Leadpipe expansion??

[cheburashka]

I have an Eb Conn stencil (Bostonian) that has very little resistance, but is also unresponsive. When checking things over, I noticed that it has a dual-bore tuning slide (.64 on the valve side, .57 on the leadpipe side) and the leadpipe is apparently a length of .50 soft copper plumbing pipe. There's no expansion in the leadpipe, and the mouthpiece slides right into the copper pipe. I'm wondering if this could account for some of the horn's unresponsiveness, or if the dual-bore tuning slide was a substitute for a leadpipe with an expanding bore. What's a normal leadpipe size (if there is such a thing) and rate of expansion for a .64 3/4 Eb horn? Where would I obtain a leadpipe that might work for this?

Thanks

[iiipopes]

Yes, the lead pipe does need to be slightly conical in order to provide intonation. How much depends on the horn, and I am not knowledgable about the points of leadpipe design, and yes, pure copper is too soft for anything but a bell. Yes, it may be difficult to find a good replacement lead pipe, but check around with the nationally known repairmen. Someone should be able to help you, as Conns are relatively common compared to other brands.

[cheburashka]

So what's the result of having too soft a metal on the leadpipe? I know manufacturers like Yamaha use a high-copper content brass in the leadpipe--I would assume that's to cut down on rot. How does that affect the sound?

[Rick Denney]

yes, pure copper is too soft for anything but a bell.

How much softer is copper than brass?

Rick "wondering where these assertions come from" Denney

[Dan Schultz]

yes, pure copper is too soft for anything but a bell.

How much softer is copper than brass?

Rick "wondering where these assertions come from" Denney

Heh heh.... c'mon Rick... you tell us! Either one can be soft or hard.... 'pending on the temper.