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J-Himmy Productions
Week five in the studio was a lot to take in, but at the same time I enjoyed learning about all the different types of microphones and polor patters that they have. Although it is hard to remeber the names of the mics and polor patters, I am getting a lot better at knowing if the mic is a Condenser mic, Dynamic mic, or a Ribbon mic. While in the studio my mentor took me to the storage room where all the mics are placed and showed me each one to help me get a better understanding on how it looks and how it works. With this knowledge I now have a better perspective on how the mic would make the clients vocals sound and if it is a right fit for the client. On the second day when I came in I got wo watch a mixing board get taken apart and put back together by another engineer at the studio. We also went over cables and how to wrap them correctly and slightly went over the mic names agin so I wouldnt forget. Later on in the week I was able to came into a session with the band La Reve from Vegas and watch them rehearse some new tracks they have. I had a great time watching them play and also got to enjoy seeing the engeneers in action in the A studio.
-Section 1:
- Microphone - Device that changes acoustic energy into an electric current that can be altered and manipulated.
- Transducer - Any device that converts one form of energy into another form of energy.
- Alexander Graham Bell bought the rights to Emile Berliner's design, which was the first widely used voice transmission device.
- David Edward Hughes gave us the first improvement in the carbon microphone around 1878
- Thomas Alva Edison - Improved the efficiency and durability of the carbon microphone.
- Georg Neumann was working for the Eugen Reisz and invented the Marconi Reisz transverse current carbon microphone.
- One job of early audio engineers was to tap the microphone to loosen up the carbon granules to increase conductivity. Unnecessary with modern day microphones, but
has remained.
- Edward Christopher Wente - Invented the first condenser (Capacitor) Microphone, which solved the problems the carbon mic faced, concerning frequency respone and
signal-to-noise ratio.
- Condenser mics were superior in quality, but "Temperamental", due to there sensitivity to moisture
- Electromagnetic (Moving Coil) - Difficult power configurations to power early electromagnetic designs. First design that became popular was the Marconi Sykes
magnetophone. Alan Blumlein and Herbert Holman refined early electromagnetic microphone designs into their HB1B model while employed with Columbia Gramophone
company (Later to become EMI)
- Electromagnetic (Ribbon) - 1930s and early 1940s Dr. Henry F. Olsen created two of the most popular ribbon designs to date. The RCA 44 and 77 series microphones.
The quality of these mics is up to par with todays standards making them sought after still today.
Section 1 review Questions:
- "Alexander Graham Bell" is credited as the inventor of the microphone
- David Edward Hughes gave us the carbon microphone in "1878"
- "Edward Christopher Wente" invented the condenser microphone in "1916"
- "Georg Neumann" invented the transverse current carbon microphone in the early 1920s
- Ribbon microphones were invented by "Dr. Henry F. Olsen"
Section 2:
- A high pass filter switch - offers greater control over the frequency response.
- High pass filter - Allowes frequencies above a designated point in the frequency spectrum to pass through unaffected, and attenuates or decreases the amplitude of
frequencies below that point.
- Polar (Pickup) Pattern - Microphone's directionality or polar pattern indicates how sensitive it is to sounds arriving at different angles about its central axis.
It is viewed from above, with a circle rotating to the 360 degrees that is part of the microphone's measurements.
- Omnidirectinal: Microphone's diaphragm is located in a sealed enclosure. Sensitive to sound sources from any direction. Simplest mic desgin will pick up all sound,
regardless of its point of origin, and is thus known as an omnidirectional microphone. Easy to use, good to outstanding frequency response.
- Cardioid: Very popluar in recording studios because it is a way of isolating vocals or instruments. More senssitive in the front of the microphone in relationship
to the rear. Has a "Front-To-Back Discrimination," "Irregular polar pattern," "Offaxis coloration," and "Bassproximity effect." First problem is sounds from back are
not completely rejected, but merely reduced about 1030 dB. Problem two, the actual shape of the pickup pattern varies with frequency. For low frequencies, this is
an omnidirectional microphone. Another problem is, frequency response for signals arriving from the back and sides will be uneven; this adds an undesired coloration
to instruments at the edge of a large ensemble, or to the reverberation of the concert hall. A third effect, is that the microphone will emphasize the low frequency
components of any source that is very close to the diaphragm. This is also known as "Proximity effect"
- SuperCardioid: A Cardioid pattern microphone where the rejection of sound from the side is increased, causing the microphone to be more sensitive to the front
source.
