The Supratek phono stages are designed for moving coil cartridges only.
Why no provision for moving magnet?
Well I'm sorry but if you are going to spend considerable money on a phono preamp then you may as well buy a quality cartridge, and in my experience moving coil cartridge always gives a better result.
Yes there are some good MM's but even a good quality budget MC will always sound better.
Its my opinion, and some will disagree, but I build the preamps to what I consider the highest standard , so MC it is.
In some ways I'm making it harder for myself- as I've pointed out MC have tiny voltages and need enormous gain , and to achieve that gain with tubes, and no feedback is difficult.
There's two ways to get the extra required gain for MC compared to MM. Passive and Active.
Passive is a step up transformer , and its the method most manufacturers of phono stages use.
They are quiet, reliable , and I'm a big fan of transformers in audio, but not for phono stage inputs, phono step ups always sound limited in dynamics and "choked" to me, they just bore me , its as though someone turned the excitement down.
Actives use electronic methods to get the gain, either more tubes (too noisy) or with FET transistors in front of the first tube.
They are very dynamic sounding and handle the tiny voltages perfectly, I dont think there is any comparism in sound quality, and its not a small difference, active is alive and exciting.
So why are most tube phonos designed to use passive step-ups?
Tubes are wonderfully linear devices that dont require feedback to give very accurate preformance, but they are not as quiet as solid state devices , or passive transformers - they have a noise floor that is louder than solid state or passives and when you amplify thousands of times the noise floor can become audible as hum or hiss.
So you cant simply add more tube stages to get the required gain as noise will become a problem.
If one is determined to use an active method, for the most realistic sound ,then fet's are the ideal solution, these little guys work more like a miniature tube than a transistor and are quiet.
In combination with very quiet and substantial power supplies, very well designed and implemented grounds and good circuit layout, the gain for low output moving coil cartridges with outputs of 0.2mV can be realized .
Its not easy, which is why very few manufacturers even attempt it, but the noise can be down below the noise floor of a vinyl record, which is all that is required.
Still not as quiet as a passive , its true, but the combination of a low output MC cartridge and an active tube phono stage easily surpasses any passive method, even the ultra expensive passive phono devices struggle to come close to the excitement of active vinyl.
Tomorrow, LCR and LR phonostages.
