Interesting. I have never heard of anyone repairing crystal cartridges.
The RIAA curve is interesting as 78s did not use the RIAA curve, just LPs and the 45s.
In the days of the 78 recording companies had their own curves. Not that it mattered much as a very large number of gramophones were entirely acoustic with no electronics, so there was no possibility of accurate playback of any curve.
In fact here is a picture of the Eq of 78s from various firms to set the correct buttons to select the correct playback EQ on my old Quad 22 tube preamp. Also shown is my Decca ffss 78 RPM variable reluctance moving iron cartridge. It is attached to a rare adapter for the SME series one and 2 PU arms. You can see the button combinations on the plastic card for the various record labels.
This is my SME series II improved arm.
The Decca cartridges were deigned to integrate to the Decca ffss and Decca professional PU arms.
Picture of my Decca ffss professional arm without cartridge on. Also shown is the Decca Brush and a very rare Auriol lift from the fifties.
Here is my Decca ffss H4E variable reluctance moving iron cartridge on the Decca ffss professional arm. The turntable is a Garrard 301.
It does seem to me you have an interest in being a collector restorer. At some point you have to decide what it is you really want to collect and restore. Especially, you want to decide on restoring gear that can actually perform and hold its won, and then some with modern counterparts, or collect museum type curios like that disc cutter. The latter is certainly a worthwhile endeavor, but the items are not of any practical use. Either they are items of historic significance or footnote curios like that disc recorder. You can't get involved in everything. Like all things in life choices have to be made.
I know you are interested in reel to reel tape recorders. Collecting and learning to restore those is certainly a worthwhile endeavor. Those of us who know, how to restore and set up those machines are now getting well past our sell by date. So it would be great to have a youngster like you want to learn that art and skill. I can't sugar coat it, but is an art and requires great skill to do it properly. You also do have to have equipment. You need physics lab certified alignment tapes, a FET meter, a signal generator a dual channel O-scope, a distortion meter, and if you work on feedback tach controlled machines, which is all the later models, then you need a frequency counter. So collecting these items is a first step. No reel to reel machines will be at peak optimal performance without regular tweeking.
There is nothing wrong with learning to record and edit analog tape. However leaning to make seamless noise free tape splices with an editing block, pencil and razor blade is an arduous but worthwhile skill to learn.
If you are planning to be a recording producer engineer then you will also need to work in the digital arena. In so many ways it is a very different skill set than what is required for analog recording.
I know you are a digiphobe, but you should not be. The fact is, with the right skill set you can make better and more life like recordings in the digital domain. By far the biggest advantage is no loss of quality after multiple dubs. In the analog world you dare not edit a master, less you ruin it, So you have to make one dub at least to do the editing, and any Eq etc. So right away you have halved S/N and doubled distortion. In addition in order to match digital you have to use noise reduction. So you have to be keenly aware of upsetting dynamics in any dub. In using noise reduction, which as I have said you must use in your masters, then the tape machines must be very carefully set up as frequency response errors are doubled versus no noise reduction.
For digital recording you need a totally different approach, especially as signal overload is much more serious. So in the digital domain you need much more extensive metering, over half a screens worth.
However editing on the computer is much easier and a more easily acquired skill then razor blade editing.
As in the analog world you need really good equipment. Don't let anyone tell you, you can use free or cheap software. For professional results you can't. The basics are a good DAW, which I strongly suggest you design and build yourself. Many decisions on DAW design and set up are very personal. You need good mics, and a selection, bout which we have spoken before. Also required is a good mixer DAC, that can be controlled from the same screen as the DAW and integrates well with your software.
If you want to get serious about this, you have to learn to make a good job in the digital domain. Unfortunately there are far too many working in the field who have not developed the requisite skill sets and produce garbage. In the world of pop the world is literally awash in it.
Here you can see what I mean. This shows my DAW and mixer screen and plays a recording made at 15 ips 2 track dbx 1 NR. It is a live recording for FM radio broadcast.
Here is a digital recording, again made for radio broadcast.