Which SUT to match Koetsu Rosewood Standard in my system?


Howdy everyone,

I’m about to move to to my first MC cartridge, and I’d be grateful for your advice in choosing a step-up transformer. First, here’s my current system:

  • Table: Thorens TD-124 (mk I, with a few upgrades from Hanze HiFi)
  • Arm: Ortofon TA-110
  • Cartridge: AT-540ML
  • Amp: Audio Note Soro Phono SE Signature
  • Phono stage: Built-in MC phono preamp in the Audio Note Soro
  • Speakers: Klipsch Forte IV
  • Interconnects: Ortofon 6NX-TSW-1010L (came with the tone arm)
  • Speaker cables: 14 gauge Audio Note bulk wire (planning to upgrade this at some point, but not until I finalize the analog front end)
  • Room: I live in a city townhouse, so my listening room isn’t huge—about 15 feet long by 12 feet wide. It has been sound treated a bit: absorption at the first reflection points, front corners, and on the ceiling slightly in front of the listening position, and diffusion + absorption along the back wall.

It seems to me that the clear mismatch now is the cartridge, and after auditioning several contenders, I’ve settled on the Koetsu Rosewood Standard. At least in my system and to me ears, it gives me the most of what I want: a rich, organic, natural sound. When I auditioned it, the dealer lent me an Audio Note AN-S8 SUT. A fantastic piece of gear, but well above my budget at this stage.

So I need some help choosing an SUT. Here are a few priorities:

  • Maximizing the natural, organic sound of the Koetsu and amplifier, which seems to balance so well with my speakers—retaining the dynamism and drive of high-efficiency horns while taming stridency that sometimes also comes along, especially in my relatively small space.
  • Favor emotional impact over technical accuracy: “good” distortion can be fine with me.
  • That said, minimize noise. I rent a city townhouse, so there’s old wiring that I can do only so much to fix, and a healthy bit of RF noise. My turntable, while about as quiet as an idler wheel can be, isn’t as quiet as the best designs of today. My amp is great, but also not silent. And at 99 db sensitivity, those horns pick up everything. So it’s important that the SUT be well shielded from RF noise and have an effective grounding scheme.
  • Favor an ideal match with cartridge, amp, speakers, etc. rather than future flexibility. I don’t mind swapping the SUT out for something else if I decide to change cartridges sometime in the future. I prefer optimizing it to what I have now, not what I might have
  • A 1:8 step up ratio, if possible. The cartridge is 0.4mv; the amp’s phono input is 3mv. 
  • Budget: $3k or less, ideally 

I really look forward to your thoughts. Please don’t hesitate to ask for any other info that might be helpful. Thank you!

zazu22

@elliottbnewcombjr 

That is the MINIMUM signal strength it needs IN to boost the signal up to line level.

does anybody have any documentation on this standard?  As stated above it seems all technical but is 100% arbitrary since "Line Level" is not a well defined standard.  If we 'assume'  2V peak to be the line level standard then the gain of the phono can easily be calculated to 56dB which is an 'interesting' choice in between the typical 40dB of an MM and 60-70dB needed for MC.  

dave

... phono input sensitivity 3.0mv. Not Ideal, not preferred: That is the MINIMUM signal strength it needs IN to boost the signal up to line level ...

That is not quite correct. 3.0 mV is what’s needed to drive the phono section to "rated output." That’s a distinction without a difference if we’re talking about an integrated amplifier. But if we were talking about a standalone phono preamp, we’d also want to know the phono preamp’s rated output, to determine if it would be sufficient to drive a line stage preamplifier.

Below 3.0 mV, the phono section would still be delivering a "line level" signal because levels vary and music is rarely at maximum.

Thanks, @cleeds. So how does that cash out for my situation? Should I then be aiming for something around a 1:10 step up for a 0.3-0.4mv cartridge?

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