- HyperCardioid: Also like a Cardioid pattern, but it is designed to reject the sound source originating from its side even more than the superCardioid. One
disadvantage of this microphone is that as it discriminates its side sensitivity, there begins to develop a sensitivity (lobe) toward the rear of the microphone
(180 degrees). This means that where simple cardioid mics pick up very little sound from their rear position, the hyperCardioid pattern is sensitive to some sound
coming from its rear position.
- UltraCardioid: Designed to greatly increase its front compared with its back sensitivity, and in doing so "trades off" some side rejection. Its front pattern is
still tighter than the hypercardioid and thus allows the engineer to focus on a smaller area.
- BiDirectional or Figure 8: The Bidirectional microphone is equally sensitive to sound sources from its front and from behind. It has almost no sensitivity to sound
directly from its sides. Has two condenser capsules back to back, and sound is allowed to reach both sides. Because the mic accepts sound from both ends, this makes
it difficult to use in many situations.
- Signal-to-noise ratio: The measure of the amount of noise to the amount of signal produced by an electronic component. Signal to noise ratings are usually listed
as a number in decibels. The higher the decibel number the better the rating. What the decibel number is referring to is the difference from the mic's self noise, and
usually a 1Hz tone at 94 Db SPL.
- Impedance - The measure of the resistance of the flow of electricity. Measured in ohms. The input impedance of a mixer mic input is about 1500 ohms. If it were
the same impedance as the mic, about 250 ohms, the mic would "load down" when you plug it in. Loading down a mic makes it lose level, distort, or sound thin. To
prevent this, a mic input has an impedance much higher than that of the microphone.
- Maximum SPL - Reference to the maximum amount of decibel level the microphone can accept before the output of the microphone will distort. A maximum SPL spec of 120
dB is good, this means that a sound wave measuring less than 120 dB SPL will no distort. 135 dB is very good, and 150 dB is excellent.
- Sensitivity - Refers to the amount of voltage produced by the microphone when exposed to certain SPL. If a mic is less sensitive then it requires more gain or
amplitude from the electronics it is plugged into. The more sensitive the mic, the less help that mic needs from the preamp. The more sensitive a mic is, the more
likely higher decibel level will be to overload the input.
Quiz review:
- "Signal-to-noise Ratio" refers to the amount of self noise the mic has compared to the amount of signal produced by the mic, usually expressed by a decibel mount.
- "Distortion" is defined as the alteration of the original shape (Or other characteristic) of something, such as an object, image, sound or waveform.
- "Impedance" is the measurement of the resistance of the flow of electricity.
- "Frequency response" refers to the difference between what frequencies a performance is actually transmitting, to what the microphone is capturing.
Section 3:
- Carbon Microphones - Has two plates separated by granules of flexible electrode carbon. The outward facing plate is usually made from a thin substance that reacts
to the sound waves that are being transmitted into it. As a steady direct current is passed between the plates, the varying resistance results in a modulation of the
current at the same frequency of the sound waves hitting the diaphragm.
- Frequency response of early microphones topped out at about 3 kHz with later designs going up to 10 kHz.
- Condenser Microphone - Changes acoustic energy into a voltage through the use of a capacitor.
- Alessandro Volta (1782) created the capacitor.
- All capacitors consist of two conductors separated by a dielectric (Nonconductive or semiconductive material). The capacitor accumulates a charge and then releases
that charge.
- Phantom power - If the mic uses a voltage from the mixing board that voltage has been standardized at 48 volts.
- Neumann U87 - Large diaphragm condenser microphone. Offers three pickup patterns via a switch mounted below the headbasket. Cardioid, Omni, and Figure 8.
- AKG C414 - Large diaphragm microphone. Features 9 pickup patterns, 3 filters, and a pad. Has a peak hold LED light that lets the user know when overload has occured.
- Neumann/Telefunken U47 - 1947, First switchable pattern condeser microphone. Original U47 employed a telefunken VF14 tube, which became hard to find in a few years,
leading to changes to the U47 design as well as the introduction of the U47fet, a FET condenser inteded to sound the same as its tubeamplified sibling.
- AKG/Telefunken ELA M 251 - Multipatter tube condenser. Made because Neumann stopped providing U47 for Telefunken.
- Neumann KM 84 - Small diaphragm FET condenser with a fixed cardioid pickup pattern. Worlds first phantom powered microphone, built to run on 48v DC. Model number
indicates the powering mechanism (8 = phantom power) and polar pattern (4 = Cardioid).
