dependent valve set up backwards?

[although]

Hi all,

I just got my first two-valve bass trombone. It's a late 70's Reynolds TO-1. So far so good! I'm enjoying how it plays

That being said, the second valve isn't working like I would have expected it to... I'm guessing that the valve is turned 90 degrees from factory. As a result, the dependent valve is normally open. If I only operate the first valve, the horn goes to flat-E tuning. If I operate both valves, it closes the second valve and the horn plays in F.

I reckon this would be handy for keeping the E tubing drained It just seems counterintuitive. Is this a thing? Or do I just need to adjust that valve to be normally closed?

cheers!

mike

[Burgerbob]

Pictures please!

[gbedinger]

I could never get my head around that setup not to mention the ergonomics.

[tbonesullivan]

Does it have split triggers, or a combined trigger mechanism? It's also possible that someone modded it to work that way, or was put together wrong. I also would love to see pictures of this. There have been a LOT of odd ducks during the evolution of the modern bass trombone.

[although]

I could never get my head around that setup not to mention the ergonomics.

Aha! So this is a thing that some folks actually do? It certainly appears to have been set up that way deliberately. The witness marks on the valve line up well. I'll go ahead and get some pics...

[GabrielRice]

I guess that's something somebody might want. Not me.

[hyperbolica]

Not quite all the advantages of a single valve Eb extension, but with 2 valves instead of one. I had a single with Eb tuning (not bE). It seems a pity to waste those first couple inches of slide. Not sure why you'd do that with a double.

Shouldn't be hard to set back to normal. Relocate the plate and maybe adjust the lever arm.

[although]

Valve with lever not-pressed


Valve with lever pressed


String side

[although]

Hmm, after a quick disassembly, it's looking like this is not an adjustable thing... It only goes together one way. I may have to learn to live with this for the time being.

[Burgerbob]

Pressing on the lower lever doesn't activate only the F valve?

[ithinknot]

I'm assuming the rotor stop arm is fitted correctly as you said the whole lot only goes together one way.

... In which case either it's been modified or it was ordered that way by someone with a massive thumb who thought pressing both triggers would be the easier default.

The second rotor bumper plate is 90 deg off the expected position, which would be essentially horizontal, mirroring the first rotor. Relocating the bumper plate would reuse one screw point and require drilling and tapping the rotor casing for the second hole; if this is a modification there will be a plugged/soldered hole where the original screw was located.

But... are you thinking of splitting the triggers to a modern middle finger setup? As part of that work, if you switch to a mechanical linkage the direction of rotation will reverse, so the current bumper plate orientation could be retained.

[although]

Pressing on the lower lever doesn't activate only the F valve?

It does. Except the upper upper valve is open unless you press it as well. It took me a minute to figure out what was going on at first.

[Burgerbob]

Pressing on the lower lever doesn't activate only the F valve?

It does. Except the upper upper valve is open unless you press it as well. It took me a minute to figure out what was going on at first.

Yes, I literally forgot it since your first post- my bad!

Very strange setup, but definitely worth having the triggers split.

[tbonesullivan]

That's a Reynolds Contempora Model 78-X "Stereophonic" type horn, right? I'm looking at some other pictures, and they definitely appear to have the rotor plate on the second valve set up differently, like 45 degrees offset from that? It's usually the opposite of the lower valve on the examples I am seeing, so that definitely does look like it was modified. Also both rotor plates look like they have been replaced with some type of plastic?

[hyperbolica]

If you put the lever arm on the other side of the valve spindle, and then reposition the stop arm to the other position and re-hook up the string, it will work normally. No tech needed as long as you can bend the arm without breaking anything. It looks like it was bent to the right already, just bend it back to the other side of the spindle.

[hyperbolica]

Ok, bad drawing with trackball, but this is the idea.

1) cut string
2) bend lever to red line
3) move stop arm to light blue position
4) restring as shown by darker blue line

ddd.jpg

[ithinknot]

this is the idea

Not exactly...

- the OP is talking about the other valve, not the one pictured
- moving a string linkage arm to the opposite side doesn't work well - you've basically just made a really sloppy mechanical-style linkage

Yes, the lever and the stop arm are now moving in the same general direction (if not the same plane), mimicking a mechanical linkage, but by reversing the relationship between the point of rotation and the stop arm, you've lost all the mechanical advantage of the proper arrangement, so the lever throw will be longer, and you've reintroduced all the "3D issues" that a real string linkage cleverly bypasses (if the stringing is loose enough to avoid the lever and stop arm contacting at certain points in the travel, the action will be very sloppy indeed).

EDIT - partial whoops, see below...

[hyperbolica]

this is the idea

No, on a few counts:

- the OP is talking about the other valve, not the one pictured
- moving a string linkage arm to the opposite side doesn't work well - you've basically just made a really sloppy mechanical-style linkage

Yes, the lever and the stop arm are now moving in the same direction, mimicking a mechanical linkage, but by reversing the relationship between the point of rotation and the stop arm, you've lost all the mechanical advantage of the proper arrangement, so the lever throw will be longer, and you've reintroduced all the "3D issues" that a real string linkage cleverly bypasses (if the stringing is loose enough to avoid the lever and stop arm contacting at certain points in the travel, the action will be very sloppy indeed).

