TromboneChat

What is the difference between a Single Radius slide crook and a Dual Radius crook?

One radius

If you are talking about visual differences, C vs [

If you are talking about playing differences, NoahGladstone has this to say:

Rounded Crook (Single Radius):
Have a smooth and easy blowing response. Many trombonists find these crooks to sound brighter and in my opinion take a focused air column to reap the maximum benefit of the single radius bend.

Dual Radius (Square) Crook:
As found on Bach 42 and 50 trombones, the dual radius crook was devised to give more resistance and focused, thus more control over the blow, giving a faster response. Think of this style crook as "power steering" as it will help you narrow and define your articulation, especially on with a wider bore crook.

Materials:

Yellow Brass: gives a big and powerful sound, capable of taking a lot of air. Articulations can be pointed with a good carry
Gold Brass: gives a dense and warm sound, more nuanced and colorful with a variety of definition and complexity to the sound color. Articulations can be veiled in soft dynamics and pronounced in loud dynamics
Red Brass: a dark sounding material with the most dynamic contrast from loud to soft, wide and blooming sound.
Nickel Silver: gives a fast speaking response with a good balanced sound. A good option for all around playing where clarity is needed and a not too dark or not too bright sound is desired

The labor will be more expensive than the part. And you can’t change back without paying labor again. Expensive Safari.

Change the stuff closer to your face (benefits are more evident, sooner) if you are just itching to do something. Mouthpiece. Leadpipe. Get your horn clean. Get your valve lubricated. Make sure the ports are aligned.