- Neumann M 49 - Multipattern large-diaphragm tube microphone. Mics pickup pattern could be adjusted remotely, by a dial on the power supply. Maintaned nearly equal
sensitivity and output level across patterns.
- Dynamic (Moving Coil) Microphone - Use the principle of electromagnetic induction. Dynamic mics contain a diaphragm that is fixed to a moving coil. The coil is
positioned in a static magnetic field generated by a permanent magnet. As the sound waves hit the microphone, they set up vibrations in the diaphragm, which
are transferred to the coil. The movement of the coil in the magnetic field induces a signal voltage at the same frequencies of the sound source. Do not need power
supply. Can tolerate very high SPL and are durable. Needs higher gain levels before feeback happens.
Dynamic Mics:
- Shure SM57/58 - Unidirectional (Cardioid) dynamic mic. Usable on just about any source in context. SM58 is same as SM57 but has a pop filter making it more suitable
for vocals.
- Sennheiser MD 421 - 1960, Has a 5 position bass roll off switch. The "flat" position is marked M for music; the other extreme is marked "S" for speech, and cuts the
low end by approximately 6 dB below 500 Hz.
- Shure SM7B - Industry standard dynamic microphone, has a high pass filter, and a "presence boost" which changes its frequency response. Has low sensitivity rating
which means you need to get more gain from your preamp.
- ElectroVoice RE20 - Industry standard large diaphragm dynamic microphone, Can be used very close to a source without losing clarity.
- AKG D112 - Classic large diaphragm dynamic kick drum mic with high SPL capabilities (160 dB). Designed with a low resonance frequency and can handle very high
transient signals with virtually unmeasurable distortion.
- Beyer Dynamic M 201 - Dynamic instrument microphone with a hypercardioid pickup pattern. Uses lowmass diaphragm made of Hostaphan and a humbucking coil to reduce
electrical interference from nearby AC source. Has a fixed hypercardioid pickup pattern.
- Ribbon Microphone - Like a moving coil, this uses a magnet and works because of a magnetic field. Use a thin, usually corrugated metal ribbon suspended in a
magnetic field. The ribbon is electrically connected to the microphones output, and its vibration within the magnetic field generates the electrical signal. Baisc
ribbon microphones detect sound in a bidirectional pattern.
- Royer R121 - Passive ribbon microphone with an innovative offset ribbon placement that gives the two sides of the microphone distinct features and sound. Made of
pure aluminum and is 2.5 microns thick, and is tuned to about 40 Hz. Offset toward the front side of the microphone case, which among other features provides a high
SPL capability of 135 dB on the front side. Rear side is equally sensitive but brighter(and less able to hangle high SPL).
- Coles 4038 - Classic studio ribbon microphone designed by the BBC and originally manufactured by STC. Coles bought the rights to the STC microphone line in 1974.
The 4038s frequency response is flat from 30 to 15000 Hz.
- RCA 77D - 1945, replaced by the 77DX. One of the standards of the broadcast and recording industries, and is still widely regarded for its quality. About eleven
inches in height. The control had three marked options, U for unidirectional (Cardioid), N for Nondirectional (Omni), and B for Bidirectional (Figure 8), The N and U
patterns were highly frequency sensitive.
- El Diablo - First ribbon mic from crowley and tripp to use their acoustic nanofilm ribbon material, later trademarked "Roswellite." It has industry leading "Shape
memory," which means it is impervious to blowouts due to wind blasts or even inadvertent application of phantom power.
Review Questions:
microphones use a capaitor. Voltage is created by the diaphragm changing the distance between two plates.
- "Ribbon" microphones use a corrugated piece of metal suspended in a magnetic field. Voltage is created through induction.
- "Dynamic" microphones use a diaphragm attached to a moving coil that surrounds a magnet. Voltage is created through induction.
- "Carbon" microphones were among the first created, and create voltage through the use of loosely packed granules of coal-like material. A.B.
Mic Picture Review:
- Coles 4038
- Shure SM57
- AKG C414
- Sennheiser MD 421
- Neumann U87
- ElectroVoice RE20
- RCA 77
- Telefunkin ELA M 251
- AKG D112
- Neumann KM84
- Condenser Mic - Use when recording vocals, sensitive. Quiet.
- Dynamic mic - use when singing live or having multiple singers. Loud
