Which SUT to match Koetsu Rosewood Standard in my system?

Thanks for providing some relevant data.  One more question: what is the gain in db of your phono stage? And just to be sure, what is the voltage output and internal resistance of your prospective new cartridge?

I don’t think that Audio Note publishes that spec. I could be mistaken, but here’s the manual: https://www.audionote.co.uk/_files/ugd/89c24f_e3f648926d024a13b9846ae2269296f9.pdf. See page 9. Is there a way to test for that? Or calculate it from the specs they do provide? Based on specs for some of their comparable standalone phono stages, it appears that it could be anywhere from about 36 db to 56 db.

As for the cartridge, output voltage is 0.4mv. Koetsu is also a bit stingy with specs, and doesn’t publish internal impedance (so far as I can tell). But other sources say it’s 5 Ohms. 

For about half what your budgeting you could get a Soundsmith MCP2 phono preamp which sounds great and features easily adjusted cartridge impedance loading. Koetsu recommends a range of 75-500 ohms. That’s a huge range and has an equally huge effect on the sound. It’s fantastic to dial in small changes while listening to find the best setting for your taste. I just recently bought the Rosewood Standard and went this route over using a step up transformer.

IMO: for that cartridge: you need a unit that has separate control of GAIN (x factor) and separate control of impedance shown to the amp's phono input.

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Your intended Cartridge (KR) is 0.4mv signal strength; 5 ohm resistance.

1:8 gain ratio (x factor 8) is not right for that cartridge, it is too low for two reasons. 

Your Amp's phono specification: 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. These amp's phono inputs also have MAXIMUM _____ mv, (before overload occurs) I cannot find what your amp's max phono signal strength  is. You can write the maker and ask. 

X factor directly effects the resulting IMPEDANCE SHOWN to your amp's phono input's impedance, (presumably 47k).

There is a 'guidance formula' for any cartridge's Impedance Shown: cartridge coil impedance x 10 (KR 5 ohms x 10 = 50 ohms). Thus guidance for IMPEDANCE SHOWN is 50 ohms, or a bit more. 

Impedance Shown Calculation: x-factor. x-factor squared. Divide phono input's impedance (presumably typical 47,000) by x-factor squared = impedance shown to phono input.

x factor 8 = x factor squared 64. 47,000 divided by 64 is: 734 ohms impedance shown to amps phono input. (over 14 times guidance of 50 ohms)

It is inverse: the higher the x factor, the lower the Impedance Shown.

x factor 16 = x factor squared 256. 47,000 divided by 256 is 183 ohms shown to the amp's phono input. (over 3 times guidance of 50 ohms)

Meanwhile, signal strength is getting higher, 0.4mv x 16 = 6.4, allow some loss, say 6.2 mv. More may be too high signal strength. i.e. KR 0.4mv x 20 x factor = 8.0. allow some loss, say 7.7 mv signal. Close to overload?.

IF you increase x factor, to lower impedance shown, the signal strength will be too high.

That is why this KR cartridge would be best with a unit with independent gain and independent impedance controls. 

Note: the other reason 1:8 x factor is not ideal: you want a phono signal strength that does NOT require a lot of gain from your preamp, BECAUSE, some (not all) preamps get noisy when you have to raise the gain control a lot. KR 0.4mv x 8 = 3.umv, allow some loss, say 3.0 mv. 

To make it a bit simpler, you’re probably OK with a SUT that enhances the signal voltage by 10X. In other words, a turns ratio of 1:10. It is unpardonable that the manual doesn’t stipulate phono gain but we can hope it’s at least 40db. We do know the fixed phono load resistance is 47K ohms. For a 1:10 SUT this means your cartridge will see a load of 470 ohms. (Load seen by cartridge = 47K/(turns ratio)-squared = 47K/100 = 470.) over the decades, I have seen output voltage for the Rosewood quoted between 0.4 and 0.6mV. Other important variables and unknowns include linestage gain and amplifier input sensitivity and speaker efficiency. 

