Quote:
Originally Posted by godchaser  .
Ah- much gratis there Ted. But i'm still unconvinced. :) No free lunch is sure so; i don't argue there's a fixed air volume. Although i feel like there'd be a cumulative increase in the players' energy or air pressure, by aid of a repetition of 'narrowing/widening' bore? Making for a more efficent use of the same volume, which would respond in the horn as greater volume, though not literally so. -You'd be getting a more intensified air-pressure, despite there being no increase of volume or energy from the player? The ratio of lost air-pressure, to gained, in the narrowing/widening bore progression would amount to a greater energy output at the bell than at the mouthpiece? Each time the air-volume cycles through the narrowing area it gatheres a little more pressure than it lost in the widening area? The volume of the air's changed character from point a to b, hasn't gained any speed, but just become a players' more effective energy?
I dunno. :) -Particularly whether it'd amount to any appreciable benefit?
Chris
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Nice post Smatt.
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Chris,
Air passing through a fixed volume system, like the one we are discussing consists of two air pressures - dynamic pressure - think of flow as dynamic pressure - and static pressure, the pressure that (in effect) acts at right angles to dynamic pressure (not strictly true, but close enough for illustration). The sum of these two pressures will always be constant so that as dynamic pressure increases (increase in flow), static pressure must decrease. All is in balance - regardless of the number of convergent-divergent-convergent, or divergent-convergent-divergent elements that are included in the system, you can't get any overall change across that system. It is simply not possible.
We are however, vibrating a fixed column of air - think of the trumpet being filled with air and we are vibrating that air - so this is our output, vibration. This transfers to the ambient air and we hear it as (hopefully) a full throated beautiful fff Double C, or a controlled and delicate p @ low F# depending on how the trumpeter creates the initial column of air, and the initial vibration. So all we can change is the frequency by vibrating the lips at a different rate, but once again, this is not the full story because it can only describe an INSTANT in time, but it is reasonably close. Have a look at NickD's website and see how slowly he inflates the soap bubble with his trumpet - not a lot of flow there - but plenty of capacity to vary the sound levels and pitch. I hope this helps.