I am just starting to learn to overblow and I have a question about the high pitched whistling that so.etimes happens...or almost always happens in my case. What exactly is going on when that happens, I can get rid of it and hold the note on certain holes of specific harps, but I am not sure exactly what I am doing to make it start or go away. Is it a matter of too much pressure, not enough pressure, just the incorrect embouchure, or something else?
None of my harps have been set up in anyway so maybe I need to figure out how to do that first. I know people say that set up is very important.
Man I hate that! Im no authority on the whys of harp absurdities but I think its cuase the reed isnt aligned...Theres various methods for fixing it I just dab a tiny bit of nail polish on either side of the square (rivet end) where the reed meets the begining of the reed slot. Theres pics online just google mail polish reed harmonjica etc... ---------- www.mooncat.org
If you are talking about what is called "reed squeal" when attempting OB, it is most likely caused by the shape of the reed from the manufacturer....Chinese made harmonicas (Tombo, Lee Oskar, etc) have reeds that are a little wider and shorter than those made from the German Design (Hohner), which are longer and narrower.
"In the beginning" of the OB revolution, we had basically only 2 choices for manufacturing and found that the Chinese made harmonicas had a lot of reed squeal whereas Hohner did not....as time went on and a few folk got into the design/set up/customization gig, it was discovered that a drop of nail polish (a la Jason description above) mitigated this effect.
I recommend going for the German design reed length/width and you most likely won't have to deal with much of the squeal. ---------- The Iceman
Start with setup, meaning gapping. That fixes a lot of issues alone.
I prefer beeswax to nail polish because it is easier to remove. Then again, I made this decision before I discovered acetone.
As for manufacturer, I don't regard German harps as superior for overblows in terms of issues (such as squeals). The most important thing is to have an airtight comb, flat reedplates, and the right gap on both the blow and draw reed.
The only eastern maker that I don't regard as great for OB's is easttop. The reason is a slight tilt to the reeds, which make OB's a little harder even at a tight gap. Suzuki's are great, Honer is great, Seydel is great.
I'll give Easttop diatonics another try if I hear they've resolved the tilt issue. Otherwise, their chromatics are amazing.
It isn't a squeal, I get that too but I can kind of feel where that is, this is literally a whistle sound, much higher pitched than the squeal that also happens. It can continue along side a clear overblow note, it seems a very slight change of something in my technique makes it go away, just havn't figured it out.
The only harps I have are a couple of Seydel Session Steels, a Hohner Blues Harp, a Hohner Big River, and a couple of Easttops. They all do it. I figured it was probably a well known phenomenon, but maybe not.
Good question, Sweetblood. I've been thinking about making a video to show some tips for reed set up and expanding on some other materials which are already around.
Andrew Zajac already has a bunch of great free videos and awesome blog that I've found particularly useful. When you have a Hohner Affiliated Customizer giving out tips, then it's probably worth investing some time in reading and listening to what they are offering.
A rectangle's oscillation patterns can be complex. It can oscillate on the long axis (its lowest frequency), or on the short axis (higher frequency = squeal), or combinations of the two, or harmonics or combinations of the harmonics of the two. Ideally your reeds will oscillate only on their long axes. This will be easiest if they are long and thin (@iceman). The more you challenge them, the more they will try to oscillate differently.
Even a guitar string can oscillate longitudinally (at a very high frequency) as well as laterally (what it usually does). ---------- Andrew. -----------------------------------------
Last Edited by Andrew on Jan 19, 2018 5:47 AM
Ridge, thank you for posting Andrew Zajac's video. It offered good information that clarified and reinforced some of my thinking on reed shaping that I either figured out on my own through trial and error or learned at a couple Richard Sleigh workshops. I do not heavily employ OBs in my playing, but do use some. Also, I like a more responsive instrument and only have a few custom harps.
I haven't bothered with routine setup on new harps beyond reed gapping, but I will now pay more attention to how the reed moves through the slot. I suspect that a number of my harps are high on the rivet/weld end, and could benefit from some reed profiling.
Andrew Zajac, thank you! ----------
Doug S.
Last Edited by dougharps on Jan 19, 2018 8:55 AM
I've never shaped a reed, but I've gapped them. I think that the whistling sound SweetBlood is talking about is just what I'd call an overblow that hasn't been locked in. I just press harder and the note locks in, albeit slightly flatter than ideal, and the whistling goes away.
Gapping--narrowing the gap between reed and coverplate--will decrease both the degree of flatness that a locked-in OB incurs and make it much easier to bang the OB into place.
I've not had the whistling but i get some noise mainly behind the high OD's #9 and #10. Like it's taking more air pressure to choke the draw reed. Don't know if there's anything you can do about it. I seldom use those one's anyway but it would be nice to get a good sound from them too.
HAving done some Finite Element Modeling of a reed I saw that there was a torsional mode of vibration woth a natural frequency that migh be in the range of the squeals heard. I suspect that exciting this mode is what causes the squeal. Some of the fixes suggested, reed centering, better attachemnt at the root (via nail polish or other method) seem to be consistant with stoping torsional vibration modes. The best way to prove this would be to have high speed video of a reed while squealing.
I don't have access to a high speed camera any more, but you can see a video I took of a reed in normal operation here. I wish I had recorded sound alng with this.
Some dental wax at the base of the reed fixes it. Dental wax is super cheap and you only need a very small amount. My guess is that it's effective because it prevents high-velocity air from escaping either side of the reed (very) near the base which causes vibration. In any case it works but just remember to only apply dental wax AFTER you've gapped the harp because often time gapping makes the problem go away all by itself. I usually gap my harps for the proper responsiveness then add dental wax to stop squeals on overblows and overdraws.
For squealing overblows you'll want wax at the base of the blow reed. For overdraws you'll want wax at the base of the draw reed.
