Sampsa55 -
"I align the cartridges based on the alignment the tonearm was designed for. Since most of my tonearms use removable head shells and were designed for a 52mm distance from the head shell connection to the stylus..." Raul -
"that's true only if those tonearms has the same effective length" "I think that you have a misunderstood on the input data for the whole calculations through diferent tonearm/cartridge alignments."
Sampsa55, You are obviously correct, but I suggest you let it go. Raul, The 52mm distance has nothing to do with eff. length or alignment in the way you're looking at it. . The designer can put the headshell collet wherever he wants along the length. In other words, 52mm from the correct overhang position for the length/alignment. Regards, |
Agree with Lew. On an arm designed for Stevenson (or close), to get a Loefgren A or B requires moving the cart forward and increasing offset angle. I've done this numerous times for people who wanted a Baerwald alignment. Often such an alignment wasn't possible because the headshell slots weren't long enough. If the mounting distance is fixed, these alignments require greater overhang and increased effective length. You can use an intermediate alignment if desired, in between Stevenson and Baerwald. Contrary to popular belief, such an alignment is legitimate. Chakster has a good point. If the offset angle is in agreement with the arm design, there might be less torsional force on the cantilever. This might be especially true in arms with removable headshells. fleib |
Lewm, When Loefgren published his alignment(s), he equated alignment error to distortion. I wonder if any attempt has been made to qualify or quantify this assertion, what kind of distortion and how much? Aside from a very small amount of phase error between channels (we're talking about rotation of contact area within the groove), it seems to me most error is subtractive and would not qualify as distortion. With underhung straight pivoting arms, reduction of torsional forces on the cantilever is also said to be a function of no offset angle and skating is reduced to the extent that it becomes unnecessary. Yamaha offered such an arm as an option on the GT-2000. It is the YSA-2.
http://www.audiocircle.com/index.php?action=gallery;area=browse;image=122280
Regards,
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Sampsa55, Interesting post. Vertical alignment error (SRA/VTA) can be measured with a test record and a distortion analyzer. I've never done this. It seems to me, it will vary somewhat from record to record and I adjust it by ear and on the fly. Most people hear this as an imbalance -bass to treble which seems more obvious than tonal and harmonic inaccuracies which I also hear. You say alignment error causes 2nd harmonic distortion. Is this documented? While vertical error is readily heard, horizontal is not so obvious. Adjusting alignment provides clarity and focus. Is this measurable 2nd harmonic distortion? Conventional pivoting arms only have 2 nulls across the record. It's the movements of the cantilever which trigger the generator. Reduction of torsional forces from anti-skate and offset is said to be responsible for increased clarity. The RS-A1 also addresses vertical torsional forces by aiming the cantilever at the pivot vertically. The rotating headshell seems a compromise between alignment and offset. There was a Grado Signature Laboratory arm which had elevated pivots and fixed alignment - offset. Regards,
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**It's in Baerwald's original derivation from 1941, where he shows the resulting distortion to be primarily 2nd harmonic.** Not to be argumentative, but that's hardly convincing. The distortion analyzer wasn't invented until '41. What did he use as a test record, a steady tone on a 78 ? For those unfamiliar with the history here, Baerwald didn't invent the alignment which bears his name. He popularized the Loefgren A alignment which has lowest average error. Loefgren B has lowest total error, primarily because nulls are closer to the center of the band where error is greatest. Sampsa55, I'm not saying 2nd harmonic is wrong, I don't know. Perhaps there is a more recent testing? Regards, |
Lewm, If the RS-A1 headshell doesn't rotate, then the only other unique feature the ViV brings to the table is the floating pivot. I'm not sure how significant this is, but I suspect you already have the better sounding arm. If the goal is to reduce torsional affects on the cantilever, your RS-A1 also does this in the vertical plane which might be more important than lateral. Vertical angular error is more noticeable and more readily heard, IMO. This might also apply to vertical torsion? I've read a couple of reviews about the ViV and they both said the 7" arm sounds best. Conjecture was, this is due to reduced resonances. It's a little hard to imagine how 10° alignment error could sound better than a lesser value, but conventional wisdom doesn't seem to work here and it would be interesting to compare these two to the Grado Signature. That one has vertical displacement and an SME type headshell with conventional alignment.
http://www.vinylengine.com/turntable_forum/gallery/image_page.php?album_id=1572&image_id=8766
Regards,
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Lewm, Sampsa, The only reason to elevate the pivot is to have the cantilever aimed there vertically. It's not beneficial for tracking like an underhung counterweight. That's the only plane where that happens on the Grado arm. The VE photo was supplied by Werner and the arm is said to sound great. There was no direct comparison of the three ViV arms. It was mentioned in Stereo Times that the shortest version reduced resonances. There was another review/comparison which I can not find now. It stated the 7" sounds better - for the same reason. Regards, |
Chakster mentioned Feickert in OP. Great device based on the Dennison Soundtractor, gets excellent results as long as it's used properly. One thing often overlooked - an arc protractor is only accurate if your mounting distance is perfect (factory). If the factory is mounting an arm they didn't make, you might want to check it with a conventional protractor. **Seems to me that a very slight error in implementing Lofgren A/B or Baerwald, or Stevenson, one that still results in two null points on the surface of the LP, is not going to make a huge difference in one's experience of the sound thus derived.** +1 Although it depends on resultant nulls. Chakster, I bet you'll wind up with Loefgren alignment. Both nulls are within the recorded part of a 7". Error will be much less through most of song. Stevenson will be better at the end, but much worse up until there. |
Cleeds, My Dennison has alignment lines for the cantilever and I believe the others also have this. I also have a mirrored protractor and results are the same. Raul, An arc protractor is great if and only if mounting distance is in exact agreement with specification. Otherwise it's useless. The other protractors mentioned are based on where the pivot is actually located, not where it theoretically should be. Why spend $100 on a Mint? You can go to Conrad's site and generate one for free. |
Chakster, sorry, I made a mistake, but so did you. None of the standard alignments have both nulls within the recorded part of a 7". Baerwald - 66.0 & 120.9mm Loefgren - 70.3 & 116.6mm Stevenson - 60.325 & 117.42mm 7" record recorded band - 57 (approx.) to 84.15mm These are all distances from center spindle. Only the inner null of each alignment will be within a 7". Loefgren will have least error at the beginning and Stevenson at the end. If you want to see the alignment error for each arm and with each alignment - you have to log in. http://www.vinylengine.com/tonearm_alignment_calculator_pro.php Regards, |
Lewm, your defense of the arc seems valid, but the Dennesen types don't need perfect arm mounting distance. As long as you can sight the pivot intersection you can get a "correct" alignment provided you have enough headshell room. I always check with a conventional 2 point protractor. As long as the apparatus doesn't move, the alignment is good. Raul, What alignment does Mint use? (measure from center to first grid and compare to alignments above) Regards, |
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