Besides internal impedance/ resistance, the other determinant of what SUT to use is based on signal voltage output of the cartridge. Any MM stage worth its salt is quite happy with 4-5 mV signal voltage at its input. Since the Urushi output is ~0.5mV, you can readily understand that a 1:10 step-up ratio is perfect. Such a SUT running into a 47K load resistance will give an effective impedance of 470 ohms (47,000/100). That would work fine too.
The rule of thumb in connecting audio components is that you want the output impedance of the driving stage to be about 1/10 of the input impedance of the driven stage. This goes for preamplifiers driving amplifiers, amplifiers driving speakers, etc. In the phono world, it's even a looser relationship. Ratios much lower than 1/10, e.g., 1/100 and lower often work fine. Likewise, you can sometimes break the rule and use a higher ratio of output to input impedance (e.g., >1/10). The only thing bad that can then happen is you eventually lose high frequency response and gain. Anyway, with the Urushi, a 1:10 SUT, and a 47K load, you are in very safe territory.
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Dear Neon, If it sounded like I don't like SUTs, that was not intended. My point is that you don't need one. While "Bob" and Dertonearm (founder of an audio business in Germany that makes a humongous megabuck turntable, a tonearm, a headshell, and lately a line of phono cartridges starting at ~$9000US and going down from there) are very knowledgeable guys who know more than I do about the why's and wherefore's of using a SUT, I would just point out that there are a slew of experts of equal stature who line up on the other side of the question. In the end, it depends, among other things, upon the phono stage. Some hi-gain phono stages sound better than others. Same goes for lo-gain phono stages that you might use with a SUT. Same goes for SUTs; some sound better than others.
On the subject of effective mass, my Triplanar has effective mass in the same range as the SME V, about 11g, I think. My Urushi sounded very good in the TP, but I have always wondered whether it will sound better in a heavier tonearm. Now that I own a few that are heavier, I need to try it myself. However, I have to wonder whether Handyman's experience (Urushi sounding like "total crap") may have had as much to do with poor alignment as with the medium effective mass of his original tonearm. |
Stringreen, Bob is a very reputable guy by all accounts I have read, I agree. But he does SELL step-up transformers. He would have to be a saint in order to provide a truly unbiased opinion. Anyway, the point is that the "right" answer is there is no need for a SUT in conjunction with the Liberty phono stage/Urushi combination owned by the OP. That is incontrovertible. If you think there is an inherent electronic benefit to using a SUT in every case where one is using an LOMC cartridge, then that is an interesting and separate argument. I am sure Bob knows how to make that argument.
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Raul, who is known for the MM thread here, owns an 801 and really likes it. Perhaps he would be able to help with the specs. But there is also no harm in just listening to the combination of 801 and Urushi. It's quite likely to be just fine. Since the resonant frequency is inversely proportional to the square root of the product of effective mass X compliance, there is quite a bit of leeway in terms of what tonearms work with what cartridges to satisfy the equation.
Nandric, It's worse than you say. My MP1 was "tweaked" by me and now has more than 70db gain in the phono section alone. And it's very quiet. I historically used the Urushi with the MP1, but it was an earlier version of the MP1, still with its factory original circuit which made less gain, but still more than adequate gain for the Urushi. So, running the Urushi into the hi-gain MP1 might be somewhat problematic. I haven't tried it lately. I also own a Manley Steelhead, which feeds into my Beveridge speaker system. I use it as a "full function" preamplifier, with no external linestage. I run my MM/MI cartridges into the MM inputs of the Steelhead and thence into the Beveridge amplifiers. The Steelhead can be well matched to the Urushi via its MC inputs. Right now, the Urushi is in its nice wooden box, at rest. The ZYX Universe or the Ortofon MC2000 feeds the MP1. Even with those cartridges, the volume control of the MP1 is barely up to 9 o'clock, where 6 o'clock is "off". I use a stereo shunt type volume control on the MP1 which does not seem to affect the sonics, even when near to the rest stop. |
I think if you re-read the posts above, you will find answers to at least some of your questions. (You seem to have added a few in this last post.) Now that you have made it more clear that you prefer to use the Liberty phono stage, I suggest you use it as is, if it has enough gain to suit the Urushi. Any of the possible choices of load resistance you mention would work just fine with the Urushi. I will repeat that the load resistance really does not make a huge difference with an LOMC cartridge, but I would agree there ARE very subtle differences, more important to some listeners than to others. I also mentioned that I have taken to using 47K for all my LOMC cartridges; this is not a religion, and I am just as happy with 100 ohms, albeit that load now sounds a tiny bit closed in at the upper frequency extremes, compared to 47K. I know for a fact that if you measured the frequency response of the cartridge with 100R vs 47K, up to 20kHz, you would see absolutely no difference, however. I also suggested (politely I hope) that you might want to try plugging your tonearm cable into the MC phono inputs of your Liberty and try different load Rs to find out what you prefer. I have no dog in the fight about SUT vs no SUT. I believe one should do as one likes in that regard. There are theoretical reasons on either side of the argument. I only say that IF you choose to use a SUT (and you seem to want someone to tell you to do that), then be sure to plug into the MM (low phono gain) inputs of the Liberty, assuming it provides such inputs, and be sure to set the load R at the phono input to 47K ohms, no lower. But be aware that the presence of a SUT in the signal path will reduce the net impedance "seen" by the cartridge, probably to below 500 ohms. (See my post above for the calculation in relation to the turns ratio of the SUT.) At one point you stated that you want to achieve a load >500 ohms; using a SUT is exactly how not to do that.
