Listening the My Sonic Lab “Eminent” cartridge and “Stage 302” MC step-up:

Even if My Sonic Lab Tokyo based company is relatively new, Mr. Y. Matsudaira San is not a new cartridge builder. He worked for Supex many years ago. His experience with transformers has been useful also to Air Tight (for which he builds the top cartridges like PC1) so you can look at him as to an old expert of this sector. That is why, when Canyon Audio (Ljubljana, SLO) asked me if I was interested in reviewing some My Sonic products, I accepted with interest.

The “Eminent” is the “entry level” of the My Sonic Cartridge list, costing in Japan “only” 300000 YEN (2500 E todays). The new model is the golden “Hyper Eminent” (costing about 460000 YEN), while the top model is the silver “Ultra Eminent”, which costs about 540000 YEN and is the cartridge with the lowest internal resistance which I know: only 0.8 Ohm but about 0.3mV of output.

Also the basic Eminent is peculiar, because its internal resistance is only 1.8 Ohm but its output is as high as 0.5mV. That means that the cartridge coil is really small and then will move very fast, giving a super reproduction of transients, but without the limit of low outputs, which can create problems with the noise or the dynamic range. This very good result is achieved using of a special Ni-Fe alloy, which My Sonic calls SH-muX. It has a permeability mu_i as high as 100000 and a saturation field of Bs=15. The stylus tip is called “semi-line contact” and has an elliptical shape with axes of 3x30 microns. The compliance is relatively high (10x10^-6 cm/dyn), as is the tracking force: between 1.9 and 2.2 g. The body is crafted from solid aluminum and has a very nice to see blue circle on the top.

Mounting the My Sonic Lab Eminent on my Kuzma Stogi tonearm (mounted on a Kuzma Stabi turntable) was not particularly difficult, because the well aligned position was with the blue circle tangent to the headshell end.

At the beginning I knew that I had to force myself not to listening at the sound generated by this cartridge, because I knew that it was not yet break-in (less than 100 hours) and it has not been used in the last months. So, after giving a “Cardas sweeping” to the whole system I put on the turntable a not hi-end vinyl, just to start the warm-in. I chose for that dirty work my beloved “Yes sir, that's my baby” featuring Count Basie, Oscar Peterson, Louis Bellson and John Heard (Mikulski cheap reissue of the original Pablo 2310-923). Before to go ahead, I had to tell you that, since the day before, I was already using the My Sonic Lab Stage 302 MC step-up (see below) with a Benz LP, so that was my first test of the full-My Sonic system.

Now, just because I don't want to annoy you, I would not only say that I payed attention to the sound even if it was the first record of a not-break-in cartridge resting for a long while, but before the end of that very first record, tears was flooding from my eyes. I never listened that records so... involving as that time. In particular, I never felt the music to be so solid as a physical living body staying in front of me. After that LP I put the Sam Cooke “Night Beat” (Abkco 1124-1), just to listen the great Sam voice and still a change was gonna come in my perception of recorded music. Then I tried the Oistrakh's Mozart duo (Decca SXL6088) and again I was able to discriminate very well each single note of the viola from those of the violin. Then, one record followed the other, giving always the same feeling of unbelievable resolution - able to discover every detail of the music - associated with extremely solid mid-bass and erupting dynamic.

Maybe the only “imperfection” was a not so sweet mid-highs, which was put “on a lower floor” in comparison with the prodigious mid-bass. But that appeared to improve after about a week of playing and was probably due to an initially too rigid suspension. During that period I tried to fix this fine tuning changing a little the VTA angle and have found that the cartridge was very sensible even to small changes of VTA. Now, I'm not a very expert analogist, but I would like to report here a schematic of my analogue fine-tuning believes.

I used a phono loading impedance of 47kOhm, which the Stage 302 transformed to about 300 Ohm on the cartridge side. The weight was about 2.0 g and the tonearm base was just slightly below the parallel level (VTA angle probably lower than the default 15 degree).

In my experience with cartridges I never felt a so believable music reproduction as with the My Sonic Lab Eminent, so none of the other babies below were true “contenders” with it. In particular, I never heard in my system even the smallest details so well defined and “clear” as with this super fast and linear cartridge.

I also tried the Eminent with other MC step-up and in particular with my 1:10 Tribute amorphous core transformer and what I missed in particular was the strong bass and dynamic that the My Sonic Stage 302 was able to provide. So it is time to present you this beast too, which is not the “top” of My Sonic step-up, because of the more expensive Stage 303.

Both are strange animals, since they are step-up designed for “low impedance” MC cartridges (1-6 Ohm), but do not provide that high gain which is usually associated to such devices. In fact, the gain is only 22dB, that is, about a 1:12.6 transformation ratio. A part the input and output connectors (rhodium type), the only other control is given by the “floating or not” ground connection between input and output. Sincerely, I have not listened any difference changing this switch.

One of the secrets of this very good step-up is the Ni-Fe alloy core, which My Sonic call PC-SX and which has a permeability mu_i as high as 270000 and a saturation field of Bs=9. If you look the B-H diagram above (comparing the PC-SX and SH-muX alloy with others) you can note how B rises steep at lower values of H and also how much linear is the BH curve for low values. I guess that this linearity is in part responsible of the great resolution and clearness of the even lowest details of the music message.

I have tried the Stage 302 also with other cartridges, like a 5 Ohm Koestu Red and a 40 Ohm Benz LP, both with about 0.3 mV of maximum output. In both cases, the result was much better than with my other MC transformers, in particular for the bass response.

