SUT - electrical theory and practical experience


Some vinyl users use a SUT to enhance the signal of the MC cartridge so that it can be used in the MM input of a phono stage.  Although I don't understand the theory behind it, I realize that a SUT should be matched individually to a particular cartridge, depending on the internal impedance of the MC, among other things.  

Assuming an appropriately / ideally matched SUT and MC, What are the inherent advantages or disadvantages of inserting a SUT after the MC in the audio chain?  Does the SUT theoretically enhance or degrade the sound quality?  What does the SUT actually do to the sound quality? 

Thanks. 

drbond

intac, btw maybe you think the same over 100khz.

 

Each one of us have our self way of thinking.

 

You said in your site:

 

" The transformers are wound on massive.."

and the " Shipping weight - 11 lbs. [5 kg] "

 

Well Denon net weigth ( not shipping. ) is  12kg and 8kg for the vintage AT 1000T. Those are really massive.

 

But as I posted , no one cares about or just does not the knowledge levels for.

 

R.

@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.