A Common Issue with Factory Horns.
I have seen this problem on some horns that I have worked on recently and I wanted to bring it to your attention. I am pointing this out to make a case for spending the extra money for a custom horn, not to say that horns made in a factory are inherently bad. I realize that there are people put off by how much more expensive a horn is from a small custom maker but there is a good reason!
The issue I am talking about for this post is with the F tuning slide on a (anonymous) Geyer wrapped horn. A tuning slide needs to be parallel, as does its outers, in order to run smoothly. The way to measure parallel-ness is to take a measurement with a caliper at the top and bottom of the slide and compare the two. The maximum difference I will allow on a horn is .005". Here are the measurements from the factory horn.
Measurement from the top of the slide (horn is upside down to get a caliper reading):
Measurement from the bottom:
The difference is .016", three times what I would allow on a horn. Why is this a problem?
As you can see, when you try to put the slide in, the legs do not match up. In order to get the slide into the horn, you actually have to squeeze the two outers together and then push the slide in. This causes a fair bit of tension in the horn when you let go, not to mention some hassle when you need to empty this slide.
The added tension from the tuning slide will certainly change the way the horn vibrates. An advantage of small boutique makers is that each horn is the most important horn. I make horns one at a time to ensure that I stay focused on quality and not quantity.
-Jacob
July 9, 2010