SUT - electrical theory and practical experience

Raul, By "passive", I only mean that it does not require or consume external power.  OK?  You can use any other definition you want.

I’m a SUT + LOMC fan. I just like the sound many (most?) SUT’s provide - rich, meaty, weighty. In my system, that’s the right direction - other systems may differ. I have an Audio Research Reference 3SE with a really great JFET MC stage. In the past I’ve had a Herron VTPH-2A, also with a great JFET MC stage. These JFET stages sound great, BUT they’re inevitably leaner and more sterile sounding than the SUTs I like. I have about a dozen MCs, so my listening experience is not limited to 1 or 2 models.

That said, there’s a pretty great variance in the sonics of different SUT brands. The difference can be as significant as changing cartridge brands, even when the step-up ratio is kept close. It’s quite striking. The blue-label CineMags (this includes Bob’s Devices Sky, 1131, 1254) are very much on the rich/lush/weighty side of things. The EAR has a particularly romantic tube-like midrange. The Quadratic MC-1 (a CineMag blue but with a MUCH bigger core than usual) has extremely low distortion through the midrange and treble with extremely powerful bass response. The Hashimoto and Koetsu are also excellent, and a bit more neutral, though still with more weight than a JFET. The Lundahl LL1931 and LL1931Ag (amorphous core) is much thinner and more "crystalline" sounding - not a bad sounding SUT, but not my personal preference! I think I actually prefer the JFET stages to these. Also - don’t skimp with a cheap SUT; I found the Red-label CineMag 3440A (cheaper than and blue-label) to be borderline bad, and the Lundhal LL9206 (cheaper than LL1931) to be fairly mediocre.

One practical consideration is you really need a very short, low capacitance run of cable from SUT to phono stage. If not, you’re going to REALLY hear this cable, in a bad way. And a 20x step-up ratio is usually a "pretty good" choice for many/most LOMC cartridges.

I’ve found a good SUT will be quieter than a good JFET stage IF (!!) you can properly address all grounding gremlins.

"One practical consideration is you really need a very short, low capacitance run of cable from SUT to phono stage."  Which is a good reason for having a high quality SUT built in to the phono circuit, on board.

Dear @mulveling : " I’ve found a good SUT will be quieter than a good JFET stage "

Only true reason for that is that your JFET unit is a mediocre overall design.

Btw, "" rich, meaty, weighty. ""

typical " audiophile/tube " adjectives that means nothing about MUSIC, specially live MUSIC seated at near field position that’s where the recording microphones are positioned. Your statement means that you like sound full of developed COLORATIONS/DISTORTIONS.

R.

R.

"One practical consideration is you really need a very short, low capacitance run of cable from SUT to phono stage." Which is a good reason for having a high quality SUT built in to the phono circuit, on board.

@lewm - That’s somewhat true. It’s an advantage to be onboard in the phono stage box. However, I have LL1931 built into my VAC Renaissance SE (another phono stage I own) and my preference for different SUTs greatly overrides the advantages of being onboard. I also have an outboard K&K SUT box with LL1931Ag (i.e. I’ve tried LL1931 both onboard and outboard), so I know it’s really the LL1931 sound that I don’t like.

Being onboard reduces the chances you’ll have a grounding hum issue. And of course it eliminates the chore of picking a transparent IC. But once you know you need a low capacitance short run IC, it’s pretty easy to find a "transparent enough" cable.

For me, the ability to choose a SUT to my preference is by far the dominant factor over issues with IC’s or grounding. I’ve yet to be super-impressed with an onboard SUT.