Installing the Schatten HFN pickup

The Schatten HFN pickup sticks to the inside of the guitar directly under the bridge.
(Not between the saddle and the bridge like a more common piezo pickup).
Therefore it is invisible. Take a look at their website.

To install it you have to reach inside the guitar, so the strings must come off for that.

I had the original strap peg, so I also had to remove that and drill out the 12mm hole for the endpin socket. Very scary the first time!
I decided to practice on an old guitar. I bought a separate endpin jack socket, drilled my old Eko Ranger6 and installed the jack. Then I had a little more confidence to work on my new guitar.
Of course, you can pay a Luthier to do this for you, if you can find one that doesn't have a six-month queue...

Technique that worked for me:-

1. Take off the existing strap button
2. Apply masking-tape over the area to protect in case of drill slip and to reinforce the varnish.
3. Lay the guitar down on some protective material and bribe an assistant to hold it steady for you.
   
4. Drill out the screw hole with a small (5mm) HSS twist bit
5. Then I used a 4-12mm step drill bit. These say they are for sheet metal but I saw several recommendations for using them, so I did.
   
6. Make sure you allow the waste material to clear as you drill.
7. But the step bit doesn't drill the full hole depth (about 25mm).
8. So I used a 12mm HSS twist bit to finish the hole. This gives a tight friction fit for the jack, but since it will experience some load, from the strap and from inserting and removing the jack, I prefer the wood to be taking the strain rather than the washer against the external vanish.
9. It took me a couple of attempts to get the right amount of protrusion of the end-pin thread, and I needed someone with a smaller arm to reach in at all!
   

I had taken the option from Schatten of including a volume control wheel which is accessible from the soundhole, but not visually noticable.
To use external power you need a specific type of cable with a TRS (stereo) jack instead of the usual guitar mono jack. Schatten sells one, but you can get greater variety. I bought an XLR to TRS jack cable .