Details, details, details! I almost forgot. While these reading may seem miniscule, each .001 represents half a decibel, small readings will be typically between .010 to .023, this correlates to 0 to 7.5 decibles. .002 is equivalent to 1 db, I assume we can hear this difference.
My initial readings, using the VPI rod method, were .011 and .019, a difference of 4.5db from one channel to other, it can be no wonder images were so unstable and sound less than involving. |
No. Crosstalk is the migration/blending of signal output from one channel to the other. Thus, left channel signal leaks into right channel, and vice versa. Using the balance control only controls gross decibels, the ratio of crosstalk (leakage) to proper signal remains unchanged.
Only by getting the stylus to ride perfectly perpendicular to groove walls will you get minimum crosstalk. The Fremer dvd explains this very well in the PDF files. |
Jerry, the ac voltage scale should be at the 2 scale, the 20 scale is not low enough for precise readings.
You measure at the speaker binding posts on your amp.
Stingreen, it would be interesting to measure your crosstalk with a DMM. I contend the DMM method is by far the most precise method because of production variations in tonearm mounting pads, cartridge mounting surface, cantilever, flatness of record, and in your case the Myrtle wood blocks. In the case of VPI's method you also have the possible variations in straightness of rod, ruler precsion and reading it.
My initial reading after having set azimuth according to the VPI method was around 20% deviation in crosstalk between channels. I also found that inperceptable movement (with the naked eye) of the counterweight resulted in quite different crosstalk measurements, ie., what may measure equal using any physical means may still not be within the 5 to 10% crosstalk tolerance level. Also, there may be added value in getting it down to about 1% vs. 5 to 10% tolerance level(I didn't listen to musical passages at different crosstalk valuations).
Your suggestion of tightning up the counterweight set screw close to its stop could be very helpful, I had the screw set loose which may have resulted in counterweight moving about too easily. Also, I wasn't setting VTF and azimuth in discrete steps, I already had the VTF set correctly. It was in trying to move counterweight about it's axis that I was inperceptably moving counterweight forward and backward which changed VTF, your suggestion of pre-tightening some may help in keeping this from happening.
Slowhand, I took it for granted the VPI allignment jig was correct. In the Fremer DVD he does allignment with the Wally tracker and it jibes perfectly with the VPI jig. I will have to go back to my DB protractor and double check allignment. |
Almost forgot, another thing that may result in azimuth error is how tight each screw is. At one point in the midst of doing my measurements I had gotten crosstalk deviation within specs, I decided to retighten the cartridge screws just to be sure, this changed crosstalk deviation beyond specs.
To reiterate, my experience teaches me no physical measurements protocol will result in proper azimuth settings. One may get lucky and find the mark, but for proper azimuth it is absolutely necessary for an electronic measurement.
With practice this method is actually quite easily accomplished, not rocket science here. Purchase or borrow the Fremer video, the PDF files alone are worth the price. Actually, now that I think of it, it may be necessary to buy that video as it has the Wally azimuth voltage to decibel conversion chart that is absolutely necessary. It may also be available elsewhere on the web for free, I haven't checked. You also need a record with 1kz test signal for both left and right channels, I used the Cardas record. |
While we are on the topic of cartridge allignment, it may be interesting to note that the vacuum state website (in their white papers) has another take on cartridge allignment. I have not read it in detail, but it may be worth further exploration. |
Jamnperry, there is the Analogue Productions test record, this even may be better as the 1kz tracks are longer.
Kotemaori, I would think they have you measure at the speaker outs in order to get the readings closest to what they would be coming out of your speakers. Therefore, taking into account the IC's between phono pre and preamp and preamp to amp, preamp, amp. It would be interesting to test at both output of the table and amp outputs and see what differences there are.
I also mis-wrote the acceptable tolerance in one of my posts as 5-10%, wrong, the acceptable tolerance is 1-5%.
I've also thought about a possible means to test electronically without the wally conversion table. You may be able to get azimuth to proper specs just by reading small reading (the actual crosstalk) in each channel.
Procedure: Play a 1kz stereo test tone and set volume to output 3ac volts (DMM at 2acVolt setting, it will read as .300 or close) at amp outs, test both channels, adjust and balance volume accordingly. Now play the left channel only and right channel only 1kz tracks. When playing the left channel tracks insert the DMM probes into the right amp speaker posts (in phase), write down the reading, you should get something between .010 and .023 or so (DMM at 2vAC scale). Play right channel, place probes in left channel, write down reading. If you have a reading that deviates more than .002 between the two you can be sure to be out of tolerance. The best I was able to achieve was a difference of .001. To reiterate: You want a differential reading of .000 to .002, no other reading will be within tolerance.
I cannot guarantee this method is best, but my own readings on big and small voltages show this should work. |
Yes, postive goes to positive and negative to negative, unless your phono pre or pre inverts signal (as my preamp does) in which case positive goes to negative, and vice versa.
Leave speakers hooked up.
I did not recheck with the rod, I don't see the point. The electronic method is much more precise than the rod method, I will never use the rod method again. |
Here is an interesting web page discussing a new tool for dynamically setting azimuth. http://www.adjustplus.de/index.php?lang=english |
Mark, I purchased my DMM from partsexpress.com, item no.390-545. $25.50 plus shipping, pretty good deal. Radio Shack also have them, slightly higher prices. Scott |
Rsrex, yes, this is the point I was trying to make when speaking of variability in manufacturing tolerances. The DMM method is the only method that accounts for all those possible deviations.
As for those who think this is a big hassle. What is the hassle of having a DMM and learning how to use it. If you consider this a hassle, you will be one frustrated audiophile in time. This hassle pales in comparison to many others I've faced through the years. Once you've used the DMM method a few times it becomes much easier, I correctly set azimuth for a Valhalla wired tonearm in about 15 minutes the other night.
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Radrog, in fact I do live in Michigan, near Ann Arbor. Send me an email if you're serious. Scott |
The only thing I can think is that the cartridge is at fault. If your output is equal on both channels, crosstalk measurements should be pretty equal as well. I would expect with cartridge manufacturing tolerance variance you will likely never get crosstalk to be perfectly equal between channels, but you should get much closer than you have. Have you tried turning the tonearm weight in the opposite direction, perhaps you're turning in wrong direction. Someone else has some ideas? |
Sonofjim, yes, the adjust + is what I was referring to in an earlier post. From what I can gather, the perfect azimuth adjustment can change from record to record, depending on how it was cut. The Adjust + allows one to make azimuth absolutely correct for each record. I know this is ultimate, but hey, fiddling with VTA is enough for me!
As for setting azimuth by rod, I think Viper z's situation makes it clear that the DMM method is the only definitive method, and an absolute necessity. It appears his cartridge is defective, or at least out of tolerance. The DMM method and results gives him the ammunition to be able to go back to the dealer or manufacturer for an exchange or refund. He would have never known this without the DMM.
Having said this, and I did mention this to Stan, I do think an experienced audiophile who is well acquainted with the sound of his particular system could set correct azimuth by listening only. With a high resolution system you can hear when that sound is 'locked in'. Even then, I still like the DMM method as it gives comfort knowing you have the optimum setting.
For the perfectionists among us, the Feikert tool will be the ultimate. |
