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skrech

Correct alignment of the cartridge on straight arm

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Hello,

 

I've recently bought STR8.150 turntable. My Question is what is the Stanton recommended placement of the cartridge on a headshell?

Should it be straight on the headshell or aligned?

Should it be on the front/back of the headshell or somewhere in between?

Why is this information not included in the TT manual?

 

There is an article in here:

https://www.kabusa.com/str8_doc.htm

which gives formula for calculating the optimum underhang of the arm. With effective length published on your site - 194mm I've calculated that optimum underhang should be around 11mm. But even when I pull the cart all the way up to the front of the headshell it underhangs around 18mm (I'm using SM.V3 cart). So...

 

I'm totally lost.

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Hello,

 

Stanton does have a calibration for each of it turntables although it does not go into specifics of needle alignment because every DJ is different.

 

http://stantondj.com/pdf/products/turntables/turntable-quick-start-guide.pdf

 

Here are my responses to the following:

 

I've recently bought STR8.150 turntable. My Question is what is the Stanton recommended placement of the cartridge on a headshell?

There is none as Dj's place it as they want for their application

Should it be straight on the headshell or aligned?

Straight is known to be better for scratching but aligned has been known to offer less wear on records. Although there is little evidence that aligned is "that" much better. The difference is so small that you would not notice a day and night difference, just a small difference in the long run

Should it be on the front/back of the headshell or somewhere in between?

Most people leave in the center if they are not aligning it.

Why is this information not included in the TT manual?

Again every DJ and Vinyl enthusiast is different there is no right or wrong setting for this. There are right and wrong ways to adjust stylus pressure which is explained in the link above and that is the bigger issue to think about and not so much the stylus alignment.

 

Cool!

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Thanks for your reply, proaudiotech.

 

However, I'm concerned with what is the correct cartridge alignment for optimal tracking error. It seems that the only place there is a piece of serious, mathematically supported, information about the straight underhang tonearm is:

 

https://www.kabusa.com/str8_doc.htm

 

So is there a person in Stanton that knows how this straight arm turntables are supposed to be aligned?! How is this effective length, that's posted on the Stanton's site, measured? What is the theoretical explanation that angling the cart on these arms really helps with something, or maybe rather makes things even worse? Why can't the optimum underhang even be achieved on these arms? Why is this design so strange?

 

Every turntable that is made follows some concrete design principles. The things are measured and calculated for concrete geometry. This can't be answered with just some random dj science - "yea, put some coin over the headshell, gives more bassy sound". It's a shame that Stanton (firm, pretending to be a major factor in this industry) have such a preposterous documentation/manuals. Full of contradicting statements, so little technical specs, absence of alignment/geometry recommendations. The manuals for the S and Straight arms are even the same, only with different picture. No word about overhang for the ST-150 even. This feels like not serious product, this STR8.150.

 

So please, let somebody from the technical support make a proper research and answer the questions adequately. My belief is that even if your sell audio products for the dj market, you shouldn't lower the standards with technical documentation. There are people that are more technically inclined that would like to know with what kind of product they are working with. You should treat your customers with respect!

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There is no "correct" alignment of a cartridge on this turntable, because you cannot align a cartridge "correctly" on a straight tonearm such as this. Reason being, a stright arm is made for scratching as opposed to alignment of the cartridge.

 

I will explain this for you if you care for the read:

 

Proper alignment for a cartridge is for the stylas, the point of the end of the needle, to be at precisely striaght with the groove of the record where it meets. If you draw a line from the center of the record to the outside, the stylas should be 90 degees to that line. That way, as the stylas is IN the groove of the record, it is dragging getting each side of the groove equally and at the same time.

 

In contrast, if it is NOT straight, the stylas reads one half of the groove before the other, so left and right channel are not in time, and also, the frequencies as the stylas tracks are not in phase.

 

Obviously, because the tonearm makes an arc, it can't be perfect everywhere. A 9.5" tonearm will be a 9.5" arc. However, an angles headshell (or "S" shaped tonearm), changes the geometry so as to be a sliding arc across the record, effectively making an arc that is more in feet then inches.

