tookatooka
1144 posts
Feb 02, 2010
3:25 PM
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There's been a number of threads on this lately and I just thought I'd let you in on my discovery. Addict very kindly gave me a LoF Sp20. It played well but I thought it was a bit breathy on the lower notes. So like you do I had a tinker and closed the gaps up. Guess what? It started to buzz on holes 1 and 2. I opened the gaps up marginally and all was OK again.
Conclusion. If the gaps are too tight, I think it causes the reeds to respond with more force than with a slightly larger gap. It may be slightly more breathy but it shouldn't buzz because the reed action will build more slowly.
That's another beer you owe me.
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nacoran
982 posts
Feb 02, 2010
3:44 PM
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Lol. I was just reeding up on low tunings. I was trying to find what the lowest free reed note was. I seem to have found evidence of a LLC Chromatic, but I think the winner may be a accordion or a reed organ or maybe some strange Thai instrument.
It makes sense that looser gapping would help with rattle. I've also wondered what could be done with cover shapes. Since the blow and draw plates are set up in opposite directions I've wondered if you could adjust the front of one cover and the back of the other to give the reeds a little more room without giving up as much total width. I've also wondered if you could put some fins on the covers over the high notes to direct the air down on the tip of the reeds.
Are there any harps out there where the top and bottom covers are different (beyond maybe what's stamped on them?)
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Hollistonharper
155 posts
Feb 03, 2010
8:00 AM
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Nacoran, I was curious about your question, did a quick search and found a number of threads which state that some low Lee Oskars have a different cover plate shape. BarbequeBob wrote that Seydel 1847s Eb and lower have a different shape as well.
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barbequebob
426 posts
Feb 03, 2010
10:17 AM
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On low pitched reeds, if the gaps are also too wide, the response gets hurt because then you get forced to play them too hard and the rattling gets much worse.
In low pitched harps, the first 2 reeds are more likely to rattle, but they tend to get really noticeable when played too hard, and truth be told, many players tend to hit those notes far too hard all the time and so they make this a much worse problem than it needs to be.
The Seydel 1847's in Low Eb has a little "bump" (for a lack of a better description) on the bottom cover plate for 1 draw because that's where the rattling usually is and so it gives the reed more clearance.
If you get low pitched harps from a customizer, every good one I know nearly always reshapes the bottom cover plate to alleviate this problem and tho from a stock harp point of view, the Seydel 1847's play better out of the box and hav fewer rattling problems, I'd still recommend getting a custom harp in those keys.
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Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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GermanHarpist
1077 posts
Feb 03, 2010
10:58 AM
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My 1847 LF has the same 'bump'.
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germanharpist on YT. =;-) - Resonance is KEY!
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nacoran
994 posts
Feb 03, 2010
12:26 PM
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Holliston- I know some lower pitched harps have wider covers, what I was wondering was if you could shape that wideness based on the fact that the draw and blow reeds point the other way from each other. For instance, the top cover plate could be wider at the back, and the bottom cover plate could be wider at the front. It might make for a funny looking harp, but it might be a good compromise between reed space and thickness. I think some low tuned harps already have thicker combs to accommodate the swing towards the middle.
It seems people do lots of works on combs and reeds, but the covers are pretty basic. You have the sandwich design like on a MB, the rounded top design like on a Seydel Blues Favorite, and the GM style. You have plastic or metal (I think I've seen only one modern one in wood), open or closed back, side vents, and maybe size and thickness, but it seems there are probably a lot more weird things you could mess around with with covers. (Ok, come to think of it, the Turbo harp plays around with covers...).
These ideas probably wouldn't work, but just some ideas... golf balls have dimples that reduce drag. Could you dimple the inside of a cover to increase airflow?
Do any harps isolate each hole in the top and bottom space?
Could you design a cover with little wind funnels to push the air down onto the end of the reed?
There are probably tons of little things you could try, but everyone seems to be focusing elsewhere.
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GermanHarpist
1084 posts
Feb 03, 2010
12:32 PM
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I don't know about dimples. I'd guess that it kinda mutes the sound. I'd go with a flat surface.
Then there is the shap. There I'd intuitively say that the B-Rad is on the right track.
And then there is the material and esp. the material thickness that probably makes the biggest difference.
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germanharpist on YT. =;-) - Resonance is KEY!
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