Hi all im a little confused , my pre amp has a mm and mc phono stage these
are the specs,
Phono Stage
MM sensitivity 2.5mV
Impedance 47k
Distortion -100dB
Mc sensitivity 100uV
Impedance 100ohms
Distortion -80dB
Now some mc cartridges say benz micro ace,work from 200ohms to 47k does
that mean i could use mm on my phono stage to run this cartridge or is it only
for moving magnet only.
You can load a MC with anything, and you can play a MC with sufficient output int a MM stage without any concern. Nothing will be damaged.
Key to how well these things work and some general points:
- Sufficient gain to avoid noise but not so much gain that volume is difficult to control or the phono stage clips.
- Using very low impedance loading on a MC. These cartridges have low internal impedance and inductance which makes them very load tolerant. The greatest audible effects come when driving them into heavy loading, say <50 ohms.
- Shunt capacitance seen by a MM cartridge. In all but a few cases this hugely impacts performance.
Two other points to consider:
When driving a MM stage with a low-ish output MC cartridge it is often assumed that noise will be high. While the increased gain will raise the the noise floor, the low impedance of the MC cartridge will provide some reduction, so where a MC has a high output (but is still classified as a standard MC) it might work fine into a normal MM stage.
Distortion from phono cartridges is high - from all of them.
THD of >10% is very common at HF so don't get too hung up on stellar phono stage distortion specs. It is likely to be marketing nonsense.
By far the most important aspects are:
- RIAA accuracy. Surprisingly variable given that this is supposed to be a 'standard'. It is responsible for many audible differences between stages. Anything other than adhering to the standard is wrong.
- Noise. Phono stages will always generate more noise than line. It can be audible at higher listening levels so it makes sense to minimise it. Some modern stages are surprisingly noisy - they don't need to be.
- LF response. Often overlooked, the RIAA standard allows for optional LF filtering in order to reduce the effects or record warps exciting the cartridge/arm resonance (and reduce rumble in the early days). This can effect the sound in two ways. Firstly, some stages start to roll-off prematurely and so sound bass light. Secondly, pumping lots of sub 20Hz into your system can have unwanted consequences. It eats amplifier power, raises loudspeaker distortion because the bass driver coils and moving in and out of their range of optimum linearity, and if you use a valve amplifier it will stress the output transformers - possibly casing premature saturation.
