SUT - electrical theory and practical experience

@rauliruegas 

Blindly parroting frequency numbers without clear designation of the related decibel level is an effort in futility.  In looking at the 3-200kHz number of the Technics you reference (SH-305MC) there is no designation of the attenuation level at the specified frequencies, They do state 20Hz to 100kHz ±0.2dB but fail to state the exact test conditions (source Z, Load R and C).  The Denon AU-1000 states 5Hz to 200kHz but also lists no other test conditions.  The Frequency response plot I found shows it to be -2dB @ 5Hz and -4dB @ 200kHz again without specifically listing the complete test conditions.  One could assume  that the source is 30Ω and the load 50kΩ and there is mention of a low capacitance accessory cable so that is more info available than the Technics. 

For any design it is easy to find and publish the optimal wide bandwidth conditions for great measured response but absent the full details of the test condition, the numbers become meaningless.  If the underlying numbers have no real value, then any presumptions based on those numbers also lose validity.  I also fail to see how you can consider both of these transformers to be "flat" for the bandwidth you quoted yet fail to see the ±1dB response from 10Hz to 230kHz of the EM/IA 1:20L driven from a 9Ω source and loaded with 300kΩ in parallel with 80pF of capacitance.

I do want to be clear that I do not think frequency response should be the sole dictator of "quality" of a SUT.  Bandwidth is just one parameter of many that has to be addressed in a given design. In fact assuming the frequency response safely covers the audio band,  I find core material, dielectric choice and winding wire to be far more dominant factors in the final sound. I find extending bandwidth (particularly at high frequencies) is simply more icing on an already delicious cake.

Elevating the merit of a SUT based on a single ambiguous parameter as you do is like purchasing a sports car because it is a pretty shade of red or has a lower curb weight than the competition.

dave

Raul, to state the bandwidth of any transformer, particularly an audio SUT, without specifying the upper and lower limits of the given bandwidth in db, the impedances on the primary and secondary windings, and the other reactive components of the load, like capacitance and inductance, is fairly without meaning, I would think. But Dave said it more eloquently.  (I saw his post above when I was about two-thirds through writing this one, so what the heck; I'm hitting the "post your response" button.)

Dear @intactaudio  : I'm not saying that the SUT FR is the only parameter to buy a SUT but always can gives us an " idea " of its quality and yes there are other parameters.

Now, the Technics measure was:  3hz-300khz +,- 0.4db, the Supex 5hz-170khz -0.5db

Denon response as you stated with this parameters: primary impedance 30 ohms, secondary 4kohmz and load 50kohm. Mine is loaded at 100k and 200k but never measured with those load resistance ( 100k by default and can't remember capacitance. ).  Who knows under your specific conditions or mated in specific to the electrical cartridge characteristics.

My take is that all those vintage SUTs even that does not been silver wired are all fenomenal to say the least and came between 1981 to 1984. I don't know you but my " hat off " about.

Your information appreciated.

Now, I know that you already read the thread where Mike Lavigne and me had a pretty hot dialogue in other thread where I was high " surprised " that instead to runs the LOMC cartridge directly in his Dartzeel he was/is really happy sending that signal to several additional steps before the Dartzeel line input and other than your SUT one of those steps is your " phono corrector " and I distubed him asking for the FR RIAA deviation of your unit because I just can't found out any where but now that we are talking of your SUT design and others SUTs I should be sure you have that RIAA deviation already measured and maybe you can share with us and your customers.

Thank's in advance,

R.

Dear @lewm  : " you would say ? " ( already those limits in dbs. )

Look, the main SUT limtation vs an active high gain SS alternative is its way limited  frequency bandwidth and I don't really car to much of the other parameters but you talk with out own a SUT and it's your rigth to do it.

Silver wired SUT does not makes a huge difference in that main SUT characteristic and only could helps for a better quality sound level.

Now, after 41 years what is really NEW in today SUTs ( any ) vs the vintage ones?

I don't know you or other audiophiles and even manufacturers but for me NOTHING at all changed even no one today SUT and even with dedicated parameters for an specific  cartridge can outperform the vintage bandwindth spec and not only at high frequency but more important at the other frequency extreme: in the low bass where in those vintage SUTs are not one but some that starts at 3hz-5hz.

Now, SUTs are for the huge mediocrity of phono stages designs and very especial with tube, not only in tubes because exist that mediocrity in some SS designs too.

The only SUT dedicated to an specific cartridge that I listened/owned for several years was the Audio Technica AT 1000T that came with not 2 but four transformers where two of them were dedicated exclusive to the great AT 1000 LOMC ( o.1mv. ), no it was not silver wired and no it was not hand wound wired because with transformers nothing can have the precision need it to the transformer wound wire as an specific tool/machine ( hand made on this device are for ignorant or stupid gentlemans. ). That AT SDUT really good and if I remember weigths around 10kg.

I think that the only silver wired SUT I experienced was the Kondo that can't ( for me ) justify its truly expensive price tag against ist quality level performance, my Denon is way superior and is not silver wired.

My modified Denon AU-1000 beats my active high gain stage? certainly not but is close to it due that my phonolinepreamp has a dedicated dual mono MM stage with no bipolars devices as the MC stage but what a MM needs and for several years is running the MM stage with 100khz instead 47k and with out input resistor.

Rigth now I'm using this MM stage along the Denon because I'm doing some modifications in the MC stage and at the same time I'm fine tunning the Denon SUT.

R.

@intactaudio "I find core material, dielectric choice and winding wire to be far more dominant factors in the final sound". 

The words used above by Dave are ones I have been party to over too many years from various contributors, who all say a similar thing. Which is basically the construction materials and skill set of the constructor, when it comes to Transformer Design and Production are critical.

I sense from all that I have come to learn about intactaudio, not just through my owning a design of Transformer produced by them, that within this establishment there are skilled individuals who are doing their best to maintain this very rare practice, by producing products that have detailing that has an emphasis on where the little things really matter.

I have yet to discover a design incorporating a JFET that has the same impact on a SQ and creates an attraction through use, that a well thought out design for a Transformer can 

My experience has been to date, if something is wanted to be produced that shines out for its attractiveness, much of what is discovered will owe much credit to the design for the Transformers that have been selected. 

In my discussions had for the producing of devices I have in use, Enclosure Environment, Topology, Schematic and Component Selection are the considerations. All are equal considerations if an optimised performance is the end goal.  

From my end, no dispute, each to their own, on what type of Topology and Components are used/not used within a Schematic for a device selected to function within a system.