This is partly repetitive of what is said elsewhere on this site, but I will still collect some of the myths here. As mentioned, many myths about the origin, purpose and use of the psalmodikon have flourished and still do today. Specially in Sweden and Norway, on web pages and blogs, etc., errors are repeated, perhaps due to the effect quoting each other, assuming that what is in a reference book is correct. At the same time, if you google, you see that many have also written real facts. However, often mixed up with the myths To make matters worse, there is no consensus about what a psalmodikon really is.
We read here and there that Bruun in the early 19th century introduced the psalmodikon and that it means a one stringed instrument. Then you read that Dillner built its first 1819. And commonly, that Dillner invented it. And in Norway, in books and on radio / TV, Roverud has received the honor of inventing the instrument. At the same time, there is information about the psalmodikon as being far older. Preserved instruments from the 1700s, as well as information about the psalmodikon as being considerably older than that. These myths have sometimes started by someone drawing hasty conclusions from facts taken out of context. Another reason may be that you do not first understand what a psalm icon is.
The fals fact that Dillner built a psalmodikon 1819, which appears in a book as well as on the Internet, is probably due to the conclusion that since the 1819 psalm book was published with Dillner's siffernotskrift and instructions on how to interpret them and play them at the psalmodikon, the instrument then existed. However, the year 1819 does not indicate the year for the publication of the coral book, but it is the year in which the contents of the psalm book are laid down. Then the psalm book came out and then the coral book. The latter are thus notes to the psalm book. Written with regular notation. But we had to wait 11 years for Dillner's edition of the 1819-year psalm book to be published.
Sources to the statement that Dillner and Roverud based on Bruun's instruments are the best possible. Dillner and Roverud in their own writings Bruun mentioned adding several melody strings to the instrument, but he meant that a string was enough for the beginner and that was enough for the purpose. I do not know any Norwegian psalmodikon with more than one melody song, that is, of Roverud's model. But it was not uncommon for the Swedish to have two melody strings and more commonly that; they had resonance strings.
I have seen just one psalmodikon with a drone string, but I don'tt know if this was an unique instrument. (However, there are many with two melody strings, which makes it possible to play with a drone.) This means it makes no sense to describe the psalmodikon as an instrument with just one single string. Dillner, like the other two, had an ambition to quickly spread an instrument that was easy to build, easy to learn and cheap. Dillner's drawing, spread in giant edition, therefore showed the simplest possible instrument. Of course, many built them just like that. But soon people began to go from the simplest design to various designs of the body and also to add strings.
From a pure typologically standpoint, Bruun's psalmodikon is not the same instrument as Roverud's and Dillners! But Roverud was the one who came up with the name psalmodikon. It's a logical name that is sometimes used not exclusively for the instrument, but for the combination of the numerical notation and this simple instrument, playes by plucking or as a bowed instrument.
As mentioned elsewhere on the site, a very widespread myth is that Dillner's purpose was to kill the fine coral singing in the congregations. He is innocent of this. He was a man of the people who notated popular corals and also other kinds of Swedish folk music. He was more or less a pioneer in that area, or in any case earlier than the big names in that area.
It has been pointed out that the instrument which was more likely to repress the popular corals was the church organ! The purpose of the psalmodikon was not to kill the tradidional way to sing the hymns, but a way to spread the new melodies in the hymn book. In all three countries there also was another very important reason. It was an aid to improve the music education in schools.
Also, something that is discussed elsewhere on the site, the idea that the psalmodikon was used only for religious music is simply wrong. It was not that the music played on violin was regarded as sinful. It was primarily the instrument violin itself that was seen as a devil's instrument. Of course, if you have access to an instrument, you play what matters to it. It was about playing the music you know. As so many fiddles was burned for religious reason, there were many fiddlers who did not have an instrument. Naturally they played their old music at the paslmodikon instead (to the extant the psalmodikon made it possible) The widespread idea that Dillner meant the hymns ought to be played very slowly is not right. Perhaps much was played that slow as a result of that the players were new to the instrument, new to the melodies - they perhaps were unable to play faster. But, according to Dillner some were supposed to be played slowly, but not all hymns. Nor in school, when you have to take into account that children have a different pace, but he also wrote :
The term monochord is often used to describe the psalmodikon. That is in fact not advisable, as it is misleading. The term monochord is often used for instruments with just one single string. Numerous psalmodikons have many strings. Even as they in most cases are resonance strings, there are also some psalmodikon's with two melody strings. It is unfortunate to define an instrument in such a way that it excludes instruments that rightly belong to the psalmodikon family. The term monocord is also used for a group of instruments that have many strings, each string just giving you a specific tone. You get the desired pitch by selecting the right string to bow. Hence the prefix mono.