The trumpeter's audio world, a transcript of a seminar I gave at the 2008 ITG Conference in Banff
Mic and Preamp Shoot-out Test Click here to listen to the Test The test is 3:25 long, and it is mp3 format, at 320 kbps.
Here is the method used for the mic shoot-out: I announce which mic will be heard, then play a short excerpt comfortably loud, then move my valves quickly (to listen for mechanical noise), then play a short excerpt (the previous two excerpts have the mic at 5" from the bell, centered), then move the mic to 1" in front of the bell bead, then play a short jazz lick.
The Trumpeter's (live) Audio World
How to hear yourself and be heard in an increasingly amplified world by Benoit Glazer, given at ITG 2008 in Banff
The Golden Rule: Good signal IN equals good signal OUT.
What this means is that one should set-up the gain structure of the signal chain so that the signal is at optimum when one plays loud, and
one can then attenuate the signal at the very last stage of the path. It also means that the sound will be as good as the weakest link in the chain.
1- The microphone
a) Dynamic vs condenser
-The dynamic mic is essentially a speaker in reverse, meaning it has a magnet surrounded by a copper coil. The membrane moves, disturbs the
magnetic field, thus creating a weak electrical current, or signal, that can be transformed back into sound by a pre-amp, an amp, and a speaker.
Pros: rugged, punchy, reliable, no phantom power required, not very sensitive (resistant to feedbacks and quite forgiving to audio instruments and technique)
Cons: heavy, unsophisticated, narrow bandwidth
-The electret condenser mic uses phantom power (usually 48V DC) running through the mic cable to power the FET. It is a common myth that the 48 volt phantom powers the condenser element. The back plate of the electret is permanently charged and does not draw off the 48 volt. Manufacturers usually take advantage of the presence of current to build active electronics into the mic to manipulate its response characteristics and amplify its signal.
Pros: can be very light and small, sometimes be more natural sounding, and have wider bandwidth.
Cons: can be sensitive to wind, may be more prone to feedback, requires phantom power, and may be too "honest" for some people.
b) Response patterns
-Cardioid, or heart shaped mics, have a capsule head that is designed to let in the higher frequency sound coming from behind the mic as being out of
phase, therefore the response is better on-axis than off-axis. In other words, it hears what is in front better than what is the back of the
mic. Shaped pattern mics are pressure gradient mics. Almost all pressure gradient mics have character. This character is exaggerated by the proximity effect.
-Omni-directional mics are designed to let in the sound from any direction as being in phase, or time-aligned, so the response is more or less the same from any angle. Omni mics are Pressure microphones. They act like a very fast barometer. Omnis can sound very neutral. Movement of the waveform is
not needed, just its pressure presence. They are almost immune to shock and vibration.
You will often hear that omni mics are more prone to feedback than cardioid mics. However, there are two things to consider:
The first is that most of the time, a trumpeter will be playing with his/her bell at less than a foot from the mic. The amplitude, or sound pressure level, is high enough that feedbacks are rare, and indicate a serious problem with the system's EQ.
The second is that an omni mic can be placed much closer to the sound source while keeping a natural sound.
The proximity effect affects pressure gradient mics, and it will basically kill the high frequencies, over-boosting low frequencies by saturating
the diaphragm. When the sound source gets close to the mic, the same design principle that phases out the high frequencies from behind now kills all the high frequencies, no matter what their angle of origin.
Of course, the proximity effect can be used to one's advantage (to get a dark sound), but this lecturer prefers to use the acoustic principles of the trumpet bell flare to achieve a similar effect (see mic placement below).
c) Mic Placement:
For a natural sound, the mic should be placed about a foot from the bell. All the harmonics that make up your sound are not present under one times the diameter of the bell bead, so keep that in mind, especially when using clip-on mics.
