Jan
Its a very nice step up transformer from Audio Note (jpn) (now Kondo).
Actually it contains two multitapped transformers per chanel, and a rotary switch fit with various carts.
It’s suppose to be a very good sut, but I had better luck with my Lundahls. But to be honest, I haven’t tried that hard to get it optimised.
I attach some pictures of mine with the cover off.
Attachments
Mine only has the low impedance transformers left. Only worth half a kidney then 😉. The fixed output cables where no success though.
Mine has all four transformers left inside it. However, the former owwner has cut some of the cables inside it, reducing some of the input choices. My guess is that he thought that it would benefit if only the winding used shall have galvanic connection.
This was probably done many years ago, and he didn’t have any memory how he did it.
One of the inputs works (not sure wich one right now), but surely this is the reason I haven’t got it sound as good as my Lundahl. The AN ought to be at least just as good.
I’ve talked to Kondo i Japan trying to get a schematic, to restore everything to its original shape, but they don’t share their diagrams.
These sensitive transformers is not that easy to measure. They dislike rms meters using dc when measuring resistance. And so far, I haven’t done any deeper analysis of it.
Sending it to Japan feels like a big thing, so now it mostly please the eye in my bookshelf.
This was probably done many years ago, and he didn’t have any memory how he did it.
One of the inputs works (not sure wich one right now), but surely this is the reason I haven’t got it sound as good as my Lundahl. The AN ought to be at least just as good.
I’ve talked to Kondo i Japan trying to get a schematic, to restore everything to its original shape, but they don’t share their diagrams.
These sensitive transformers is not that easy to measure. They dislike rms meters using dc when measuring resistance. And so far, I haven’t done any deeper analysis of it.
Sending it to Japan feels like a big thing, so now it mostly please the eye in my bookshelf.
I have had the same problem from a friend who bought a similar AN second hand with a mod inside; terrible!
But with some time spent to found the routing of cables at the end I found the solution
Confirmed that AN Japan didn't share any infos, and this is funny!!!!!!!!
Walter
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Thank you Hearingspace.
Kevin’s approach is the most common one with loading the secondary winding load for proper cartridge loading.
Loading the secondary winding also tames transformer ringing.
However, this hard loading (10K for 100R seen by the cart at a 1:10 ratio) also has a drawback, it cost some gain.
Menno describes a more sofisticated/complicated approach, where one resistor is loading the cart (and thereby also the transformer primary winding). Then he adds a RC-link that precisely damping the ringing frequency at the transformer secondary. A more complex method, but one that saves you a couple of dB gain/noise (without any losses).
The component values suggested at Memmos webpage is for Memmos transformers and does go for other brands. So the only way to do this is to measure it by myself.
I have done similar measurements with other transformers. However the very small signal levels here makes it very scars. To my precious experience, just picking component values from a datasheet, and theoretical calculations doesn’t cut it. There are too many things in play here, so I need to practically measure the actual transformer to get optimal values.
So do I understand it correctly that your question is , Is there a measurement technique that gives results that can be trusted as definitive of best loading without having to confirm by listening?
Can you give a brief summary of its points of disagreement with the other papers? Google Translate doesn't work on the page as the accept/reject cookies window won't work on that page.
Regarding the Menno paper I am not agree to put a resistor in parallel to cartridge ( primary of trafo).
It is my opinion, also the use of Zoble on secondary.
In other word the quality of trafo allow you to have a perfect test lab without additional elements but only the possibility to trim, by a switch on secondry with multiple values, the reflected Z on primary.
This helps when the cartridge is workin
With the R connect on primary there is a possible additional attenuation of signal mainly in the low and high end.
It is not related to article that I post that speak of general theory with lot of digram to explain it.
About the link with Chrome you can have the trslation
Step-Up Transformers: What You Wanted to Know About Step-Ups but Never Had the Chance to Ask
by Fabrizio MontanucciIt was perhaps late 1978, or early the following year. At "Stereoguida," the magazine I was then contributing to, we tested a series of cartridges, many of them moving coil, which were already beginning to invade the high-end phono cartridge market, although the leadership was still held by the best moving magnet models. Since all the group's audio magazines (Suono, Stereoplay, and Stereoguida, as well as the various special editions) had a single listening room, and several dozen components were tested each month (meaning one had to "fight" to gain access outside of nighttime hours), when the equipment wasn't excessively large and bulky, the contributors would take it home and plug it into their own systems; in this case, obviously, transportation wasn't a problem. It was then that I noticed that at least a couple of cartridges (one was almost certainly the Fidelity Research FR1, the other was also Japanese, perhaps a Dynavector, but I forget the details) in my house sounded very, very different from how they had been described in previous technical and listening tests. In particular, the "brilliance" (but it would perhaps be better to call it "invasiveness") in the high range was essentially compatible with what I had read, but the low range was not; that in my house had almost disappeared, and the overall sound was so unpleasant that even my mother noticed it, even while listening distractedly from two rooms away. As a shy twenty-year-old student, I didn't have the courage – wrongly, because he would certainly have listened – to ask the already legendary Paolo Nuti to do some measurements on the matter. However, several years later, having become the technical director of Stereoplay, I encountered a similar case again: a Sansui preamplifier, which in response measurements had proved perfect, was connected to an MC cartridge and lacked bass and, to some extent, even high notes. At that point, it didn't take long to figure out what was happening. It was a model that implemented the MC input using a very small and apparently very well-made step-up transformer. The problem was that its internal impedance dropped so much in the first octaves that it created a true high-pass filter in combination with the cartridge's internal resistance, which typically varies between a few ohms and a few dozen ohms. A similar phenomenon, albeit less pronounced, occurred in the high ranges, and I absolutely couldn't detect it during standard laboratory tests because in those cases, to avoid partitions and be able to express sensitivity directly in terms of applied voltage (rather than in EMF, which would have complicated the concept), we used a generator with internal impedance less than a tenth of an ohm.