Thanks for all of the advice so far. I’ll reach out to Audio Note to see if they’ll provide that info.

One other piece of potentially relevant info: I do have the Hegel V10. Would it be useful to play around with gain and capacitance settings on that first, and see what works best? I just wasn’t sure if the combination that might sound best on the Hegel would necessarily translate to what would sound best on an SUT. 

@lewm on the question you asked: 

Other important variables and unknowns include linestage gain and amplifier input sensitivity and speaker efficiency. 

The Audio Note manual says that line level input efficiency is 300mv, and line level input impedance is 100 Ohm. I’ll report back on gain.

As for speaker efficiency, it’s 99 dB. Thanks. 

1:20 is the best match for the Rosewood into the Audio Note.

Do you not like the Hagel? I’d try it first. At least that should give you an idea of how much gain you need.

I do like the Hegel overall, but it’s almost too “clean” and precise, if that makes sense. It does something to the signal that, at least to my ears, takes away some of the warmth and magic of the 6L6s in the Soro. I suppose I could be imagining that—it’s always so hard to separate physics from psychology in this endeavor.

But the dealer who sold me the amp said that Audio Note designed its phono stage to be used with SUTs, and he thinks it really shines best with a SUT rather than an active phono stage. He actually steered me away from Audio Note SUTs for now, as he thinks there are better bargains to be had at my budget than AN’s mid-tier offerings. So I don’t think that he’s just trying to sell me another Audio Note component. 

When the SUT Route is adopted, the device 'dependent on model' will add a Rich Tone to the presentation, there are models able to impact on the mid's and low frequencies that can have a perception of producing added weight. this can extend, again 'model dependent' to a perception of a Overly Lush Tone where there is a very loose bass and a subdued mid and upper frequencies.

I use two Different Brands Transformers for my SUT's, as each offers a different perception of a Rich Tone, if I want to move away from the influence of the SUT I use a Head Amp or one of the owned Phon's Built in MC Stage.     

Dear @zazu22  : "  takes away some of the warmth and magic..."

Well, at that kind of price level AN always is colored because what you like/statement just does not exist in live MUSIC.

Now, your unit does not needs a SUT it does not matters what your dealer said it. It has enough gain to handle the Koetsu, a SUT only can degrade the cartridge signal it can't to enhance because the SUT is an addional stage ( rca connectors, IC cables, solder joints, etc, etc. ) where the truly delicated and sensitive cartridge signal must pass through. Makes no sense that SUT.

In the other side you own the Hegel unit that M.Fremer said is " remarkable " and was truly impressed with when in his review he said used two top LOMC cartridges the Umami Red and nothing less that the Ortofon Verissimo and compared against his 45K dollars dedicated phono stage: Dartzeel.

Hegel let to listen what is recorded in those grooves on each LP. That you or any of us like it or not is in reality not the main issue but that what we listen stay truer to the recording.

Regards and enjoy the MUSIC NOT DISTORTIONS,

R.

Hegel V10 is exactly the kind of unit I thought you would need: independent gain control and independent impedance control.

I have 3 tonearms, but if you have 1 arm and several cartridges, it is nice if they have similar output regarding the positioning of your volume control when you switch them

Me, I would go for anything in a range 1:12 1:14, no higher than 1:16

KR 0.4 x 12 = 4.8mv. That is close or higher than many MM cartridges: mine range from 3.2mv to 5.0mv

Several Grados are 5.0mv

All my Audio Technica’s are 4.0mv including your 540ml

My Shure’s: V15V is 3.2mv

97xe is 4.0mv

Ortofon range is 4.0 to 5.0 to 5.5mv

@rauliruegas , even if the Audionote Sorro had enough gain the fixed 47k loading will sound like poop with the Koetsu cartridge. I’m finding it most pleasing in the 50-100 ohm range in my system.

@rauliruegas You do make a good point, raising the age-old debate of accurate reproduction vs. subjective pleasure. In my experience, having listened to some of the most accurate systems on earth, reproducing exactly what’s in the grooves doesn’t always equal subjective enjoyment—which for me is the sound of live performance.