 

The cartridge at an angle causes the record to drag the stylas at that angle, rather than straight pull from the center of the arm. The stylas, being agled towrd the center, is now being pulled toward the center. So usually, anti-skate is applied to slightly pull the arm away from the center to balance the forces. There is no perfect there either, as that force changes according to the amount of drag caused by the record, which changes according to what is cut in the grooves of the record.

 

For a "DJ" table for scratching, angled tonearms will cause stylas to have opposite forces as the DJ moves the record backwards, and the stylas will jump out of the groove. To compensate, you either have to apply way more force downward to keep it from jumping out, or, get the cartridge straight as to not have any forces left or right. Or some of both. Long story short, to make it work, you HAVE to sacrifice proper alignment and tracking to be able to "scratch".

 

For proper alignment of the cartridge for fidelity, the STR8 is NOT the turntable to do it.

 

If you actually read this and care, or have more questions, I'm more than happy to answer and explain.

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Hello stein, very grateful for your response!

 

Of course, I read what you've written! And of course I have more questions! I hope you don't mind answering them. :D

 

So to recap:

1. From what you have explained, I don't think it's sensible to angle the cartridge on the straight underhang arm. As one can't achieve two point tangency with short straight arm (as opposed to S shaped arm), the only thing that one will make is increase the possibility of skipping. Moreover, I can't see why angling the cart on straight arms could lead to less record wear as the tracking error remains in the same range, just a little bit shifted maybe on the +/- side. So the opinion that angling the cart on straight arm is better for the records is false?

 

The other questions are:

2. Why, in your opinion, are these straight arms made so short that one can't reach the optimal underhang (the formula for which is in the previous post)? Even if I place the cart all the way to the front of the headshell there is about 7-8mm to the optimal underhang.

 

3. If we assume that the parallel placing of the cart with the headshell is the way to go and the fact that I can't reach the optimum underhang, where should I place the cart - in the front (closer to the optimum value) or in the back (Vestax recommends the distance from the stylus to headshell joint with the tonearm to be 50mm in their manuals). Or somewhere in between?

 

And yes, I know that underhang arms are not made for hi-fi audio, but anyway I'm interested in how I can minimize the tracking error despite the improper for that design of the turntable.

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Well Skrech, I guess your guess might be as good as mine.

 

It sounds like you are familiar with turnatables to a degree, I get that, in particular you are aware of the "two point tangency". And really, in the end it doesn't matter what cartridge overhang gauges might come with the table, because aligning with a two-point guage is the ONLY accurate way to align a cartridge anyway.

 

So for sure, I would get one of these if you don't already have one.

 

As for "proper" overhang, I honestly don't know how the term could even apply to a straight arm, being that normally the proper overhang is determined by both the angle of the cartridge AND the length of the arm.

 

Now, I suppose the thing to do would be to use a "two point" alignment gauge, and get it as close as you can. You might end up angling the cart a little to achieve that.

 

I have to tell you, I am NOT familiar with this turntable. Does the arm have replaceable headshells? is the armtube replaceable?

 

I have to ask another question: what are you using the table for? are you "scratching" with it? Or just playing records?

 

As for minimizing "tracking error", that is going to have as much to do with tracking force, and that is determined by the design of the cartridge. 90% of record wear is cause not by heavy downforce of the needle, but by tracking errors. Tracking errors of the tracking force kind. That is, in the act of the stylas "following" the recorded humps and bumps in the groove, it bounces around rather than staying ON the humps. Generally speaking, any "extra" force going to one side of the groove is subtracted from the other. So say your cart wants to have a vertical tracking force of 2 grams: you might need to give it 2.5 to compensate for the "light" side, while the side getting the most force will see more than 2.5 grams.