In some way, I was feeling like if the Stage 302 was able to “boost” the low frequencies and dynamic range. In particular, I felt intrigued with the specs of this step-up, speaking of a Vishay Bulk Metal Foil Z201 resistor and of a ERO polypropylene capacitor. While I have read of people very interested in loading the MC transformer with a resistor (typically in the 10-20 kOhm range, see for example the Arthur Salvatore's nice web pages on MC step-up), I never heard before of involving capacitors in MC loading. After some reasoning, I understood that the resistor (R_D) and cap (C) should be connected in series and this series is connected in parallel to the step-up output, as visible in the scheme below.

To explain their effect in a simple way, for low frequencies the cap will be an open circuit, then the output of the transformer will be loaded only by the phono input impedance (R_L). For high frequencies, instead, the cap will be as a short cut, so that the load is given by the parallel of the internal damping resistor and the phono input impedance, R_D//R_L =(1/R_D+1/R_L)^-1. That means that the high frequencies will be damped more than the low frequencies (for which the maximum energy transfer is warranted). If one transfer the cartridge internal resistance (neglecting its coil inductance and the transformer DC resistance, which is usually less than 1 Ohm) to the secondary, then he will obtain a sort of low pass filter, given by the voltage partitioning among the transformed cartridge resistance and the impedance loading, which varies with frequency. I thought that this filter could be designed to damp the typical MC high frequencies peak, that you can see also in the output response if my Benz LP above. Was I right?

I never saw something like that, but surfing the network I found that the well known US transformer builder Jensen suggests to load the output of his MC transformers with a RC series. If you don't know Jensen transformers, just consider the fact that their MC step-up is used in the Audio Research Reference Phono, which has a MC input impedance of about 250 Ohm at 250 Hz and only 30 Ohm at 20kHz. Using the RC values suggested here http://www.jensen-transformers.com/datashts/347damp.pdf I was finally able to simulate the complex load connected to the MC output transformer, finding what can see below. Another example is visible here, where the Sowter 8055 1:10 phono transformer is loaded with a 2.4k Ohm in series with a 1.5nF cap for a 4 Ohm cartridge.

On the left column you can see the complex parallel impedance (loading of the transformer secondary) for the Jensen AXT347 1:12 MC step-up for 40 Ohm cartridges (above), for the same transformer with a 2 Ohm cartridge (middle) and for the My Sonic Stage 302 (below, RC tentative values). You can read the impedance module on the left scale, while on the right one this value has been transformed to the primary side. To do an example, the My Sonic Eminent will see a load going from about 300 Ohm below 500Hz to about only 80 Ohm at frequencies above 20kHz.

On the right column you can see the output voltage attenuation given by the partitioning of the cartridge resistance, transformed to the secondary side, and the complex load shown on the left column. To do an example, the My Sonic Stage 302 will have an attenuation of the highest frequencies lower than 0.5dB: too small to be heard. That claims that my hypothesis, that the RC damping load was designed to decrease the MC high frequency peak, was probably wrong, at leas for cartridges with very low internal resistance, like the Eminent (2 Ohm will become about 317 Ohm on the secondary side, when the minimum loading module is 12.5 kOhm).

What we surely have is a loading impedance variable with the frequency and... a phase shift of almost 40 degree around 5kHz. The only other idea that I had, was that this RC load was designed to compensate the effect of the cartridge internal coil inductance (of the order of 10microH?) or the transformer characteristics, which can't be as ideal as in my simple simulation. In any case, I had the feeling that this step-up was able to boost the bass response, and from my theory above, that was surely true when I used it with the Benz LP, which has 40 Ohm of DC resistance. After all that reasoning, I decided to add a Zobel network also to my home made Tribute 1:10 step-up, using a Riken 22 kOhm resistor in series with a Soshin SE99 0.47 nF silver mica cap.

Yes, of course I have also tried to do the good boy(scout), that is to try the Eminent also directly on my CJ phono preamp, set at 52dB of gain, and of course it... worked, yes, why not? But, really, if you will buy this cartridge and use it without a MC transformer, well, why not spend that money in something else? Dunno, what about a nice holiday in Japan?

You may wonder why to spend a lot of money to buy the Stage 302 and transform your 47kOhm phono input into 300 Ohm on the cartridge side, instead of loading the Eminent with a real 300 Ohm resistor, since the law of Ohm should give the same result and with many phono preamp you don't really need those additional 22dB of gain. Well, I asked myself many times this kind of questions and the only answer I gave me was the evidence that with the transformer the sound was much more dynamic and involving. Hey, we are speaking of a maximum voltage of 0.5mV on a 302 (2+300!) Ohm load: that means a maximum current of only 17 microAmpere (17 10^-6 A)! Do you think that the law of Ohm is the only rule at this level? Aren't the thermic noise figures much more important here? Is this the secret of good MC transformers?

Lastly, if I have to summarize this review in few words I would say that the My Sonic Lab Eminent + Stage 302 are the best analog source that I have tried. The cartridge is able of very fast transients and very high resolution (even of the low levels details) while the MC step-up is able to add that impressive bass and dynamic power. The only “less than perfect” characteristic which I have found was the not always sweet (let say a little toward the “aggressive” side) mid-to-high frequencies, but I don't know if that was due to the rest of my system (“entry-level” turntable-tonearm, NFB power amp,...) or really was generated by the My Sonic gears (maybe due to that 40 degree phase shift produced by the Zobel load?). In any case, I want to finish my sonic dream with my sincere compliments to Mr. Matsudaira San: these gears are really wonderful, in particular when used together!

Ah, if someone of you is interested, Canyon audio is selling these demo gears at 1950 Euro each one. Please, don't write me but ask directly to canyon.audio@siol.net.

Tino © February 2009