SUT With a Manley Steelhead RC?

Good question don't recall will ask and get back to let you know.

Dear Snackey, Your response, "Matching the gain setting on the SUT or preamp with cartridge output rating.", is not quite the way to think about it.  The cartridge has a certain signal output, expressed in mV in relation to stylus velocity. The standard stylus velocity is either 3.54cm/sec for older cartridges or 5cm/sec for modern cartridges. So that number in mV is the output at that velocity and is just a guideline for thinking about phono gain.  Since the typical MM cartridge makes about 5mV at standard velocity, and since a SUT is connected to MM inputs, the paradigm is to choose a SUT with a step-up ratio equal to whatever it would take to raise the voltage output to about 5mV (give or take).  So you need to know the turns ratio of the SUT.  The limiting factor is the effect that the SUT has on the impedance seen by the cartridge.  The input impedance of the phono stage is reduced by the square of the turns ratio.  So for a SUT with a 1:10 turns ratio, placing it between the MM inputs and the cartridge output will reduce the impedance of the phono stage as seen by the cartridge by a factor of 100, etc. The convention is that the phono input impedance ought best to be about 10X higher than the internal R of the cartridge for best signal transfer (although there is no danger in using a lower ratio, but as you go below 10X, there is loss of cartridge output to ground and possible high frequency roll off due to capacitance).  So, in choosing a SUT you want to have enough boost to result in a about a 5mV output at the MM phono inputs without violating that 10X rule of thumb.  But with a high gain MC phono stage or with an outboard active voltage booster stage (see Hagerman Piccolo for example), you don't have to think about any of that.  You just need enough total gain ahead of the amplifier to drive the amplifier. (Typically, that requires about 1V more or less.) There is no need to worry about "matching". To make this more confusing, most SUTs are labelled for the internal R of the cartridge that works best, e.g., a "3 ohm" SUT is intended for LOMCs with a very low internal resistance but it doesn't have to be exactly 3 ohms.  A 40 ohm SUT is for those LOMCs with a rather high internal resistance (Denon typically), but it doesn't have to be exactly 40 ohms. You need to do some digging to discover the turns ratio of such SUTs. What I am trying to get across is that a SUT is just a tool, not necessarily an embellishment to SQ.

@lewm Thanks for this.  I don't understand all of this fluently, but I'm getting there.  Your help is appreciated.

Cheers

Matching a cartridge to an SUT is a black art for me I would reply on other opinions. With that being said I'd also be one to go with a manufacturer of a particular cartridge say Koetsu and then buy a Koetsu SUT. Or if using an Audio Note Japan cartridge then I'd opt for their own SUT. Same with MSL. Would it not be safe to assume these manufacturers know what works best with their own products?

I don't think it is a dark art. @lewm will correct me if my terminology is wrong, but look up the internal impedance of the cartridge. You need the SUT to present it with a load that is 10X that number. They all "output" at 47k, which is standard MM input. That's the "step up" part.

For example, I had a couple Airtights, very low impedance and set my transformers to the closest setting of 10x their impedance. When I switched to Koetsu stones, I found a slightly higher impedance worked best. Some SUT set ups are more adjustable than others and SS stuff can be tweaked with changes in resistors or boards. (I use tubes for the phono, but the unit, an Allnic, is  adjustable with knobs on the transformers). I have an outboard SUT in my vintage system. Not a terribly expensive unit either and it's good, runs at a setting to match a Franken 103 with a MR stylus and potted into a wooden body by Steve Leung. 

The transformers themselves get attention too. There are some highly regarded older transformers- collectible, and modern high end ones like Slagle produces.