Did you perform the checks with the Fozgometer and the voltmeter AFTER performing all the replacements and adjustments that you described, as well as before doing them?
If not, consider the possibility that there may be two problems present, causing similar symptoms. So the replacements or adjustments might have fixed one cause of the imbalance, but not a separate problem further downstream that may be causing a similar symptom.
That would seem to be pretty unlikely, but given all the things you have tried, whatever the explanation turns out to be will probably be something unlikely.
Swapping channels at the Steelhead inputs would be the obvious way of either ruling out or ruling in that possibility.
Good luck!
-- Al |
I never enjoy being the bearer of bad news, but I would absolutely not put an ohmmeter across a phono cartridge, or across a cable that is connected to a phono cartridge, especially a low output moving coil. The meter measures resistance by measuring how much current flows through whatever it is connected to, in response to a voltage it applies through its own internal resistance. That current will be very small in relation to the current-carrying capabilities of most devices or circuits that might be measured, but I see no grounds for confidence that it won't be large enough to cause damage to a lomc. Is there any difference between a MM cart and a MC cart that would cause a complete circuit on an MC and not on an MM? Since there are far fewer turns in the coils of a lomc compared to a mm, the resistance will be much less in a lomc. As a very rough ballpark guess, perhaps a few ohms in the case of the lomc, and many hundreds of ohms or more in the case of a mm. Depending on the resolution of your meter, and the resistance scale you are using, the resistance of the lomc may be low enough to appear to be a short even though it is not. Regards, -- Al |
Gentlemen,
Please note that Audioraider indicated in his initial post that he has already replaced the tonearm wiring, as well as the tonearm itself (perhaps twice, if I am interpreting correctly). My interpretation of what he has said is that those replacements encompassed all of the wiring, from headshell to phono stage input.
Also, he appears to have stated in a subsequent post that he swapped channel connections at the cartridge pins, and the problem followed the swap.
Ergo, it seems to me that there are only two possibilities. Either both cartridges are bad, or some kind of error in the mounting, alignment, settings, or adjustments of the cartridges or the tonearms caused both cartridges to behave in a similarly incorrect manner.
"Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth." -- Sherlock Holmes, as authored by Sir Arthur Conan Doyle.
Best regards,
-- Al |
Audioraider 12-08-10: Here is the problem; when I disconnect the cart, the meter reads perfect continuity from red clip to pos, green clip to neg on the RCA and white clip to pos and blue clip to neg on the RCA BUT when I hook up the cart, the red then has continuity to both pos and neg on the RCA. The green also has continuity to both pos and neg on the RCA. The same goes for the white and blue on the other RCA. This leads me to believe that the cart has the short. With the cart disconnected, I also checked to see if there was any continuity from each clip lead to the base of the tonearm, thinking that a wire may be shorting to ground, and found no problem. As I said in an earlier post: Almarg 12-07-10: Since there are far fewer turns in the coils of a lomc compared to a mm, the resistance will be much less in a lomc. As a very rough ballpark guess, perhaps a few ohms in the case of the lomc, and many hundreds of ohms or more in the case of a mm. Depending on the resolution of your meter, and the resistance scale you are using, the resistance of the lomc may be low enough to appear to be a short even though it is not. Are you certain that the "continuity" you are seeing when the cartridge is connected is in fact a zero ohm short, or might you in fact be reading the very low resistance of a few ohms that I would expect the LOMC cartridge's coils to normally have? Regards, -- Al |
Thanks, Hifihvn. If I understood one of Audioraider's earlier posts correctly, he already tried swapping channels at the cartridge, and the problem DID move to the other channel.
One further note to Audioraider: If you measured continuity using a yes/no "continuity" function the meter may provide, that for example simply indicates the presence or absence of "continuity" via a buzzer or some other comparable mechanism (as opposed to measuring the specific resistance quantitatively), then the detection of "continuity" with the LOMC connected would definitely have been expectable, and not indicative of anything abnormal. That kind of meter function will indicate "continuity" even when a considerable number of ohms are present.
Regards,
-- Al |
Hifihvn, all of the specs that I've ever seen for digital multimeters do not provide enough information to determine the safety of their resistance or continuity functions with respect to a LOMC. The things that have to be known are the voltage the meter puts out into an open circuit when in those modes, and the output impedance of the meter when in those modes. That information together with the coil resistance specification of the cartridge would allow calculation of how much current would flow through the coil.
Without intimate knowledge of the design of the cartridge, it would then still not be possible to precisely say how much current would be safe, or for how much time a given amount of current could be safely applied.
The meters on analog multimeters typically move to full scale (which would indicate 0 ohms for the ohmmeter function) when the current flow is somewhere between 50 ua (microamps) and 1 ma (milliamp). The Lyra Titan i cartridge is spec'd to provide 0.5 mv (millivolts) into a load that can be as low as 10 ohms. 0.5 mv/10 ohms = 50 ua. So an analog ohmmeter for which 50 ua results in full scale meter deflection would certainly be safe. But one which required 1 ma for full scale deflection would be putting 20 times as much current through the cartridge as it would normally be called upon to provide under worst case loading.
Regards,
-- Al |
Good points by Hifihvn and Atmasphere, of course.
Audioraider, in line with my earlier posts I would advise that you resist any temptation to perform any resistance or continuity measurements that would include your new $5800 cartridge in the measurement path. As I explained earlier, doing that may or may not be harmful, depending on the design of the meter, the design of the cartridge, and how long the test voltage from the meter is applied for, but an overabundance of caution would certainly not be inappropriate.
Regards,
-- Al |
Ralph, note that in the first paragraph of his post of 12/11 Audioraider indicated that the new cartridge had not ever been connected to the phono stage, yet still measured identically to the previous cartridge (with the Fozgometer, I assume).
And the Fozgometer itself can apparently be ruled out as the cause of the measured imbalances since the imbalance followed the channel swap that was performed with the cartridge connections. And also because of the consistency that was observed between the measurements on the first two cartridges and the listening results.
It is indeed baffling. Perhaps another rope should be obtained, and spliced onto the first one....
Best regards,
-- Al |
Glad to hear the problem is finally solved, Audioraider. Thanks for letting us know.
In my (extensive) experience as an electrical engineer, it often turned out that when problem investigations involved baffling, confusing, or contradictory symptoms, there were two problems simultaneously present.
I'm left wondering, though, why the Foz's erroneous indication would have moved to the other channel when the cartridge connections were swapped. And why, as reported by one of your correspondents, the design anomaly it apparently has would be brought out by some turntables but not by others.
In any event, congratulations!
Best regards,
-- Al |
