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Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 12:07 am
by TerryMcGee
Finally got to John's recordings of a bell played with a fresh faced and a slightly worn faced clapper.

See: http://www.mcgee-flutes.com/slightly-worn-clappers.htm

I also felt the need to create a table of what partials we might expect in bells of various pitches. It saves me counting on my fingers! Others might find it handy, so I've put it at:

http://www.mcgee-flutes.com/BellPartials.htm

Maybe such info exists elsewhere - let me know! Alternatively, if there is other technical information that it would be handy to have on-line, I'm happy to host it.

Re: Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 1:31 am
by JohnGouwens
Clarification: I turn the clappers every year! They were last done in September, so what wear there is comes from six months' wear, no more. Adjustable clappers were original to the G&J installation, 1951, but over the years we replaced most, once I ran out of new spots. The new ones, like the one in the photo, were made with a raised ridge to help keep the contact area small. The clapper used in the recording has such a ridge. The originals had an overall curve, but not a special, raised area.

Re: Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 1:48 am
by TerryMcGee
Great, thanks for the clarification, I'll make the appropriate changes.

How would you best describe the equatorial ridge? It appears to be relatively shallow in terms of increased diameter (sides just a few mm high?), with the face curved at about the same radius as the rest of the clapper? I imagine the (vertical) width of the ridge is guided by how big a spot you were prepared to countenance in that dimension. Maybe about 10mm (3/8")?

Is that a good-enough description or how would you describe it?

Do you feel the first or second six-months brings the most audible degradation, or is that hard to tell because the playing seasons differ in terms of hours use per week? I.E. does the degradation accelerate or decelerate?

Re: Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 2:04 am
by JohnGouwens
Well, the more I play, the more wear there will be. In general, the raised ridge is essentially parallel to the rest of the surface of the clapper, but these were done in two batches, and the two batches aren't identical. The photo shows one from the first batch, the one used in the recording was from the second. I wasn't specific about the size of the ridge. Ideally, one probably should be. The intention had been for the replacement clapper balls to equal the weight of the originals. Most of the originals were made of brass, however, and when changing them, I weighed each. The newer clapper balls were cast iron and were lighter in weight. None of those quirks show up in the sound of the instrument, however.

A whole lot more wear shows up after a full year of use - and even more so after two. Of course, if somebody is a really heavy-handed player (certain Dutch carillonneurs come to mind), there will be a whole lot more wear.

I would agree the ridge is just a few millimeters high. It's only purpose is to keep the size of the contact point on the clapper from expanding as rapidly as it otherwise would. It has helped!

Re: Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 2:10 am
by JohnGouwens
Hey Terry! I can't get to your sound files! I'm getting file not found messages. Please check your links!

Re: Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 5:12 am
by TerryMcGee
Sigh, silly me. Try that now. Was it just this one or others too?

Re: Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 5:14 am
by TerryMcGee
JohnGouwens wrote:Well, the more I play, the more wear there will be. In general, the raised ridge is essentially parallel to the rest of the surface of the clapper, but these were done in two batches, and the two batches aren't identical. The photo shows one from the first batch, the one used in the recording was from the second. I wasn't specific about the size of the ridge. Ideally, one probably should be. The intention had been for the replacement clapper balls to equal the weight of the originals. Most of the originals were made of brass, however, and when changing them, I weighed each. The newer clapper balls were cast iron and were lighter in weight. None of those quirks show up in the sound of the instrument, however.

A whole lot more wear shows up after a full year of use - and even more so after two. Of course, if somebody is a really heavy-handed player (certain Dutch carillonneurs come to mind), there will be a whole lot more wear.

I would agree the ridge is just a few millimeters high. It's only purpose is to keep the size of the contact point on the clapper from expanding as rapidly as it otherwise would. It has helped!


Great, thanks for that. I'll tidy up the article and resubmit!

Terry

Re: Effect of slightly worn clappers

PostPosted: Sat Apr 20, 2013 6:37 pm
by JohnGouwens
You'll want to tidy up this contradictory bit of wording:

"So now, the big question. Will our analysis show a different pattern of partials for the admittedly fairly similar sound of the slightly worn clapper? And the answer is......No! Differences are quite apparent."

Well, the answer obviously is YES!! Because there is so little wear even on the "some wear" example, the difference won't be radical, but it is nevertheless musically significant, and happily, also measurable!

Re: Effect of slightly worn clappers

PostPosted: Sun Apr 21, 2013 12:06 pm
by TerryMcGee
Sigh, right again. Trying to fit too much into the day as usual!

OK, I've touched it up. Let me know if there are any other howlers.

I've added the observation that the fact that the first new partial is harmonious probably explains why the sound of slightly worn clappers is often more attractive than perfectly rounded ones, which can sound a little dull. Conceivably, one could start with a rotatable clapper that had a narrow flattened band all round, so that it already sounded a little brighter than a perfectly round one. Trouble is, it would then be downhill all the way from there. Hmmmm.

Terry

Re: Effect of slightly worn clappers

PostPosted: Sun Apr 21, 2013 11:08 pm
by JohnGouwens
Well, I agree that just-turned (or just-filed) can be a little too dull. I like it best after a week or two of wear (playing daily), and past that point, it stays good for a long time. The "slightly worn state" on this recording is not worn enough for me to turn it. It has to get much brighter (which indeed it will do) before I turn it. Odds are good that with more wear, additional - and probably less harmonious - partials would show up. I really think that wear is a big factor with your external clapper example - probably a bigger factor than the inside-outside issue (though I am convinced that also matters). Try tooling down the strike spot on one of those hammers and see how it compares then!