Counterdsunk Reed Plates
Countersunk Reed Plates
Winslow HI there is always lot of talk and concern about the potential of leaking air via combs not being flat or reeds not set correctly. There is never any mention of the potential to lose air from harps that do not have countersunk plates and cover plates such as the Manji the Crossover and many others. I expect that manufactures make them like that because its easier from a manufacturing point of view and the tradition of old manufacturing methods with wood combs. The Special 20 have countersunk plates because they are easily made with a plastic mould allowing for the reed plates to be countersunk, great design. In my view a much better design as far as breath efficiency is concerned. Other material like wood or bamboo becomes too fragile when machined to recess but the composite in the Manji could easily be countersunk producing a much more efficient instrument. I expect that even the best embouchure would still result in some air leakage where the plates and cover and comb meet. Can you tell me what I am missing in this.
Winslow many thanks for your reply. My theory is that all other airtightness issues being equal, flat combs etc, lipped combs with the comb protruding beyond the reed plates and cover plates should be more airtight than the sandwich style of construction even with a correct embouchure. This is best experienced when doing a two hole shake with bends. Air escapes on the sandwich style between the cover pates the reed plates and the comb more so than with a lipped comb. With the lipped comb there is a cleaner contact with the embouchure/tongue onto the comb surface and no/less leakage along the junction of the plates. I notice that some customisers sand down the reed plates to achieve a smoother transition from the cover plate to the reed plates and recessed comb. Brenden Power offers combs that allow the option of the comb to be set flush with the reed plates, my preference. This I theorise is better but still not optimal given air still leakes along the junction of the plates and comb. Both the Crossover the Manji and other sanwitch style contruction have the comb set back from the reed plates. Is this a reasonable assumption or just baloney.
The trough formed by extending the reedplates slightly outward is for the tongue to travel in when tongue blocking.
I've never experienced air leaking when warbling. I suspect that this is more an embouchure issue than a construction issue. Or possibly one of air leaking through the reed slots due to reed action during the bend.
How does a comb lip make the seal more airtight? If the lip were so tightly wrapped to the reedplate edges than it held the reedplate in place by friction, that could be true (but could also create difficulty in installing and removing reedplates, and if not precise and too tight could prevent the reedplate from fully seating). Even a slight interstice between the reedplate edge and the lip could defeat any seal that the lip might offer.
With good flatness of mating surfaces, I doubt that leakage along the edges of those surfaces is significant. Perhaps someone has done measurements of edge leakage and its effect on reed action and wasted air.
Factory combs, whether milled or injection moulded, are often not flat enough for a good comb-to-reedplate seal. Wood may have saw marks or have undergone some warpage or may simply be imprecisely cut, while uneven cooling, or flaws in the mould, may compromise flatness in an injection moulded comb.
You can easily flat-sand a simple milled block comb (Marine Band, etc.) but it's very difficult to do with a lipped comb (one that has the reedplate sunk into the comb with a "lip" around the edges, like the Special 20), because the lip gets in the way. Some players actually take Special 20 reedplates and mount them on block combs.
Some players feel that the lip – or anything that adds distance between the reed and the player's mouth – compromises playability. True? Well, if you believe it, you'll prefer a non-lipped comb.
Likewise, players vary in preference between "sandwich" construction, where edges are exposed and all the layers of the sandwich are visible (i.e., no lip), and lipped construction, on the basis of how it feels in the mouth.
For many years, harmonica customizers by far preferred sandwich construction due to the difficulties in flattening the surface inside the rim of the lip, or in milling a lipped comb out of whatever materials they preferred. In recent years, comb specialists like Tom Halchak of Blue Moon Harmonica, have found ways to make aftermarket lipped combs by machining in metal as well as plastic, with precision flatness and great appearance.
Milled wood combs are fragile if you try to drill holes behind the slot for, say Hole 1, but are otherwise robust enough to last many decades, so I'm not sure why you feel they're too fragile.
I'm also not sure why you see greater breath efficiency in a lipped comb. Care to elaborate?