AUDIO
Batteries… those indispensable little items that we all depend on for remote operation or backup. How many times have you put a cell in backwards? Come on now, admit it! I’ll bet every one of you has done it at least once. Remember that panic battery change in the middle of the night, in total darkness, when the director was screaming at you?
With equipment using two or four cells, the mistake is usually very evident because of improper or non-operation after the battery change. What about the Nagra or a field mixing panel that used a dozen D cells? If you accidentally put a cell in backwards, it will still work fine and is hard to detect. They do make batteries very distinctive in appearance to reduce the problem, but it still happens.
What is the effect of this mistake? A reversed cell will still conduct; however, the battery voltage will be several volts lower, and that is a very easy warning sign to miss. Now, for the bad news: That cell will discharge very quickly, rupture, and release very caustic liquid electrolyte. If the equipment is stored in a position where the electrolyte leaks onto circuit boards and chassis parts, they will be destroyed and will have to be replaced. It is almost impossible to stop this corrosion once it starts.
If you open a battery compartment and find leaking cells, and none of them are reversed, take a good photograph before removing the batteries. Battery manufacturers will not warranty equipment where a cell has been reversed.
My recommendation is to be extremely careful during a battery change, take it very seriously, and don’t let anyone rush you.
http://www.locationsound.com/proaudio/ls/tips/techtips1.html?id=86jqdQtH
by Marc Lesonsky, LSC Microphone Technician
1. DO NOT disassemble your mic in the field. Microphone parts are incredibly delicate, so unless you know what you’re doing, leave it to service technicians to inspect it. You’ll appreciate the savings.
2. Shotgun mics are aptly named because of their design, not because they can pick-up gun shot sounds. High sound pressure levels, unless recorded from a distance of at least 25′ away, can damage a microphone’s diaphragm, distort its membranes, and wreak havoc with its frequency response.
3. And while we’re on the subject, shotgun mishaps aren’t limited to the artillery kind. When removing a shotgun mic (namely Neumann KMR 81 types) from a suspension mount clip, lift the mic vertically. DO NOT slide the mic from the clip or you could pull out the mic’s internal screen asembly… it can happen to the best of us!
4. Microphones, not just humans, need readings too. Okay, we’re not talking about what the future holds for your mic but rather precise readings of frequency response and dB levels. This can be done thanks to our Audio Precision audio analyzer and anechoic microphone chamber.
5. For some mics, phantom power works even when batteries are removed. Try this with the Sennheiser K6 preamp, Sony ECM lavs 55 through 77, and Sonotrim power supplies.
http://www.locationsound.com/proaudio/ls/tips/techtips8.html?id=86jqdQtH
by Ron Meyer, President, Professional Sound Corp.
Thirty years have gone by since Bell Telephone Laboratories, NBC, and CBS joined together to develop and standardize the Volume-Unit meter. The VU meter as we commonly know it, has remained unchanged since its introduction and is widely used in the audio field, even today. Though the VU meter has been in use for a long time, many people still have misconceptions about its properties and use.
The VU meter was designed to have ballistics (dynamic characteristics) that roughly approximates the human ear. In this manner the meter proved useful in determining signal levels for audio broadcast and recording. The meter itself has a response that is RMS or “average” reading. This stipulates that it will respond with a reading that averages out the complex wave forms that typically make up an audio signal, and this can lead to problems when recording audio that is of a transient nature. The transients may have a peak level that is 10 to 15 dB higher than average and are virtually ignored by the VU meter, thus causing overload during recording. To compensate for this, many users and manufacturers incorporate a six to eight dB lead into the calibration of the meter. This in effect helps to overcome the transient response to the problems.
The VU meter is based on the telephone company’s 1939 reference level of zero dBm being equal to 1 mW into 600 ohms, or as the better known 0.775 volts into 600 W. This reference level was chosen by the telephone company as the best compromise between crosstalk and signal to noise ratio in their system. It should be noted that the VU meter is a relative reading meter in that its zero is always relative to some other standard such as +4 dBm outputs on today’s audio gear.
Even though the quality of electronic equipment has improved dramatically over the past 50 years, these early standards developed by the telephone companies are the basis for most electronic measurements used today.
http://www.locationsound.com/proaudio/ls/tips/techtips11.html
A majority of the production dialogue recorded in major “Hollywood” theatrical productions and television series is miked from overhead, utilizing either a fishpole or studio boom.
Overhead miking provides a natural sound. Normal sound effects and some background ambiance are also picked up, and at a lower relative level than the dialogue, thus rounding out the total track. One of the big advantages of shotgun mics is the ability to capture sound with perspective. The sound perspective matches camera perspective when the boom mic is able to get in close on tight shots, and is further away on longer shots.
In contrast, the use of lavaliers and radio mics produces dialogue that is often sterile in texture – lacking natural sound effects and ambiance. Perspective is always forced and “close-up” – regardless of camera angle. Audio is often subject to abrupt changes in presence, such as those caused by talent turning their head off-axis to the lav, or leaning over a hard surface (such as a desk or podium). Last, though surely not least, lavaliers are prone to distracting clothing noise and other interference.
A good technique is to follow the same approach towards dialogue recording as practiced by feature mixers: Use lavaliers with discretion and take advantage of overhead miking as much as possible.
Microphone selection plays an important role in overhead miking technique, along with choosing a skilled and experienced boom operator. Just like camera lens focal length, there is no one choice of specific microphone that will be right for all situations. A professional package should include an assortment.
It cannot be over stressed that, for best results, only the highest quality condenser microphones – such as those discussed in this catalog section – should be used in capturing dialogue. Although most electret condensers are very good microphones for their price and features, they simply do not perform as well as condensers for professional or theatrical dialogue applications. Top of the line condensers offer superior reach and sensitivity over the electrets, and that can spell out the difference on those more demanding shots between getting ‘rich’ dialogue versus ‘weak’ or ‘thin’ audio.
Allow the extra room in the budget to purchase or rent a package of true condenser microphones along with the proper accessories (power supplies, shockmounts, blimp windscreens) to make them work.
Similar to telephoto lenses, shotgun microphones tend to compress the distance between foreground and background. Avoid pointing the mic as if it were a rifle, unless you are totally unconcerned about bringing up the background. Be careful of what is in the “line of sight” behind the talent.
The best way to eliminate this “telephoto” effect is to aim the mic down from above, so that the only “background” in the microphone line of sight is the silent ground.
The most popular microphones for exterior use are long shotgun microphones. Long shotguns offer narrow pick-up patterns and excellent sensitivity and reach. Deployed overhead of talent, tilted just slightly towards the mouth – these mics will eliminate considerable background ambiance while still picking up natural sound effects such as footsteps and hand business. Because of their directionality, these long shotguns can be played at greater headroom above the actor when necessary (up to several feet depending on ambient noise), thus facilitating the wider frames more common on exterior set-ups.
The disadvantages of the long shotgun are its directionality and physical dimensions. The narrow pick-up pattern requires that much more care be taken in cueing (aiming). Moving talent must be meticulously followed; multiple talent requires rapid and precise repositioning of the mic for each person’s lines. The physical length sometimes becomes a problem, for example, in interiors with low ceilings.
The extended length of the shotgun is usually not a problem when working outdoors, although situations may arise where a shorter mic is necessary. Weight, on the other hand, can be a definite problem. Do not underestimate the strength and stamina required to manually support a fully extended fishpole complete with shotgun mic, shockmount, and windscreen over the course of a long day!
The short shotgun is characterized by its more manageable length and wider pick-up pattern (supercardioid or hypercardioid). The somewhat wider (though still very directional) pattern makes it easier to follow, or cue the talent. On the other hand, the effective working range (maximum distance) of the mic is diminished. Also, the wider pick-up pattern tends not to isolate talent from ambient noise as well as the long shotgun.
