Light Box

Hello Harp Techs
The holiday season provides me extra time on the bench. This year, I turbocharged my light box and discovered unexpected results that helped expedite the entire reed slot sizing (embossing) process.

Light boxes are essentially an enclosure with an internal light source, topped off with a clear surface of glass or plastic. Popular with artists for tracing, and photographers for viewing slides (remember those?), light boxes have been an essential tool for harmonica customizers for years--typically blacking out the entire surface with exception of one slot opening to concentrate the light. In fact, I have seen variations of this theme on Richard Sleigh's and Jon Harl's workbenches.

With the reed plate laid on top of the light box, it is easy to see the light shining through the openings surrounding the reeds and exposing all the gaps. Harmonicas with excessive gaps require more huffin' and puffin' from the player--they simply don't sound or play well. Our goal, therefore, is simple--reduce the amount of light shining through the cracks by shrinking the reed slots (Review Harp Tech Study #6 Reed Slot Sizing). This will increase compression (efficiency of air) and greatly improve the playability, tone and volume of the harmonica.

For my light box, I removed the linear fluorescent lamp (mean 330 lumens) and replaced it with a 700 lumens LED light source*. Essentially, doubling the light output with color corrective Light Emitting Diode lighting, and concentrating this illumination through one slot opening.

What was so unexpected with my light box retrofit project, was now I am able to gauge better the optimum amount of sizing required for each slot. This is made possible by watching an image of the reed edges pop into view--as it reflects against the sides of the reed slot ... sort of like the ghost of the reed--weird I know. The benefit of watching for this imaging eliminates "over-doing" the sizing process (too much shrinking of the slot will cause the swinging reed to hit the reed plate). If I had a nickle for every time I had to un-do a clicking reed ;o)

* I purchased the LED light bar from TerraLUX Part#TLM-L06A-A064012R

Your Harpsmith,
Kinya