Overblowing an instrument

[DCottrell]

At loud voulmes, a brass instrument gets an "edge." How does this happen? Is one part of the system overloaded? By that I mean, is this tone a result of a fault in air flow, lip tension, or a result of the instrument itself not being able to process the input through the mouthpiece, and it becomes "overblown."

[Alex Reeder]

Something I find interesting is that this sound is acceptable on trombone and french horn in an orchestra, but is discouraged for tuba and trumpet. Why? Just a difference in what is considered acceptable tone, or does it happen easier on trombone and horn, and so is considered inevitable?

[windshieldbug]

You need someone more versed in physics, but I've always assumed that it was the horn metal of the bell in sympathetic vibration above a certain volume. And yes, one of the things I looked for in a symphonic horn was resistance to that, despite volume, whereas for quintet I used a Mirafone 184 which, as Bloke put it "would peel paint from the ceiling" if pushed right.

I've never heard a fiberglass sousaphone do that (or I've always heard fiberglass sousaphones do that, take your pick... )

[brianf]

Most of the time this caused by using to much air pressure instead of air flow.

[DCottrell]

Most of the time this caused by using to much air pressure instead of air flow.

So is it due more to the player or the instrument? Extreme instances aside (like Warren Deck on a 3J), could a good player get the same volume of sound with different tones on the same instrument? In other words, are there instruments that, no matter how much air pressure is put in, no blattiness emerges?

[windshieldbug]

So is it due more to the player or the instrument?

Yes. (no, I'm not just trying to be a wise guy... )
A good player can control it, while some instruments are by design more prone to it.

[Chuck(G)]

Check out Benade on this subject:

http://ccrma.stanford.edu/marl/Benade/d ... t-1973.pdf

[Leland]

Check out Benade on this subject:

http://ccrma.stanford.edu/marl/Benade/d ... t-1973.pdf

Hmm.. okay...

I can't find "blat" or "sizzle" or "edge" or "distortion" in that document, though.

[Chuck(G)]

Check out Benade on this subject:

http://ccrma.stanford.edu/marl/Benade/d ... t-1973.pdf

Hmm.. okay...

I can't find "blat" or "sizzle" or "edge" or "distortion" in that document, though.

Not specifically, but use his model...

At low volumes, wtih a steady air stream, the aperture between your lips doesn't close completely--there's not enough energy in the resonance to do this and the effect is one of a fairly linear system. So the sound has nice smooth edges and not a lot of high-order harmonic content.

Now increase the volume; eventually, there's enough entergy being fed back as resonance to cause your lips to close completely while vibrating. This creates a nonlinear type of system with a waveform with very sharp "edges" and it soiunds "blatty" and high harmonic content.

You do have some control over the volume level at which the blatting occurs, however. Lots of lower-speed air and a loose embouchure will allow getting louder without breaking up. What Brian said, IOW.

Also note that the same effect causes high-order harmonics to increase more rapidly in volume than low-order ones, so as you get louder, your sound becomes "brighter".

[oldbandnerd]

So..... is it ever appropriate to over blow ? Is it ever desired by a conductor to get a certian sound or effect ?

I am currently playing "Russian Sailors Dance" in community band . We ( the euphoniums ) play the main melody along with the tubas . When we first started practicing it the conductor keep asking for " more" and " more " to the point that I just overblew my euph like I never have before. That seem to satisfiy him . Not disstorted or superloud but with that crispness that low brass can have . Like a trombone does very well. I wonder if it sounds good when I do it like that but the conductor has never asked me to change it.

[Leland]

So..... is it ever appropriate to over blow ? Is it ever desired by a conductor to get a certian sound or effect ?

If desired, and for a certain effect or intent, then yes.

[Art Hovey]

The blatty sound that you describe is unrelated to metal vibration, as you can easily verify by stopping the bell vibration with your hand. It happens because the graph of air density versus pressure is only approximately linear. If you increase the sound pressure variations inside your tuba (by playing louder) the non-linearity of that relation becomes more significant, causing higher harmonics to be generated. The same thing happens if you overdrive a cheap loudspeaker, but with worse-sounding results. You may notice that a note that can be played with two or more different fingerings will blat more easily when the fingering with longer tubing is used. That's because more harmonics are generated in the longer tubing. You will also notice that a larger-bore instrument can be played much louder than a small-bore instrument without getting into the blatty region. That's because sending the same sound energy into a smaller-diameter tube results in greater pressure excursions, causing more harmonic generation.