Interior situations pose an entirely different set of problems for the sound mixer. It becomes a question of striking a balance between reach versus acoustics.
Shotgun microphones with interference tubes tend to exhibit loss of definition when used in confined, hard-walled interiors such as kitchens, bathrooms, small offices, and so on. This phenomenon is caused by reflected sound waves interfering with the acoustic noise canceling principles employed with the interference tube.
The solution is to use the wider angle condenser mics without interference tubes. The problem is that these wider angle mics (cardioids and hypercardioid) also have less reach. It becomes a matter of trade off between choosing the crisp sound offered by the wider pattern mics versus getting the reach needed to isolate dialogue from the background noise due to higher distances often demanded by the camera angle. Pick your poison.
Very popular condenser microphones offered at LSC include: AKG, Audio-Technica, Beyerdynamic, Neumann, Schoeps, Sanken, and Sennheiser.
http://www.locationsound.com/proaudio/ls/tips/techtips8_6.html
by Edwin J. Somers, CAS
In this article, we will discuss frequencies available for wireless microphones in the United States. We are seeing a tremendous increase in the use of wireless and a decrease in frequency availability. This is causing an increase in congestion among wireless users as well as an increase in interference from other users, legal and otherwise.
The frequencies available for wireless use include the hydrological band 169-172 MHz, the VHF television band channels 7 through 13, 174-216 MHz, and the UHF television band channels 14 through 67, 470-794 MHz. Not all UHF channels are available in all areas.
We are allowed to transmit on these frequencies as secondary users. This means if we get interference from the primary users, such as the broadcasters, we must move to another frequency.
The FCC has allocated the broadcasters licenses to operate HDTV transmitters on the UHF television band. This effectively makes these channels unusable for radio mics because of the uniform distribution of power on each channel, as well as the tremendous power levels involved. We are going to see more and more HDTV stations on the air as we approach the deadline for startup.
I am often asked what the industry is doing about the loss of spectrum, and I do not see any efforts to obtain or reserve spectrum. I think the primary reason is the fact that, as operators, we are not required to have a transmitter license except under specific circumstances. In the eyes of the Federal Communications Commission, if we do not have a license, we do not exist.
The one thing that is happening is that manufacturers are offering very effective multi-frequency or frequency-agile systems which work exceedingly well in harsh interference environments.
The transmitting power for VHF transmitters is limited to 50 mw (milliwatts) in the United States, and 250 mw for UHF. Most manufacturers limit their UHF transmitters to about 100 mw due to the reduced battery life of a higher power transmitter. Some high power transmitters are offered with multiple batteries.
When operating multiple transmitters, frequency coordination is mandatory. With single channel transmitters, it was not much of a problem because the vendor usually coordinated the frequencies. With frequency-agile systems, some form of field coordination is required. All manufacturers have developed coordinating software for their respective systems and will readily assist users with coordination, as will the vendors. Some of the manufacturers even offer the software to the end users. Now how convenient is that?
http://www.locationsound.com/proaudio/ls/tips/techtips13.html
The ANTENNA Factor
The CABLE Factor
The RANGE Factor
IMPROVING RADIO MIC PERFORMANCE: THE ANTENNA FACTOR
by Edwin J. Somers, CAS
Let’s talk about ways to improve radio mic performance. Let’s start by talking about antennas. You already know that high gain antennas increase range. Well, how much better do they work? Let’s examine the facts. It would be difficult to put a high gain antenna on the transmitter in most cases, so we will look at receiving antennas. The whip antenna that comes with the receiver has a gain of 1 dBi (dBi stands for isotropic, and is used for the measurement of antenna gain). Ground plane and di-pole antennas have a gain of 3 dBi.
When you increase the received signal by 3 dBm, it is the same as doubling your transmitter power (dBm is used for the measurement of power). Wh
en you increase the received signal by 6 dBm, it is the same as quadrupling your transmitter power. Log Periodic antennas have 6 dBi or more gain.
Due to the losses involved in transmitting radio signals, you will get approximately a 20 to 25% increase in range when you double the power, or increase the antenna gain by 3 dBi. In physics, it is called the Inverse Square Law. You don’t need to understand the laws of physics; you just want to know how the performance will improve. The use of gain antennas is a very inexpensive way to increase range. In the case of beam antennas (Yagi and Log Periodic), you will have the added advantage of a directional antenna that can be positioned to ignore identifiable interference.
There is one instance where you can increase the gain of a transmitting antenna, and that is when using a VHF plug-on transmitter first developed by Lectrosonics. We have found significant improvement in range by adding a counter-poise antenna to the H series transmitters. This is nothing more than a thin 17″ stainless steel wire attached to a copper clad, one sided piece of circuit board material, strapped to the side of the transmitter (there is no direct connection, it is capacitively coupled).
Another very important rule is antenna polarization. If the transmitting antenna is vertical, then the receiving antenna should also be vertical. This is called vertical polarization. If the antenna alignment is off by 90°, the loss is infinite. You will only be receiving reflected signals. Obviously, antenna alignment will always be a compromise, so you should pay close attention to it. Receiving antenna height is almost always an advantage; the higher the better.
by Edwin J. Somers, CAS
As promised, the next few articles will discuss ways to improve radio mic performance. One factor and the focus of the first article, was on using a better antenna to increase range. Now we will be discussing how to get the radio signal from the antenna to the receiver.
The importance of using the proper transmission line cannot be stressed strongly enough. The term “transmission line” refers to any cable system used to transfer an electrical signal between pieces of equipment, a good example of which is an antenna cable. It is possible to use several different kinds of cable to deliver the signal from the antenna to the receiver; however, for radio mic applications, coaxial cable is the most effective. Coaxial refers to a design where there is a center conductor surrounded with an insulating spacer, which in turn, is surrounded with a shield. The main advantages of this design are convenience, and even more important, immunity from interference.
One of several issues with coax is characteristic impedance. For maximum transfer of energy, the impedance of the coax must match the antenna and the receiver. Almost all communications equipment is designed to be 50 W (Ohms) with the exception of television,
which is either 300 W or 75 W. Video cable is not suitable because it is 75 W, and using it for radio mics is one of the more common mistakes.
What would be the effect of using the wrong impedance coaxial cable? Unfortunately, wherever there is a change in impedance, there will be a reflection of the signal at that point. Reflections cause loss of signal strength and ringing. A good example is with television; reflections show up as ghosts in the image.
Another issue is design loss. Different models of coaxial cable exhibit different degrees of signal loss, and it is frequency dependent. The higher the frequency, the greater the loss. With VHF wireless, coax was not a major issue; however, with UHF it is.
Let’s look at some specific examples.
Manufacturers normally rate their cable by so many dBm of signal loss per unit length at specific frequencies. The most popular coax is RG-58. It is less than 1/4 inch in diameter, light, flexible, and inexpensive. Unfortunately, it is very lossy. A 100′ length of RG-58 coax at 400 MHz will attenuate the signal 11.5 dBm. At 700 MHz, the loss for 100′ is 17 dBm. You should realize that for every 3 dBm of loss, you cut your signal in half.
That’s a rather large amount of loss, isn’t it? Let’s look at the types of coax suitable for our application.
Type RG-58 RG-8 Belden
9913F IW&C
9096
O.D. Inch .193 .405 .405 .405
Impedance 50 ohms 50 ohms 50 ohms 50 ohms
Attenuation
dB/100 ft.
@ 400 MHz
11.5 dBm 4.1 dBm 2.7 dBm 2.7 dBm
Attenuation
dB/100 ft.