Alignment you have to do for yourself. Or if you feel incapable of doing it, ask a friend or a dealer to do it for you. By all accounts the Acos GST801 is a very fine tonearm, as good as or better than any you are likely to be able to buy new for anywhere under $2000. But I do not know its effective mass. Someone else may be able to help. |
Sorry. I wrote: "Your internal argument seems to be based on wanting to provide less of a load resistance..." Actually, you want a higher load R which is less of a load. Hence the confusion of my earlier sentence. The higher the value of the load resistor, the lesser is the load on the cartridge output. You want a higher load R, which means less of a load. |
Dear Quincy, Contrary to your assertion, the Urushi and other Koetsu's have a rather "high" output signal voltage, compared to many other expensive LOMC cartridges. It's from 0.4 to 0.6mV, depending upon which stylus velocity you use as standard. The "Platinum" line of Koetsu cartridges does produce less output voltage. The Urushi is not one of those.
Dear neonknight, I do not follow your logic, at all, in arriving at the conclusion that you need a SUT. Your internal argument seems to be based on wanting to provide less of a load resistance for your Koetsu, something higher in value than 500 ohms, based on what you wrote. But adding a SUT will REDUCE the load "seen" by the cartridge, by a factor equal to the square of the turns ratio of the SUT. For example, if you run a 1:20 SUT into the 47K ohm fixed load resistance of your NuVista, the net load seen by the cartridge will be 47,000/400 = 117.5 ohms. This is apparently lower (or more of a load) than you desire. (See also below about why not to use a SUT into an MC phono section capable of 70db gain.)
You state that the Urushi sounds best to you, or most open, with the 47K ohm load afforded by your NuVista at its MC inputs. Why not go with that? There is absolutely nothing wrong with that. And finally, if you are going to use a SUT with either of your two phono stages, they must have an alternate pair of inputs for MM cartridges (lower gain) that provides at least a 47K load resistance if not higher in value. With 70db of gain from your NuVista MC section, using a SUT would overload your phono stage and probably would sound bad, besides also reducing the net value of the load on the cartridge, thereby loading down your cartridge (see above).
As an aside, I have lately been using 47K as a load for all of my MC cartridges; it sounds excellent. I historically used 100 ohms as a load for my Urushi, and I was also satisfied with that for many years. The value of the load resistance should have at most a very subtle effect on apparent frequency response of an LOMC cartridge, most likely to be heard at the very top end of the spectrum. It's more of a "feeling" than a measurable roll-off.
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Thanks, Nandric. I too do not subscribe rigidly to the "rules" about matching cartridge compliance to tonearm effective mass, but just like the rumor that the Urushi is a painted Rosewood, there is a rumor that the FR64S is a really good match with Urushi. And the benefits are said to derive from the rather high effective mass of that tonearm. Whereas the TP is "medium" effective mass, at best. (Of course, one can always add mass to a low mass tonearm to suit any low compliance cartridge.)
For a year now I have been running my Acutex LPM320 (stated compliance = 42!) on my FR64S, albeit with a light weight headshell, and the combination produces no issues related to bass resonance. (This is where I got into a big hoo-hah with Raul, as you may recall.)
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Nandric, Where have you ever heard or read that the Urushi is a "painted Rosewood"? That runs completely contrary to all that I have read about the two models, as regards their respective sonic characteristics. When it was introduced in fact, the Urushi was heralded as a departure from the traditional Koetsu sound, which was characterized as midrange emphasis with rolled off bass and treble. (Not that there is anything wrong with that. I have never heard a Rosewood of any kind in my system, so I don't want to demean that cartridge, but that is what others wrote, especially reviewers of the Urushi.) If the Urushi is a painted Rosewood, then the paint must have a major effect on frequency response. That is certainly possible, I guess.
The FR64S is often mentioned as a great match for the Urushi. Do you use the FR headshell, or the Arche? I am thinking about mounting my Urushi in my FR64S with an Orsonic AV101 headshell. (This is bound to upset Raul.) My long term experience with the Urushi was with it mounted in my Triplanar. I suspect the effective mass of the TP may not be high enough to get the most out of the Urushi, but I don't know that for a fact. |
There are a lot of questions contained in your two paragraphs, and I cannot take the time to sort them all out, but I have owned a Koetsu Urushi for about 10 years. I have used it exclusively with a phono stage that has enough gain such that I do not need to use a SUT (Atma-sphere MP1), but I don't think anyone has enough data on all possible users of the Urushi to tell you what "most" audiophiles do, whether they use a SUT or not. Even if you get a bunch of responses on that subject, it still won't constitute a statistically valid sampling of Urushi users. Far as I know, one or both of your phono stages will have adequate gain to dispense with use of a SUT, so that is what I would try first.
With regard to your other questions, I try to mate cartridges with tonearms, not with turntables. So, I suggest you mate the Urushi with a high mass tonearm that is also well suited to either of your two (very fine) turntables. (I happen to own a DP80 and an SP10 Mk3.) The Urushi is low in compliance, which is why I suggest a high mass tonearm. |
