[Harp-L] the valve "gargle"

[Slim Heilpern]

Jut picking up one point from the GASKET-VALVE System discussion:

Vern said:

"Not often, but I have experienced a closed valve of hard, springy material standing up and vibrating much as a reed does.  The variations of sound pressure seem to prevail over the more steady breath pressure. This makes a noise that I would describe as a “gargle” instead of a “rattle”."

This is something I've bumped into more and more over the last several years, always on CX-12s. It's taken me a very long time to understand what's happening, but I think I do now. At first it was a huge mystery and I was encountering it on random reeds, usually on draw reeds, regardless of pitch, and only when the airflow is relatively strong. Replacing the valve, regardless of brand or type would not usually solve the issue. Removing the valve always solves the issue for the simple reason that it's the valve that's vibrating (just like in Vern's description above). And reed alignment never seems to be the problem, but it could be a very tiny adjustment or some imperfection in the reed, hard to say. This was happening right out of the box on new CX12s.

One day while struggling with this issue, just trying to save some time, I reassembled the harp with only a few of the reed plate screws, just to test the new valve I had installed and the problem was gone -- not just on one reed but on two others that were having the same problem. So, perhaps if the axe is too airtight this can happen? I ended up not tightening the reedplate screws as much as I would usually do and the problem mostly went away.

Fast forward a couple of years and I purchased a new set of reed plates for one of my CX12s. No 'gargle' sounds at all up and down the axe -- what a relief! However, after several months of playing that axe I decided the slide was rather noisy so I flat sanded the front of the comb and installed one of Brendan's power slides, problem solved.... except that several of the reeds started having the 'gargle' issue. So I loosened a few of the screws a bit and that fixed it. 

So, perhaps, when the tolerances are too tight, the valves aren't strong enough to stay closed?

Or something else?

Thanks,

- Slim