Plug-in second valve (for Conn 70h)

[MStarke]

I have a nice 70h and really enjoy playing it, but don't really know when I will be able to play it outside my practice space.

I might be considering adding a second valve to increase the likelihood of using it in a bigband or ensemble.

My goal would be to keep it as close to the original as possible, so I would appreciate your inputs, ideas, pictures etc. on how to best integrate a modular/plug-in second (dependent) second valve.
Pictures would be really fantastic!

Some thoughts and questions from my end:
- I would want to change as little as possible on the instrument. What would be the best way to realize the second valve trigger/valve lever (for the middle finger)?
- How would you shape and place the valve tubing (for a second valve in D) so that it doesn't get in the way?
- I understand the plug-in valve would basically replace the current valve tuning slide. That slide is pretty narrow. What actual valve would be the best choice? In my expectation best would be a rotary valve that is pretty open, but has a relatively narrow casing to fit into that space

Any totally different inputs?

Looking forward to your ideas!

[Burgerbob]

I also have a 70H that I want to be more useful (and perhaps more importantly, more balanced).

A neat fact: the 70H J bend only expands by .10 in the space it would take to put two modern rotors.

Since my '55 isn't a pristine example, it's getting chopped up and getting two independent rotors for sure.

[MStarke]

I have seen your video already, liked it as always! I would definitely stay with a dependent setup and this time prefer a modular option.

[WGWTR180]

A plug-in is the way to go!!!! Luckily Conn tubing is on the larger size for bass tubing so matching a valve up with the tubing diameter would be easy. Maybe a vintage Conn valve would be best if you can find one.Someone was selling a Conn 72H with a plug-in valve somewhere-

[blast]

I made a slot in for a friend's 71H which worked very well. For reasons too lengthy for here, he no longer needed it, so I bought it back. It would be nice on my 70H, but when I checked, the 70H valve tube is a fraction smaller. You will need to get the valve made as a custom fit, as tube size changed over time.

[MStarke]

Good to know! would you be willing to share some pictures of how it is built?

[blast]

Sure. Will do tomorrow.

[Kbiggs]

Here’s a few pics from my library. I’m not sure where they’re from, but probably Horn Guys or Brass Ark.

kanstul1580D_3.jpeg

kanstul1580D_4.jpeg

Kanstul1580D_2.jpeg

kanstul1580D_1.jpeg

[blast]

Ken, that is a Kanstul slot-in. Very nice.
Here are a couple of pics of my slot-in. It's very dirty looking as it's been in storage.

20251020_132907.jpg

20251020_132928.jpg

[mrdeacon]

Funky reversed tuning slides Chris!

[Burgerbob]

It's not like a typical slot in, it's all to one side. No reverse tuning slides.

[blast]

It was built for a 71H, so the extra tubes run down the middle of the bell section. The original valve tuning slide completes the set up.

[hornbuilder]

Similar to one I made for Max Seigel
The only issue with the drop in valve may be the amount of clearance from the main tuning slide/bell branch. Not a huge issue, but takes a.little bit of reconfiguration, and potentially one new part on an existing instrument

[mrdeacon]

It's not like a typical slot in, it's all to one side. No reverse tuning slides.

Doh. I see it now!

[Kbiggs]

Chris and Matt, those look awesome.