The same idea works regardless which valve it's applied to. If he's going to split the paddles anyway, he's going to need to replace the lever. Plus, it will fit better on the other side of the valve spindle if it is hinged in the normal place. Putting the string on the other side rotates the valve the other direction. The string takes the mechanical tension out of the mechanism, which is part of the brilliance of a string to begin with.

[ithinknot]

The same idea works regardless which valve it's applied to. If he's going to split the paddles anyway, he's going to need to replace the lever. Plus, it will fit better on the other side of the valve spindle if it is hinged in the normal place. Putting the string on the other side rotates the valve the other direction. The string takes the mechanical tension out of the mechanism, which is part of the brilliance of a string to begin with.

Sorry - I misread the overlapping blue strings on your picture and was thinking the string passed around the stop arm screw direct to the lever... hence the quasi-mechanical stuff.

Obviously if it's tied in the conventional way, passing around the central shaft to the lever, it'll work the same way.

You'd still have clearance issues with the stop arm that are normally avoided.

[JohnL]

The valve core is 90 degrees out; one of the timing marks on the spindle should line up with the mark on the bearing plate at each end of the valve's travel.

How is the stop arm keyed to the spindle? Hopefully it's square so you can just pop it off and rotate it 1/4 turn clockwise (from the POV of the pictures).

[ithinknot]

How is the stop arm keyed to the spindle? Hopefully it's square so you can just pop it off and rotate it 1/4 turn clockwise (from the POV of the pictures).

That was my first thought, but

It only goes together one way.

suggests no luck on that front.

[JohnL]

How is the stop arm keyed to the spindle? Hopefully it's square so you can just pop it off and rotate it 1/4 turn clockwise (from the POV of the pictures).

That was my first thought, but

It only goes together one way.

suggests no luck on that front.

Depends on whether the OP is talking about the valve only going together one way or the linkage only going together one way.

[tbonesullivan]

The valve core is 90 degrees out; one of the timing marks on the spindle should line up with the mark on the bearing plate at each end of the valve's travel.

I just noticed this, because I'm not attentive. If the witness mark on the backing plate matches the casing, that valve is definitely 90 degrees out of alignment from when it was produced. Something is definitely off.

[although]

Yeah, the valve spindle isn't a square shape, it's a sort of "D" shaped affair. I also fooled around with swapping parts from the two valves with each other, thinking that maybe someone had disassembled it and put it back together wrong. But, that didn't work at all. It seems to me that the stop arm on the dependent valve is just the wrong part. Perhaps the original was damaged or lost at some point and a tech went to the parts bucket and cobbled it back together as best they could with the parts at hand...

I think I will visit my local tech tomorrow and ask his opinion. Maybe he has a parts bucket with the stop arm that I need!

[JohnL]

It seems to me that the stop arm on the dependent valve is just the wrong part.

It certainly has a different type of screw than the one on the f-valve...

[Fairlane57]

Have you checked to see if the valve parts are on the correct valve bodies? Stop arms switched? Rotor , casing and plate should have matching numbers. Check stop arms first.

[JohnL]

Have you checked to see if the valve parts are on the correct valve bodies? Stop arms switched? Rotor , casing and plate should have matching numbers. Check stop arms first.

Consider...
The f valve is working correctly. If one were to start swapping parts, there's two possibilities:
1) The parts are identical, so nothing changes, or
2) The parts are different, so the E valve might start working properly - but now you've changed the F valve, so it stops working.

[timothy42b]

Have you checked to see if the valve parts are on the correct valve bodies? Stop arms switched? Rotor , casing and plate should have matching numbers. Check stop arms first.

Consider...
The f valve is working correctly. If one were to start swapping parts, there's two possibilities:
1) The parts are identical, so nothing changes, or
2) The parts are different, so the E valve might start working properly - but now you've changed the F valve, so it stops working.

That sounds self evident. However, hard experience suggests binary choices are rarely binary - there's usually some worse possibilities I've missed.

[JohnL]

[quote=timothy42b post_id=200412 time=1674749222 user_id=211

Consider...
The f valve is working correctly. If one were to start swapping parts, there's two possibilities:
1) The parts are identical, so nothing changes, or
2) The parts are different, so the E valve might start working properly - but now you've changed the F valve, so it stops working.

That sounds self evident. However, hard experience suggests binary choices are rarely binary - there's usually some worse possibilities I've missed.
[/quote]
Like I said - the E valve might start working. It's also entirely possible that mixing and matching parts could result in configurations wherein neither valve works.
(which is why it's important to not lose track of what parts were where initially if one does start tinkering)

[although]

So, I took the horn to my local tech this morning. He looked at it and agreed with my diagnosis. He didn't have the correct part, but he did have a cut-off wheel and a torch

He cut the arm off, and brazed it back on in the correct position. Now it works just fine!

So, now I just need to put together that audition video...

[tbonesullivan]

Enjoy it! I believe that is one of the first double valve bass designs, and there are definitely fans worldwide. I mean, it does have limitations compared to more modern designs, but for regular playing it should be great. I have seen a lot of examples online where they had an Eb or D crook made for the second valve.