SUT - electrical theory and practical experience

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.   

Look, the main SUT limtation vs an active high gain SS alternative is its way limited  frequency bandwidth

If you are using opamps, you'll need a fair amount of feedback and that feedback will correct phase shift. So even though an opamp can be really wide bandwidth, it becomes less important because phase shift is minimized.

When you have a passive device or if the circuit is zero feedback, that's when you need the bandwidth in order to prevent phase shift. Now its well-known that the smaller you make an audio transformer and if that transformer does not have any DC in its core, its actually pretty easy to get wide bandwidth, often well past 100kHz. 

Put another way, the reason to have wide bandwidth is to get low phase shift in the audio band if you don't have any other method (such as feedback) to control it.

The concern IMO isn't the high end! its how well it goes low. But again with small audio transformers this is fairly easy to do.

Dear @lewm  : This is  the Denon design explanation, it's interesting to read it by any one:

""" 

 DENON has already released the DL-1000A, the highest grade cartridge, but in order to fully demonstrate the outstanding music playback capabilities of this DL-1000A, we have developed the AU-1000 as the highest model of step-up transformer. I did.
In order to boost the minute music signals sent from the cartridge, physical characteristics such as frequency characteristics were pursued, and countermeasures against external induction, i.e., strict shielding of the transformer unit and main unit, anti-vibration structure, connection cords, etc., were thoroughly examined in detail. and improved the degree of perfection.
In addition, in terms of sound quality, we have repeated sufficient listening tests to create a product worthy of the name of "the highest peak of step-up transformers."

Features

1. Basic design born from thorough pursuit of sound quality.

For the transformer core, under strict material management, special-shaped large permalloy thin plates that pass strict specifications are laminated . Magnetic permeability, which is the basis of transformer quality, is about 1.5 times higher than conventional products (compared to our company) in the bass range, and achieves high saturation magnetic flux density over the entire .
A special split sandwich winding reduces the line-to-line capacity and extends the high range. In addition, a primary winding that is about 1.4 times thicker than conventional products (compared to our company ) is used to reduce resistance loss. Combined with the high saturation magnetic flux density, the dynamic range is wide, realizing a rich sound reproduction .

2. Thorough pursuit of sound quality with a simple structure.

Since it is dedicated to the MC cartridge DL-1000A, the impedance selector switch and intermediate taps have all been eliminated, and the structure to improve sound quality.

3. Multi-shield structure that is resistant to externally induced vibration noise.

A single transformer is double-shielded with a permalloy shield case, put in a thick gunmetal case, and fixed with a filler. Also, since the LR channels are wired independently in separate gunmetal cases, there is no crossover of wiring. Furthermore , the entire body, including the input/output pin jacks, is covered with a thick casting shield case and can be used as a high-grade universal transformer.

I owned that maybe the best Denon cartridge ever and when I bougth the cartridge in Laredo, TX I did not know about the Denon SUT.

R..