phono pre loading and gain question


I have a Motif mp-11 phono pre. Inside, through switches, the gain can be set between 40, 45, and 48 db. On the front is a knob selector for loading with positions: 70 ohm, 100, 150, 250, 470, 1k, 2k, 5k, 10k, 20k, and 47k. I have read most of the threads and am still confused about how low of an output mc I can use. This feeds into a Sonic Frontiers preamp with 20db gain. I don't want to get a step-up transformer if I don't need one...but I would like to try a Shelter cartridge out. Also, why would my phono pre have so many loading choices but so little maximum gain. One more thing...are step ups very prone to noise or hum. thanks
skeyebox
I never used a T-3000, so I have no personal experience with it. I have heard it is a very nice unit. Make sure it has the gain you want, and the loading selections you want.

Another choice that is good, is the EAR MC3 step up transformer.
I now use a phono stage with 45dB gain in MM configuration in conjunction with an internally wired Lundahl LL9206 step up transformer set at +20dB gain for MC. I have a Shelter 501 MkII pickup.

When I ran it through a passive linestage (no gain) and into a McCormack DNA-225, 30dB gain, I experienced very good performance, indeed. I tried this setup with and without the step up and found greater dynamics when using the additional 20db gain, As such, I can see where Tom feels that Skeyebox might be teetering on the edge with respect to gain and the Shelter. As a side note, I find that, in my system, the Shelter sounds much better on most recordings when loaded at 300ohm, as opposed to the 100ohm recommended by Shelter. For some reason, the sound is generally just a bit thin when loaded at 100ohm. Too dumb to know why, just know what I hear.

I have used the same phono stage running through a linestage with 14dB and, of course, have more than enough gain and, in fact, am thinking of dialing back a bit on the MC step up.
OK, I tried the gain calculator at Kab Acoustics www.kabusa.com/pregain.htm and for a MC output of .2mv and a desired preamp output of .5 volt the calculator recommends 64db of gain. The problem with the whole game is that gain only tells you if you can drive your amp to clipping, not what the noise structure will be when you get there and not how badly you are compromising dynamics. A lot of this mess is very cartridge and stepup specific.
Well, my amp is very low power, maybe I don't have alot of gain there, so I need to get it earlier in the system. I don't have a gain spec on my amp. Heck, all I know is that is what it takes to sound good in my system.
Tom, my comments were made to point out how important noise structure is to the whole equation, not to call into question the veracity of your statement. You own the cartridge, as I said, I don't. I would always, always, defer to your expertise in this area. It is a fascinating area of discussion though. The calculator is just some mathematical game really and cannot substitiute for the real world experience that you, and other owners, have with a given setup. Now captured bearing versus unipivot, knife edge and oil bearing arms, that's where we can have a hearty and respectfull disagreement.