TromboneChat

I have a silver played Bach 50B that at some point was modified with a single Thayer F attachment (i have no idea what vintage the Thayer is, it's stamped with the number 1818). I'm more and more noticing the lack of a second valve.

So far I have come up with three options:
1. Modify the horn to add a second valve, most likely a standard rotor. My initial thought was to see if there's any way to make a tuning slide with a valve, though if I could figure out a way to add an independent second valve that would be even better.
2. Buy a standard valve section (there's currently a silverplated bach 50B2 valve assembly on ebay that looks interesting). For an added challenge I'm sure I could drive whoever I can convince to take this on crazy trying to make the whole thing modular so I can swap between double valves and a Thayer setup.
3. Sell the horn and put the money towards a horn that already does what I want.

I'm posting here for the hive minds input because I really have no idea what I even have and how concerned I should be about potentially ruining something interesting/cool.

Posting pictures would help to see what would need to change… but making a bass that has a Thayer modular;while not easy, is very straightforward. Drop in valves into a tuning slide are not as straightforward, mostly as nothing in the assembly will be off the shelf.

Making the silverplate look good after work will take a lot of skill and probably money. I wouldn’t do it, but some of my horns look like they came out of a dumpster.

Picking up, say a used Shires double rotor section and making it modular would maybe be a fairly standard Mod. Cost? Depends on who is doing the work and how much of a mess needs to be cleaned up as soon as you take the torch to existing.

Cheers,
Andy

If you are able to sell a single valve bass and also are able to acquire a pre-owned double valve bass, that is going to be your cheapest option almost certainly. But there's a bit of luck involved there, on two fronts.

As Andy pointed out, if you are okay with just a rotor, which actually I've seen at least twice before (a Thayer valve as the main valve and a dependent rotor branching off of it), that will probably be not too far off from the first option, though. Depending on what type of rotor you want, you can get them pre-owned as cheap as $100ish, again though - luck. There are some good quality rotors like Instrument Innovations that aren't too expensive and they sell tubing too. Price is going to vary from tech to tech, but I'd put a ceiling at around ~$1k.

Slightly more expensive than these, but almost certainly the most "stable" and least reliant on luck: if you buy a pre-owned double valve section it'll cost that plus ~$150 for mounting hardware. You'll also need a tuning slide, which often go for ~$250 used. It's like 2-3 solder points so the labor will be minimal with this, but you have to find someone selling a pre-owned valve section for this to make sense.

FWIW, someone was selling a double valve section here at a very good price recently in the classifieds, but I can't remember when, might do a little digging to see if it's still available.