Adding 4th valve to 3 valve compensator Eb?

Sam Gnagey · Post by **Sam Gnagey** » Sat Jul 28, 2007 10:36 am

Do any of you know of anyone adding a 4th valve to a Besson 3 valve compensating Eb tuba? I just got one of these and like the way it plays and sounds. I'm thinking about adding a rotor to it that would give me most, if not all, of the chromatic range down to the pedal. Perhaps this has already been discussed here. Any thoughts or guidance gratefully appreciated.

cjk · Post by **cjk** » Sat Jul 28, 2007 12:52 pm

Ask Chuck G. I believe he knows of a 3 valve compensated Besson CC that had a fourth (piston) valve added. I think the 4th valve was a quint valve.

Chuck(G) · Post by **Chuck(G)** » Sat Jul 28, 2007 1:29 pm

It was a 3-valve Besson CC that was the size of an Eb--but yes, the 4th added valve gave you an F, not a G. Seemed to work pretty well for the owner.

I thought the extra valve made things a little stuffier, but that it was a fair tradeoff for getting below Gb. (The false tones just weren't there on the horn.)

iiipopes · Post by **iiipopes** » Sat Jul 28, 2007 2:00 pm

Here's the problem: the whole reason for a comp is to get the multi-valve combinations in tune by adding the necessary proportional lengths of tubing without having to pull. When you add a 4th valve, you've just altered the entire geometry of the horn, so 4+2 and the rest still need pulling, since the comp loops are not plumbed through it. About a year ago, with some time on my hands, I did the whole math on what it would be. The only two real options are to either make it a quint valve and lip the combinations down from there if you can't pull them, or add a 5th valve as well. Then you would play everything down to 123 A nat as a 3-valve, then Ab as 4+T and lip the other combinations from there.

Bottom line: you're better off with a 4-valve comp or a 5-valve conventional. Don't butcher the 3-valve comp.

cjk · Post by **cjk** » Sat Jul 28, 2007 2:53 pm

If I were you and I had one of those, I'd discard the 3 valve compensating valve section altogether, flip the horn around, and use a King valve set to make it 4+1 non-compensating.

Sam Gnagey · Post by **Sam Gnagey** » Sat Jul 28, 2007 5:27 pm

cjk wrote:If I were you and I had one of those, I'd discard the 3 valve compensating valve section altogether, flip the horn around, and use a King valve set to make it 4+1 non-compensating.

That thought hadn't occured to me. It might be worth the effort and parts to do it, and I'd probably find some use for that 3-valve cluster eventually. The problem with going that route is that I use those King clusters for my CC conversions. I'm not certain that I'd want to make the trade off.

With keeping the compensator in place I was considering putting a 4th valve on it that would only be a low register valve as seen on some of the older American 4 valve instruments tuned to make the low Ab in tune played 1&4. It would be about a quarter step too long to be used by itself and not necessary to replace 1&3 and 123 since those combinations would already be in tune with the compensation system.
My other consideration was to make the 4th an in tune replacement for the flat 2&3 combination on the 3 valve horn. I know that wouldn't allow for a low E-natural, but would it work for a lippable low F-natural?

cjk · Post by **cjk** » Sat Jul 28, 2007 6:05 pm

Sam Gnagey wrote:
cjk wrote:If I were you and I had one of those, I'd discard the 3 valve compensating valve section altogether, flip the horn around, and use a King valve set to make it 4+1 non-compensating.
That thought hadn't occured to me. It might be worth the effort and parts to do it, and I'd probably find some use for that 3-valve cluster eventually. The problem with going that route is that I use those King clusters for my CC conversions. I'm not certain that I'd want to make the trade off.

With keeping the compensator in place I was considering putting a 4th valve on it that would only be a low register valve as seen on some of the older American 4 valve instruments tuned to make the low Ab in tune played 1&4. It would be about a quarter step too long to be used by itself and not necessary to replace 1&3 and 123 since those combinations would already be in tune with the compensation system.
My other consideration was to make the 4th an in tune replacement for the flat 2&3 combination on the 3 valve horn. I know that wouldn't allow for a low E-natural, but would it work for a lippable low F-natural?

If you made your 4th valve play Ab by itself, you'd have a chromatic scale. 2+4 low G would probably be pretty sharp, but other than that, you'd probably be OK.

Chuck(G) · Post by **Chuck(G)** » Sat Jul 28, 2007 10:51 pm

iiipopes wrote:Bottom line: you're better off with a 4-valve comp or a 5-valve conventional. Don't butcher the 3-valve comp.

On the other hand, the valve combinations using 3 on a 3-valve tend to be more in tune than those on a 4-valve comp. 23 on a 4-valve comp is no more in tune on a 4-valve comp than it is on a 3-valve non-comp.

I honestly can't say--it depends on what you want to use the eefer for. If you can get by with only the occasional foray to Ab and below, add the 4th valve as a quint.

I will say that I left my own Besson CC as a 3-valve comper without the 4th valve added. If used in small ensembles, it works just fine.

cjk · Post by **cjk** » Sun Jul 29, 2007 2:09 am

bloke wrote:A Rube Goldbergish/Dr. Youngish suggestion,

but if the 4th valve lowered the fundamental to AAb, couldn't you then play Ab - 4 / G - 124 / Gb - 234 / F - 1234 / ...and trigger or pull the 4th slide if you ever need a low E?

bloke "sticking to his original suggestion"

If the 4th valve were tuned to AAb, you'd have as much tubing (actually more with the 3v compensating system) with 4 valves as you would on a 5 valve instrument with a flat whole step fifth. 4th would equal 4+5, so this ought to come close to working.

Ab = 4th
G = 4+2
Gb = 1+2+4
F = 2+3+4
E = 1+2+3+4

(but then again, I'd toss the 3v compensating valve set in the trash...)