@ 700 MHz 17 dBm 6.5 dBm 3.6 dBm 3.6 dBm
The final issue is signal loss per unit length. All coaxial cable attenuates radio signals – the longer the cable the greater the loss. Since the loss is linear, if you double the length, you’ve doubled the loss.
So, what can we deduce from all this glark? You should use the shortest cable you can get away with, and you should use the lowest loss cable you are willing to put up with. You will notice from the chart that the low loss coax is thicker and, of course, stiffer than the small stuff. The low loss coax is available with BNC, PL-259 and “N” connectors. Location Sound stocks International Wire & Cable 9096 coax, and we can make cables in any desired length.
This is the third article in a series of ways to improve your radio mic performance. In previous issues, we discussed how using a high gain antenna with the proper polarization in conjunction with low loss transmission line (coaxial cable) will have a dramatic improvement on range. But what else can you do to maximize range?
The first thing you should think about is keeping a fresh battery in the transmitter. Manufacturers tell us that their transmitters have a 6 to 8 hour battery life, which is very true; however, in most systems, as the battery voltage drops, so does the transmitter power. The range will definitely drop off as the battery gets weak. When you want to maximize the range, change the battery after about an hour. Trying to stretch battery life is false economy, especially if you lose an important scene because of a weak battery.
Some manufacturers make high power transmitters. Typical power for VHF transmitters is 50 milliwatts. In fact, that is the maximum allowed by law. Typical power for UHF transmitters is 100 milliwatts. The maximum allowable power for UHF is 250 milliwatts. Some manufacturers do make 250-milliwatt UHF transmitters that will give you about a 4-dBm boost in signal.
UHF is slightly more efficient, so you will realize an increase in range just by switching away from VHF.
Switching to a diversity receiver will have an ‘apparent’ increase in range. I say apparent because the primary advantage of diversity receivers is to reduce drop outs; however, the net effect is an increase in usable range (which is the subject of another article).
I have been able to demonstrate a drop in signal (and range) when the transmitter is on one side of the performer and the receiver is on the other, at least with using UHF. This means that the radio signal must pass through the performer’s body and is partially absorbed by it. If the transmitter is placed on the performer’s back, then place the receiver behind them.
The final suggestion is to keep the transmitter gain adjusted properly. The mic gain adjustment controls the percentage of modulation of the FM radio signal. You want it as high as possible. By law, all transmitters have a limiter circuit to prevent over-deviation and co-channel interference. If you set the mic gain so high that it triggers the limiter, it will sound terrible. It is not designed to sound good. The trick is to adjust the gain so that it just triggers the limiter, and then back off a bit. Under normal conditions, you will not have to adjust it very often, only when you encounter a very loud or very soft-spoken performer. The important thing is to think about it each time you use the transmitter. When you maximize the transmitter gain, you get the best signal-to-noise ratio, which translates into greater range.
http://www.locationsound.com/proaudio/ls/tips/techtips16.html
by Edwin J. Somers, CAS
This is the third article in a series of ways to improve your radio mic performance. In previous issues, we discussed how using a high gain antenna with the proper polarization in conjunction with low loss transmission line (coaxial cable) will have a dramatic improvement on range. But what else can you do to maximize range?
The first thing you should think about is keeping a fresh battery in the transmitter. Manufacturers tell us that their transmitters have a 6 to 8 hour battery life, which is very true; however, in most systems, as the battery voltage drops, so does the transmitter power. The range will definitely drop off as the battery gets weak. When you want to maximize the range, change the battery after about an hour. Trying to stretch battery life is false economy, especially if you lose an important scene because of a weak battery.
Some manufacturers make high power transmitters. Typical power for VHF transmitters is 50 milliwatts. In fact, that is the maximum allowed by law. Typical power for UHF transmitters is 100 milliwatts. The maximum allowable power for UHF is 250 milliwatts. Some manufacturers do make 250-milliwatt UHF transmitters that will give you about a 4-dBm boost in signal.
UHF is slightly more efficient, so you will realize an increase in range just by switching away from VHF.
Switching to a diversity receiver will have an ‘apparent’ increase in range. I say apparent because the primary advantage of diversity receivers is to reduce drop outs; however, the net effect is an increase in usable range (which is the subject of another article).
I have been able to demonstrate a drop in signal (and range) when the transmitter is on one side of the performer and the receiver is on the other, at least with using UHF. This means that the radio signal must pass through the performer’s body and is partially absorbed by it. If the transmitter is placed on the performer’s back, then place the receiver behind them.
The final suggestion is to keep the transmitter gain adjusted properly. The mic gain adjustment controls the percentage of modulation of the FM radio signal. You want it as high as possible. By law, all transmitters have a limiter circuit to prevent over-deviation and co-channel interference. If you set the mic gain so high that it triggers the limiter, it will sound terrible. It is not designed to sound good. The trick is to adjust the gain so that it just triggers the limiter, and then back off a bit. Under normal conditions, you will not have to adjust it very often, only when you encounter a very loud or very soft-spoken performer. The important thing is to think about it each time you use the transmitter. When you maximize the transmitter gain, you get the best signal-to-noise ratio, which translates into greater range.
http://www.locationsound.com/proaudio/ls/tips/techtips16.html
A Little Info About Dynamic Microphones
Dynamic microphones used to be the basic workhorses of the film and video industries, although in more recent years there has been the changeover to electret condenser and condenser microphones. Nevertheless, dynamic microphones remain as important tools to the production sound mixer.
For starters, dynamic microphones can be counted on to work when other mics won’t. Dynamics require neither batteries nor powering of any sort. They are built extremely rugged, and are resistant to harsh climatic conditions including RF and electromagnetic interference.
Dynamic mics offer less sensitivity and reach, than electrets and condensers. This makes the dynamic mic unsuitable for most overhead dialogue applications.
On the other hand, this same lack of broad reach becomes a valuable asset in non-theatrical applications, such s when recording spokesperson commentary in high ambient noise environments. Dynamics are recommended for recording location narration, since they isolate voice extremely well from background sounds.
Dynamic microphones are also very useful for recording loud and sudden sound effects, such as crashes and explosions. Not only are these microphones virtually impervious to damage from high noise levels, but they also tend to compress or dampen the audio in such a way s to make these sounds easier for the recording electronics to handle.
When recording dynamic scenes, in which the actor is using a handheld microphone as a prop, it is better in most cases not to take the dialogue feed form that same mic. Actors may use their hand mics as objects to accentuate their visual performance, without regard for what their broad gesturing and handling may to do the sound. Instead, mic your pretend “stage performers” either from overhead from a fishpole or boom, or off a concealed lavaliere.
The outward appearance of most handheld mics can be easily and temporarily change merely by the use of colored foam windscreens and the addition of color shrink tubing over the sleeve of the mic.
From SoundWave – The Production Sound Newsletter.
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Microphones – Polar Opposites
The polarity of some condenser microphones that are made in Europe or for use with older film equipment may be opposite from that of mics made in North America. Reversed polarity typically is indicated by a small red dot painted on a mic’s barrel. If you try to use one of these mics switch video equipment and it seems dead, you may be able to make it work by placing a phase reverser in the line between the mic and the powering video equipment.
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
Alternative Mic Placement
During a recent roundtable meeting, I needed to mic a stenographer who was recording the proceedings; however, she didn’t want to hear the lavaliere, and I had no table mics. I folded an index card several times to create a stiff tab, slid it under the protective glass on the table where the stenographer was sitting, and attached her mic’s tie clip to it. To Keep the cords from her mic and the others from being tangled, all were taped to the underside of the table.
