saxes in the heat

[oliver_bentley]

"It would also go out of tune with any change in temperature, as the metal stretches as it gets hotter, thus giving a "larger" sax. Humidity changes also have a similar, albeit smaller, effect."

I read this in by TJV in the "Tuning" Thread, and it reminded me of something I couldnt figure out when I first started out, and thinking about it still dont understand.

When saxes warm up, usually on gigs under bright lights, they expand right. So why do they go sharp? Surely if the sax gets bigger, the note gets lower?

Am I being daft, or missing something more complicated to do with sound waves etc.

 

[Rogerb]

The heat doesn't have a significant effect on the sax itself(the expansion is insignificant), but it does affect the air density and hence the speed of sound(and hence the tuning!).

"Speed at which sound travels through a medium, such as air or water. In air at a temperature of 0?C/32?F, the speed of sound is 331 m/1,087 ft per second. At higher temperatures, the speed of sound is greater; at 18?C/64?F it is 342 m/1,123 ft per second. It is also affected by the humidity of the air. "

 

[lee_]

I play all the time in a horn section with two trumpets. It's a total waste of time for us to tune until the gig is underway, until, say, after the first set. But I've never understood whether it was because we were waiting for the horns to warm up (as goes the common saying) or if it's something else, like waiting for the lips to calm down, embouchures to relax, or whatever. Maybe some combination.

I cannot tell you for sure, but I think we start off sharp and work our way to a lower pitch. The effect seems to be greater for the trumpets, too.

 

[oliver_bentley]

Ah ha - presumably then the sound waves travel faster from one end of the horn to the other (all this closed tubes, muscial acoustics physics stuff coming in here - though not sure I understand it fully. Great site if anyone wants to know mind - http://www.phys.unsw.edu.au/~jw/woodwind.html - got a shed load of info on) so creating a wave at a higher frequency and so a higher pitched sound, making the sax sharp?

Interesting what Lee said about getting flatter. Usually in bands I play in the horns will start off cold, and then as they warm up go a sharp. Never considered the embouchure factor though.

Hmmm - I wonder if beer has an effect as the night goes on... :erm:

 

[lee_]

You must have seen us play! It's definitely a factor. 😉

 

[tengu01]

DEFINATELY a factor. Hours sitting around between soundcheck and performance eased by a few cold ones.

Post-performance glow, enhanced by a few more cold ones.

And the performance? Sharp? Flat? NEVER!!!!!!!!!

Always absolutely pitch perfect on the gig

(recorded evidence (usually) to the contrary reviewed with growing humility and blame enthusiastically apportioned the following day.

:laugh:

 

[Bobby G]

I don't know about sharp or flat, but gigs have a tendency to make the tempo increase. Now is not the time or the place for drummer jokes, but you have to ask yourself who could be responsible for this....