 

"Scratching" ir REALLY hard on records. Regardless of the table/arm. With a curved arm, or angled cartidge, all that stuff that makes it in proper alignment goes out the window when that record goes backwards, and in fact, opposite. A straight arm, while imporper for alignment, makes the two directions more equal. That means less wear going backwards, and less compensating by MIS-aligning the whole shebang to be able to scratch.

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Thanks, stein!

 

However, someone care to explain why Stanton recommends angling the cartridge on a headshell if this is contradicting every theoretical evidence? Stanton even sells their pre-mounted cartridges angled. Why?

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OK, I've made some research on the matter and read Stevenson and Baerwald works, which are mainly concerned with offset/S shaped pickup arms, but some of the formulas are independent of the shape of the arm. So, I've made small program in Python for calculating the LTE (lateral tracking error) and the tracking distortion for 12" record.

 

The program's code is:

 

#!/usr/bin/python3
# -*- coding: utf-8 -*-

import math

r1 = 60
r2 = 146
le = 194
h = -21 # sign is "-" because of underhang

for r in range(r1, r2 + 1):
   lte = math.degrees(math.asin(
       r/(2*le) + h*(2*le - h)/(2*le*r)
   ))
   distortion = 44.4 * (lte / r)
   print("R = {:3}mm, LTE = {: .2f}deg, distortion = {: .2f}%".format(
       r, lte, distortion)
   )

 

For STR8.150 turntable with 215mm mounting distance, 194mm effective length and 21mm underhang, results are:

 

