SUT - electrical theory and practical experience

@mulveling 

The SUT I used include Cinemag 1254 transformers wired at 1:10 for my Lyra Delos.  

It sounded louder because of the extra resulting gain and really good but ultimately not as refined overall as my Sutherland fully active.  

Thanks. There are better SUTs (for more money), but the 1254 is indeed a good one. I was afraid you were using a 3440 but that's not the case. A good mark for the Sutherland, indeed. I'll have to try one someday!

I think you do not re-read carefully that Palmer/holmz posts.

Anyway, I think is enough for that.

R.

Btw, @intactaudio  : you capacitance parameter of 80pf coukld be not real to make SUT measurements as the 300k load.

Normally what sees the MM stage + SUT is a load of 47k and capacitance around 200pf. Then measures arwe different that with your " choosed " parameters.

Unfortuntaelly cable manafucterer almost never gives the cable capacitance but almost all are higher than 150pf and even over 200pf.

R.

Btw, @intactaudio  : you capacitance parameter of 80pf coukld be not real to make SUT measurements as the 300k load.

Normally what sees the MM stage + SUT is a load of 47k and capacitance around 200pf. Then measures arwe different that with your " choosed " parameters.

Unfortuntaelly cable manafucterer almost never gives the cable capacitance but almost all are higher than 150pf and even over 200pf.

I think everyone who prominently recommends SUTs on this forum also cautions to select low-capacitance cables. There are ample phono-targeted ICs optimized for low capacitance. Select one of those models, keep the run short (ideally under 1m), and hitting a capacitance under 80 pF is quite easy.

Here’s my current assessment, which has been nicely summarized by @intactaudio :  basically, the cartridge is naturally developed as a current generator,

I was pretty convinced of ^that^ myself, but I still have some lingering confusion.

however for the past decades, phono stages were created to unnaturally transform the cartridge into a voltage generator by adding the load in the phono stage.

Unnatural is a bit subjective. If one shoves the current across a resistor then they can measure the voltage across the load like ohms law states. Ohms law seems like it is “natural”.

 However, when the cartridge operates as a current generator, no external arbitrary loading needs to be added to the signal created by the cartridge.  So, it seems,  based on my limited knowledge, that the current based phono stages would be most naturally associated with phono cartridges.

Many people use the Sutherland, and other trans -impedance phono stages, and love them. Usually with carts that have a very low output impedance.
And they do have an allure.

And many phono stages use a voltage based design, and/or SUTs and love them.

I was leaning heavily towards the Sutherland, but got a phono stage with SUTs built in, mostly because I liked the look of it, and it had two inputs.

if we look at a step up transformer, with an input to output ratio of 1:2, then we see that the voltage is doubles, and the current is halved.
If it is 1:20 then the voltage is x20 and the current 1/20.

A cart does not look too dissimilar as the input winding is serviced by the magnetic field of the magnet. The magnetic flux varies with the cantilever movement.
The output winding is the coil.

• When there is a lot of windings, like on a MM, we get more voltage and less current. (Probably better for a voltage based amplification.)
• When there are fewer windings we get less voltage and more current. (Maybe it is better for a current based amplification?)
• Then there is a middle ground with a bit higher output voltage or with a higher output impedance were it seem like it is unclear and all bets are off.

^This^ is not much of an answer, other than the choice of phono stage sort of relies on a cartridge in front of it.

And in this case we sort of need to “put the cart before the horse”.
Or…
We already have the selected phono stage, and we damned well better select a cart that will work with it.