Hello,
Thank you for any advice may have for me.
Can I modify my straight tone arm to accommodate an off-set headshell?
Images are attached
The back story
I own straight tone arm made of ebony (see pics) It sounds fantastic. However, I am afraid of shortening the life of my records due to tracking error. My solution has been to reposition the base when the cart is about half way through the lp. It slides very smoothly on a polished granite block with no noise evident. This created a second null point at 92mm. The first null pint is at 120mm.
When the cart is tangent at 120mm the tracking error at 146mm is 3.6 degrees and 2 degrees at 106mm.
At about the 103mm mark I slowly slide the base to its new position where the cart is tangent at 92mm. In this position the the inner groove has a tracking error of 3 degrees and at the 106mm it 3.3 degrees. I use the DB Systems protractor.
I have two questions:
1. Is this tracking error too much?
2. Can I modify my tone arm to accommodate a headshell with an off-set?
My other point is I can't relax and zone out when listening because I am constantly repositioning the arm every 8 mins.
Thx so much for any help/advice you may have for me.
Kind regards, Bob
Thank you for any advice may have for me.
Can I modify my straight tone arm to accommodate an off-set headshell?
Images are attached
The back story
I own straight tone arm made of ebony (see pics) It sounds fantastic. However, I am afraid of shortening the life of my records due to tracking error. My solution has been to reposition the base when the cart is about half way through the lp. It slides very smoothly on a polished granite block with no noise evident. This created a second null point at 92mm. The first null pint is at 120mm.
When the cart is tangent at 120mm the tracking error at 146mm is 3.6 degrees and 2 degrees at 106mm.
At about the 103mm mark I slowly slide the base to its new position where the cart is tangent at 92mm. In this position the the inner groove has a tracking error of 3 degrees and at the 106mm it 3.3 degrees. I use the DB Systems protractor.
I have two questions:
1. Is this tracking error too much?
2. Can I modify my tone arm to accommodate a headshell with an off-set?
My other point is I can't relax and zone out when listening because I am constantly repositioning the arm every 8 mins.
Thx so much for any help/advice you may have for me.
Kind regards, Bob
Relocated to the more appropriate analog forum.
Is the bar that serves as a headshell removable? If so, I'd purchase another one
without the hole from the mfr, and have it drilled at the proper angle locally.
If they won't sell you one, perhaps a 3D printed headshell would work well enough.
A number of internet companies can make one at a reasonable price from your CAD file.
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Thank you for your comment Ramya,
I guess the issue then, is that the balance of the cart (centre of gravity) would need to be adjusted so as to avoid the 'yawing' on the tone arm. If that was possible, would there be any downsides in terms of sonics on my new set up? I'm not an engineer and I'm limited in knowledge of the 'forces' at work in the tone arm.
Bob
I guess the issue then, is that the balance of the cart (centre of gravity) would need to be adjusted so as to avoid the 'yawing' on the tone arm. If that was possible, would there be any downsides in terms of sonics on my new set up? I'm not an engineer and I'm limited in knowledge of the 'forces' at work in the tone arm.
Bob
Yes, you can
Hi,
You need to know the dimensions of your tone arm and the locations of the two null points which you prefer. If I had those dimensions, I could help you. The hole in the headshell could be plugged and redrilled at the correct angle, or a new headshell could be made because it is quite simple to make.
I am curious as to why your tone arm is straight. Is it a DIY arm?
Sincerely,
Ralf
Hi,
You need to know the dimensions of your tone arm and the locations of the two null points which you prefer. If I had those dimensions, I could help you. The hole in the headshell could be plugged and redrilled at the correct angle, or a new headshell could be made because it is quite simple to make.
I am curious as to why your tone arm is straight. Is it a DIY arm?
Sincerely,
Ralf
Hello Ralf,
Yes, a friend of a friend made it for me after I had listened to a few arms he had made. Unfortunately I have no contact number and my friend has passed away 🙁
The cart tip to pivot is 324mm.
Thx so much Ralf.
Bob
Yes, a friend of a friend made it for me after I had listened to a few arms he had made. Unfortunately I have no contact number and my friend has passed away 🙁
The cart tip to pivot is 324mm.
Thx so much Ralf.
Bob
I was seduced by the tone colour, dynamics of the straight arm. The tracking force is 1.8g which is on the lighter side for the ZYX Airy3 - but it just sounds fantastic. But I just keep having nightmares about mis tracking.
