Metal Disk...

[Hawkwind]

My Father went Amherst College, late 1930s/early 1940s. While there, a speech he made was recorded on a 12 inch metal disk. The hole in the middle was the common small size. It spun at 78 RPMs. Written on the sleeve was something like this: "Play with fiber needle". Played it anyway with an expendable cartridge. So, what is it? A master for a stamper?..

[ppppenguin]

Greeting from London. I have some similar discs. I don't know the full history but here goes. In the 1930s a cousin of my father was an engineer and designed a turntable which had two pickup arms. One for recording on to aluminium discs, the other for replay. I had one of these turntables as a kid. The record arm was broken but it was driven by a kind of lead screw.

AFAIK, the discs were meant to be played with a fibre needle and they did indeed play, using the replay arm. A steel needle would have badly damaged the disc. I think I have tried a couple with an ordinary 78s stylus on a modern turntable. Most of the discs had very shallow modulation and gave very poor results. I think I could hear my father singng on one of them. The best one was a recording from the radio of King Edward VIII abdication speech in 1936.

I think my father's cousin's company was called EAR. We certainly had an EAR gramophone when I was a kid. Collaro(?) 3 speed autochanger. Amplifier was probably ECC83+EL84+EZ80.

In the 1930s there was lots of work on audio recording. On steel tape with machines like the Blattnerphone and on disc such as the MSS. These were for professional use but I wouldn't be surprised if a number of people tried to make a domestic/semi-professional disc recorder.

By the late 1930s, direct disc recording was well established with machines such as the BBC Type C. http://www.orbem.co.uk/repwar/wr_recorders.htm

[Electronic M]

I remember when I was a kid finding a similar disc in an antique shop and ruining the styli on a couple of phonos I liked only to get nothing but noise off the disc...I eventually got mad and bent it like a taco.

Wood needles were fairly common pre-war especially on windup machines and were available in a wide variety of materials from thorns to cut bamboo...The main purpose was to reduce volume on acoustic machines, but they could also change tonal characteristics and both electric and acoustic phonos used them for that.

[ppppenguin]

I still have some fibre needles and a sharpener. This rotated the needle against an abrasive disc which was also rotated.

This page has a lot of information on fibre needles: https://www.wardworks.org.uk/Gramophone/index.html There is at least one incorrect statement on that page: "...but repeated playing of 78's with a stylus will result in some wear to the records"

Technically correct, but any wear cause by a diamond or sapphire stylus tracking at 5 grammes or less is negligible. Fibre needles gave a softer and smoother sound than steel needles. They caused less damage to discs though I've heard that they can cause a sort of burning effect due to higher friction than steel.

"....and you sharpened fibre needles to make it soft again..."
https://www.youtube.com/watch?v=7fJmmDkvQyc