Version: Sept. 16, 2000

Roger Arnhoff


by Lars Gaustad, 2000



Tobias is the cylinder replay machine at the National Library of Norway, Rana division.

At the Media Laboratory we use a custom-made replay machine for 2-minute cylinders. It is developed by Roger Arnhoff, former head of the laboratory and well known to the Norwegian sound and music community for his lifelong contributions to various aspects of the recording industry, among which his recording studio, Roger Arnhoff Studio, and his record pressing facility Hønepress, are well known even to a larger audience.

Tobias was constructed in-house at the National Library with "ORPHEUS" technology, which means that the pick-up is transported along the cylinder as it is replayed. The basis for the machine is a watchmaker's grinder from EMCO. The cylinders are mounted on the machine by two rubber-coated cones in a way that enables us to minimise the use of power to hold it tight.

The DC motor runs the shaft and the cylinder, via separate tooth wheels, so that a cradle mounted on the shaft, maintains correct speed along the cylinder. Onto the cradle we have placed an SME arm in a position that assures correct placement of the stylus in the groove, and allows for it to float in the groove causing minimal wear to the original.


Speed is adjustable from 1 to 300 rpm, both forwards and backwards, and is measured with an optical reader.

We use a Stanton stereo cartridge that is fed to a preamp with two switchable filters, one 100 Hz high-pass and one 6 kHz low-pass filter. The signal is then fed into a MS-matrix witch enables us to phase out a lot of the surface noise from the signal, due to the fact that cylinders is recorded in hill-and-dale mode. A soft padded "pusher" closely follows the pickup, and comes into action if the stylus is hindered by cracks in the cylinder.

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