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

Am I the only one shaking my head?

No @antigrunge you are not.

 

Holmz, Make no mistake, Dave (Intact Audio) knows more about this subject by far than I ever will. So if my advice to check out the Jensen website seems counter to or only partially correct in view of Dave’s insight, go with what Dave says.

I am open to understanding, so anything many say is received including @intactaudio comments.

But I’ll need to check the diagram to see if that built-in 1:4 SUT is loaded on the primary or secondary side.

 

I don't believe I have expressed any negativity (or keeping it Seasonal 'Nativity' towards your endeavour 🎅🤶).

@pindac I may have seasonal naïveté 😀

As said in a previous post and one said with sincerity, as a result of my interaction with the analog forum.

" I wish you and all Forum Members in equal measure,  the very best for the Festive Season and hope for a Prosperous 2023 to be met. " 🥂

@holmz 

But I’ll need to check the diagram to see if that built-in 1:4 SUT is loaded on the primary or secondary side

There are two possible loads that this SUT could have. The unintentional which is the typical 47kΩ input of a MM phono and the intentional which would be an additional filter on the secondary to "correct" any misbehavior of the device.   Both of these loads would be on the secondary of the device.  If there are specified cartridge loads for MC then is possible there could be an additional combination of primary and secondary loading and with the low turns ratio this is a possibility. 

I do think that the typical "dull" sound from loading a cartridge down too much is purely a function of the SUT behavior.  Since you have such a low ratio transformer an interesting experiment would be to find out the "calculated" reflected impedance and then try the following experiment.  (below I am assuming a 47kΩ load and a 40Ω Denon 103 and you can scale the values for different cartridge impedances.)

Assuming the 1:4 is terminated with 47kΩ  and a the cart should see 3kΩ as a load.  Now place a 1.6kΩ resistor across the secondary to reflect just under 100Ω to the cartridge and give it a listen.  Next remove the 1.6kΩ resistor and place a 100Ω resistor across the primary and listen again.  In a perfect world the load the cartridge sees will be the same (roughly 2.5X the internal impedance).  The gain of both situations will also be the same and my experiences tell me the sounds will be quite different.  To be clear... any differences heard will be a function of the SUT behavior and not the load the cartridge sees which puts this squarely in the purview of this discussion.

now that I am done with my airing of grievances it is on to the feats of strength.  Happy Festivus to all!

dave

Dave, I’m getting my Festivus pole out of storage now. I just aired my grievances with my wife. Then we’re going out for Chinese food.

Dear @drbond  : Yes, is more easy posted that way that give an answers that affect you because what I posted seems to me is true.

 

Ignore is your proble. Fine with me.

 

You have a huge problem that I posted in some of my posts: why with your CH are you asking so " deep " in a SUT other than buy one of same preamp manufacturer? This has no sense to me but obviously has a lot of sense to you that are not 100% satisfied with the CH. Maybe I'm wrong.

 

R.