Society & Culture & Entertainment Music

Fifty Years of the Ortofon SPU Cartridges

The Ortofon company was established in Denmark nearly 100 years ago.
Acknowledged among audiophiles, DJs and studio engineers for its range of record player cartridges, almost certainly its most famed product is the SPU cartridge, which is still being manufactured by Ortofon over fifty years since it was first introduced to the market.
Although Ortofon started out making equipment for the movie industry, and were responsible for the first ever synchronised soundtrack, the firm is best known for its record player components.
The company also produces some very serious scientific measurement equipment, a lot of which is aimed at the audio industry and broadcasters.
In fact, the SPU is a perfect example of a kind of reverse engineering.
Ortofon was involved in manufacturing cutting 'heads' for record manufacturers and pioneered stereo cutting equipment.
From this, one of the companies brightest engineers, Robert Gudmandsen, effectively turned the technology around and produced the SPU.
Standing for Stereo Pick Up, the SPU was originally designed and intended for broadcasters and the music industry, but despite its relatively high cost, soon found favour among serious audio enthusiasts.
Prior to Mr Gudmandsen's idea, LPs were nearly always played using a crystal cartridge.
In this design, the stylus (or needle as they were then known) is connected mechanically to a crystal, which produces electric currents in response to the vibration of the stylus as it tracks the LP's groove.
These crystal cartridges were quite efficient and produced relatively high level electrical signals (similar to a microphone) but suffered from poor quality, quite severe distortion and a lack of treble.
The SPU was a revelation by comparison.
The signals it produced from its moving coil design were significantly lower and the construction required a miniature transformer to be built into the cartridge body.
However, the performance and quality was revolutionary.
The moving coil design basically uses a magnet which is fixed in position.
The stylus is mechanically coupled to a miniature electrical coil, and moving relative to the magnet, this coil generates small electrical currents.
Inherently this design is intricate, difficult to manufacture and as a result, costly! Over the years, the design has been honed to near perfection through developments in microelectronics and improvements to materials and manufacturing.
Today, the sort of amplifiers used by audio enthusiasts are capable of dealing with much lower signal levels and the Ortofon SPU in its current form no longer incorporates a transformer.
Many audiophiles consider a step-up transformer still produces the highest possible quality, though these are now comparatively large units, in separate boxes.
Over the years, Robert Gudmandsen achieved significant recognition for his work and was awarded a title by the Danish royalty.
However, it was his fame amongst audio enthusiasts that gave him the greatest satisfaction and to this day he is known as 'Mr SPU' in many parts of the world.
As for the cartridge, it remains seriously sought after and is still near the top of many enthusiasts lists.
There is little doubt this will continue to be the case for many years to come.

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