Great explanation by Tim. One addition: you need a notch filter to reduce frequencies above/below the test tone. Otherwise, at the tiny levels we're trying to adjust for, background surface noise from the vinyl will swamp the results at the meter. Wally's device includes this, or you could DIY your own. |
I can't stress Doug's suggestion enough (even Fremer left this out in his instructions) - if you measure without a bandpass at 1kHz, your azimuth measurements will be close to meaningless. Alternatively you could use an oscilloscope or spectrum analyzer, but a 1KHz bandpass filter with a multimeter will do. |
Sorry guys, you've confused me. Dougdeacon calls for a notch filter above/below the test tone. Restock agrees, but suggests a 1KHz bandpass filter. I'm showing my electronics ignorance here but what filtering point(s) is/are needed for a 1K test tone? Is there a source for plans to build this filter? Thanx. |
Pryso: Doug and I meant the same thing, but notch filter is wrong and does actually the opposite. The correct one needed here is a bandpass that passes only frequencies in a narrow band around 1KHz. Here is a link to some info about bandpass filters: Band-pass filters Band-pass filter on Wikipedia I hope this clarifies things. Rene |
Sorry for the inaccurate term. My electronics skills are easily a match for yours, Pryso. ;-) At least I knew what I meant, and fortunately Rene did too! Doug P.S. Paul and I are among those annoying guys that Tim mentioned in his excellent post. After using the Wally Analog Shop (which works great) to adjust azimuth on several cartridges, we learned we could get just about as close by listening. Our main cartridge goes below the resolution of our multi-meter, which worked out to < 0.1db crosstalk. When azimuth's correct L/R images are so tight they're almost invisible. ;-) Less fiddling time and more music time works for us now, but it was useful to be able to measure and confirm what we were hearing. |