That said, you’re quite right that the Hegel is a great unit. That’s why I bought it in the first place, after all. Fremmer’s rave review, among many others, certainly sold me on the Hegel.

It’s quite possible that the Hegel sounds “clinical” to me only in direct contrast to the Audio Note’s built-in tube phono stage. Also, I’ve only tried the Hegel with my 540ML (which is ”cooler” and more clinical than the Koetsu, at least to my ears) and only through the Audio Note’s line stage. It may be that the Koetsu + Hegel + AN phono stage combination would work quite well.

And as @elliottbnewcombjr mentions, the Hegel gives nice flexibility with independence gain and impedance control. Perhaps I can find a combination that gives me what I’m looking for, and can hold off on the SUT search. I think the wise thing would be to start there and see what I learn.

I still welcome any thoughts on the SUT in the meantime. I’m a tinkerer, and I know I’ll want to give one a try sooner or later.

Thanks to all so far for the quite helpful advice. In my short time on the forum, I can already see that this is a welcoming, productive, valuable community. 

Also, @elliottbnewcombjr thank you very much for this clarification:

Your Amp's phono specification: 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. These amp's phono inputs also have MAXIMUM _____ mv, (before overload occurs) 

I had no idea that’s what that specification indicates. You learn something (or several things) new every day!

Go look for a used Denon AU-340 SUT. They use high end Tamura transformers and can be found under 500 bucks from Japan auction sites. I've had good luck there and got mine for about 400 shipped.

Your cart's requirements are close to a DL-103, that SUT was made with that cart in mind.

BillWojo

I've had great results with my Cinemag 1254 SUT by Ned Clayton. It has 4 gain settings so you can experiment with what works. I found that 1:20 is best for my Koetsu Black, it's nice to have plenty of drive, and 8mV shouldn't overload your phono stage. But there's also 1:10, 1:13, and 1:40. Pretty much future proof yourself for any cart, i.e. the 0.12mV AT Art7 (which is now on my wishlist). The unit also has 3 ground positions, my MC setup has never been so quiet, or had this much dynamics and details. A great SUT that's way under your budget. 

Live Music does produce colour, a visit to a Rock/Blues Concert will put that idea to bed immediately, if the attendee also gets them positioned in the Centre of the Stage and choose a suitable distance from the speakers, the Stereo effect will have a similarity to a Home System.

Music produced at a Live Performance that is not dependent on electronics to present the sound created, will not have a directional sound, the sound will radiate from the instruments used in a multitude of directions and will not be a match to how the same type of music is heard as sound on a Home System, where the Speakers are producing sound that is constrained by the engineering/design and radiates from the speaker in a controlled directivity. This is a condition that is overlooked by most who believe listening to a live performance is able to be replicated through using electronic devices to revisit a version of the live experience encountered.

Maybe a used Koetsu SUT?

@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

elliottbnewcombjr

... 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?

That should be fine.

For Koetsus I like the Koetsu SUT best, followed by the EAR MC-3 / MC-4. But the CineMag / Bob’s Devices 1254 / 1131 / Sky models are also excellent for the money -- musical and fun to listen to. The EAR’s have a 10x tap but for my 0.3mV Koetsus (I have more than a few) I find a ~ 20x ratio ideal. The 0.4mV level is ideal from ~ 15x - 20x. The 0.3mV will be fine even at a 30x ratio. Perhaps I like the higher ratios because it helps keep noise floor (from the phono stage) to a minimum. ** Higher SUT ratio won’t help with noise floor related to your sensitive horns, since you’ll have a downstream volume control in the line stage -- at that point noise floor is up to your line stage and amplifier having "not too much gain " plus a high signal-noise ratio. However, minimizing noise floor from the phono stage is certainly beneficial too :)