R = 60mm, LTE = -12.37deg, distortion = -9.16%

R = 61mm, LTE = -11.87deg, distortion = -8.64%

R = 62mm, LTE = -11.38deg, distortion = -8.15%

R = 63mm, LTE = -10.89deg, distortion = -7.68%

R = 64mm, LTE = -10.42deg, distortion = -7.23%

R = 65mm, LTE = -9.96deg, distortion = -6.81%

R = 66mm, LTE = -9.51deg, distortion = -6.40%

R = 67mm, LTE = -9.07deg, distortion = -6.01%

R = 68mm, LTE = -8.64deg, distortion = -5.64%

R = 69mm, LTE = -8.22deg, distortion = -5.29%

R = 70mm, LTE = -7.81deg, distortion = -4.95%

R = 71mm, LTE = -7.40deg, distortion = -4.63%

R = 72mm, LTE = -7.00deg, distortion = -4.32%

R = 73mm, LTE = -6.61deg, distortion = -4.02%

R = 74mm, LTE = -6.22deg, distortion = -3.73%

R = 75mm, LTE = -5.85deg, distortion = -3.46%

R = 76mm, LTE = -5.47deg, distortion = -3.20%

R = 77mm, LTE = -5.11deg, distortion = -2.95%

R = 78mm, LTE = -4.75deg, distortion = -2.70%

R = 79mm, LTE = -4.39deg, distortion = -2.47%

R = 80mm, LTE = -4.04deg, distortion = -2.24%

R = 81mm, LTE = -3.70deg, distortion = -2.03%

R = 82mm, LTE = -3.36deg, distortion = -1.82%

R = 83mm, LTE = -3.03deg, distortion = -1.62%

R = 84mm, LTE = -2.70deg, distortion = -1.43%

R = 85mm, LTE = -2.37deg, distortion = -1.24%

R = 86mm, LTE = -2.05deg, distortion = -1.06%

R = 87mm, LTE = -1.73deg, distortion = -0.88%

R = 88mm, LTE = -1.42deg, distortion = -0.72%

R = 89mm, LTE = -1.11deg, distortion = -0.55%

R = 90mm, LTE = -0.80deg, distortion = -0.40%

R = 91mm, LTE = -0.50deg, distortion = -0.24%

R = 92mm, LTE = -0.20deg, distortion = -0.10%

R = 93mm, LTE = 0.10deg, distortion = 0.05%

R = 94mm, LTE = 0.39deg, distortion = 0.18%

R = 95mm, LTE = 0.68deg, distortion = 0.32%

R = 96mm, LTE = 0.96deg, distortion = 0.45%

R = 97mm, LTE = 1.25deg, distortion = 0.57%

R = 98mm, LTE = 1.53deg, distortion = 0.69%

R = 99mm, LTE = 1.81deg, distortion = 0.81%

R = 100mm, LTE = 2.08deg, distortion = 0.93%

R = 101mm, LTE = 2.36deg, distortion = 1.04%

R = 102mm, LTE = 2.63deg, distortion = 1.14%

R = 103mm, LTE = 2.90deg, distortion = 1.25%

R = 104mm, LTE = 3.16deg, distortion = 1.35%

R = 105mm, LTE = 3.43deg, distortion = 1.45%

R = 106mm, LTE = 3.69deg, distortion = 1.55%

R = 107mm, LTE = 3.95deg, distortion = 1.64%

R = 108mm, LTE = 4.21deg, distortion = 1.73%

R = 109mm, LTE = 4.46deg, distortion = 1.82%

R = 110mm, LTE = 4.72deg, distortion = 1.90%

R = 111mm, LTE = 4.97deg, distortion = 1.99%

R = 112mm, LTE = 5.22deg, distortion = 2.07%

R = 113mm, LTE = 5.47deg, distortion = 2.15%

R = 114mm, LTE = 5.72deg, distortion = 2.23%

R = 115mm, LTE = 5.96deg, distortion = 2.30%

R = 116mm, LTE = 6.21deg, distortion = 2.38%

R = 117mm, LTE = 6.45deg, distortion = 2.45%

R = 118mm, LTE = 6.69deg, distortion = 2.52%

R = 119mm, LTE = 6.93deg, distortion = 2.59%

R = 120mm, LTE = 7.17deg, distortion = 2.65%

R = 121mm, LTE = 7.41deg, distortion = 2.72%

R = 122mm, LTE = 7.64deg, distortion = 2.78%

R = 123mm, LTE = 7.88deg, distortion = 2.84%

R = 124mm, LTE = 8.11deg, distortion = 2.90%

R = 125mm, LTE = 8.34deg, distortion = 2.96%

R = 126mm, LTE = 8.57deg, distortion = 3.02%

R = 127mm, LTE = 8.80deg, distortion = 3.08%

R = 128mm, LTE = 9.03deg, distortion = 3.13%

R = 129mm, LTE = 9.26deg, distortion = 3.19%

R = 130mm, LTE = 9.48deg, distortion = 3.24%

R = 131mm, LTE = 9.71deg, distortion = 3.29%

R = 132mm, LTE = 9.93deg, distortion = 3.34%

R = 133mm, LTE = 10.16deg, distortion = 3.39%

R = 134mm, LTE = 10.38deg, distortion = 3.44%

R = 135mm, LTE = 10.60deg, distortion = 3.49%

R = 136mm, LTE = 10.82deg, distortion = 3.53%

R = 137mm, LTE = 11.04deg, distortion = 3.58%

R = 138mm, LTE = 11.26deg, distortion = 3.62%

R = 139mm, LTE = 11.48deg, distortion = 3.67%

R = 140mm, LTE = 11.70deg, distortion = 3.71%

R = 141mm, LTE = 11.91deg, distortion = 3.75%

R = 142mm, LTE = 12.13deg, distortion = 3.79%

R = 143mm, LTE = 12.34deg, distortion = 3.83%

R = 144mm, LTE = 12.56deg, distortion = 3.87%

R = 145mm, LTE = 12.77deg, distortion = 3.91%

R = 146mm, LTE = 12.98deg, distortion = 3.95%

 

These are the results for straight alignment of the cart on the headshell.

