I hope this will end up as a series of articles in the APS magazine.

Well, I am stunned at how much you were able to see, derive from that, and draw imho logical conclusions from it. I can almost envision your attempt to construct one of these. Hopefully I am right and I believe it will be electrical as opposed to acoustic. I have no insight beyond what conclusions you’ve drawn but I think you’ve got it right! Thank You for all you’ve done here and for everything else you do! I for one am quite grateful to have some small connections to you, and hope to provide useful access to my library of Diamond Disc Records. Yours with appreciation, David A. Logan Sr.

If you look at the lateral recording head which appears at 17:40 a radio collector will notice some familiar components. The greater part of the head is made up of the driver from an RCA 100 type loudspeaker, a mass produced device which was designed and manufactured in the hundreds of thousands by General Electric, the company which provided the leased electrical recording equipment to Edison. The vertical cut recorders appear to involve more custom fabrication.

Very interesting video! Thanks for making it! If only Edison were alive today!

The massive electrical cutter with stylus tension wires, if you look carefully the driving armature is located top middle, left of the advance ball adjustment screw. and has a rod that runs down to drive where the cutting stylus hooks up to. I find this interesting, as I used a similar method on my electrically cut cylinder records. You will see the armature in the middle of the coil winding.

Good job. Thank you.

you are my hero

Very wonderful pictures. It seems that while it answers some questions, it creates more questions. I also find it odd, that on my own, I have put similar combinations of papers, micas, rubber dampening and some compressor experiments that I see on these recorders.

I`m Also looking for How a Blue Amberol Cylinder Record was Pressed and made! ??? Thank You for this! FASCINATING!

Diamond Disc wax masters were 1" thick, and made of lead stearate and montan wax. I am also definitely certain that the triangles on the recorders are to attach the recording stylus. On the acoustic recording facebook discussion group, I have patents of the various late-model Edison studio recorders (although they do not have tension wires mentioned in the patents, it was a trade secret.) The patent helps to see how a bushing goes down to the center of the diaphragm, and the cutting stylus on the wire ones, attaches to the body with glass reeds, with burnt rubber between. Those adjustable boxes on the sides of the recorder is an acoustical compressor, working the same as an LA2A compressor, except mechanically, it makes the recorders sensitive to very soft sounds and keeps very loud sounds from over modulating the diaphragm. I have experimented with this with acoustical recording. I have 2 advance ball acoustical vertical recorders, one from an original cylinder or disc studio. The diaphragm platform for mounting on my original studio head is 1.8" It has two alignment rings, one for 33mm (1.380") and another ring at 1.530" for a larger diaphragm. The opening though that goes to the trunnion on the recorder is only. 0480" I just measured these with dial calipers.

The triangle part on the one recorder may have been for a particular kind of stylus holder, mount where a knife edge was secured under the triangle and an adjustable spring was then used to put some back tension on the stylus, (again a mechanical audio compressor) or forward tension. Sometimes these recorders had two conical bushings, one in the center of the diaphragm, and the other on the bottom of the cutting stylus, bar, and this bushing in between, the idea that less of an arc of the travel of the stylus, thus more energy going to the stylus. It seems many Edison studio recorders had this tension wire system for the cutting stylus, (not on the advance ball) the front part of the stylus bar attached to the body by rubber, or a spring (either spring steel or glass reeds) and then the stylus floated with the wires and then the conical bushing down to the diaphragm. Supposedly the diaphragm is set on burnt rubber, where you take a stick of white rubber and set it on fire, and let it drip around first on the recorder body, secure the diaphragm quickly to this burnt rubber for viscous dampening. The idea is that when sound waves hit the diaphragm they vibrate only once, and that with regular rubber they have some harmonic distortion of vibrating several times with each sound wave that hits the diaphragm. The cutting stylus usually is in the middle of the recorder, the cutter usually even with the advance ball, however in setting up you have to move the advance bar assembly back and forth in very small increments, noting the performance and test for the quietest and clearest cut. Mostly what the advance ball does is keeps the stylus from recording too deeply due to how heavy the recorder is, and you then can carefully set the depth of cut. If set to shallow, the groove is too shallow, and the sound is raspy, if you have it too deep, you have a noisy cut the high frequencies then don't record well, and the sound waves are then too far in the groove for the playback stylus to pick all the sound up, and also because it is pressing up on the diaphragm, the recorder is not as sensitive. The right cut is a continuous swarf, no distortion in the soundwaves and high sensitivity to high frequencies, and then can record loud and soft sounds. I have been working with a similar studio recorder since 2010 that is original, from some professional studio 1903-1920, and have many tens of hours of time working with it, maybe several hundred.

I am looking at the mysterious pipe with holes in it, and from what I can tell, the pipe slides so that the holder for the reproducer can line up with each one of them for testing. What I imagine it most likely does, is that they wanted to load the reproducer with different acoustic impedances, which could possibly be for testing the response of the reproducer to the record under different horn setups as one would find in various models of Edison machines. In other words, they were probably checking to see if the record made the reproducer rattle under various simulated setups.

Would one of those lathes have been used to cut the Needle Cut discs, or was that an entirely different lathe?

I Would Love to see how they made the Diamond Disc! Especially the Etched Labeled one`s! And Why did Edison Press His Paper Labeled Records with a stamp on label over a Paper label that was pasted over a Already pressed into the Record??? This is VERY Interesting!