I have had the best results working on this one by actually playing it with "breath attacks" after each breath. A breath attack is simply a matter of starting the note with air alone, without the aid of the tongue--kind of like a "Haaa", but without the vocalization. I have to pause here to state what I like to tell all my students when dealing with issues of articulation as far as discrete attacks are concerned, and that is: "The tongue does not make any sound--" (at least not any that you want to hear as part of a musical presentation) "--only the air does."
So in the Hungarian March I breathe thus...
This puts me in mind of a saying [last place I read it was in one of Brad Edwards' etude books]: "Put the vowel at the beginning of the note." What does that mean? The air has got to be there at the beginning and the oral cavity set and steady from the start. Otherwise the tone, pitch, volume, or any combination thereof will change after the attack.
Jay Friedman is on this same wavelength in his advice to me about getting more sound at the beginning of the note. For example, on Ride of the Walkyries: "Play it (in rhythm) with each note as short and loud and accented as possible." This sounds really gross--but is really effective at getting the sound out at the beginning of the note." (Of course, it's not the way you perform it, just practice it for the type of attacks and accents you want.)
May I just say that there is nothing more frustrating to listen to (or execute) than a sound that doesn't speak immediately! Anything you can do to combat this problem (that we all have from time to time) is worthwhile.
Interestingly enough, after starting this post, I had a serendipitous conversation with Richard Brady (who plays bass trombone in Atlanta Opera) at a recent rehearsal; he just happened to bring up the issue of articulation in the low register. He told me that Ed Kleinhammer, former bass trombonist with the Chicago Symphony--"Clamslammer" as he was affectionately (if irreverently) known to some of us--told him to use a "Lah" attack in the low range.
Now this also might seem counterintuitive at first. But if you do some experimentation with it, you will notice that this consonant uses just the tip of the tongue (even more so than my previously preferred "Tha") and allows the tongue to remain really soft and relaxed. I am getting better airflow when I do this, but haven't yet figured out to what extent it works in the upper register. It can be tricky trying to figure out exactly what you're "saying" when you articulate, because it likely changes with variables such as range, volume, type of articulation, etc. And different people may pronounce or execute a consonant differently. But try it--you can multiple tongue like this into the extreme low range.
The other troublesome thing I alluded to regarding the difficulty of the Hungarian March is the rhythm itself. I'll save that for another blog.