For your consideration, a pristine Nottingham Space Arm. Condition is listed as "8" for age only. This would make a perfect upgrade to your Horizon or SE w/ a Rega arm. Simple, easy to set (and STAYS set), and sounds great with the right cartridge (think higher compliance).
From the Positive Feedback review in Issue 19:
Continuing with the simpler-is-better motif, the ACE Space arm is a mechanically damped unipivot. The arm tube is made of carbon fiber. Like all unipivots, the ACE Space has tons of pressure per square inch at the pivot. If I understand this correctly, the mechanical damping results from using two hardened steel stabilizing bars as close to the center pivot as possible. The bars are in contact with a precision miniature roller bearing that is fixed to the hardened steel unipivot shaft. Resonance from the bearing shaft is dissipated into the bars. Unlike other carbon fiber designs, the grain of the fiber in the ACE Space arm runs the length of the arm rather than around the diameter. This, Nottingham's importers say, gives it better resonance control and rigidity. Also, there is a second carbon fiber arm tube inside the first arm tube, but with a smaller grain structure.
Arm height is adjusted by a threaded bolt. You can adjust VTA on the fly, which is very desirable. It is almost as easy as to use as it is to describe. There is no finger support for cuing records at the headshell. Tom Fletcher insists not only that there is there no need for it, but that there are reasons for not having it. Cuing aids act like tuning forks, and can add energy/vibration at the cartridge, where they are least desired. Once you've slid the arm across to position the cartridge, just flip the cuing lever, and the needle drops precisely into place. I found the arm to be the very best for accurate cuing. However small a victory that is, I loved it.
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In operation the arm isn't as skittish as other unipivots I've tried. VPI's JMW arm sounded a bit nervous in my bouncy living room, but it wasn't until I heard the RS Labs unipivot that the JMW arm's nervousness became apparent. I expect that my bouncy subfloor can excite some unipivots. I experienced no such issues with the ACE Space. It sounded excellent, even in a bouncy environment. It did not sound skittish. It sounded more continuous and less nervous than the JMW, though perhaps less stalwart than the SA-1. The SA-1 is quite heavy, and utilizes its mass to maintain its position rather than needing to be bolted to a turntable. I expect that its excellent resolution can be attributed to its weight. The ACE Space, despite its lighter weight, was no slouch either. It's a brilliant implementation that allows for excellent results.
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If the VTA is off, you'll know it, quickly. With all of the stuff going on for me right now, I'm not eager to tweak, yet I found myself making fine adjustments to the VTA. In part, that's because small adjustments resulted in large alterations to the sound, and in part it was because making those adjustments was quite easy. Adjusting VTA is rewarded with increased clarity, imaging, and better tone. At a tariff of thirty seconds of adjustment time, it's quite affordable.