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
Attaching a Microphone to the Body
The problem: An actor in a live performance has to make several very fast costume changes. There’s not enough time to remove and replace his wireless body-pack microphone with each change.
The tip: The body pack can be hidden in the small of the actor’s back and held in place by an elastic bandage wrapped around his body. (Commercial holders with a pocket for the transmitter and Velcro-type closures are also available.) The microphone can be run up the back of his neck and hidden in the hair just above the forehead. Most lavaliere microphones are deigned with a built-in roll-off to compensate for the excess low-end frequencies that contact with the chest produces. Contact with the head produces almost the same low-end excess, and the microphone works very well.
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
Emergency Mic Holder
Kort Grydenborg of Gilford, Connecticut, read the tip in the March issue about using a tape dispenser as an emergency microphone stand and wrote in to say that he had come up with a different fix for the same problem. He solved his microphone emergency with a gaffer’s grip – a metal clamp that’s normally used to hold a small lighting instrument.
The Electrovoice RE-50 microphone is double-insulated to prevent contact noise from getting into the signal, but Kort provided further isolation by placing the gaffer’s grip on a mouse pad.
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
Caring for your Boompole
Some damages to bumpiness are the result of accidents and some, simply neglect. The only accidental damage that can be avoided is the abuse caused during shipping. One way to avoid this is to ship your boompole in an appropriate container, which can be of the commercially available type such as the fishing rod holders made my Plano available from Location Sound Crop,. or you may elect to make your own from 3″ or 4″ PVC pipe. Either way, your boompole is protected.
A majority of all boompole repairs stems from neglect. Most of the poles in use today are made of carbon fiber and/or fiberglass hybrids which are very tough and should provide many years of service IF GIVEN JUST MINIMAL CARE. The single most destructive element to guard against is dirt. When dirt gets into your pole, it acts like an abrasive and slowly cuts and wears away at the tubing and locking collars. In time, those collars will begin to fail, making cueing of a microphone impossible. If you are working in a dirty or dusty environment, your pole can be cleaned by simply extending it to its full length and wiping it down with a slightly damp rag. Make sure the pole is completely dry before returning it to its collapsed position for storage. Not e that the use of any lubricants is NOT recommended since this will attract more dirt and lessen the effectiveness of the locking collars.
The vdB (van den Bergh) line of boompoles can be disassembled by hand without the use of any tools. This allows you to thoroughly clean all of the locking collars and nylon guides. Also worthy of note is that the nylon collars used in these poles should be kept as dry as possible. Exposed to wetness, these collars absorb a small amount of moisture and expand, causing the pole to seize up. If you pole is accidentally dunked in water, it should be disassembled and allowed to dry out.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
How Do I Maintain My Microphones?
Microphones are precision, delicate instruments that require periodic maintenance much in the same way as Nagra recorders or wireless microphones. Various microphones have unique functional characteristics that require attention. Failure to maintain your microphones properly can result in poor frequency response, improper level, distortion, poor noise readings and a poor pick-up pattern.
For example, Sennheiser condenser microphones have a tunable oscillator circuit and an extremely critical RF discriminator adjustment. If either of these adjustments (made via variable coils) drift, performance of the unit suffers greatly.
Schoeps capsules contain two filter screens located between the inlet port and the diaphragm. These screens, intended to keep contaminates from reaching the membrane, inhibit optimum performance one they become congested with debris. Lavalier microphones, though generally less serviceable, should be checked periodically as well. Their tiny elements fall prey to the same afflictions as condenser microphones. Many lavaliere power supplies have active circuitry and need to have battery and ground contact checks.
All microphone should be checked regularly for reliable ground connections. Similarly, connector and contact surfaces should be inspected and cleaned. Routine inspection, cleaning and calibration are your best assurance to continued, trouble-free operation of your microphones.
From SoundWave – The Production Sound Newsletter.
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How Do I Select and Use My Lavalieres?
A lavaliere is generally defined as being any small microphone designed to be worn on a performer’s body. In the majority of cases. Lavalieres are omnidirectional in pattern they pick up sound in all directions). Modern lavalieres tend to be electret condenser in design, which allows them to be highly sensitive to a full frequency of sounds, and also facilitates miniaturization.
Up until recently, lavalieres could best be described as “proximity” oriented – that is, they work best when the sound source is close to them. Thus, when these lavalieres are employed in the normal manner, they tend to favor the close, or dominate source, and downplay background ambiance.
This “close -up” sound, emphasizing the voice and holding back the ambiance, has long been associated with lavalieres, and is both their strength and their weakness.
Some of the problems that may be encountered with lavalieres include the difficulties of hiding them under clothing, clothing noise, wind noise and the loss of audio perspective in relation to the camera (the dialogue always sounds “close-up” regardless of framing).
Lavalieres may be used as either “hardwire” or “wireless”. Hardwire means that the actors are physically connected via audio cable to the mixing panel or recorder. Wireless refers to plugging the lavaliere into a small transmitter and broadcasting the signal back to the receiver, which, in turn, feeds an audio signal into the mixing panel or recorder.
Regardless of whether the signal is conveyed by wire or radio, the microphone capsule remains the same!
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
How do I make lavaliere microphones “noise free”?
One of the ever-present difficulties in hiding lavalieres under wardrobe is clothing noise. In actuality, there are two different causes of “clothing noise”: Contact noise and Acoustic noise.
Contact noise is the result of garments rubbing against either the mic capsule itself or the leading few inches of cable (equally sensitive to friction). Contact noise can usually be controlled – if not completely eliminated – by careful positioning and taping down of the mic and cable.
Begin by securing the clothing on both sides of the mic capsule. This can be done by sandwiching the mic between two sticky triangles of cloth, camera, or gaffers tape. Form these triangle by folding a few inches of 1″ wide tape corner over corners, similar to folding a flag.
By immobilizing the mic between both layer of clothing, you have eliminated the possibility of either layer of clothing rubbing against or flapping onto the microphone.
If the lavaliere must be positioned between skin and clothing, or attached directly to the skin, then a professional medical/surgical tape should be used against the skin.
Once the mic capsule has been secured, the next step is to for a strain relief for the thin cable. Make a small loop just under the mic capsule. In the case of very sensitive mics, such as the Sony ECM-77, the Sennheiser MKE2, and the SankenCOS-11, make the loop goes around twice. Tie a small thread or use a thin strip of camera tape (sticky side out) to preserve the loop. Tie the loop loose enough so that it can “Breathe” (change diameter to absorb tugs).
Apply a few inches of tape along the cable below the loop. Any tension on the cable will be absorbed by the garment, rather than by the microphone (which is somewhat isolated by the floating loop).
The remainder of the mic cable can be run under clothing and can terminate either at the waist or the ankle. The end of the mic connector should be secured so that it does not dangle freely.
During a take it becomes a simple matter to plug in an extension XLR cable. Afterwards , the talent can easily be disconnected so that he or she is free to roam around.
When using an external “tie clip”, it is still important to think in terms of creating a strain relief. Loop the thin cable up and under the tie clip, forming a semi-circle , and passing through the wide hinge of the clip. Continue the loop behind the garment, and bring the cable around downward, thus completing the circle. As the cable loops downward, it should be inserted between the jaws of the tie clip and the back of the garment Hide the balance of the cable behind the wardrobe. SEE PHOTO FROM PG 83 FROM LOCATION SOUND CATALOG.
Not only is this arrangement more pleasing to the eye than a dangling cable, but the floating loop of the cable isolated the mic while the grip of the tie clip serves as a strain relief.
Acoustic clothing noise is the sound generated by the clothing itself as garments or layers rub against each other when the actor moves. Noise is much more prevalent from synthetic fabrics than from natural cottons or wools. There is no simple remedy, only prevention, so it is wise to consult early with the wardrobe department.
