Have you ever wondered how to increase the volume of your harmonica?
Cover plates are designed to capture the sounds from the vibrating reeds and channel, direct, amplify, and project the
sound waves to the listener. Let's begin at the end, more specifically, the back of your harmonica, and notice how the size
of the opening varies depending on the model and make (can you see the reeds?).
For both the Hohner Marine Band and Special 20 harmonicas, a three-inch (3") long by one-eighth
inch (1/8") wide, sheet metal right angle hem is bent on both the top and bottom cover plates. This means a total of three
quarters of an inch (3/4") of sheet metal is restricting the sound from flowing out the instrument. A technique referred as
"opening the back" will increase the volume of your harmonica.
- Remove the cover plates (careful not to lose the nuts, bolts, or nails) and place the outside of the cover plates face
down onto a scratch resistant cutting board (PVC cutting mats and pine boards work well), we will begin with the top cover
plate …
- For right-handed people, hold down the body of the cover plate with your left hand. Using a polyurethane
headed hammer, gently begin "pushing" the hem inward. Once the hem starts bending, lightly tap the hem over,
and finish flat by gently tapping directly the full length of the crease. (Repeat the above described procedure for
the bottom cover plate.)
- Craftsmanship comes into play here, so be mindful to match the top cover plate with the bottom.
- Before re-assembling
your instrument, polish your cover plates with Simichrome - this German made product will return your instrument to it's original
factory sparkle (thanks to Paul V. for this recommendation). And finally, spread an even layer of Chapstick onto the inside
surface areas of the cover plates. The wax will help retard rust and corrosion.
The shape and size of the cover plates influences the sound.
The cover plates create a tone chamber. If you
increase or decrease the volume of this enclosure (cavity), your tone will be altered.
Examples:
1. Compare the Hohner Special 20 with the Golden Melody harmonica. Although the combs vary,
the reed sets are identical (just and equal tuning not withstanding). What is distinctly different is the shape and size of
the cover plates. Notice how the Golden Melody cover plates envelopes the entire reed plates from side to side, and the depth
is wider. The cubic measurement of the tonal chamber is greater than that of the Special 20.
2. I recently went
through my collection of vintage harmonicas and found the first Hohner Blues Harp that I had purchased in 1973. I was amused
to discover that my vintage Blues Harp was none other than a Marine Band harmonica with "Special 20" type (enclosed) cover
plates! Hohner marketed this harmonica to "blues" players' wanting to achieve a fatter and muted sound without the difficult
techniques employed by the 'Founding Fathers' of Blues Harmonica who used the original Marine Bands (vented cover plates).
Try this out:
With a little bit of effort (relative term isn't it?), replace the cover plates from your Hohner
Special 20 harmonica with Suzuki ProMaster harmonica cover plates. This remarkable fitting combination looks terrific and
plays great. When amplified, this hybrid harmonica produces fat and muted tones!
Until next time, keep tinkering and remember:
"Arrange whatever pieces come your way"
- Virginia Woolf
Kinya Pollard,
the "Harpsmith"