I obviously described this experience in the article on the Sansui preamp/power amp pair, and I returned to the subject on other occasions over the years, but I never wrote any vertical articles. For two reasons: first (in the mid-1980s) it seemed that vinyl and all related technologies were destined for a very rapid disappearance; secondly, for purists of the material, the step-up transformer represented a "second-rate" choice; the "second-rate" one consisted of direct coupling to a phono circuit with deemphasis specialized for very low voltages and impedances (or at most a linear preamp/preamp, perhaps battery-powered, to be fed into a good moving magnet phono preamp). The very concept of a "transformer" intrinsically recalled anti-audiophile elements, because its insertion immediately implied the introduction of a double response cut (low and high) and because the hysteresis of the ferromagnetic core material is necessarily non-linear. All the concepts related to "weak interactions" (AR 138-139 and others) were yet to be developed, and even balanced signal transmission—in the few components that used it—seemed like an extravagance intended to mimic the professional world rather than a technique that would be advantageous even for consumers. But aside from these reasons—which are also very sound—there may still be other good reasons for resorting to a step-up.
The limit in the signal-to-noise ratio
When a weak signal needs to be amplified, the most important parameter for determining how "clean" the amplification effect will be is the signal's energy. Maximum energy transfer between a generator and a load occurs when the facing impedances are "complex-conjugate," meaning they have the same magnitude and opposite phase at the given frequency (or, at most, zero when the exchange is between resistive components). The "average" internal impedance of a moving magnet cartridge (in every possible variant) is on the order of hundreds or a few thousand ohms, with a series inductance roughly between about 100 millihenries and 1 henry. Its output voltage (assuming a groove modulation speed of 10 cm/s) falls on average between 3 and 12 millivolts. Under these conditions, the cartridge could transfer power of the order of 27 nanowatts to the load (assuming R = 600 ohms, V = 8 mV). A moving coil cartridge can have an internal impedance of – again as a guideline – between 2 and 40 ohms for parasitic inductances ranging from a tenth of a microhenry (to give an idea, this is the inductance of a straight conductor 1 mm in diameter and 10 cm long: just measuring it with acceptable precision is a very delicate problem...) to around ten microhenries.The output voltage can (with the usual approximations) vary between 0.15 and 0.6 mV. Assuming an “average” MC of 10 ohms and 0.4 millivolts, we have a possible power transfer of 4 nanowatts.
This would result in a rather significant intrinsic "average" advantage for moving magnet cartridges (also called "magnetodynamic", where MCs are "electrodynamic"), equal to approximately 8 dB [10 log10(27/4)], which however is highly illusory, for a very simple reason, coinciding with what audiophiles (and in particular our Marco Benedetti) have indicated as " the genetic superiority of moving coil cartridges ".
Figure 1. Magnitude (black trace) and phase (red) of the electrical response of a magnetodynamic cartridge with an internal impedance of 600 ohms + 500 mH loaded with 600 ohms of resistive load. A moving magnet cartridge CANNOT be loaded with a resistor of a value similar to its internal resistive component, because the enormous inductance value would cause the response to decline from around 100 Hz.
At this point, the speaker expert might even protest, reasoning along the lines of: " If I change the resistance of the generator that drives a speaker, and in particular if I go from a very high value to one equal to the resistance of the voice coil, I completely alter the electrical quality factor and therefore the frequency and time response of the transducer! " This is true, but in the case of the phono cartridge, the electrical component of the damping is irrelevant, meaning the circuit is almost entirely controlled by the mechanical damping (total mass brought back to the stylus, elastic and dissipative characteristics of the suspension).
Figure 2. As in Figure 1, but with a "standard" 47,000 ohm load and no capacitive component. Here too, the response drops off at the top end, but only moderately, and this trend can (and usually is) used to tone down the emphasis caused by the inevitable mechanical resonance of the moving coil.
