Yamaha YHR-567 Owner's Manual page 7

Tuning
Use the main tuning slide to make sure that the instrument is in tune before playing.
Since temperature has an effect on the instrument's pitch, blow some warm air through
it to warm it up before tuning. The amount of tuning slide adjustment needed to get the
horn in tune will vary between individuals so there is no standard rule to follow
(however, at 68°F pulling the main tuning slide out about 0.6" should more or less tune
the instrument to A=442Hz).
Take notice that when temperatures are warmer, the main tuning slide should be pulled
out a little more, while cooler temperatures will require that you push the slide in. Also,
the position and angle of your right hand in the bell will have an influence on pitch as
well.
Single Horns
Slide the main tuning slide in or out to tune the
instrument.
Double Horns
1.
Use the main tuning slide to tune the Bb side.
* Instruments with a Bb tuning slide should
tune with the main tuning slide as well.
2.
Use the F tuning slide to tune the F side of
the instrument.
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