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

Dear @holmz : Could be interesting to make some tests looking for the transient response rise time of a cartridge in an active high gain phono stage and other using SUT.

 

Exist a very old measurements made it by an electret vintage cartridge designer where he found out that the rise time of his designs was 2 micro seconds at 1khz generated square wave ( Osciloscope. ), moving magnet 25 micro seconds and a moving coil through a SUT 30 micro seconds.

 

That rise time is critical in transientes response by obvious reasons and you like to make measurements maybe you can do it. Just curious.

 

R.

 

 

Dear @holmz  : Things are that's really weird that the rise time in a MM cartridge been faster than in a MC cartridge because it must be the other way around and maybe was the SUT who could had the culprit, at least everything point at the sut.

 

R.

Dear @holmz  : Things are that's really weird that the rise time in a MM cartridge been faster than in a MC cartridge because it must be the other way around and maybe was the SUT who could had the culprit, at least everything point at the sut.

 

R

If you had an ishikawa chart of causal mechanisms, then it is possible that the inductance of a SUT could be on the list of things that limit the bandwidth.
Whether 500kHz or whatever the rise time corresponds to… is better or not, is uncertain.

Dear @holmz : Maybe you are rigth but today I know that the best SUT goes from 2hz-300khz almost flat and you have to think that are electronics that have not even that bandwindth.

 

My point about rise time is something different because transiente response live MUSIC is what " makes " MUSIC that at the end is a concecutive transient response notes.

By its design construction the fastest magnet cartridge is the LOMC against MM/MI/IM designs however the transiente response rise time at 1khz was measured and MM cartridge is fastest that a LOMC/sut combination and as I said the SUT made " slower " when thing must be the other way around.

With out facts my common sense tells me that a LOMC through an active bipolar hifgh gain design is way fast than the same LOMC cartridge + the additional IC cables and the SUT it self where both signal must pass through. So transient response that defines the notes/harmonics is slower through a SUT and this sole characteristic is an additonal and crucial disadvantage for a SUT.

All we know that, for example, the Etna SL quality level performance is better than the Etna that has higher output level, that’s higher inductance/impedance. Transient response rise time in the SL is faster.

 

R.

I forgot that rise time is from steady to the time to achieve 10% to 90% of the step response.