+1 London Decca. A good friend has a collection of London Decca carts the best ones are very good, if not some of the most musical carts I’ve heard. If my arm would take one, I’d have one for myself. Very interesting design, no cantilever is strange to look at but works remarkably well. The carts body runs very close to the record surface as well.
What innovative, unconventional cartridge designs can you recommend?
Most cartridges have a stylus and cantilever where the transducer (magnet, iron or coil) sits on the far end of the cantilever. What other designs are there?
I am mindful of two designs which put the business end right on top of the stylus. The first is the moving coil (MC) Audio Technica AT-ART1000 which places two tiny coils, each 0.9-mm diameter, with eight turns of wire directly above the stylus. Australian price is about AUD-7000 and there apparently is a newer model, slightly less exxe. the ART1000X. This has square coils for a bit more output, and threaded mounting holes.
A downside is that stylus replacement involves a factory maintenance program and the Australian website page describing this service does not exist.
Another design is optical, exemplified by DS Audio's range. While these still need a stylus to trace the groove, the signal is produced by reading the intensity of light produced by a Light Emitting Diode (LED) hitting two sensors. Between the LED and the sensors are two 'shades' mounted above the stylus which change the amount of light as the stylus vibrates. These cartridges need a special "photo-stage" to replace the conventional phono-stage which is an additional expense.
Australian prices including photo-stages range from AUD-2,150 for the DS-E1 to the DS Master 3 at approximately AUD-40,800, which is a bit outside my price range! Where is the sweet spot?
What other way-out designs are there?
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Actually, less than 2,000-Gs, and most <1,000-Gs by design - read: “Disc cutting in theory, Hugh Finnimore, Studio Sound and Broadcast Engineering, July 1975” Studio-Sound-1975-07.pdf |
Thanks for the correction. I claim a typo, or at least a brain fade! 1000-G will do but it is still a lot of acceleration, and it is driven by side-wall pressure from the groove acting on the effective inertia of the cantilever, etc, seen at the stylus. A ton on its own is not a measure of pressure until you add the area the force is acting on, eg tons per square inch. The contact area is determined by the stylus shape and the deformation of the vinyl it is pressing into. The actual tip does not contact the groove at all. It seems that line contact styli distribute the downforce over a greater area than conical styli, which are a poor fit to the groove |
Thanks for the need for a SUT in addition to my MC input. Puts me off the ART-1000X a fair bit, especially as I find out more about the unique features of the DS Audio series 3 range. Conventional cartridges have to do physical 'work' as they generate electricity from the movement of the stylus. DS Audio cartridges use an external power source, and the stylus does no work to generate electricity. Instead electricity is generated when photons hit two light receptors. The photons stream from two powered light-emitting diodes, one for each channel. In between the emitters and the receptors is a 'shade' made of extremely light beryllium, attached just above the stylus. The output of each receptor is proportional to the amount of shade not in the way. Unlike conventional cartridges, the output varies with the position of the stylus. Electromagnetic cartridges generate signals proportional to the transverse velocities of the stylus. At the limit of excursion, DS Audio generates maximum output, conventional cartridges none. That is why conventional phono stages won't process DS Audio output correctly. The signal produced by the powered cartridges is huge, so signal to noise can be far lower. I think I am sold, if only I had the money! |
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