Obviously you know nothing about quality resistors. Vishay is a big company, and they make dozens of different types of resistors, much like Caddock. So not all Vishay resistors are created equal. One might debate the need for or an expensive nude Vishay in this application, but in my experience there is a soupçon of an increase in SQ associated with that choice, and it’s a cheap luxury item. Like I said, Caddock TF030 are very transparent as well. I doubt I could hear a difference between a nude Vishay TX series and the TF030. Form factor of the Caddock can make it difficult to install in a PCB designed for a standard through hole resistor. 1/4W would actually be overkill; both of these types are >1/4W.
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Tomic, your point, other than the notion about personal preference, is lost on me. Can you be more explicit? Do you really not know what comes after the load R? I’m guessing that was rhetorical.
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The finest Vishay nude resistor costs more like $13. Caddock TF030 costs about $7 each and is nearly as good, maybe indistinguishable. For phono loading, quality counts but the watt requirement is tiny. The change in load resistance is compatible with any MC cartridge. There are no cartridges that “require” 100 ohms. So there’s no need to determine in advance whether one likes the Zephyr. And of course the change is not unreversable anyway, if one ever felt the need.
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If the OP wants to sell his Zephyr cartridge, I am interested. Just saying. I don’t advise it, but I’m interested.
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That's for sure. If he wants to let the tail (the 100 ohm resistors) wag the dog, then he must acquire a LOMC with typical LOMC inductance. But also gain must be high enough to work well with the inherent gain of the MC section (plus the linestage gain) of that Luxman. (I don't know what that is in db but evidently it was not a problem with the 0.3mV output of the Zephyr.)
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Larry, The low output Zephyr already has a low internal DCR of 10 ohms. That's not the problem. The problem is its inductance, which, at 2.5mH, is about mid way between a typical LOMC (about 50 microhenries) and a typical MM (500 millihenries, or about 10,000X more than the LOMC). If the Luxman was mine, it would have been "modified" last week. I don't really view this as a modification in the usual sense that we use it, because the change does not alter the circuit or alter ("upgrade") the parts content. I'm envious of your Orpheus, BTW.
audiojan, I realize the die is cast, but to say you "might as well spend the money to get a different cartridge" indicates money is not an object. Because changing the resistor, even if you must hire someone else with the expertise to do it, is bound to be the less expensive alternative. Anyway, your problem is solved one way or the other.
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Larry, If you read the responses, you will know that the problem is almost certainly the fact that the fixed value of the load resistance at the phono inputs of the Luxman is 100 ohms. The Zephyr is a rare low output MI type, which has high inductance compared to a typical LOMC type. Thus it needs a higher value load resistor. The high inductance cartridge into a 100 ohm load would be expected to exhibit all the characteristics that the OP is not happy with, and justifiably so. That issue would have to be dealt with before one could fairly evaluate other elements in this system.
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Changing the phono load resistors is neither a mod nor a tweak in my book. But why do you hold the opinion it shouldn’t be done?
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I have no idea what you’re talking about. I never advocated a SUT to solve this particular problem. I really think you ought to reread whatever previous post of mine has got you confused, and maybe then you will understand better what I was trying to say. Anyway, I think you would agree that a clear pathway to a solution has been agreed-upon by just about everyone who has commented in the past 48 hours. So there really is no need to bring up whatever it is you don’t like about me or my previous comment.
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Dave, the Luxman website page on the 590ax2 ( not the 250 or 500) indeed gives very little useful information regarding the phono section, but the many photos of the many PCBs reveal no evidence of a SUT anywhere. Furthermore the unit seems built with discrete components rather than op amps and SMDs. So I am guessing it would be easy to remove the putative 100R load resistors and replace them with 470R or higher. I’d use 1000R or even higher, unless PL has a preference for exactly 470R. I knew that Luxman use a SUT in their flagship 500 phono stage, so my a priori expectation was to find there is a SUT also in the OP’s unit, but that doesn’t seem to be the case so far as I can tell from the scant information.
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The fact that the sound seems rolled off in the treble to you suggested that the relatively high inductance of the cartridge, compared to that of a typical LOMC, is causing a loading issue, as Atma-sphere just showed us. This was mentioned in my previous analysis as a possibility. SS do recommend a higher than minimum load resistance, and now we have confirmatory evidence that this is to compensate for the inductance. But I repeat, all you have to do is open the chassis and change the phono load resistors to any value equal to or above 470 ohms. I believe it would be a mistake (or at least an unnecessary expense) to go to a SUT, but if you do, be sure to consult Peter Ledermann who made the cartridge and probably has a deep understanding of how to match a SUT to it. Of course, then you use the MM inputs. I don’t understand why changing the phono load resistors, the simplest solution imaginable, incurs any more of a limitation in the future than the 100-ohm resistors constitute in the here and now. Worst case scenario: you switch back to 100 ohms for some future hypothetical cartridge. There really is NO cartridge that requires a 100-ohm load, actually. A cartridge that works well with a 100 ohm load will also work well with a 470 ohm load, but the reverse is not the case, as you now know. Good luck.
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I looked at the specs for both the Zephyr Star and the Luxman 590. There is no obvious reason why this pairing cannot be made to work well. First, I don’t understand quite why SoundSmith recommends a 470 ohm load for this cartridge. It’s internal DC resistance is only 10 ohms, so in theory it should be able to drive the 100-ohm load of the Luxman MC input stage. The problem might be that this is not actually an MC cartridge; therefore it has an inductance much higher than that of a typical MC. (About 100X higher, if a typical LOMC cartridge has an inductance of about 25uH. Inductance of Zephyr is 2.75mH.) Maybe Atma can comment on how that would be an impediment, but perhaps that is also why SS recommends a 470 ohm load. We also know from specs that the output of the Zephyr (0.4mV) is not too low for the MC inputs to handle, because Luxman tells us that the MC gain (NOT stated on the Luxman website but can be calculated) is adequate for a cartridge with an 0.3mV output. Before doing the research, I had assumed that the MC gain of the Luxman is derived from using a SUT placed ahead of the MM stage, but the website, while very lacking in phono-related info, suggests that MC gain is done by an active stage. For one thing, in their many photos, I see nothing on the PCBs that looks like a SUT. OK, so if there is no SUT, then there is no problem to replace the 100 ohm load resistor with a 470 ohm load resistor. Any skilled technician can do that. I would do that way before throwing either baby out with the bathwater. I am a big fan of MI or "fixed coil" cartridges.
Oh, by the way, this problem cannot be fixed by paralleling an external resistor with the 100-ohm input resistor, net parallel resistance is always lower than the value of any one resistor in the bundle. So paralleling an external resistor can only lower the net input resistance, not increase it.
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