This question, "What are the differences between a one-stringed diddley bow and a canjo?" has come up in my mind, and I'm sure other newbies will wonder the same thing. I have begun to answer the question for myself. Just wanted to share and open up the discussion to you all as well. Here is what I have discovered using CBN as a research source:

1.) A diddly bow is designed to be played in your lap while you sit, much like a mountain dulcimer. So, a plank of wood like a floorboard would make an ideal "foundation" for a lap-played diddley bow. A canjo, on the other hand, is played like a guitar, banjo or stick dulcimer - sitting or standing with the instrument held across your chest/stomach area.

2.) Traditional diddley bows were made using a pair of glass soda or beer bottles positioned at each end of the plank of wood, often just held in place by a few nails and the tension of the wire (apparently they didn't use guitar strings way back when). Only later did can-resonators appear on diddley bows. These days diddly bows can be found using just an altoid (or similar) can and piezo pickup (or even a magnetic electric guitar pickup). This can-resonator version of diddley bows kind-of clouds over some of the distinctions between canjos and diddley bows. But there are still more distinctions.

     [ I've noticed that the "altoid style can" used on some diddley bows is propped up with a wedge
       of wood so that that the leading (high) edge of the can serves as the bridge. This idea might be
       useful for altoid- or square-can canjo makers as well. ]

3.) Almost all diddley bows are fret-less and are played with a slider in your "fretting" hand and either a pick, a stick or some other object in your "strumming" hand. The stick (or other object) is often used to beat the wire rather than pluck or strum the wire. This, of course, means the style of music played on the two categories of stringed instruments differs.

4.) The style of music played on the diddley bow is called the "Delta Blues" and though much different than the "traditional" mountain tunes I like to play on the canjo, is none the less a very interesting and "good sounding" genre. Another genre played on the diddley bow might best be called "Experimental Music".

Here's a good video showing how a diddley bow is played...
     http://www.cigarboxnation.com/video/diddley-bow-blues-part-ii

5.) Most (if not all) diddley bows are fret-less while most (but not all) canjos are fretted. But, even fret-less diddley bow players use a scale, known as the "Blues scale" when playing their music. Sometimes the Blues scale is marked on the "neck" of the diddley board where canjo players would expect to see frets. So, in addition to being fret-less, most diddly bows are played (if not marked) with the Blues scale, while most (but not all) canjos feature either a diatonically or chromatically fretted neck. However, a recent trend among some canjo makers/players is to experiment with a blues scale fretted (or fret-less) canjo, further blurring the distinctions between the two classes of one-stringed instruments.

6.) The "action" for a diddly bow is purposely set high to allow for sliding and banging on the wire with a stick (such as a chopstick). And while some canjos, especially the kind with a soda can on the end of a stick, tend to have high action, the direction most builders are going is to lower the action so that their canjos can be more easily fretted as well as picked or strummed. [No, let's not discuss the merits of using various types of cans to play the Can-can on the canjo!]

What other things differentiate these two instrument types? Or what else make them similar? Any constructive comments are welcome.

-Rand.

Hm-mm... I wanted to post this in the Can Jo Consortium Discussion Area. The "Category" box below doesn't allow this. Oh, well... Click!