One question I get in my emails a lot is, "How do I extend my Conn 12M Baritone Sax neck so I can use modern mouthpieces on it?"
My answer is usually that the neck should not be extended if possible. I see these neck extensions as a non reversible job that will alter the instrument and cause it to no longer work with the larger chambered mouthpieces for which it was designed. That said, something has to be done to these wonderful instruments to allow them to work with small-chambered modern mouthpieces. What I have done on my personal Baritone and for many of my clients is to extend the mouthpiece itself. This extension allows a player to use the modern mouthpiece without altering the instrument.
My personal mouthpiece is a Lawton 6, notice in the picture below the extension on the mouthpiece. -Also, if you're curious about the engraving, that was done by Eric Drake in CA. I was at IAJE with Eric Drake years ago and he happened to have his engraving tools, I happened to have my mouthpiece. As usual, Erics work is spectacular, even when done on a noisy trade show floor.
OK back to the extension, take a look at the extension I put on my Mouthpiece years ago.
You can see that this extension is nice and clean. Also the inner diameter is the same as the inner diameter of the mouthpiece's original shank.
OK, so that extension worked great for years with one flaw. I could not use my mouthpiece to test modern baris that came into the shop. This is (was) a real problem for me. I would have to use a more unfamiliar mouthpiece to test horns. Even though I like to use the players set-up to test a horn, it's always nice to play my set-up as well to be sure I'm not missing anything.
So, I started talking to Matt Scott, the now-famous saxophone repair technician, about my plan to have a removable extension. Luckily Matt and I work together so we were able to plan and work at the same time. 2 days later Matt came to me with a few parts. In the picture below you can see the new part that Matt made on the lathe for my mouthpiece.
With these parts, Matt's plan was that I can unscrew my extension and remove it leaving the original, shorter, mouthpiece ready to be put on a modern instrument. The threaded part above was to be soldered to my mouthpiece allowing the knurled extension (threaded inside) to be screwed on.
As luck would have it we also just finished a MKVI Bari overhaul that needed testing. In just a moment I was able to unscrew my extension and play the VI, then screw my extension and blow a few notes on my 12M.
This is what the mouthpiece with the removable extension looks like complete. Note that I will someday send it off to be plated properly.