Methodology for Evaluating Intonation
by, 10-01-2011 at 06:00 PM (6078 Views)
I have been testing intonation for euphonium manufacturers since around 1980, and it soon became clear to me that there are many possible ways to get inaccurate results. Is the horn warmed up fully? Am I playing the horn's Ab or I am playing the way I always play an Ab on a different horn? Am I unconsciously bending the pitch to make it look better than the horn really plays because I favor the horn? Etc.
Whenever I ran these tests I wanted the results to represent what the horn actually tends to produce. Whether comparing brands for my own purchase or helping a company make a better instrument, accurate results are critical. Surely no two people running this type of test would product identical results. But I believe I have a methodology that works consistently enough to be of value to me and others.
Note: I have versions of my own mouthpiece in small, medium, and large shank sizes. I always use my own mouthpiece so that I don't confuse results by using a mouthpiece I don't know well.
First, it is important to get the instrument fully warmed up. A cold instrument will not only be flat overall, but the relative tendencies on certain notes will be skewed. As I warm the horn up I use all valve combinations so that I don't leave one slide tube cooler than the rest.
Once I am satisfied, I still may continue to play a while before testing, especially if I haven't had much time on that horn. I want to become familiar with its general playing characteristics, especially response and tone. (Tone color may incorrectly affect one's perception of intonation.)
Main tuning slide. I tune the horn's B-flat with the main tuning slide and proceed to find the best compromise for the valve slide positions. (Because it is useful to be able to adjust the individual slides, they are usually made to be too sharp when pushed all the way in, which leaves you with more control. This is the same reason that the horn is not built to play a perfect Bb with the main tuning slide pushed in.)
2nd valve slide. I almost never adjust this one. One leg of the slide is too short to offer effective intonation adjustment without risking losing the slide while playing.
3rd valve slide. The balance most affected by this slide is intonation of 23 notes like concert F# and 12 notes like G. Let me explain. If the F# is too sharp, then pulling the 3rd slide will help. But if G is too sharp with 12, using 3rd instead is a practical alternative. But if 3 is pulled to help the F#, it may be too flat for a G. So my decision is based on the best comprise for intonation of the 23 F# and then either 12 or 3 for the G.
1st valve slide. Part of this decision can be the intonation of 12 combinations, which are usually sharp and will benefit from pulling 1 slightly. However, there is often a stronger consideration among the intonation tendencies of notes played with 1st valve only. The 6th partial is usually sharp on brass instruments. For euphonium this is seen in the pitch of the upper Eb, E, and F (concert). But nearly as often, compensating euphoniums are flat on the high Ab (1st valve). There can be other issues on the remaining 1st valve notes, so I need to find the best compromise for all 1st valve notes. Usually this means pulling the 1st slide a bit.
4th valve slide. Because I have tuned the open horn to a Bb, I start the 4th valve tuning by playing a middle concert F using 4. The 4th valve lowers the open horn 5 half steps, so the open tuning Bb is lowered to an F. Once I adjust the 4th-valve slide for middle F, I play the C below it, which is normally a 4th-valve note, as a final check. If the C is not quite right, I adjust the 4th slide for it.
When I am convinced I have the best combination of valve slide positions, I start the real testing. I will have already prepared a sheet with all the note names, and room for 3 entries for each note. (I want to be able to double- and triple-check my results conveniently.) Naturally I have an electronic tuner to show me the results.
I find it best to not just go up a chromatic scale, but rather to play notes more-or-less at random, changing ranges often. This helps keep me out of any ruts, mentally or physically. As I play each note, I start by closing my eyes. Then I bend the note's pitch up and down to shake off any tendency to play a note where I want it rather than where the horn wants it. When I have lost my own notion about the note, I move the pitch around, while I feel and listen for the most resonant sound - that is where the horn wants to play the note. As soon as I have that note locked in, I open my eyes and read what the tuner says. Then I check the pitch by approaching it from above and below using intervals and scales to make sure I have truly found the horn's pitch. As a final check I play a short forte version of the note to see if it agrees with my long-tone version. If I see too much disagreement among the methods, I know I need to go back and try the note again. When satisfied, I write its result down and move on to another note, repeating the same process.
After testing a few notes at a time, I always return to the Bb to make sure the horn has not drifted off center overall.
A final step is to look at the overall tendencies and see if there are patterns that could be improved by slide adjustments. I check to see if the patterns show that my initial settings were not as good as they could have been, and I also check to see if further compromises would be helpful. If there are some tendencies that are too extreme, it might be a better choice to make a small negative change on some other notes in order to make the extremes less so.
The end result is the chart I publish on my site (and often share with the manufacturers). My results would perhaps be different from results another player might produce. However, other players will probably experience the same tendencies I found, but possibly to a greater or lesser extent.
There are two other factors I have not included in the charts. One is the improvements that could be made with a standard-equipment trigger. For example, if most inaccuracies are in the sharp direction, a tuning slide trigger could easily fix them. And second, the pitch on different horns can be more difficult or less difficult to adjust with your embouchure. Both factors are worth considering if you are evaluating euphoniums to purchase.
See the euphonium intonation graphs...