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PHILIPS 9535 - Elegant Crystal Microphone



In the thirties, many microphone makers used the new patented crystal cartridges, from the American Brush company, for their own microphone models.

The Philips 9535 was one of these. These crystal pick ups made it possible to reduce the size of microphones significantly: the regular Philips 4210 carbon microphone had a diameter of 120 millimeter, the new 9535 crystal mic had a diameter only half of that; just 60 mm.

Because this technique was easy to fit into slim housings, the designers could now concentrate on stylish design, making these microphones small but beautiful.

Compared to carbon microphones, the sound quality of the crystals was also good. Although they picked up less low frequencies, they did not produce a hiss like the carbon types, and reproduction of high frequencies was much better.

Philips boasted that neither vibration, humidity nor shock could excert the slightest influence on these crystal types, and with their high output and without the need for a dedicated power source they became very popular.

There were three different types: the 9520, an exact copy of a Brush model, but with a Philips logo, the 9529, nick named 'the Acorn' and the 9535.

Although the cartridges seem to have been the same in all three, the 9529 was presented for music and voice (with a horizontally placed cartridge), the 9535 was just meant for voice and had an extra moisture proof seal.

In fact Philips produced one more type, the 9533, a throat microphone; a small round shape that could be mounted in an aviator's helmet or in a collar.

There seem to have been different versions of the 9535: at first it was silver plated and had a closed back, later it was chromed with a similar front and back and larger Philips logos.

Production lasted about ten years, from 1935 until 1945. The light weight of just 120 grams made handheld use of the 9535 easy, Philips' carbon handheld was much heavier: 600 grams excluding batteries.

My later version of the 9535 has a wonderful history: it was used in the garage of the NSF company (Nederlandse Seintoestellen Fabriek / Dutch Signaling Equipment Factory), the oldest Dutch radio company (est. 1918) and the origin of Dutch radio broadcasting.

From that garage departed the first cars with mobile radio equipment and reporters to hunt for news all over The Netherlands.

Many more types feature in my book Witnesses of Words. More information about that can be found at

wow cover

Philips 9535
9535 back side
9535 old version 9535 old back

Top: the stylish 9535 on its original NSF base

Middle: back side & front and back of the earlier version

Below: Sound, French ad from 1940, models 9520 and 9529 'Acorn'

Listen to the sound of the Philips 9535:

French ad 1943
Philips 9520
Philips 9529