I don’t like the leaner and tonally "cleaner" sounding SUT’s like Lundahl LL1931. Hashimoto HM-7 are good, fairly neutral, but not my thing either. I prefer warmer, full-bodied sound SUT’s to showcase the true nature of Koetsus :)

The Quadratic MC-1 is an interesting option, though it’s a bit darker sounding which might push it too dark with Koetsu in some systems. Very powerful bass with clean & detailed midrange. If you look inside it's a CineMag blue label like 1131 / 1254 / Sky, but with large cores that are at least twice the size of those models :o 

@mulveling Is from my reading Posts on this forums Analog Section, is one of most experienced SUT users. His descriptions of Tranx Windings I have experienced in use in my system are with a content that is almost identical to how I have a recollection of experiencing the Winding.

There is guidance in the previous post to help the OP get an idea, of how much of a Rich Tone they can add to the sonic, by creating a interface with a certain type of Brand of SUT.

I have a Hashimoto SUT and keep it at hand, as it the leanest of the owned SUT's. If I want a more lean sonic, adding a Head Amp in place of the SUT's works, the Head Amp in my assessment is able to present with a perception of leanness that is cleaner than a built in MC Stage on a owned Phon'.  .  

The step up ratio needed for any pairing is system dependent. What someone else “likes” in terms of turns ratio is moot. Furthermore it seems Mulv has platinum magnet Koetsus, which would give the lower voltage output he quoted, 0.3mV. In that case, and depending upon the downstream equipment, I could see using 1:20. But the Rosewood makes more output voltage than any platinum magnet Koetsu. Certainly more than 0.3mV.

The step up ratio needed for any pairing is system dependent. What someone else “likes” in terms of turns ratio is moot. Furthermore it seems Mulv has platinum magnet Koetsus, which would give the lower voltage output he quoted, 0.3mV. In that case, and depending upon the downstream equipment, I could see using 1:20. But the Rosewood makes more output voltage than any platinum magnet Koetsu. Certainly more than 0.3mV.

@lewm  It's really not THAT system dependent with Koetsus. There's only so much output range in the lineup. I have a non-Platinum Onyx in my collection and while I don't have a spec on it (maybe an Onyx Signature or Gold from the late 80s / early 90s; had it rebuilt by Koetsu 3 years ago retaining the original magnets), if anything if "seems" like a bit more than 0.4mV compared to the 0.3mV Platinums (which are quite consistent among themselves). Since its magnet is small (modern short body), it must be samarium-cobalt or permendur like the current 0.4mV line.

Anyways this non-Platinum Onyx works fantastic with 15x - 20x. ~20x is a good ratio for all Koetsus. 1. Very effective at keeping noise floor down to a minimum (from the active gain parts of your phono stage). 2. If your stage has decent overload margins at all it won't cause a problem there, and 3. Phono stage is upstream from line-stage volume control so that protects the downstream from overload conditions and you just adjust volume to your preference. 

The numbers say a 1:10 SUT will likely work. This means 1:20 and anything in between will also work. If overload would be a problem at 1:20, that’s a poor design, which is to say I don’t think it’s a problem. It’s all good.

Thanks for all the recommendations and advice. Now to see who out here on the west coast might have some of these options to audition. 

Auditioning some of the options will be difficult.

I would just buy a used Koetsu SUT, then sell if you don't like it.

I had been demonstrated many SUT's over the years. I have even been very impressed with my last demo's that took place in 2022.

Prior to the 2022 demo's a selection of models have been immediately repelled, as the sonic was far too overbearing for my tastes.

If I want a taste of how it feels to trudge through the Bass Notes, I can route one of my MC's through the MM Stage, usually only done for a demonstration, but it certainly becomes overwhelmingly bloated presentation.

It is a good practice to be patient and have a few experiences to get a idea of how differing devices will interface with a set up, and decide on the Rich Tones that will be present, being at a level that are attractive to ones preferences and would be wanted to be maintained.

If a Phon' is at hand, that will enable the MC to be used, the SUT selection can be carried out with a inquisitiveness and a careful approach.