[Harp-L] Full length covers

["geoff atkins" <geoffatkins@xxxxxxxxxxxxxx>]

 Re comments by
 11. Re: Something with full-length covers! (JohnnieHarp)
 12. Re: Re: Something with full-length covers! (Winslow Yerxa)
 13. Re: Re: Something with full-length covers! (Arthur Jennings)
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I was tempted to say that the shorter cover warns me when I'm trying to play
the solid pearwood at the ends of the harp.

But could an extra property of longer covers be the changed resonance?

I'm measuring Hohners here, and using effective lengths, as some edges are
splayed:
We have Short covers of 84mm effective transverse length and a full cover
would be about 104 mm. The longitudinal direction is the same, 27mm, and
open-faced. The profile varies from Pro Harp to Deep River, and affects
embouchure as well as the free air gap over the reed length.
 
The 84mm has a primary resonance of 4083 Hz,  between D8 and D#8
and the 104mm would resonate around 3230 Hz,  that's G7 / G#7 on an equal
tempered scale.

Eighth wave resonance (the last that has much of an effect on perceived
tone?) takes us down to roughly 500 - 400 Hz, G4 to B4, where we play, and
higher too into areas where quarter wave harmonics are present. 

I think the exiting  tone could possibly benefit. 
I know for a fact that, say, opening the restricted face on some cheaper
experimental harps has been beneficial, why shouldn't a longer cover have an
effect?

Regards, Geoff Atkins