I would like to know what the extension for the 5th valve on the CC does? I know it is suppose to make it a whole step lower but thats with the regular tuning slide for the 5th valve. I’ve yet to know what the extended slide they included does. Could you explain? The fifth valve is usually lowering a whole step. Or to be exact: one and a quarter step. this might sound strange but the reason is that you use it as an alternative to the first valve in the low register.
Here is the explanation:
The length of the valve slides are relative to the whole length of the instrument. Ex: an F tuba has shorter valve slides than the C tuba. Because the general length of the C tuba is longer.
Imagine that you are pressing the forth valve on your F tuba. This lowers the tone with a fourth letting you play a C.
Keep the fourth valve in and you have actually transformed your F tuba into a C tuba.
Lets say you would like to play a Bb. Then you would press the fourth to get the C and add the first calve to lower it another whole step down to Bb. When you play it should sound like a Bb. The problem is that the tone will be to sharp.
When you press the fourth valve you transform the F tuba into a C tuba. And C tubas have longer valve slides than F tubas, remember? Used alone the F tuba fist valve is totally in tune. However, in combination with the forth valve it will be to short.
This is a common problem on all brass instrument in all keys and the instrument factories have three main solutions:
Most fifth valves will lower one and a quarter step. A few players prefer the fifth valve to lower two steps or more. This is probably the purpose of your extended tuning slide. Personally I have a one and a quarter step solution on all my instruments.
Remember that no bass instrument is 100% in tune. The tuning will always depend largely on your ability to listen and adjust the pitch with your slides and lips. On the other hand; some instruments make this job a lot easier by being fairly in tune from the start.