Pickup Arms ST
Manufactured: 1958 - 1976
Designer: Erik Rørbæk Madsen & Acton Bjør
Bang & Olufsen ST pickup arms were available in four different types: ST/M, ST/L, ST/A and the ST/P (professional studio model).
These arms were statically balanced by means of a specially engineered counterbalance so that they were in a state of neutral equilibrium if ever the spring under the arm was removed. Consequently, when the spring was put on it, this was the only factor determining the stylus pressure, which was always at right angles to the gramophone record regardless of the placement of the gramophone motor or of vibrations in the motor. B&O pickup arms were so perfectly balanced in fact, that you could play a record with the player standing on its edge.
Bang & Olufsen pickup arms had built-in compensation for the ingoing force or "skating effect" arising on account of the interaction between the offset angle and the friction between stylus and gramophone record. With B&O pickup arms, the stylus would always exert equal pressure on both groove walls which was of great importance when playing stereo records, where each groove wall contained a separate signal. If a pickup arm that has not been compensated in this manner was permitted to run on a smooth disc with no grooves in it, the arm quickly pulled towards the centre. This never happened with Bang & Olufsen pickup arms (if correctly balanced) in that they always kept the same distance from the centre of the record.
The Integrated tone arm ST/P won the iF Design Award in 1963.
Type ST/L-15 Pickup arm
Is statically balanced by a specially designed counterweight so that it will be in a state of neutral equilibrium if the spring under the arm is removed. Consequently the spring when in place will be the only factor determining the stylus pressure. The pickup arm, has compensation for the ingoing force - "skating effect" - arising on account of interaction between the offset angle and the friction between stylus and gramophone record, so that the stylus will exert equal pressure on both groove walls. This is of great importance when playing stereo records, in which each groove wall contains its separate signal.
The B&O type ST/L15 pickup arm is 223.5mm long and stylus pressure is adjustable between 1 and 4 grams. Awarded the Danish D-Prize as well as the German iF Prize for excellent design.
Stereo cartridge type SP7 was for installation in B&O type ST/L 15 pickup arm, while type SP6 was for installation in pickup arms of other makes with American 1/2" mounting, 15 micron stylus. Type SP9 and SP8 were special versions of the SP7 and SP6, respectively, with 17 x 5 micron elliptical stylus for more exact faithfulness in following the groove.
Specification: 7 mV per channel at 47 000 volts.
Pickup Arms ST Product Specifications
Distance from centre of pivot to centre of turntable
Height above base
Length from centre of pivot to the stylus
Recommended stylus pressure
Created: 22nd January 2007
Modified: 15th February 2007