If someone prefers to hunt around for their preferred impedance, I have no strong objection. Just don't go below your cartridge's internal impedance. IME some cartridges (eg OC9) are very sensitive to impedance loading. Some (eg Lydian Beta) are not very sensitive to loading.
A lower load impedance loads up the cartridge with higher current, making it harder for the cantilever to move. So the manufacturers spec may also take this into account, to provide optimum damping.
I always use the manufacturer's recommended spec for MC loading. I set VTF and antiskate using the manufacturer's spec and a test record, because I find that minimizing the number of variables allows me to concentrate on finding an ideal VTA. If everything's changing, it gets very confusing, and you can get way off base. This is compounded by the fact that impedance loading and VTA have very similar effects on the sound.
Just a few thoughts on the posts above:
MC cartridges react very little to capacitance. Less is best, because capacitance causes phase shift. MM's require the manufacturer's exact specified capacitance to provide proper frequency response.
Transformers and preamps sometimes carry different impedance specs (eg OC9 says 20R for tx, 100R for a gain stage) because a transformer works optimally with current, while an amplifier prefers voltage. Current is maximized at a point slightly above the cartridge's internal impedance, and that will be the specified load for a transformer. The impedance for a gain stage is spec'ed for a reasonable voltage and current, but maximum efficiency.
Dan Bonhomme
A lower load impedance loads up the cartridge with higher current, making it harder for the cantilever to move. So the manufacturers spec may also take this into account, to provide optimum damping.
I always use the manufacturer's recommended spec for MC loading. I set VTF and antiskate using the manufacturer's spec and a test record, because I find that minimizing the number of variables allows me to concentrate on finding an ideal VTA. If everything's changing, it gets very confusing, and you can get way off base. This is compounded by the fact that impedance loading and VTA have very similar effects on the sound.
Just a few thoughts on the posts above:
MC cartridges react very little to capacitance. Less is best, because capacitance causes phase shift. MM's require the manufacturer's exact specified capacitance to provide proper frequency response.
Transformers and preamps sometimes carry different impedance specs (eg OC9 says 20R for tx, 100R for a gain stage) because a transformer works optimally with current, while an amplifier prefers voltage. Current is maximized at a point slightly above the cartridge's internal impedance, and that will be the specified load for a transformer. The impedance for a gain stage is spec'ed for a reasonable voltage and current, but maximum efficiency.
Dan Bonhomme