SUT - electrical theory and practical experience

@intactaudio Your last response is what I would call an IP reveal and very generous as an offered information. 

I carry info' like this from my Bespoke Designs I own,but have always felt my liberty was best constrained when the opportunity arose for sharing the Designer/Builders IP.  

I once had an awkward conversation with a not very well known to me EE at an event where I was demonstrating a device, they were keen for me to allow them to remove a Chassis bottom plate and let them see inside. I was adamant that that would be quite a betrayal to the designer with whom I have developed a close to 30-year friendship.  

Some observations:

I always found the specs for a cartridge confusing: 0.25mV output at 5 cm/second.  Into which load?  Open circuit?  Load=Cart impedance?  Load=recommended impedance?  Why not state the output voltage and the impedance at which it is measured?  Most recommended load impedances are specified over a large range (100Ω-1K), and they are all usually 10x the cart source impedance so the voltage divider effect will be small, but in some cases, it could have a significant impact on the output.

Matching the cart source impedance into the load would only be relevant if you are trying to transfer the maximum power from source to load which is not the goal of a phono preamp.  It would be like trying to match the load a speaker presents to the output impedance of an amplifier which can have an output impedance measured in milli-Ohms.

What you do want to match between cart and load is the conjugate match of the imaginary (reactive) part of the impedance so the cart sees a purely resistive load.  The cart has a complex source impedance which may not be a simple series or parallel capacitive or inductive component but a combination of those elements.  The complex impedance will most likely change with frequency as well, complicating the matching network calculations. 

Perhaps what is needed is an S-parameter measurement file for the cart that can be used in a linear simulator to design an appropriate conjugate matching network.  Most RF devices are spec'd this way and is the only practical way to design matching networks that work;  absent this data, it's like trying to find your way out of a maze with your hands tied behind your back and wearing a blindfold.

Dear @intactaudio  : Thank's.  I understand that normally the dielectric in SUT is air but I can be wrong.

The only SUT silver wired I tested in my system vs SUT's cooper wired was the Audio Note Kondo that was compared vs the AT 1000T, Denon 340 and Denon AU-1000 and in all tests I prefered the cooper wired SUTs ( phono input 100k. ) and you the silver wired ones.

Maybe the SUT kind of wire is more or comes along with the room/system and owner targets. Different with speaker croosover inductors where silver is superior to cooper wired and ribbon shape over rounded ones.

Btw, the Kondo goes down to 2hz ! ! and Audio Note builded around the end of the 70's a SUT with an exceptional FR: 2hz to 200khz at -o.5db and 0.001% distortion. I never seen in the market and I don't know neither if was silver wired but probably not because was at the midle of Audio Note SUT line.

R.

Maybe just maybe drbond is just " trolling " in his latests posts, lewm in the very first page of the thread posted:

Audiogon Discussion Forum

Of course that the op as any one of us has the rigth to post almost what ever we want.

R

This Thread with the content on SUT's has served as a very valuable and relevant thread for anybody with a curiosity about the method to be used with a MC Cartridge.

There has been very valuable Posts contributed to this Thread and if read in Conjunction with the SUT Thread that resurfaced as this thread has developed is potentially a reference place for subjective evaluations and guidance on how a inclusion of a SUT might be perceived.  

For the record,

I have been influenced by Copper Wire over Silver Wire, for all interface cables s and Transformers used in my system.

I have had a period of using a Silver OCC Wire Phono Cable, but this is now Superseded with a Copper Wire Cable.

I even had two very heavily modified CDP's trialed where the main differences were that one model was with Bespoke Produced Silver Tranx's and the other Copper.

I was quite impressed with the Copper, and it was this design that was instrumental in my consideration of a CD source in my system.

More recently I was being demonstrated Two SUT's in another system, one with Copper Wire Windings and produced to be an ideal match for a Miyajima Cart'. 

The other a usable match for the Cart' with Silver Wire Windings.

I thought I was done on the SUT front and was where I wanted to be, with the EAR TX4 (The Head) being the Holy Grail to aspire to.

What was experienced was beyond what was expected.                                            I was blown away by the demonstration of both SUT's, as were the other attendees, of which a few have the opportunity to receive demonstrations of (The Head) in the system in use. Their assessment being there are similar impressions being made and it would be great to hear The Head and these Models A/B compared. Not many models would be considered as a contender.

A SUT that is an ideal match for a Cart' is quite something and to have the Brands Models demonstrated in my own system in a winding ratio that is a match for my Cart', along with the Silver Wire version is the Top of the List for when I have a Vinyl Source back in action.