However, there are a couple of tricks that may help. Anti-static sprays, such as Static Guard, will reduce static electric discharge, clinging, and reduce friction. Dry silicon spray lubricants sometimes help, but be careful of staining. Stiff or starched clothing can be softened with water or alcohol (make sure the colors don’t bleed). Saddle soap, silicon, or light oil can take the bite out of hard leather.
Another noise problem common to lavalieres is that of wind noise. Manufacturers usually supply small foam or metal mesh windscreens with their lavalieres, but these are usually more effective against breath pops than against outdoor gusts of wind.
Lavalieres used under clothing have the advantage of being partially shielded from the wind, but may still require added protection.
Clothing rubbing against windscreens can be extremely noisy, so great care must be taken when using hidden lavalieres out of doors. Surrounding the windscreen with sticky tape and securing it to both layers of clothing, as you would a bare mic, will reduce the friction noise. However, the tape may destroy a foam windscreen with it is removed! Inexpensive, expendable windscreens can be make by wrapping the mic in acoustafoam; or by pulling the foam booties off of video cleaning swabs.
Cheesecloth over a mic works very will against wind. Another Hollywood variation is to snip the fingertips off children’s woolen gloves, and pull the wool tips over lavaliere wrapped in foam or cheesecloth.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
About ENG Shotgun Mics
The phrase “ENG shotgun” has come about as an informal means of referring to moderately priced (compared to true condensers) directional microphones. All of these microphones are commonly described as permanently polarized, fixed charge, or electret condenser design.
Electrets are definitely a major step up from dynamic mics and are suitable for ENG, corporate, and other applications where budget, convenience, ruggedness, and self-contained mic power may be important.
Unlike regular condensers that require higher voltages to operate (12 to 48 volts), these electret mics require only a the microphone body provides the necessary power. Since the electret condenser microphone is self-powered, it can be plugged directly into the regular low impedance “dynamic” mic input of professional mixers and recorders.
We do believe it is important to point out that, although all of these ENG shotguns offer excellent value for their moderate price, they do not offer the high sensitivity and extended reach of the more sophisticated (and more expensive) condenser models.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
Selecting a Microphone
A majority of the production dialogue recorded in major “Hollywood” theatrical productions and television series is miked from overhead, utilizing either a fishpole or studio boom.
Overhead miking provides a natural sound. Normal sound effects and some background ambiance are also picked up, and at lower relative level than the dialogue, thus rounding out the total track.
Perspective matches camera angles, since the boom mic is able to get in closer on tight shots, and is further away on longer angles.
In contrast, the use of lavalieres and radio mics produces dialogue that is often sterile in texture – lacking natural sound effects and ambiance. Perspective is always forced and “close-up” – regardless of camera angle. ?Audio is often subject to abrupt changes in presence, such as those caused by talent turning their head off-axis to the lav, or leaning over a hard surface (such as a desk or podium). Last, though surely no least, lavalieres are prone to distracting clothing noise and other interference.
A good technique is to follow the same approach towards dialogue recording as practiced by feature mixers: Use lavalieres with discretion and take advantage of overhead miking as much as possible.
Microphone selection plays an important role in overhead miking technique, along with choosing a skilled and experienced boom operator. Just like camera lens focal length, there is no one choice of specific microphone that will be right for all situations A professional package should include an assortment. It cannot be over stressed that, for best results, only the highest quality condenser microphones – such as those discussed in this section – should be used in capturing dialogue. Although most electret condensers are very good microphones for their price and features, they simply do not perform as well as condensers for professional or theatrical dialogue applications. Top of the line condensers offer superior reach and sensitivity over the electrets, and that can spell out the difference on those more demanding shots between getting ‘rich’ dialogue versus ‘weak’ or ‘thin’ audio.
Allow the extra room in the budget to purchase or rent a package of true condenser microphones along with the proper accessories (power supplies, shockmounts, blimp windscreens) to make them work.
Similar to telephoto lenses, shotgun microphones tend to compress the distance between foreground and background. Avoid pointing the mic as if it were a rifle, unless you are totally unconcerned about bringing up the background. Be careful of what is I the “line of sight’ behind the talent.
The best way to eliminate this “telephoto” effect is to aim the mic down from above, so that the only “background” in the microphone line of sight is the silent ground.
The most popular microphones for exterior use are long shotgun microphones. Long shotguns offer narrow pick-up patterns and excellent sensitivity and reach. Deployed overhead of talent, tilted just slightly towards the mouth – these mics will eliminate considerable background ambiance while still picking up natural sound effects such as footsteps and hand business. Because of their directionality, these long shotguns can be played at greater headroom above the actor when necessary (up to several feet depending on ambient noise), thus facilitating the wider frames more common on exterior set-ups.
The disadvantages of the long shotgun are its directionality and physical dimensions. The narrow pick-up pattern requires that much more care be taken in cueing (aiming). Moving talent must be meticulously followed; multiple talent requires rapid and precise repositioning of the mic for each person’s lines. The physical length sometimes becomes a problem, for example, in interiors with low ceilings.
The extended length of the shotgun is usually not a problem when working outdoors, although situations may arise where a shorter mic is necessary. Weight, on the other hand, can be a definite problem Do not underestimate the strength required to manually support a fully extended fishpole complete with shotgun mic, shockmounts, and windscreen over the course of a long day!
As mentioned before, there are situations when a long shotgun may not be the microphone of choice due to size, weight, or narrow degree of pick-up.
The short shotgun is characterized by its more manageable length and wider pick-up pattern (supercardioid or hypercardioid). The somewhat wider (though still very directional) pattern makes it easier to follow, or cue the talent. On the other hand, the effective working range (maximum distance) of the mic is diminished. Also, the wider pick-up pattern tends not to isolate talent from ambient noise as well as the long shotgun.
Interior situations pose an entirely different set of problems for the sound mixer. It becomes a question of striking a balance between reach versus acoustics.
Shotgun microphones with interference tubes tend to exhibit loss of definition when used in confined, hare-walled interiors such as kitchens, bathrooms, small offices, and so on. This phenomenon is caused by reflected sound waves interfering with the acoustic noise canceling principles employed with the interference tube.
The solution is to use the wider-angle condenser mics without interference tubes. The problem is that these wider-angle mics (cardioids and hypercardioid) also have less reach. It becomes a matter of trade off between choosing the crisp sound offered by the wider pattern mics versus getting the reach needed to isolate dialogue from the background noise due to higher distance often demanded by the camera angle.
Very popular condenser microphones offered at Locations Sound include AKG, Audio-Technica, Beyerdynamic, Neumann, Schoeps, and Sennheiser.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
About Foam Windscreens
Foam windscreens and pop filters are intended to provide protection against low velocity moving air, such as would be encountered from performers exhaling onto the mic. Foam windscreens also protect sensitive condenser mics against the motion of room air caused by normal ventilation ducts as well as from the physical act of moving the microphone while mounted on a boompole.
Although some handheld performance mics come equipped with built-in wind or pop protection, condenser microphones should never be used without a protective windscreen!
Do not expect a foam windscreen to function adequately out of doors even on calm days, there will occur occasional soft gusts of wind that will penetrate the foam and cause audio overload. Employ a blimp type windscreen, such as a Rycote. However, it is beneficial to use a slim foam windscreen inside of the blimp, providing that at least ½” or more of airspace remains between the foam and the inner walls.
Foam windscreens also provide a quick means of altering the color and appearance of microphones. Some sound mixers place a white band of tape around the front tip of the windscreen. This facilitates the camera operator identifying the microphone through even a dim viewfinder, where otherwise it might go unnoticed until brightly projected during dailies.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
Free Production Music!