[tubeast]

Great subject.
I think blatting can be used as a neat special effect. The music rarely provides good spots to make use of it.
This is like using your horn as a weapon, though.
The thing with weapons is: clubs wear off, knives get blunt, and magazines get empty when overly used.

I have a lot of loud(est) non-blatting playing to do this summer. For a long time, I´ve been trying the "It must be the player, so go practice"-approach. The idea was to play in that blatting region to learn to feel comfortable up there and raise the level at which it occurs. It did help, to a certain extent, but didn´t really solve the problem.
My general approach was to widen the distance between the lips, letting the upper lip do most of the job.
Observation: below 2nd partial blatting is real "hard" to do, so you´re not likely to overblow. Above that, it´s possible to sound like a huge trombone.
The higher I get, the more it helps to open up the embouchure, but the sound will get another quality I don´t like: just like when you pronounce the words "Hall" vs. "Curl" and observe what the vowel does.
Right now I´m experimenting with using the lower lip when playing loud (I use the upper lip most of the time). It seems to help, but I´d have to practice a lot to improve sound. I guess at some simes one has to accept one´s own and the horn´s limits.
What really helps me on noise and articulation work is the use of ear plugs as noise protectors.
Besides the obvious ear protecting (this can be important over the years) this provides a better feel for what lips, tongue, palate and throat are doing to my tone.

[Shockwave]

Actually.... I thought of my user name while learning about why brass instruments sound brassy.

The brilliance that brass instruments get when blown loud is from nonlinear distortion of the sound wave by the air itself. When air is compressed it heats up, and when it expands it cools, so the positive part of a wave is hotter than the negative part of a wave. Sound travels faster in hot air than in cool air, so the high points of the wave catch up to the low points. The effect of this is a function of the intensity of the sound wave and how far it travels, but overall it can convert a nice mellow sine wave into a raspy sounding sawtooth wave.

Cylindrical brasses such as trombone make the wave continue down a pipe that doesnt expand, meaning the sound wave stays the same intensity and a maximum amount of distortion is added. Trombones can actually produce shockwaves inside when blown very hard. Tubas are conical, so the intensity of the sound inside the horn progressively lessens as the horn expands and less distortion is added leaving a mellower tone. Notice that the tone becomes more brilliant playing a particular note when more valves are pressed. This is because more cyclindrical tubing is added.

This nonlinear distortion is the major thing that makes brasses sound so different from soft to loud, but there are other effects from the air column shape, mouthpiece design, etc etc that affect the sound in more constant ways.

-Eric

-Eric

[tubatooter1940]

Great discussion on blatting,guys.Threads by Chuck(G),Art Hovey and Shockwave were brilliant.
High school marching bands in this area are using thier whole tuba section blatting in unison to really knock your socks off. Even the cheerleaders are impressed.
In my trumpet tooting days,I had to blow shots with electric lead guitar and the expensive horns would top out.More air would not increase volume.A cheap,big bore Olds Ambassador trumpet never topped out.It was the only horn that could stand up to a hundred watt Fender amplifier.

[MartyNeilan]

I just noticed my college textbook on Instrumentation and Orchestration by Alfred Blatter! Coincidence?? I think not!

[DCottrell]

I sometimes play in a Brass Band with Al Blatter. Great guy. Horn player, if that means anything. He definitely does not "blat" on his Willson alto horn. I almost did not sell him that horn because (I can't wait to see what response this next phrase creates) that was a NICE alto horn!!

[windshieldbug]

a NICE alto horn!!

OK, I'll bite. Is that like a Jumbo Shrimp? (big shrimp or small jumbo... ). Why do you park your car in a driveway and drive your car on a parkway?...

[THE TUBA]

I have found that tubas with larger bell flair with a smaller bell "throat" and smaller bores are easier to "blat" on than ones with little bell flair and larger bores. I belive that's one of the reasons why it is so easy to blast on sousaphones and french horns. My high school uses Yamaha 641 BBb tubas, with a 16.5" bell and .812 bore. I have a Kalison DS with a 18.5" bell and .770 bore, and I have found that it is a heck of a lot easier to blast on my horn than my school's.