Should you want a darker sound, you can play off-axis on a cardioid mic, you can get very, very close to a cardioid mic, or you can place the mic close to the edge of the bell, or a combination of the above.
d) A partial list of mics useful for live performance:
-dynamic (and cardioid): Shure SM-57, beta 57, SM-58, Sennheiser e905, e604, e906, MD421, MD441, ElectroVoice RE-20, PL-20, ND-468, ND-478, Audix I5, and many more
-condenser (cardioid): Shure SM-98, Audio-Technica AT-35 (pro), SD System LCM 77, DPA 4080BM, AMT P800
-condenser (omni): DPA 4061BM, 4037
a) From the mic, the signal now goes to a pre-amp. The primary function of this very important piece of gear is to bring the mic level signal up to a line level signal, and to provide phantom power to condenser mics. Many other features are sometimes included, such as EQ, compression, effect loop, insert point, direct out, multiple outputs, headphone amp, and so forth.
b) There are different operating principles in pre-amps. Tube, solid state, pure class A, class A-B, class D, and many hybrids. The operating principle is not as important as the quality of the components and the signal path topography. Ultimately, it's how you like the features, the sound, and often times it is a compatibility issue between the mic and the pre-amp. Pretty much like trumpets, mouthpieces, and the relationship between them.
c) A partial list of pre-amps that could be useful in live situations:
-Drawmner1960, Joe Meek, API, Vintek X73I, Avalon 737sp, ADA, Focusrite VoiceMaster Pro, ISA One, TrackMaster Pro, TwinTrack Pro, Pendulum SPS-1, SPL Channel One, and many others.
3- Some important pre-amp features
-Gain -48V -Phase -High Pass Filter -EQ -Compression -Effect Loop -Aux In -Aux Out
-Impedance -Insert Point -Output Level -Pad
4- Some important signal processing
Equalization, in the context that interests us, is used primarily to correct the disagreeable coloration of the microphone, pre-amp, or FOH system. It can also be used to create a special effect or a specific sound.
Main EQ parameters:
-Frequency, expressed in Hertz (or KHz), or cycles per second. There are several ways to learn which frequency does what to your sound. You could buy a CD that contains pure sine waves at specific frequencies, easy to find on the web, you can find note-to-frequency charts also on the web, or you can play around with an EQ until you get good at it. Knowing your frequencies is a great way to communicate with audio engineers.
-Gain, or the amount of boost or cut that you want to affect to your frequency center, expressed in dB.
-Q, or the width with which you will affect your frequency center, expressed as a decimal fraction (0.1 being very wide, 12.0 being very narrow), or in terms of octaves (1/6 octave being fairly narrow, 2 octaves being fairly wide)
Compression is (over) used to lower the dynamic range of the signal. By squishing the louder dynamics and then boosting the overall signal, one gets fewer peaks and more presence overall. Theoretically, it can help making the softer passages cut through the mix better, but the danger is that the trumpeter will strain trying to play loud, and not obtaining the corresponding response. Also, rare are the compressors that do not color the sound, usually shaving off some high frequencies, making the trumpet sound a little boxy.
Main Compressor parameters:
-Threshold (down from 0.0dB)
-Ratio (2:1=half the dynamic range)
-Attack speed (slow=more punch, fast, more transparent)
-Gain, or make-up gain, expressed in dB
In a live situation, with the gain structure being optimum, a typical setting would be 2:1 ratio at -12 db threshold and a 0 to 3dB make-up gain, with a fairly slow attack and a fast release.
A more heavily compressed setting is often used by Randy Brecker, just as an example.
As a rule, it is better not to send any reverb to FOH, so that the engineer can use a common reverb for the horn section, or whatever he/she feels is right.
Should you need reverb for monitoring purposes, you can either find a way to route it only to yourself, or if using headphones or in-ears, a tiny bit of reverb will make a big difference for you, and the FOH engineer will not hear it at all (it is always best to confer with the engineer on those subjects). Note: condenser mics, having more high end, are better at creating a nice reverb tail.
Depending on the music, the additions of effects can contribute greatly to the musical result, and it can be a way to personalize your sound. Commonly used effects for the trumpet are: delay, symphonic (the doubling of the tone, with a slight detuning can work well with the harmon mute), harmonizer, chorus and/or flanger (those have to be tweaked very carefully to work with the trumpet)
Remember to use effects sparingly, for a nice change of texture, and keep working on your effects as a tool to make your sound more personal, not more generic.
There are several methods available to monitor yourself in a live situation.
