This is a listing for a Dennesen Geometric Soundtracktor, a versatile tool for aligning an LP vinyl phono cartridge.The Soundtracktor utilizes alignment geometry set forth in a December 1941 journal article by H. G. Baerwald. (The same geometrics were actually reported in 1938 by Lofgren.) Baerwald disclosed design equations for optimum cartridge offset angle and overhang. The resulting "best fit" stylus arc has two points where the tracking error is zero. These points are called the inner and outer null points. The Baerwald inner null point is 2.6" (66.04 mm) from the spindle and that is where the "bulls eye" stylus point is etched on the Soundtracktor locator base plate. The stylus point is surrounded by an etched grid. The bulls eye establishes the optimal overhang and the grid is used to set the optimal offset angle. The Soundtracktor is covered by U.S. Pat. No. 4,295,277. P2S is an acronym for the distance between the tonearm pivot point and the turntable spindle. The manufacturer of a tonearm usually specifies a desired P2S. The Dennesen tool is very useful for setting up P2S and/or establishing a pivot point location on a turntable plinth. If, for example,
the specified P2S is X, a ruler may be used to fix the distance X between the center of the base plate aperture and the pin point on the arm that engages the base plate. After the setscrew on the base plate is temporarily employed to lock the arm, the base plate aperture is placed over the spindle. The pin point then points to the tonearm pivot point. The Soundtracktor facilitates fast one-step cartridge alignment. It requires cartridge adjustment at a single null point. The base plate stylus point (null point) is fixed, not floating. In a typical dual null-point protractor, often a paper template, the stylus points and grids are free to rotate around the spindle. The stylus overhang must be found by trial and error at two nulls while simultaneously setting the cartridge yaw (offset angle) for zero tracking error at two nulls. This means the stylus arc must pass through both null targets at the same time the cartridge sides are parallel to both null grids. This complexity increases the chances for alignment error. The beauty of the Dennesen tool is that it is P2S neutral. One need not know the P2S to make an alignment, and it makes no difference if the desired P2S was not achieved through set-up error, or the tonearm base loosened and moved, etc. The Dennesen Soundtracktor also includes a bubble level and a tonearm stand which may be used to make VTA (vertical tracking angle) tonearm adjustments. The bubble level has an aluminum base with a longitudinal V-groove (see photo). The groove enables the level to straddle tubular tonearms. An economy model of the Soundtracktor was made of plastic. The instant tool is the metal (aluminum) version. It comes with the original box and instructions. I am the original owner. The photos were taken by me, not "borrowed."The separate components have always been stored in the original foam sleeves. Normal wear and tear has produced some small, shallow nicks in the metal. The seven rating mainly reflects the age of the unit. The utility of the tool has not been compromised. Shipping only to the 48 states is free and via Priority Mail. Payment by U.S. Postal Money Order. eBay Feedback: meloroony
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