Getting The Most Out Of A Koetsu Urushi

@lewm
Thank you for the response, it is appreciated. If the cartridge is minimally affected by loading, then there is very little to do to the system as far as getting it optimized. I can load it at 100K, 500K, and if memory serves there is a way to get to 47K on the Liberty. That would be interesting to do in order to make a 1 to 1 comparison against the internal stage of the MF NuVista.

As far as the Liberty goes, there is not a separate input for MM and MC, but rather internal jumpers that need to be made up to engage any particular setting. Not unlike a motherboard on a computer. Gain in MM is 44 dB, and in MC it is 64 dB. The history behind Liberty is that it is the factory direct offering of Peter Noerbeck of PBN Audio, and uses a more basic offering of his circuit that is found in his Olympia phono stages.

So, given the line of reasoning you put forth, my first step should be to change out the tone arm cabling on the Acos and see what the result is.

As far as effective mass of the GST 801, that is a number I have yet to come up with. I have the original owners manual and box for mine as I was able to source it NOS, and that information is not in there. Neither is it in Vinyl Engine, or any other site I can find. I do use the LP Gear Zupreme head shell with this cartridge, as it is 12 grams. The arm pipe is stainless steel, overall length is 337 mm, and there is an internal flexible tube for resonance control of the arm tube and shielding of the tone arm wire. The tone arm wire is silver. The GST 801 was the top offering from Acos, and given its time frame I would make the educated guess it is intended to be used with low compliance moving coils from the 80's era, which almost all of them had pretty stiff suspensions. 

Perhaps that is all that is required. If that does not provide the net results, then perhaps I am not a Koetsu kind of guy.

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.  

This manufacture utilizes a very low output (mV) design strategy. What is your current loading and gain setting on your phono stage?

The loading is for the benefit of unstable preamps and does not affect the cartridge. If the phono stage is stable, 47K will be fine.

I would suggest you get in touch with Bob@bobsdevices.com.  He can tell you the right answer.  Even though you might have enough gain and loading, he'll tell you the optimum.