If you desire an easily recognizable song for your video, but you don’t have a budget for using copyrighted music, you might want to consider music from the public domain.
For more information about the public domain, a list of songs in the public domain, and links to other related sights, go to: http://www.bright.net on the web. The site contains a wealth of information. If you still have questions after reading all the information available, you can always leave questions via e-mail.
Bryan Mecklenburg
Hudsonville, Michigan
From: Videomaker
May 1997
Wedding Audio Insurance
If your camcorder has a stereo mike input jack, you can record wedding ceremonies with both a wireless mike placed on the groom, and a zoom mike mounted on the camcorder.
Using a cable with a 1/8-inch stereo mini plug on one end and two mono 1/8-inch jacks at the other end, two sound sources can be recorded simultaneously, each in synch with the video.
For the final edit, you will have at your disposal general sound from the zoom mike mounted on camera and close-up audio of the exchange of vows recorded through the wireless mike.
If you discover later that the wireless mike has static or drop-out, or that you were too far away for your zoom mike to be effective, don’t seat it. You have a back up!
Jeff Goldberg
Manalapan, New Jersey
From: Videomaker
March 1997
About Equalization
Although the temptation is often great, the novice production sound mixer should avoid attempting to “improve” location soundtracks by means of equalization. Adjusting the highs, mid-range, and bass from shot to shot may sound fine in the headphones, or even in dailies, but when shots are intercut during the editing process, changes in voice and backgrounds often become annoyingly apparent.
Any equalization one chooses to employ during the course of the productions should remain consistent throughout the audio tracks. For instance, some mixers like to add a pinch of mid-range boost to enhance the clarity of the dialogue- and this same setting is used virtually all of the time, regardless of actor or location.
It is common for mixers to “roll off” excess bass, since the extreme low frequencies contain rumble and wind noise. Low frequencies are often not accurately reflected by many audio level meters, and low frequency noise can contribute to overload distortion. On interior sets, use a mild bass “roll off”, around -6dB at 90 Hz. Exteriors often cal for a more sever low cut, around -6 dB at 150Hz.
Finally, use EQ sparingly. If in doubt, leave everything in the “normal” positions. Any EQ changes that are necessary to improve the track are best left for post-production, where “improvements” can be timed, rehearsed, previewed, and undone when they don’t work!
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
AC Power
A few words on the improper use of household wiring (110 Volt AC power) on the set. Our Service Department is seeing an alarming increase in the number of mixing panels that have been subjected to 110 volt AC on their line outputs. Depending upon how the mixer is wired, exposure to 110 volt AC can produce damage range from something as minor as a blown fuse all the way to the total destruction of the mixing panel.
I’ll bet I have your attention now!
The scenario I am referring to is sending an audio feed to a video assist system. In the past, it wasn’t much of a problem because most sound mixers used Nagra based battery powered systems. With the increased demand for R-DAT based recording systems and their accompanying increased power demands, we see more people resorting to AC to power their equipment. This means that the recording channel is grounded, and if there is a wiring error in the AC feeding the Video Assist or in the Video Assist system itself, the potential for disaster is set.
My recommendation is never ever send a hard wired feed to anything running on AC power without an isolation transformer like the Sescom IL-19, or better yet, send the audio out using a Comtek or any other wireless system, and the potential for this problem is eliminated.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
UHF Provides Significant Advantages Over VHF
In recent years the Federal Communications Commission (FCC) has seen fit to open up the UHF frequency range for wireless mic use. Frequencies between 450 and 960 MHz are now available, and are being used to full advantage by such major manufacturers as Sennheiser and Cetec-Vega.
The uncrowded nature of this frequency range, as opposed to the cramped quarters of the VHF band, have made one-time frequency placement problems a thing of the past. Television stations on UHF are a much more rare commodity than those on VHF, so potential interference from our TV colleagues has been reduced drastically.
Also, the sheer number of available frequencies reduces potential interference. These, along with the manufacturers using slot frequencies whenever possible, have made UHF radios the choice of may professionals in the audio field.
Don’t get us wrong, potential problems do exist. In the Location Sound Corporation Rental Department, we always find out where our customers are using their wireless. But with UHF, it takes only a quick glance on a frequency map as opposed to the sometimes extensive scheduling and coordination problems faced VHF.
Other advantages of UHF include and FCC approved 150-milliwatt transmitter versus a 50 watt maximum for VHF (great for stage use).
All of us in the Rental Department are certainly sold on the new generation of UHF wireless mics. Their performance, dependability, and well though out features make them a problem-free rental item. The next time you need wireless, try UHF. Give us your critique. We’re sure you won’t be disappointed.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
About Wireless Transmitter Input Gain
The transmitter input gain is the single most important adjustment on any wireless mic system to insure optimum signal to noise ration. The audio signal to noise ratio will never be any better than it is at the transmitter input. If the input signal is noisy at the transmitter, there is nothing else that can be done later to restore it to its original quality. The audio level is adjusted with the gain control on the transmitter, with some sort of level metering on either the transmitter or receiver.
The most difficult problem with properly adjusting the transmitter input gain involves duplicating the user’s voice level in advance of the actual performance or use. Obviously, you need some sort of metering in order to correctly set the transmitter input gain. The metering must indicate the modulation level of the radio signal and also limiting in the transmitter. All Lectrosonics Pro Series transmitters provide LED level metering for this purpose. Metering is also provided on the receivers, but often times the transmitter metering is easier to use, since the receiver may not be accessible or visible from the transmitter during setup.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
All About Wireless Companding
Many of today’s more popular wireless microphones such as he Vega Dynex III and the Sennheiser HIDYN rely on analog companding to increase their dynamic range.
Companding is a term used to describe the compression and re-expansion of an audio signal. Both Vega Dynex III and Sennheiser HIDYN work in a similar fashion: The incoming audio signal is compressed in the transmitter, used to modulate the RF carrier, and again transmitted. Upon reaching the receiver, the audio is detected (separated from the RF signal) and expanded to its original amplitude. Although it seems quite simple, the process requires that all compression and expansion rate be precisely matched.
The use of companding in wireless mics allows greater dynamic range without the need for increased RF carrier deviation. This pleases both the sound mixers and the FCC.
It should be noted that the compression portion of these companding circuits is independent from the externally adjustable compressor limiter (affecting microphone gain) found on most wireless equipment. Due to the precision matching required, Dynex III and HIDYN circuitry are not user adjustable.
However, because the compressor limiters are externally adjustable on the transmitter, poor dynamic range and/or distortion can occur as a result of misinformed use. This user adjustment is made via the mic gain control and should be set so that the loudest expected portion of audio just activates the limiter – which is generally indicated by meter deflection or a lit LED.
Normal audio should remain low enough so as not to trigger the built-in limiter. Desired increases in gain can be achieved by raising the input level at the mixing panel or recorder, rather than by increasing the mic gain on the transmitter. A few minutes spent properly adjusting mic gain & limiter with regard to vocal attributes of the talent will greatly improve recordings.
Microphones are precision, delicate instruments, which require periodic maintenance much in the same way as Nagra recorders or wireless microphones. Various microphones have unique functional characteristics which require attention. Failure to maintain your microphones properly can result in poor frequency response, improper levels, distortion, poor noise readings, and a poor pick-up pattern.
For example, Sennheiser condenser microphones have a tunable oscillator circuit and an extremely critical RF discriminator adjustment. If either of these adjustments (made via variable coils) drift, performance of the unit suffers greatly.
Schoeps capsules contain two filter screens located between the inlet port and the diaphragm. These screen, intended to keep contaminates from reaching the membrane, inhibit optimum performance once they become congested with debris.