 

However, Stanton recommends angling the cart on the headshell to "simulate" S-shaped arm. Let's see what happens when we offset the cart with 23 degrees towards spindle:

 

R = 60mm, LTE = -35.37deg, distortion = -26.18%

R = 61mm, LTE = -34.87deg, distortion = -25.38%

R = 62mm, LTE = -34.38deg, distortion = -24.62%

R = 63mm, LTE = -33.89deg, distortion = -23.89%

R = 64mm, LTE = -33.42deg, distortion = -23.19%

R = 65mm, LTE = -32.96deg, distortion = -22.52%

R = 66mm, LTE = -32.51deg, distortion = -21.87%

R = 67mm, LTE = -32.07deg, distortion = -21.26%

R = 68mm, LTE = -31.64deg, distortion = -20.66%

R = 69mm, LTE = -31.22deg, distortion = -20.09%

R = 70mm, LTE = -30.81deg, distortion = -19.54%

R = 71mm, LTE = -30.40deg, distortion = -19.01%

R = 72mm, LTE = -30.00deg, distortion = -18.50%

R = 73mm, LTE = -29.61deg, distortion = -18.01%

R = 74mm, LTE = -29.22deg, distortion = -17.53%

R = 75mm, LTE = -28.85deg, distortion = -17.08%

R = 76mm, LTE = -28.47deg, distortion = -16.63%

R = 77mm, LTE = -28.11deg, distortion = -16.21%

R = 78mm, LTE = -27.75deg, distortion = -15.79%

R = 79mm, LTE = -27.39deg, distortion = -15.40%

R = 80mm, LTE = -27.04deg, distortion = -15.01%

R = 81mm, LTE = -26.70deg, distortion = -14.64%

R = 82mm, LTE = -26.36deg, distortion = -14.27%

R = 83mm, LTE = -26.03deg, distortion = -13.92%

R = 84mm, LTE = -25.70deg, distortion = -13.58%

R = 85mm, LTE = -25.37deg, distortion = -13.25%

R = 86mm, LTE = -25.05deg, distortion = -12.93%

R = 87mm, LTE = -24.73deg, distortion = -12.62%

R = 88mm, LTE = -24.42deg, distortion = -12.32%

R = 89mm, LTE = -24.11deg, distortion = -12.03%

R = 90mm, LTE = -23.80deg, distortion = -11.74%

R = 91mm, LTE = -23.50deg, distortion = -11.47%

R = 92mm, LTE = -23.20deg, distortion = -11.20%

R = 93mm, LTE = -22.90deg, distortion = -10.94%

R = 94mm, LTE = -22.61deg, distortion = -10.68%

R = 95mm, LTE = -22.32deg, distortion = -10.43%

R = 96mm, LTE = -22.04deg, distortion = -10.19%

R = 97mm, LTE = -21.75deg, distortion = -9.96%

R = 98mm, LTE = -21.47deg, distortion = -9.73%

R = 99mm, LTE = -21.19deg, distortion = -9.50%

R = 100mm, LTE = -20.92deg, distortion = -9.29%

R = 101mm, LTE = -20.64deg, distortion = -9.07%

R = 102mm, LTE = -20.37deg, distortion = -8.87%

R = 103mm, LTE = -20.10deg, distortion = -8.67%

R = 104mm, LTE = -19.84deg, distortion = -8.47%

R = 105mm, LTE = -19.57deg, distortion = -8.28%

R = 106mm, LTE = -19.31deg, distortion = -8.09%

R = 107mm, LTE = -19.05deg, distortion = -7.90%

R = 108mm, LTE = -18.79deg, distortion = -7.73%

R = 109mm, LTE = -18.54deg, distortion = -7.55%

R = 110mm, LTE = -18.28deg, distortion = -7.38%

R = 111mm, LTE = -18.03deg, distortion = -7.21%

R = 112mm, LTE = -17.78deg, distortion = -7.05%

R = 113mm, LTE = -17.53deg, distortion = -6.89%

R = 114mm, LTE = -17.28deg, distortion = -6.73%

R = 115mm, LTE = -17.04deg, distortion = -6.58%

R = 116mm, LTE = -16.79deg, distortion = -6.43%

R = 117mm, LTE = -16.55deg, distortion = -6.28%

R = 118mm, LTE = -16.31deg, distortion = -6.14%

R = 119mm, LTE = -16.07deg, distortion = -6.00%

R = 120mm, LTE = -15.83deg, distortion = -5.86%

R = 121mm, LTE = -15.59deg, distortion = -5.72%

R = 122mm, LTE = -15.36deg, distortion = -5.59%

R = 123mm, LTE = -15.12deg, distortion = -5.46%

R = 124mm, LTE = -14.89deg, distortion = -5.33%

R = 125mm, LTE = -14.66deg, distortion = -5.21%