Tone arm geometry
Hi Bob,
based on the numbers given in the above posts, the dimensions for your tone arm are as follows:
Pivot to stylus: 324mm
First null radius: 120mm
Second null radius: 92mm
Spindle to tone arm pivot: 306.49mm
True offset angle: 19.09651935 degrees
Overhang: 17.51mm
I could not find Lofgren null radii on the internet. If they differ from your null radii, I'll do the calculations over. It is simple enough.
If you want to maintain the minimalist headshell design, I can make one for you. However, I'll need the distance from the tone arm pivot to the end of the arm wand because the angle between the arm wand and the headshell is slightly different from the true offset angle.
Finally, is this a unipivot tone arm?
Sincerely,
Ralf
Hi Bob,
based on the numbers given in the above posts, the dimensions for your tone arm are as follows:
Pivot to stylus: 324mm
First null radius: 120mm
Second null radius: 92mm
Spindle to tone arm pivot: 306.49mm
True offset angle: 19.09651935 degrees
Overhang: 17.51mm
I could not find Lofgren null radii on the internet. If they differ from your null radii, I'll do the calculations over. It is simple enough.
If you want to maintain the minimalist headshell design, I can make one for you. However, I'll need the distance from the tone arm pivot to the end of the arm wand because the angle between the arm wand and the headshell is slightly different from the true offset angle.
Finally, is this a unipivot tone arm?
Sincerely,
Ralf
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It won't mistrack, nor damage records. Baerwald and Lofgren papers concern themselves only with harmonic distortion. That's very different from mistracking, which is where the stylus loses contact with groove walls, and no reason that should happen in your setup - indeed since it sounds good, that's confirmation tracking is working well, you can relax.
Harmonic distortion arising is not as audible as you might expect: this is because it shows up most on loud passages, and audibility of it is tolerated well. Indeed, it can sound good, and in any event is part of vinyl.
Enjoy!
If you wish, in future you might fit an extra plate that accommodates an offset angle, and re-mount the arm according to Baerwald's and Lofgren's papers. But the world will not collapse if you don't, as you've already discovered !
HTH !
LD
Just to add that Baerwald considered a straight arm of length 15" to yield about the same harmonic distortion as an offset arm of length c 9" IIRC.
Also, contrary to popular modern belief, long arms don't necessarily have high effective mass. This is because of a lucky maths cancellation. If it were not for the impracticality of 15" arms, a straight arm could be standard issue.
However, even with a straight arm, it is worth getting mounting location and overhang exactly right, following Baerwald's calculations for straight arms.
You have a straight arm of approx. length 13", which hardly seems a compromise over Baerwald's 15" consideration. I think in the proper mounting location it will not benefit from offset angle, and straight arms have other advantages too.
HTH!
LD
Also, contrary to popular modern belief, long arms don't necessarily have high effective mass. This is because of a lucky maths cancellation. If it were not for the impracticality of 15" arms, a straight arm could be standard issue.
However, even with a straight arm, it is worth getting mounting location and overhang exactly right, following Baerwald's calculations for straight arms.
You have a straight arm of approx. length 13", which hardly seems a compromise over Baerwald's 15" consideration. I think in the proper mounting location it will not benefit from offset angle, and straight arms have other advantages too.
HTH!
LD
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Looks very good. How does the headshell attach to the arm, friction, glue, or what?
Headshell
Hi rayma,
The original is held to the wand by friction. Since it is very hard to provide a properly fitting headshell based on verbal information, I provided two 2-56 clamping screws which can be seen to the rear of the new headshell. The bore in the headshell is .096" which is .0003" larger than the diameter of the wand, provided to me by Bob.
Sincerely,
Ralf
Hi rayma,
The original is held to the wand by friction. Since it is very hard to provide a properly fitting headshell based on verbal information, I provided two 2-56 clamping screws which can be seen to the rear of the new headshell. The bore in the headshell is .096" which is .0003" larger than the diameter of the wand, provided to me by Bob.
Sincerely,
Ralf
Hello Ralf,
I'm so sorry to have taken a week to get back to you. My wife and I left for a quick holiday to the Queensland Tropics to escape the cold Melbourne weather.
We have just returned.
The head shell looks great. Thank you so much. I'm really excited!
Kind regards, Bob
I'm so sorry to have taken a week to get back to you. My wife and I left for a quick holiday to the Queensland Tropics to escape the cold Melbourne weather.
We have just returned.
The head shell looks great. Thank you so much. I'm really excited!
Kind regards, Bob
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