Lavaliere microphones, though generally less serviceable, should be checked periodically as well. Their tiny elements fall prey to the same afflictions as condenser microphones. Many lavaliere power supplies have active circuitry and need to have battery and ground contacts checked.
All microphones should be checked regularly for reliable ground connections. Similarly, connector and contact surfaces should be inspected and cleaned. Routine inspection, cleaning, and calibration is your best assurance to continued, trouble free operation of your microphones.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
Applications and Types of Wireless Microphones
Wireless microphones can be categorized as handheld, body pack, or plug-on; VHF or UHF; and diversity or non-diversity.
Hand helds refer to the hand held microphones that have transmitters built into them. They are popular for vocalists, and variety stage performance. Body packs consist of transmitters only and can be thought of as “wireless cable” rather than “wireless mics,” since any microphone (with the appropriate adapter cable) may be plugged into them. Body pack transmitters are generally used with lavaliere microphones. Wireless units can also be used with a condenser mic on a fishpole or a stationary mic planted on the set.
Wireless mics can be VHF or UHF. Most professional units share the upper VHF television bands (TV channels 7 through 13). If you expect to be shooting out of town or on the road, make sure there are no local TV stations broadcasting on the same frequency as your radio mics. For instance, manufacturers’ designated (A) “traveling” channels (169-172MHz) are popular for use in most places across the United States.
Wireless microphones are available in the UHF frequency range. The UHF frequencies, compared to VHF, are less susceptible to most common sources of radio interference. A greater number of UHF units can be operational at the same time without cross interference, a definite advantage when doing stage and variety work. Another advantage of UHF is that the transmitter antennas on the body packs are very short and do not require careful rigging to the actor’s clothing.
“Diversity” receivers work on the principal of switching between two receivers, with antennas placed at least ¼ wavelength apart. The diversity unit compares the incoming signals continuously, and instantly switches to the better signal, thus eliminating “drop outs” or dead spots.
Without question, the most difficult aspect in using radio mics is correctly attaching them to the body of the actor or actress.
Body pack transmitters can be hidden almost anywhere. The most common sites include the small of the back, rear hip, inside thigh, ankle, pants pocket, and inside chest pocket of a jacket, or in the heroine’s purse. When talent is wearing a scant bathing suit, for example, radio mics can sometimes be hidden under straw hats, or even on the back of the neck under long tresses of hair. Leg warmers provide a convenient place to hide radio mics when dealing with exercise attire.
There are a number of ways transmitters may be secured. Belt clips work fine under a jacket or loose top. Special pouches or pockets can be pinned (or permanently sewn) into wardrobe. Sometimes it is possible to merely hang the unit with a safety pin that has been tapes onto the transmitter casing. Specially constructed elastic belts known as belt and pouch kits, such as those manufactured by PSC, can be worn around the waist, thigh, calf, or ankle. Transmitters can be also held in place by elastic bandages.
Any time camera and gaffer tape is used, special care must be taken not to tape directly to skin or delicate wardrobe (such as nylon stockings). Fold the tape over itself to form a non-adhesive strip to wrap around first. Better yet, use some sort of liner, such as a strip of cloth. Avoid placing the transmitter directly against the skin; since body moisture tends to interfere with (absorb) the outgoing signal.
Care should be taken in securing the flexible transmitter antenna cable. To prevent the antenna from being torn from its connector the first time the actor moves or bends over, use a rubber band to provide elastic strain relief. Attach one end of the rubber band to the tip of the antenna. The free end of the rubber band can be safety-pinned to the clothing or taped in place (use medical tape on skin). Thus, the antenna can be maintained reasonable straight (a little bit of slack is okay) yet protected against damage.
The transmitter antenna can be run vertically up or down from the body pack. However, if the antenna trails downward, then the transmitter should be mounted in an inverted position to avoid making a loop in the Antenna. The transmitter antennas can also be run horizontally, such as partially around the waist. However, in these instance, the receiver antenna may need to be tilted sideways (matching the angle) to improve reception.
Under no circumstances should the mic line and antenna wire ever cross. This will definitely reduce your range. Run the mic cable out from the body pack in the opposite direction of the antenna. When the transmitter is mounted on the body upside down (the antenna running downward), it is okay for the mic line to loop upward, as long as it doesn’t cross the antenna. Install a fresh battery in the transmitter every time you use it. It sounds like a detail that should be obvious, but all too often, radio mic problems boil down to a weak battery in the transmitter. Change the battery frequently – every four to six hours with most brands.
There are a couple of ways to soften the problem of forced close-up perspective. The first is to select a lavaliere with an open sound, such as the PSC MiliMic, Tran TR-50 or Sennheiser MKE-2, rather than a lavaliere that tends to isolate, such as the Sony ECM-55. Another solution is to attach the lavaliere a little lower on the body than usual. When there are two people playing close to each other, it sometimes helps to mic each person off of the opposite person’s microphone.
The antenna of the receiver should initially be adjusted to match the angle of the transmitter antenna. Then experiment with changing the angle, for sometimes an unusual condition on the set may favor an odd combination of antenna angles to yield best signal.
A clean line-of-sight between receiver antenna and transmitter is important, since almost any object or body and deflect or absorb the RF signal. Mounting the receiver on a wooden ladder usually helps.
Wireless mics come equipped with one of two forms of receiver antenna: the straight wire “whip”, or the shorter helical “rubber ducky”. The straight “whip” will yield the best reception, although the “rubber ducky” offers more convenience in terms of mobility.
There are some special antenna systems that can be used to improve reception. Directional antenna systems can be used to reject radio interference, when the source is identified. High-gain antenna systems can significantly increase the range of most wireless mics.
Anytime the receiving antenna is separated from the receiver, care in selecting low loss cable becomes important. 50 ohm RG-58U is a standard cable, however it has significant loss especially at higher frequencies, keep the cable length as short as possible, and select lower loss cable for longer cable runs and higher frequencies.
Strive to maintain minimum distance between the transmitter and receiver. Move the receiver/antenna from shot to shot in order to achieve close and clean line-of-sight placement. Don’t’ be afraid to locate an antenna just outside of camera frame, or even to conceal it behind a prop right in the shot or set itself.
Sometimes, it maybe expedient to have the boom person or third person physically carry the entire receiver during the take in order to maintain proximity with the actors. Given the option, it is better to run long lengths of audio cable (from receiver to recorder) than to have long lengths of antenna cable (from antenna to receiver).
Virtually anything can interfere with good radio transmission and cause bursts of static. Check for metallic objects of any kind, such as jewelry, zippers, coins, and keys. If you cannot eliminate the metal, then at least reposition the antenna on the actor.
Carefully look at the path of transmission between the actor and the receiver. Pay attention to lighting or grip stands that may suddenly have appeared. A new influx of crewmembers or spectators can also block the RF signal.
Examine the location itself. Check for additional electrical lines, especially coiled feeds, which can generate magnetic fields. Dimmers and special effects equipment (especially neon) are always a problem. Motors can produce interference: Be aware of golf carts, forklifts, camera cranes, automobiles, and kitchen appliances.
Video and computer equipment can create strange fields. Be aware of Steadicams and other camera mounts relying on high intensity video or radio-controlled camera functions.
From: Location Sound Corporation
http://www.locationsound.com
800-228-4429
Does the cable of the lavaliere microphone that you have clipped to your subject’s tie keep popping out from behind the tie? Try running the cable through the loop formed by the label that is sewn onto the back of the tie.
