Shaftesbury Velodyne Supreme

A review from Wireless World, April 2nd, 1937, page 330.

"SHAFTESBURY MICROPHONES, LTD., 24, Aldersgate Street, London, have introduced a new and improved model of the Velex velocity ribbon microphone, which is now described as the Shaftesbury Velodyne Supreme Microphone. A considerably larger output than is usually obtainable from ribbon microphones is provided by this model, as in place of a single ribbon, which is customarily used, the Velodyne type is fitted with several ribbons arranged in series but with a common magnet system. The output is such that a good three-stage amplifier suffices to give adequate volume for most purposes.

The equipment sent in for test comprised a table model Velodyne microphone and an AC /DC three -stage amplifier designed for use with it. This amplifier embodies two top-grid triode valves feeding a pair of Tungsram PP36 valves. Included in the full equipment are two loud speakers, but as these did not accompany our apparatus the test was made with a loud speaker of known characteristics and of about 55 ohms impedance. The equipment is so arranged that it can be assembled in a few minutes, since the several parts are interconnected by cables with plugs.

Though only aural tests were made, these sufficed to show that the quality of reproduction is exceptionally good ; speech is clear and entirely free from sibilant accentuation, while the sound of keys shaken and similar tests for fidelity left no doubt in the mind of the listener as to the nature of the items employed.

Despite the fact that the amplifier gives a high gain, the hum level is very low, and so also is the background of the microphone. A final test, using the output from an AF beat oscillator, failed to reveal any resonances either in the microphone or in the amplifier from zero to 10,000 c /s.

Judging from the tests carried out, it can be said that the microphone is free from resonance and has an ostensibly flat characteristic up to at least 9,000 c /s, while even above this upper limit an appreciable output is evident.

The new Velodyne Supreme Microphone finished in chromium plate costs £12 12s. including a transformer, while the complete equipment, comprising the microphone mounted in a floor stand, a 50-watt universal amplifier, twin loud speakers, and all necessary cables, is available at £50."

Momics View:

The concept behind the Velodyne was to give increased output by using a super-long ribbon. Normally that would not give as high an output as it should, because of 'rippling', or other incoherent vibrational modes. But by fixing the ribbon in multiple places the inventors claim to avoid this problem. 

In practice the microphone has one giant ribbon that goes round corners, and each length of ribbon has a 'node' in the middle, so in total it has 8 elements, each at 45 mm x 4 mm. So 360 mm of vibrating ribbon.

This microphone has no transformer. I assume that the designer thought it had sufficient impedance already and did not need one. This would make it very prone to damage by phantom power when it came along. Nobody was using phantom back in 1935.

I know of no other transformerless ribbon microphones. The Shaftesbury Velodyne Supreme was sufficiently novel at the time for the inventors to apply for protection. (Patent GB460775A).

Xaudia blog post about the Velodyne Supreme

Patent for the Velodyne microphone

Wireless World archive at World Radio History