1) The intrinsic S/N ratio of an MC , evaluated in terms of energy transferred to the load, is on average higher than that of an MM .
2) An MC cartridge can be designed regardless of the load it will be offered. If we offer a 47 kohm load to the MM cartridge considered above (600 ohm, 500 mH) (as in fig. 2) but add 250 pF in parallel (an “average” value, which represents the typical weight of the connecting cables and the preamplifier input) we obtain the response in Fig. 3 , which presents the well-known effect of emphasis on the medium-high frequencies due to the electrical resonance that is thus established (in practice, the MM cartridge can be considered the series of two second-order low-pass filters, one mechanical and one electrical). None of this happens even with the most “spiraled” of MCs , which will therefore always be tendentially more “open” than MMs (which, as is well known, “historically” coincides with the comparative listening impressions between these two technologies).
Figure 3. As in Figure 2, but with the addition of 250 pF in parallel. An MM cartridge loaded with a load other than the optimal one can introduce electrical resonance in the audio range and accentuate the mid-high range, which CANNOT
happen with an MC, given the always insignificant value of its parasitic inductance.
The contradiction
If on average an MC can transfer several dB more power to the amplifier, why then have the signal/noise ratio measurements of these inputs always been several dB (about 10) worse than those of MM inputs ? It should also be noted that this happens despite the fact that the measurement procedure makes MCs easier , for which measurement is expected with the input shorted, whereas MM inputs are instead measured on R=600 ohm and therefore with an input thermal noise equal to Vn=sqr(4 k TBR)=0.197 µV, considering a temperature ( T ) of 20 C and that the measurement bandwidth ( B ) is 22 kHz (the term k is the Boltzmann constant [1.38×10^-23]).Simply for technological reasons, that is, with current active components, even operating with circuits at the lowest possible internal resistance (parallelizing many stages and possibly increasing the bias of each one - which however increases another noise component), it is not possible to obtain noise voltages reported at the input that are lower than the thermal resistance of the internal resistance of MC cartridges . If we continue to refer to the MC described above, its 10 ohms correspond to about fifty nanovolts, which is less than what can be obtained from even excellent commercial preamps and without even considering their noise current component (which is cancelled out when the input is short-circuited).
One might wonder why we should give so much consideration to the signal-to-noise ratio associated with the cartridge when the signal-to-noise ratio associated with the reading process is significantly worse. The question is perfectly legitimate, however, if our goal is to minimize signal "pollution" as much as possible, then from everything we've discussed so far, it follows that directly coupling an MC cartridge to its preamplifier is not the best way to minimize noise.
Figure 4. How does the response of a step-up transformer change as the input resistance of the phono preamplifier connected downstream varies? Given that there is no logical (or practical, as Marco Benedetti argues in his article) reason to use loads significantly lower than the standard one for MM phono amps (47 kOhm), it may be interesting to observe what changes when going from 47 to 100 kOhm. The output impedance of a step-up follows (in theory and as a first approximation) that of the cartridge connected to the primary according to the square of the transformation ratio, and with high ratios it is not
difficult to reach values of tens of kOhms, which are comparable with the downstream load. It follows that low-gain transformers are favored. Here we see a comparison of the responses obtained by the Tango in the minimum gain version (20 dB, theoretical Zout 2500 ohm with 25 ohm
source) going from 47 kohm to 100 kohm: apart from the obvious, minimal level shift, there is no alteration in the response.
There is anothe article with tests of a lot of SUT
We have a friend that is owner of around 40 SUT and 105 pcs of MC cartridges
Walter
We have a friend that is owner of around 40 SUT and 105 pcs of MC cartridges
Walter
Thanks for taking the time to post the article. I find the Google translation almost impossible to read and follow but I gather its main point is that MC > Step-up = better S/N ratio than can be obtained with MM.
It might be more helpful for those looking to buy and searching cartridge info to read your 40 SUT/ 160 MC Cart friend's listening impressions . . . . . though it would have be as big a work as the Audio Cyclopedia.
Anyway, thanks.
It might be more helpful for those looking to buy and searching cartridge info to read your 40 SUT/ 160 MC Cart friend's listening impressions . . . . . though it would have be as big a work as the Audio Cyclopedia.
Anyway, thanks.
Its been some years ago since I looked inside my AN-S7s. It wasn’t obvious wich cables had been cut, so in fear to make it worse I didn’t investigate it any further.
Do to the fact that the transformers can be destroyed if measured with a dmm, it’s not that easy to figure it all out. And measuring the wire connections with AC is a hassle, so it hasn’t been done.
@Walter. You don’t happen do have any notes left, from when you recovered the unit for your friend?
Any help would be appreciated.
I suggest the use of a good tester who can read low value of Rdc
The read ing is safe
Then step by step you need to find the cooils where the lowest value is the primary
Then you need to know the phase of each coil
To do this you need a generator and a scope with two channel
It is the fastest way
Walter