I think that the hybrid solution it would be the answer to the question. Low noise mosfets or opamps can make an excellent RIAA and at the output, a low noise tube as CF . I have a CJ PV10. It is a very good preamplifier but its phono stage is a disaster! Ihave been forced to connect my Technics SL1200 MKII(Stanton cartridge) to my pro DJ mixer phono input which sounds much much better than CJ. So I have decided to make a good RIAA preamp(without output stage-I can put a CF intead), with tubes or SS or hybrid for connecting my phono to the CJ via any line in. Any suggestions? Thanks a lot in advance.
For a typical moving magnet cartridge as they are made now, there isn't much point in using a step-up transformer and it would need to have a very high magnetizing inductance.
The advantage of a step-up transformer for moving coil is that it is easier to get a good noise match into the transformed impedance than into the very low original impedance, especially when you don't have large bipolar transistors with low base spreading resistance at your disposal (or don't want to use them because you like valves better). Moving magnet cartridges already have a fairly high impedance at the higher audio frequencies. I don't see how transforming it up would make anything easier.
The advantage of a step-up transformer for moving coil is that it is easier to get a good noise match into the transformed impedance than into the very low original impedance, especially when you don't have large bipolar transistors with low base spreading resistance at your disposal (or don't want to use them because you like valves better). Moving magnet cartridges already have a fairly high impedance at the higher audio frequencies. I don't see how transforming it up would make anything easier.
MM cartridges are often upto 20k or more at higher frequencies, and already sensitive to stray capacitance - boosting the impedance further is likely to lead to cutting the high end response. MM cartridges are already wound with many 1000's turns of ultra fine wire, ie they internally step up the impedance as much as possible in the form-factor.