Recommandation for 1:6 1:8 SUT under $5K?

Elliot, I know how it works.  His way of describing it is emblematic of what Einstein is supposed to have said, to the effect that an hypothesis to explain a scientific observation should be as simple as possible, but not simpler.  I don’t really know whether Einstein ever uttered words to that effect; it could have been Yogi Berra.

In my opinion, the person who first adopted the custom of labeling SUT inputs with resistance values (ohms) ought at least to have spent a little time in a bad place, as punishment.  It’s diabolically confusing to the average end user. What you need to know is the turns ratio (in your parlance, the ratio of Voltage in to Voltage out, or vice-versa).  Period. From that, it is a piece of cake to determine the impedance seen by the cartridge once you also know the value of the input resistor on the phono stage.  You don’t need no stinkin’ tables.

On the pages you referenced from the AudioNote UK website, nowhere can I find the turns ratios of the respective transformers.  What is the rationale for the ohmic designations they provide for the various versions of SUT, as quoted by you above? They really don’t say on the website.  They want no questions from the buyer; just do what they say and pay your >$5000 for it. A transformer by itself has no impedance except that of the resistance of the primary. So, in isolation, a resistance value means nothing.

@lewm 

What you need to know is the turns ratio (in your parlance, the ratio of

 

This most basic detail is the point I am trying to get across.    I agree the turns ratio is the key factor and what you need to use to compute impedances and gain.  Then you go on to mention  "voltage in to voltage out" which represents the gain and this number includes the effects of the source and load impedance and the gain is not used to calculate anything impedance related.  Turns ratio is a simple definable constant for a device.  Determining gain requires info unique to the specific situation.  

In the attempt to simplify things and make it easy for the end user, the process of specifying and labelling SUTs has made a simple topic clear as mud.  What is needed is the use of accepted math and known well defined terms.  The introduction of the yet to be defined X-factor simply makes no sense when proper well defined terms exist.

dave

One example from the AudioNote website: One option is

AN-S4/M - 27.5 Ohm input impedance - For cartridges with an impedance of 7 to 9 Ohms

I guessed that means the SUT has a turns ratio that results in the cartridge seeing a 27.5 ohm impedance when the secondaries are terminated in the standard 47K ohm resistance. So I started by calculating what number when squared and divided into 47K ohms will give you 27.5, or 47K/X^2 = 27.5. This gives a turns ratio of about 1:40, slightly higher in fact. That does not make sense; nearly no cartridge ever made needs that much boosting into an MM stage with the typical 40 to 50db gain. So I am stumped.

lewm

guidance for a cartridge of 7 ohms x 10 = 70 ohms or more

8 x 10 guidance is 80 or more

9 ohms x 10 is 90 ohms

Surely Audio Note knows that

THUS, I figured, their 27.5 input impedance was not/could not be what was shown to the cartridge.

It's another absurdoid number

Perhaps I'll write them, and see what they reply