing the load) worth the effort?
seventies
The loading only needs attention if the phono section is sensitive to RFI at its input. The RFI is generated by the cartridge itself in part due to the afore-mentioned resonance that is set up by the inductance of the cartridge and the capacitance of the interconnect cable from the tone arm. If that is kept low and if the preamp is stable the loading will have very little effect.

What is happening here is Audio Technica is essentially stating that the preamp they use isn't stable. Just because that is so does not mean that it is that way with you. If you do hear a difference (usually an improvement) with loading, it suggests that the phono preamp is unstable at ultrasonic or RF frequencies.

Bottom line: loading is about the phono section and not the cartridge.
In all the years I have been reading and talking to engineers who are involved with step up trans and carts this is the first time I ever heard this.

You can argue that the best impedance match on paper might not be the best sounding one.  But there Is a difference in sound.  It sounds like he may not want to go through the effort to experiment but it may be well worth the effort in his system.

You might look to some other forums where there are a lot of comment on this subject.

Enjoy the ride
Tom

While loading is always the question i want to remind about phono preamps with so called "Automatic Impedance Matching" for any cartridge. One of them is WLM Phonata from WLM Acoustics. I believe it was probably made by Trafomatic Audio for WLM Acoustics (Austrian-Serbian collaboration) and i think it’s out of production now. Anyway, that’s what i use, not sure if i miss something with loading, but with this device i can forget about loading at all - right? "This unique preamp has automatic impedance matching so that the input impedance for the cartridge is perfect each and every time."

p.s. I've posted WLM Phonata's specs here on audiogon before.


There is a kind of rule which state '' 10x the cart impedance value''.

I like such kinds of rules because they provide a kind of orientation.

I don't like quessing with my ears because one is never sure while

this uncertainty lead away from our primary goal: listen to the

music.

Jonathan Carr, the designer of Lyra cartridges says much the same thing as Atmasphere--loading is only needed with some phonostage which overload when presented with RFI. 

I have found that with most high quality phonostages, not much more loading than the typical, built-in 47k ohm loading is needed.  I once helped with a setup involving a Hovland preamp.  There was obvious RFI interference (noise) even when the tonearm was sitting on its rest and not playing (external RFI).  It turned out that the "default" loading on the Hovland was 100k and that just switching to 47k cured the problem.

The problem with a simple rule like 10X is that it will simply be wrong under certain circumstances.  I have a Transfiguration Orpheus cartridge which has an extremely low source impedance of 1 ohm; the 10X rule would mean an extreme amount of loading at 10 ohms.  Because it is a quite low output cartridge, that amount of loading would throw away a significant amount of signal and would mean, in my system, not enough gain.  Also, a lot of loading does affect tonal balance--it substantially reduces the top end; I paid a lot of money for the kind of open and extended top end that good MC deliver and that would go to waste with this kind of loading.  This rule is also not very useful when it is applied in the case of using a step up transformer where one has to consider where the loading is applied--on the primary side of the transformer or the secondary side?

The best approach is to try different loading to see what sounds best.  If one is not so inclined, stick with a modest amount of loading that would work reasonably well under most circumstances, something in the range of 100-150 ohms--that would cure any RFI issues and is not so much loading that high frequencies would be severely attenuated.