Does anyone know what the offset angle is of the Gray Research 108 tonearm? The only references I've found say it's somewhere between 15 and 16 degrees.
Since the mounting angle of the cartridge is fixed in these tonearms, the only way to change tracking geometry is to change the pivot-to-spindle distance when you mount the tonearm on the arm board. That's why it would be really helpful to know what the offset angle is with some precision.
Anybody?
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Since the mounting angle of the cartridge is fixed in these tonearms, the only way to change tracking geometry is to change the pivot-to-spindle distance when you mount the tonearm on the arm board. That's why it would be really helpful to know what the offset angle is with some precision.
Anybody?
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Thanks, I have been looking there. There's nothing very conclusive. I'm sure if I had better skills, I could figure out the geometry from the overhang and effective length specs. The mounting template claims
effective length = 279.4
pivot-spindle distance = 269.9 mm
overhang = 9.5 mm (note that this is with a GE VR series cartridge)
I don't think it's possible to nail down the offset angle from those measurements alone, since the alignment's null points aren't mentioned.
I put a Denon DL102 in the headshell clip, and found that the effective length increased by 2 mm to approximately 181.5 mm. (The position of the stylus vs. the mounting screws on the DL102 puts the stylus approx. 2 mm farther away from the arm pivot than it is with the GE VR cart.)
I've posted to the vinylengine forum twice, once a while ago and again recently. No replies yet.
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effective length = 279.4
pivot-spindle distance = 269.9 mm
overhang = 9.5 mm (note that this is with a GE VR series cartridge)
I don't think it's possible to nail down the offset angle from those measurements alone, since the alignment's null points aren't mentioned.
I put a Denon DL102 in the headshell clip, and found that the effective length increased by 2 mm to approximately 181.5 mm. (The position of the stylus vs. the mounting screws on the DL102 puts the stylus approx. 2 mm farther away from the arm pivot than it is with the GE VR cart.)
I've posted to the vinylengine forum twice, once a while ago and again recently. No replies yet.
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Perhaps something to try (and I am facing a similar situation with an obscure linear tracker I just got) would be to print out a protractor for the alignment you prefer and see if you can figure out a reasonable mounting position to minimize errors. IIRC there is no provision for adjusting overhang so best to determine with the cartridge you are going to use or with a mock up of the cartridge.
I recall these arms have a 3 point mount? If you have access to a machine shop a a two piece mounting plate where a top plate carrying the arm slides on top of another with appropriate slotting for the wiring might be a bit more flexible. The top plate would have two slots with screws and nuts to lock it in place when properly adjusted?
I recall these arms have a 3 point mount? If you have access to a machine shop a a two piece mounting plate where a top plate carrying the arm slides on top of another with appropriate slotting for the wiring might be a bit more flexible. The top plate would have two slots with screws and nuts to lock it in place when properly adjusted?
The B version says 20 degrees.
http://akdatabase.org/AKview/albums/userpics/10007/Gray 108-B arm instructions.pdf
Then there's this. http://www.ebay.com/itm/112085437729?rmvSB=true
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Rongon,
I don't have a direct response, but I checked my NEAT clone and it might be possible to build an adapter to the cartridge sled that would allow a bit of angle adjustment. I did something like that for a ROK headshell and it worked fairly well. As I'm sure you know, a lot of the older tonearms had idiosyncratic alignments and didn't offer much information beyond effective length, mounting distance, and overhang.
You might try contacting this guy. GRAY 108 tonearm clone from magnesium alloy. – Old Turntables Repair & Restoration He makes a Gray 108 clone and might share his alignment.
Have you tried just setting up the arm with the numbers you have to see what happens?
Rayma beat me with better stuff.
Regardless, good luck.
I don't have a direct response, but I checked my NEAT clone and it might be possible to build an adapter to the cartridge sled that would allow a bit of angle adjustment. I did something like that for a ROK headshell and it worked fairly well. As I'm sure you know, a lot of the older tonearms had idiosyncratic alignments and didn't offer much information beyond effective length, mounting distance, and overhang.
You might try contacting this guy. GRAY 108 tonearm clone from magnesium alloy. – Old Turntables Repair & Restoration He makes a Gray 108 clone and might share his alignment.
Have you tried just setting up the arm with the numbers you have to see what happens?
Rayma beat me with better stuff.
Regardless, good luck.
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Here it says 15.5 degrees (second photo).
Gray Research 108 Custom Designed Phono Cartridge Stylus Alignment Protractor | eBay
I ran 9.5 mm overhang and 15.5 degrees through the VE overhand adjustment calculator. The resulting curves didn't look promising.
I've been toying with incorporating the pivot from the NEAT clone I have into a wooden arm, but with angle/overhang numbers that give more accurate tracking.
This thread has been helpful because otherwise I probably wouldn't have given the Gray design much thought and just copied it.
I've been toying with incorporating the pivot from the NEAT clone I have into a wooden arm, but with angle/overhang numbers that give more accurate tracking.
This thread has been helpful because otherwise I probably wouldn't have given the Gray design much thought and just copied it.
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