If you play a steady job (say, Tower of Power or Gloria Estefan), and there is a good monitoring engineer, you can use molded in-ear monitors. I own serial number three from Forget-Parent, the world pioneer in that technology, so I have a lot of experience with those.
If you freelance and need to be independent, I do not recommend molded in-ears, as they block enough outside sound to require a system to enable you to hear the rest of the band. They also have a fair bit of bone induction (block your ears with your fingers and hum, you will understand bone induction), so you have to drive them pretty loud to hear a nice trumpet sound. Also, they cost upward of $1000 for a good system.
So if you freelance, you can use monitors (speakers on the floor or small speakers on mic stands), or small, high-end ear buds. I ended up using the latter for many years, as they lower the ambient sound a little bit (from 3dB to 6dB, depending on the model), but not enough to require mic'ing the stage to hear the band. I used $100 Sony buds that have lasted 15 years so far, attenuate ambiance by 3dB, and have little or no bone induction. If you are going to play with a harmon mute, make sure your monitoring method does not emphasize 2kHz, as it makes the mute sound unbearably buzzy and bright.
-Whenever I arrive on a gig, one of the first things I do is to locate the audio engineer. I introduce myself, and ask if he/she needs help with anything. Helping the sound engineer achieves two things: it may get the gig ready in less time, allowing more time to work on getting a good sound, and it is also a
good way to make a friend, and in such a subjective field of work, being friendly with the audio engineer can only be a good thing for you...
Since you have your own gear, and it may be different then the set-up the audio engineer usually uses, you have to think of the resistance you need to overcome. It is human nature to have an instinctive reaction to change, and the more experience, the stronger the reaction... It is much easier to be open to change for a friend than for a somewhat cold stranger.
I did not talk about wireless in Banff, due to lack of time, but I know many people are curious about that, so here it goes:
In the US, the FCC has auctioned off the frequency bands that were reserved for wireless mics. Since there are no planned replacement yet, it seems that now may not be the best time to invest in a wireless system.
In any case, there are many inherent problems with wireless mics. Without going into technical details, there is no system out there as of yet that transmits the sound in an accurate fashion. Companding, audio compression, tight compression algorhythms and a host of other problems arise when you go wireless. I personally went wireless many years ago. I went ahead and bought myself a $10000 top of the line Sennheiser system (to this day, nothing comes close audio path wise, although new systems are much more flexible on the frequency choice side of things). In any case, I worked on my rig for two weeks to get the best possible sound, and I got close to something I was happy with.
Well, the first opportunity to use it came in the form of a TV show (the equivalent of the "Tonight Show" in Québec). True to my beliefs, I sought the audio engineer and tried to make myself useful and friendly. When I unpacked my rig, he noticed the wireless (tried pretty hard not to look impressed with the model I owned), he then asked me what frequency I was on, and proceeded to tell me it was their com frequency and that I could not use it ! I plugged in a cable, and I was happier with the sound anyways! Like I said, today's models can change frequency very easily, but back then, you had to change the crystal, and it was a major undertaking.
The other side of the wireless issue is the monitoring aspect. You see, if you are mic'ed wireless, you probably will end up with a wireless monitoring system as well, and that complicates things a lot. Batteries, frequency problems, spikes, interference, and the high cost of good equipment, all seems to conspire to keep this musician from liking the wireless world.
In any case, should you need to go wireless, avoid the Audio-Technica and Shure in-ear wireless systems, as they are barely usable. Sennheiser makes a decent in-ear wireless system, but you still need to process the audio before going to waves. Many people use the DBX IEM processor, but there are others out there.
As for the mic systems, Sennheiser make a pretty good system ($600-$700), and many people use the Lectrosonics systems ($1100-$3450).
Any way, as we are getting pushed higher and higher in the frequency range, the sound is getting worse.
Hopefully, someone will come up with a new technology that will transmit well, and sound good. In the meantime, I suggest you use a cable whenever possible.
At La Nouba, I use a DPA 4037 as my microphone, an Avalon Design 737sp as my preamp, and a Yamaha SPX 990 as my effects processor.
On other occasions, I still use the DPA 4037 and the SPX 990, but I use a Pendulum SPS-1 as my preamp. It has the most complete connectivity scheme on the planet, and t is only 1 rack space.