M.C cart.output. 3.54 or 5 cms/sec. How do they compare?

[Mike Reed]

Does anyone know how to compare the American (Japanese?) and British (European?) ways or stating a moving coil cartridge's output?

For example, my old Koetsu Goldline Black was quoted at 0.4 mV in Americaln reviews, but the output as stated by Absolute Sounds is 0.6mV. It would seem, then, that the difference between an output at 3.54 cms/sec. and 5 cms/sec. is in a ratio of 2:3.

I doubt that working out the equivalence is so easy, however, and I wonder if anybody can shine some light on this.

 

[sergeauckland]

The difference between 3.54 and 5 is Root 2, or 1.414. It's the difference between a purely lateral motion where L and R are equal and a L only or R only modulation.

The same cartridge that gives 0.4mV at 3.54 will give 0.56mV at 5cm/sec. This is close enough to the 0.6mV and can be easily understood in terms of sample variations.

S.

 

[Mike Reed]

Thanks, SERGE.

I'd worked out 1.4124 (close!) but didn't know how to use this figure. My maths is not up to working out a simple ratio which can be used throughout, though. Maybe it's as simple as 1: 1.4 (approx.), but could one use a ratio consistently across the range of v.t.f. or is a geometrical progression involved?

 

[sergeauckland]

Vertical Tracking Force (if that's what you meant by v.t.f.) has no effect on output voltage. Output voltage is dependent only on the velocity of the stylus (hence the output quoted in so many cm/sec.) That's the velocity of the stylus, and that's a function of the frequency and amplitude.

If you want to know what input sensitivity you need on the phono stage for the cartridge, then use the 5cm/sec figure, as that's a nominal figure for the velocity on the LP. Note that LPs can have levels up to 20dB (10x) that amount, so the cartridge can generate outputs of up to 6mV, so the phono stage has to be able to handle that high level without cliping.

S.