- - Please visit: Legacy Horn Experience - -
Over the years a number of times the topic of what is a compensating horn has come up for me a number of times. In the early years of the use of the double horn this type of horn saw much use. Kruspe was a leading innovator in horn designs, and 
they made several different types of compensating horn at that time — the Wendler model illustrated here being probably the most popular. I have played on one of these; it was actually a rather responsive, light instrument, with much the feel in the hands of a single B-flat horn.
As one type of compensating horn seen are compensating triple horns (the “double horn” part of the triple is the compensating part of it), and as the triple horn I settled upon is a compensating triple, I addressed this topic in my publication Playing High Horn as follows:
In some parts of the world (e.g., the United States), this design is only rarely encountered today. A full double horn is set up so that it has full length valve slides for the F and Bb horns, while a compensating double is set up with full length valve slides for the Bb horn only. On the F side of the instrument, the sound waves travel through the Bb slides plus smaller slides that add enough length to produce the appropriate pitch for the F horn. For example, when the player performs a written middle line Bb in the middle range on the Bb horn nothing remarkable happens: the sound waves travel through the main part of the instrument plus the first valve slide. However, when the player performs that note on the F horn, the first Bb slide plus a smaller slide behind the Bb slide are added together to equal a whole step below the open pitch on the F horn. Visually, a compensating double horn will look, at a distance, like a double descant horn with the longer Bb slides on top and shorter slides underneath.
Comparing the top illustration with this second illustration from a Kruspe catalog will make the differences pretty clear. This is the 1930s version of the Horner model full double with the separate B-flat tuning slide (the classic version was laid out like in the pattern copied by Conn in their 8D).
At the time these instruments were made they were both solid, professional quality instruments, and the compensating double is still a design worthy of use today–one of the players in the new London horn recording is using one in fact. I often think that it is about time some maker revisit the compensating double as a compact, light model for use by younger students; certainly it would be better to have a double horn of some sort in the hands of every horn student instead of starting them on the single F.
