Oldstyled 3V compensator with 4th valve???

[iiipopes]

Been there, considered that for my own 3-valve comp, tossed the idea in the hamper with the old t-shirt. In a word, no.

1) Adding a rotary as a 4th valve of the proper diameter and finding a place to put all the tubing is a chore because the backside is already filled up with stuff; at the very least you'd have to remove the nickel "handle" and use part of your 4th valve tubing as the new "handle."

2) Because of the comp loops, the only reason you'd add a 4th valve is the low near-pedal tones from Eb down to "real" pedal BBb. Aside from being just slightly stuffy, low C and lowest F are perfectly in tune with 1-3 because of the comp loops.

3) Because of the nature and flare of the bows, the 17 inch bell, and the fact that "false" pedals, for some reason or another, are practically non-existant, you can't be sure the horn would even resonate the lower pitches.

4) The last 3-valve comps were made decades ago. So if you're going to add a 4th valve, in order to make sure you're actually doing something positive, you would probably have to spend more than the horn is worth going through it to make sure there are no leaks from bangs, dents, red rot, or deteriorating solder joints elsewhere so that it would actually intonate the low notes, again with no assurance it would, or that you'd have anything playable when your mods are completed.

5) Because adding valve and tubing necessarily involves a change in a passage somewhere either in proximity to the main tuning slide or somewhere as the bugle starts, you can't be sure that the slight change in the path of the air, to say nothing of the added rigidity points extra braces that would have to be fitted to secure the valve, linkage, and tubing, would interfere with another node somewhere and cause intonation problems at specific partials with other valve combinations.

6) Adding a valve, at the very least, adds a tiny bit of effective length to the bugle, and since the main tuning slide on most of the tubas is pretty close, with usually no more than 1/2 to 3/4 inch pull needed to fine tune the mains, you might find the result to be too long and the horn play marginally flat, regardless of the tuning slide being pushed all the way in. This actually happened on the first 19 inch bell Sovs, because the larger bell diameter also effectively lengthens the bugle, which had not been taken into account, giving rise to variations on the "Sov cut" on either the tuning slide or one of the inner bows to get the tubas back up to pitch until Besson reengineered the inner bows.

7) If you want to make it a vertical 4th pinky valve, like on some Yammy and Jupiter models, there isn't enough space between the 3rd valve and the inner bow to fit it.

8 ) If you want it to be a left hand valve, what's the point when you can get a 4-valve comp already in that configuration?

There is one place I have considered it: as a dependent 4th valve "long half step" off the 3rd valve slide curling the tubing back up under the valve block in order to get the low Eb, since a lot of literature is in flat keys, especially a lot of marches, and it would be fun to have that sub octave tonic at the end of a piece. But that's a whole lot of work for just one added semitone, which, depending on how it is written, you can set it up to play low Eb anyway by all three valves down and pulling the 3rd valve slide to within a fraction of its falling out.

No, if you want those low near-pedal tones, the best thing to do, if you want a comp, is to just get a 4-valve comp and be done with it. I don't, so I am very happy with my 3-valve for small rehearsal spaces and small gigs, like Shrine band. If I need those pitches, if at all, it is usually 8va ad libito in concert band on my 186, and then only rarely, and then I usually let one of the other guys do it so I can provide the proper foundation pitch as written.

[eupher61]

if you do add a 4th valve, do it as a tritone length. That will give you the fundamental + halfstep, and you won't be tempted to use 4 for the P4 pitches.

I've played a couple of different horns with this setup, it works well IF 1)the original 3valve instrument is good and 2) the customization is done well.

[iiipopes]

I can understand the initial thought at using the tritone length, but even if you do that, you would have to make it a flat tritone, since 123, although slightly sharp, is lippable and no more sharp than 12 on a standard instrument, and otherwise 2-4 and 1-4 would still be sharp, and other combinations unusable as in the gaps between semitones.

Since you don't need 4 for intonation on a 3-valve comp, the only really usable situation is to have it as a "long 4," so that you can get the low Eb in tune and the low D as being lippable. Again, you're only talking about two rarely used notes (anywhere but contemporary brass band) as the tubing lengths just don't work for anything else.

Enjoy a 3-valve comp for what it is: a solid instrument in its own right for conventional, not extended low range, literature.