Hollistonharper
183 posts
Jul 06, 2010
8:05 PM
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Ok I'm a relative noob (playing 2 1/2 years) who can now consistently overblow the 6 hole without making people cry "stop scratching the chaulkboard with your fingernails," the 5 hole not so much and the 4 not really that much at all.
So I'm having fun with the 6 ob and setting it up on my harps with fair success, until I tried on my bushman soul's voice in C. (not a bad harp by the way). The ob sounds beautiful with the covers off, but when I put them on, I can barely get it to sound. Now I've experienced that with my others harps and figured it's just a matter of slight adjustments but I just couldn't get it.
I noticed the SV covers are not just ventless, but have no cut-out notches on the corners. I thought maybe this was the problem--covers are too airtight. So I rummaged in my junk harp box and managed to fit a set of MB blues harp covers on it with just a little fiddling. Like the SV, the blues harp covers are ventless but they are notched. Long story short, I get a fairly decent 6 ob without any further adjustment.
So my question is, do others have the same problem with this type of cover, and is there a fix short of replacing the covers?
Edited for typos
Thanks for any responses.
Last Edited by on Jul 06, 2010 8:10 PM
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jim
209 posts
Jul 07, 2010
12:05 AM
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Covers change the reedplate curve. And that affects reed tolerances. And overblows disappear. That's normal behavior.
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nacoran
2358 posts
Jul 07, 2010
11:50 AM
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On a side note, I don't think that notch in the corner is a cut out. I think it's just an artifact of the stamping process. Think of the cover as a flat piece of metal, then think how you would bend it to make a typical harp cover. You could test Jim's approach by putting the covers on very loosely. Tightening down the covers might be affecting how the reed plates sit. Or it could be how the air is moving around inside the harp.
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Nate
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tookatooka
1507 posts
Jul 07, 2010
12:31 PM
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May be because when you play without covers your pucker is different because you have a smaller area to pucker up to?
@jim ???? can't see how that could be so with plastic comb.
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Hollistonharper
184 posts
Jul 07, 2010
3:31 PM
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@Jim--Not sure I follow how the cover affects the reed plate curve, i'd think you'd need to be putting a lot of torque on the screws to do that. But I defintitely agree that covers affect OBs. If I wasn't clear I was trying to ask if there was anything specific one should know about airtight cover plates. It's probably just my lack of tech skills.
@Nate--whether you screw the covers on or just hold them on definitely makes a difference in the quality of the OB,but I thought it had to with airflow since that's what
makes the reeds sound. And that's why I was wondering if there was any special technique for gapping a harp with airtight covers.
Tooka--I don't think my pucker with covers on or off made any difference with the OB on this harp. I've gapped enough of my harps for OB to get a good sense of this.
Edit: don't want to give the impression that I think I know what I'm talking about when it comes to tech skills. I bought a great basic handmade tool kit from Buddha a while ago--I use maybe 2 of the tools and maybe someday I'll get around to asking Chris what the other ones are used for!
Last Edited by on Jul 07, 2010 3:40 PM
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nacoran
2365 posts
Jul 07, 2010
7:26 PM
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Hollistonharper, I don't think it takes much torque to mess with a reed plate. It's not that it warps the reed plate much, just that it doesn't take much to affect the reed plate. I was looking around the forum archives today and there was a post from Harpwrench saying that even using self-tapping screws could screw it up.
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Nate
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