Price: $75 (USD)
Application Notes
We've implemented this nut on both RB-250's and RB-300's. We have no experience with other Regas, but we know that the RB-900 has a different arm stub and will not work with this or any other "nut style" adjuster made for the 250 and 300 arms.Installation Notes
If you have any doubts about your implementation, we suggest contacting us and going so far as to drill a prototype out of scrap wood to test your measurements with your cartridge. We'd hate to see you ruin a one-piece plinth/armboard by rushing this project. We can also discuss reducing the thickness of your arm mounting area to gain VTA adjustment range.
Study your Rega arm. You'll note that the arm stub is approximately 1.25" long. The range of VTA adjustment available to you is the amount of left over thread after your arm has been mounted. This is the post length minus all of the pieces which it passes through:Armboard Mounting Plane Height
1) the VTA nut height addition = .080"Assume the typical turntable with an armboard thickness of .750". These numbers add up to 1.080" which means that the total +/- (peak to peak) VTA range available to you is only .170" (1.250 - 1.080 = .170). Not very much room for error!
2) the thickness of your armboard (.500 to ???)
3) the bottom fixing nut = .250"
This is the reason that the Rega armboards we provide for our Galibier Quattro series are .440" thick (armboards we provide for other pivoted arms are .875" thick). An armboard thickness of .440 increases the available VTA adjustment range to .460" (peak to peak) over that which would be available with a nominal .750" thick arm mounting area.
With careful planning, this will easily cover the broad range of cartridges we've measured. We've observed the median height of most cartridges to be 16.9mm with a very small variance. This dimension is the measured distance from the cartridge's mounting surface to the stylus. Should you later purchase a cartridge which drastically varies from industry norms, you can use shims under the headshell or the VTA nut to compensate for the height difference. If you're measuring your cartridge, be mindful of keeping a steel ruler well clear of your cartridge. Failure to exercise caution could have catastrophic effects on the life of your cantilever. Some cartridge magnets are very powerful!
There are numerous ways to think of arm mounting height. We'll reference this dimension as the drop from platter surface to the plane at which the arm is mounted. With our .440" thick armboards, the arm mounting surface should be 1.400" below the platter surface.
As noted above, the thicker the arm mounting area, the less VTA adjustment range is available to you. In order to maintain an equal upward/downward adjustment range as your armboard thickness increases beyond .440", you'll need to raise the mounting plane by half of the thickness differential.
So ... if you have a .750" thick armboard, the mounting surface must be .155" higher than the above example with a .500 thick arm board (.750 minus .440, divided by 2). This means that the armboard should be raised so that it's now only 1.245" below the platter surface (1.400 minus .155 = 1.245).
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