To ensure the microphone performance is maintained, the under-belly is fully coated on the inside with high density open-cell foam to absorb internal reflections and reduce phase cancellation. Plus the innovative design features an extended cable cutout that allows the microphone to be articulated for precise placement, further optimizing the performance.
Once in place, the CrashGuard surrounds the microphone with a sonic barrier. By reducing the spill from the cymbals, more of the drum can be captured. This enables the engineer to add EQ to the drum such as increasing high end for more attack without accentuating the sound of the cymbal. On close proximity sources such as the high-hat and snare, the engineer enjoys greater balance over each sound.
The CrashGuard is an easy to use instrument shield designed to control the spill of cymbals entering the drum for greater control during the recording process.The Science Of The CrashGuard
It would be great if we could claim that we 'invented' the CrashGuard. Truth is; devices like the CrashGuard have been custom built by recording engineers for years. Some have tried cardboard and duct tape, others have attempted to cut & glue plastic bottles.
Although these home-made jobbies work to a certain degree, they are usually fragile, hard to position and probably do not afford as much isolation as one would like.
The point here is that necessity is usually the driver for innovation. The CrashGuard is a device whose time has come to break out of obscurity and this page explains how it works.Isolating High Frequencies
It is well known that wherever air is free to wonder, sound tends to follow. Sound travels through air like waves on water by compressing air molecules. High frequencies and low frequencies both sound different and behave differently. The table below shows some examples.
Given the fact that bass goes everywhere and high frequencies are more directional, highs are easier to predict. And since high frequencies contain less energy than lows, they require less effort to control. This is, in fact, why the CrashGuard is designed to control spill from the cymbals. Highs are easy to mange compared to bass. And controlling low frequencies from the toms is practically impossible.Cymbals and High Frequency Splash
When the hi-hat is played, the high frequency sound from the cymbals will travel outward in a straight line in all directions. You can be certain that some of it will end up right at the nearby snare drum mic. By shielding the snare mic with the CrashGuard, the direct sound from the hi-hat is attenuated. It is important to note that high frequencies easily bounce off of hard surfaces. This can include drum shells, other cymbals and even the drum skin.
Even with the CrashGuard in place, some of the cymbal sound will find its way into the drum mic. The CrashGuard is merely reducing the level to give the engineer more control. This is particularly important when trying to add some attack to a drum. This is normally done using an EQ by adding high frequencies. If the cymbals are left unchecked to spill into the drum mic, their high frequency content will also be accented.The Shield and Internal Acoustic Absorption
In the old days, studios use to line their walls with lead to stop sound. Today, they use multiple layers of gypsum board. To stop sound you need mass. And if you look inside a modern control room, you will find a mixture of both absorbent materials and diffusers. This is because in order to control sound, you have either to absorb it or deflect it away.
The CrashGuard is made from ABS plastic. ABS is a fabulous material it is rugged yet springy. This means that when you hit it with a drum stick, it will not break. You can find photos of extreme measures where engineers have taped forks and other shields over microphones in effort to protect them from overly aggressive drummers. The CrashGuard offers a good measure of protection and is also heavy enough to actually attenuate some of the high frequency sound. You will also notice that the CrashGuard incorporates angles on both sides. This helps reflect energy away from the microphone inside. In fact, this is exactly the same approach used to build the Stealth bombers: the angular shape of a Stealth bomber is designed to reflect energy away so that it makes it difficult for Radars to pinpoint their location.
The underbelly of the CrashGuard is coated with a layer of open cell acoustic foam. This is designed to help reduce some of the internal reflections that are generated when the drum is hit. The CrashGuard will affect the polar pattern of the microphone, which will slightly alter the tone. But by aiming the mic further downward, the effect is minimized.
Who would have thought that such as simple device would actually such in-depth science behind the design When it really comes down to it, the most important issue here is performance. And the CrashGuard does exactly what it is supposed to do.How To Use The CrashGuard
The CrashGuard is extremely simple to use. It is designed to fit any standard boom arm or gooseneck. Begin my taking the mic clip off your mic stand boom arm. Make sure you leave the knurled washer on that usually comes with most booms. The CrashGuard comes equipped with a spare in case you do not have one.
Push the CrashGuard onto the mic stand boom arm. Then, take the mic clip and screw it onto the boom to hold the CrashGuard in place. Do not over tighten. Rotate the CrashGuard so that the microphone clip is pointing in the right direction and then slide the mic into the clip. You can now connect the mic by passing it through the rear access port. Snug tight the mic clip and boom so that everything is secure and you are set to go.
The CrashGuard is designed to fit most microphones and since most microphone clips allow the mic to be adjusted forward and backward plus be articulated up and down, you will find positioning the mic easy.
Keep in mind that for the most part, the CrashGuard will be used with a cardioid microphone. The cardioid pattern is created by mixing the sound coming in the front of the mic with the sound going in the rear, behind the capsule. Since the rear sound hits the diaphragm on the back side, it is out of phase and therefore causes cancellation. Try to leave some space between the mic head (capsule) and the inside top of the CrashGuard. This will reduce any effect the shell may have on the polar pattern.Application 1 - Drum Kit:
The CrashGuard can be used on one or more instruments in the drum kit. When used on snare drum the high frequencies from the hit-hat are attenuated and the audio engineer has more control over the HF response. Tom Toms are often electronicaly gated to reduce bleed but when toms are played the gates open and the sound of the cymbals gets louder. This creates the "pumping and breathing" sound asscociated with compressors and gates. CrashGuard can reduce this noise naturaly through attenuation making gates a little easier to set up.Application 2 Percussion:
Percussion instruments have the high frequency response and sharp trainsient attacks that cut through the loudest stage volumes. Experienced percussion players know they don't have to be on-axis or even close to the microphone to be picked up. For the mix engineer this means an instrument may appear at equal volumes on several percussion mics. CrashGuard can be employed to create better seperation between percussion micsApplication 3 - Acoustic Instruments:
Acoustic instruments are often at the mercy of louder electic instruments forcing engineers to use contact pickups that just don't sound as good as a quality microphone. CrashGuard can give acoustic instrument an advantage that allows better seperation and gain before feedback. Try the CrashGuard on piano, acoustic guitar, violin, flute, etc. before reaching for that contact pickupProduct Features:
- Reduces sound of cymbals from spilling into drum mics
- Light weight design fits most popular microphones
- Allows drum mic to be articulated for precise aiming
- Improves isolation for added control over each drum
The CrashGuard is a drum microphone shield designed to isolate the drum microphone to reduce it from picking up the spill from nearby cymbals. This allows the engineer to increase the attack of the drum by adding high frequencies without the cymbals becoming overly present.
Made from high-impact ABS, the light-weight CrashGuard attaches to the boom arm and is held in place using the microphones clip. The inside or under-belly of the CrashGuard is completely lined with high-density open cell acoustic foam to reduce internal reflections. And the innovative design features an extended cable access port that allows the microphone to be articulated for optimum placement.
Once in place, the CrashGuard helps control spill from cymbals into the drum delivering greater control over each drum for an improved mix.
The CrashGuard has been tested for fit with many major brands of instrument microphones. However there may be some mics that will not work because of size or the configuration of the clip. Please consult your local Primacoustic dealer about the make and model of microphone you want to use.
- Shell Material: ABS plastic, black (75% recycled material)
- Inner Liner: High density acoustic foam
- Dimensions: 7 x 3.75 x 2