R = 126mm, LTE = -14.43deg, distortion = -5.08%

R = 127mm, LTE = -14.20deg, distortion = -4.96%

R = 128mm, LTE = -13.97deg, distortion = -4.85%

R = 129mm, LTE = -13.74deg, distortion = -4.73%

R = 130mm, LTE = -13.52deg, distortion = -4.62%

R = 131mm, LTE = -13.29deg, distortion = -4.50%

R = 132mm, LTE = -13.07deg, distortion = -4.40%

R = 133mm, LTE = -12.84deg, distortion = -4.29%

R = 134mm, LTE = -12.62deg, distortion = -4.18%

R = 135mm, LTE = -12.40deg, distortion = -4.08%

R = 136mm, LTE = -12.18deg, distortion = -3.98%

R = 137mm, LTE = -11.96deg, distortion = -3.88%

R = 138mm, LTE = -11.74deg, distortion = -3.78%

R = 139mm, LTE = -11.52deg, distortion = -3.68%

R = 140mm, LTE = -11.30deg, distortion = -3.59%

R = 141mm, LTE = -11.09deg, distortion = -3.49%

R = 142mm, LTE = -10.87deg, distortion = -3.40%

R = 143mm, LTE = -10.66deg, distortion = -3.31%

R = 144mm, LTE = -10.44deg, distortion = -3.22%

R = 145mm, LTE = -10.23deg, distortion = -3.13%

R = 146mm, LTE = -10.02deg, distortion = -3.05%

 

SO, STANTON, HOW DO YOU DARE RECOMMENDING OFFSETTING THE CARTRIDGE ON STRAIGHT UNDERHANG ARMS?

 

Not to mention that you sell your turntables with pre-mounted carts in the package which are with offset! That's preposterous!

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I think if you read the responses, particularly the response from customer service, most of your questions have been answered.

 

As for the ones that were NOT answered, your response and claim are barking up the wrong tree.

 

To re-state the obvious, the STR8 arm is NOT made to reduce tracking error, it is made for scratching. That can't be stated strongly enough. And again to re-state, VTF (vertical tracking force) and anti-skate are more of a concern for a turntable to work PROPERLY for scratching.

 

In order for your calculations to be of use, you would also have to account for cartridge compliance, VTA and anti-skate, because deflection of the cantilever (needle) WILL change your "measurements". These calculations you have presented for the STR8 apply to minimizing tracking error for headshell angle, but they do not apply to forces that cause skipping, aligning and adjusting a turntable for performance in scratching. THE STR8 IS MADE FOR SCRATCHING, NOT MINIMAL TRACKING ERROR.

 

For use as a turntable for playing records with minimal tracking error and more accurate sound, the STR8 is the wrong product. Get another turntable, or at least an arm, that is designed for what you want it to do.

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Skrech,

 

I also have the exact same issue and want to limit my tracking error. Granted the STR8.150 is the wrong turn table to focus on such things, nevertheless it's the turntable I have and I want it to track as good as possible. Your investigation seems to be the best one I have seen for the STR8 150. CAn you explain your variables a bit more.

 

"For STR8.150 turntable with 215mm mounting distance, 194mm effective length and 21mm underhang, results are:

 

R = 60mm, LTE = -12.37deg, distortion = -9.16%

R = 61mm, LTE = -11.87deg, distortion = -8.64%..."

 

I'm a newbie and don't know what the R=60mm is refering to. Could you do a little hand sketch to explain so that I can do my best to limit my TT tracking error.

 

Much obliged

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