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
If you work as a one-person video crew and need to record audio delivered at widely varying volumes, Joe Salerno of Bellaire, Texas, suggests running a normal audio level on one track and setting a second track considerably lower. (Most professional video recorders have more than one audio track.) If the first channel peaks too high, you’ll still have a good chance of getting a usable signal from the backup channel.
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
While I was working on a documentary recently, the director asked me to record the chatter on the intercom system. A check with Clear-Com, the intercom company, yielded a schematic for an interface with a line-level recorder input. Clear-Com warns, however, that plugging it into a microphone-level input can cause problems with the intercom system.
The parts were small, and I was able to build the entire unit inside a Switchcraft XLR3f-to-Phono male adapter.
From:From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
Wig tape is a very thin, double-sided adhesive tape normally used -you guessed it – to keep wigs on people’s heads. But it is also handy for videographers. Mike Saxton of Lutz, Florida, uses it to secure small lavaliere mics in actors’ clothing. He says the tape also keeps clothing layers from rubbing against each other an making airborne noise that could be picked up by the mic.
I’ve also found that a piece of wig tape will keep an actor’s wayward necktie centered an looking neat.
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
The most common kind of microphone is the handheld type. This style is the most flexible, because it can be held by the user, mounted on a floor or desk stand, or attached to a flexible “gooseneck” on a lectern. A good quality handheld mic should have an internal shock mount which will minimize handling noise (thumping sounds transmitted through the handle and picked up by the microphone cartridge), and it should be ruggedly constructed to withstand physical abuse. If you can have only one microphone in your kit of audio gear, it should be a handheld mic. Models at the upper end of the price scale will usually offer clearer, wider-range sound, better shock mounting, and more durable construction.
Tips:
Whether held in the hand or mounted on a stand, the microphone should be positioned about 6-12 inches from the talker’s mouth, pointing up at about a 45-degree angle. With some types of microphones, holding the microphone very close (3-6 inches) will cause additional emphasis of the lower frequencies (known as proximity effect), resulting in a “warmer,” bass-heavy sound.
From: Shure – Guide to Better Audio
Written by Christopher Lyons
Another popular mic for video use is the lavaliere type. Historically, the word “lavaliere” refers to microphones which are hung on a cord around the wearer’s neck, but in recent years the term has grown to include models which mount with a tie-clip, tie-tack, stick-pin, or other similar arrangement.
Lavalier microphones leave the talker’s hands free to gesture, hold notes, or demonstrate a product. In addition, they are usually very small and therefore tend to “disappear” on camera. Also, using a lavaliere will keep the distance from the microphone to the talker’s mouth fairly constant, reducing the need for frequent mixer adjustment once levels have been set.
A disadvantage of lavaliere mics is the fact that they tend to be “single-purpose” microphones – they rarely sound good if handheld or used away from the body. While the lavaliere mic’s small size makes it easy to conceal behind lamps or other objects, an equalizer is usually necessary to make the mic sound “natural” when it is not attached to the person talking.
Tips:
For best results, lavaliere mics should be clipped to the tie or lapel at the breast pocket level. Try to avoid placing the mic behind the tie or any material having more than one layer-this reduces pickup of high frequencies, which results in a flat, “muddy” sound. In addition, noise from the movement of clothing against the mic or its cable can be severe; experiment before risking the quality of your audio track. On women, the mic may often be attached to a stickpin or small chain with good results.
From: Shure – Guide to Better Audio
Written by Christopher Lyons
These are microphones that are designed to work on a flat surface. They are usually physically contoured to look less intrusive on a conference table or desktop. The microphone element is located very close to (but not touching) the surface, which allows it to take advantage of the reflected sound as well as the direct sound. This effectively doubles the sensitivity of the microphone over a free-standing handheld type at the same distance.
Tips: Surface mount microphones work best when positioned on a smooth, flat surface, such as a table or desk. If table vibrations are a problem, try putting a very thin piece of soft foam rubber underneath the mic. In some situations surface mount mics can even work well when mounted on a wall. Keep in mind that the sound quality of this type of microphone is affected by the size of the surface it is placed on. For best results, use a surface at least 3 feet square; using a smaller surface will tend to reduce pickup of low frequencies.
From: Shure – Guide to Better Audio
Written by Christopher Lyons
The shotgun microphone is so named because the long, slotted tube in front of the microphone cartridge makes it resemble a shotgun. This “interference tube” helps to reject sounds coming from more than about 30 degrees off to the sides, while still picking up sounds from the front. This extremely directional pickup pattern (called a Line/gradient pattern) makes shotgun mics popular for TV news and on movie sets.
Shotgun microphones are not “telephoto Lenses” for sound. They do not allow you to “zoom in” on a conversation from 100 feet away. Here’s a much more accurate analogy: imagine looking through a long tube at a person standing 20 feet away. The person’s image does not appear to be any larger or closer, but it is somewhat easier to see, because the eye is not distracted by things happening off to either side. This is exactly what shotgun mics do best – screen out sounds coming from the sides. You can use this advantage in two ways: position the mic at the same distance as you would a handheld mic, and enjoy clear pickup of the source with very little background noise; or position the mic farther away, and get the same amount of background noise as the handheld microphone would have given you.
Tip:
Shotgun mics can be positioned either slightly above, below, or to the side of the sound source, so that the mic does not appear in the camera frame. Try to avoid moving the mic rapidly, since shotguns are sensitive to wind noise, and use a foam windscreen if possible. Larger “zepplin” or “blimp” type windscreens are usually necessary outdoors. Also, it’s a good idea to use a rubber-isolated shock mount to minimize handling noise.
From: Shure – Guide to Better Audio
Written by Christopher Lyons
When we record panels, we don’t close mics because we don’t want to miss the first word of a speaker who suddenly decides to chime in. But, as at least one former President can attest, there is nothing worse than having an under-the-breath comment heard by the world. To help prevent embarrassment, Richard Johns, a freelance producer in Chicago, puts a note in front of each participant that says, “Mics are live at all times.”
From: Dick Reizner
To share your tips for possible inclusion in his article in Videography magazine, contact Dick at:
Reizner & Reizner Film & Video
7179 Via Maria, San Jose, CA 95139
dickreizner@worldnet.att.net
All submissions become the property of Reizner & Reizner. None can be returned.
I recently had a carbon fiber boompole crack at the end – not a pleasant occurrence by any means, and rather than spend a lot of cash for a new section, I thought to do a repair. I’m sure the folks at van den Bergh would wince at the thought of what I’m about to describe, but here goes:
The crack was just at the end, past the hole the cable exits through after going through the metal plug onto which the shockmount goes. A small piece fractured off but was still hanging on. After talking with a variety of others ranging from a very good (and thrifty) soundman to a friend who does oddball construction (sets, residential, and whatever) I came to the conclusion that this would be repairable by someone like me.
I finally settled on marine epoxy – very thick stuff meant to be used for hull patching and plumbing work, among other things. The plug at the end of the boom had ridges in its exterior that provided a good lot of places for the epoxy to bond. Glopping a good but not excessive amount on the plug, I pushed it back into the pole end. The tiny fractured piece was replaced at this time.
Fiberglass filament packing tape was cut to the proper width and tightly wrapped two or three times around the circumference while the epoxy was still setting, to compress and secure the fracture and provide reinforcement. All this was allowed to set for two days.
Two days after, the plug felt solid with plain hand manipulation, no movement whatever. To make really certain, I put a small tie-wrap (non-releasable) over the tape and pulled it tight.
I tested it with the Rycote in place, and it feels rock-solid. Oh, I also got a small XLR jumper to go from the 416 to outside the Rycote, so disassembly of “Cousin Itt” is no longer required to dismount the Rycote rig.
Alan Lloyd – Video Mercenary
alanlloyd@worldnet.att.net