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  1. #1

    Just want to know

    I want to know much about the following:
    1.Clipping
    2.Subgroups
    3.Relationship between gain level and feedback
    4.Feedback
    5.Padding
    6.Panning


    I would also like to know more about drum sets and kits

    I also wish that i could know more about setting up for different types of concerts and live shows

    Thanks

  2. #2
    Overview of clipping

    When an amplifier is pushed to create a signal with more power than it can support, it will amplify the signal only up to its maximum capacity, at which point the signal will be amplified no further. As the signal simply "cuts" or "clips" at the maximum capacity of the amplifier, the signal is said to be "clipping." The extra signal which is beyond the capability of the amplifier is simply cut off, resulting in a distorted waveform.
    Many electric guitar players intentionally overdrive their guitar amplifiers to cause clipping in order to get a desired sound. See Guitar distortion.
    All amplifiers have a maximum amount of power, so theoretically they all can clip. However, many amplifiers will not allow a user to turn gain up beyond that point, so that the amplifier never clips. This is sometimes to reduce accidental distortion, or more importantly, to keep from damaging the amplifier as some amplifiers cannot withstand the heat generated by some forms of clipping.
    [edit]Effects of clipping

    In power amplifiers, the signal from an amplifier operating in clipping has two characteristics that could damage a connected loudspeaker:
    Because the clipped waveform has more area underneath it than the smaller unclipped waveform, the amplifier produces more power when it is clipping. This extra power can damage any part of the loudspeaker, including the woofer or the tweeter, by causing overexcursion, or by overheating the voice coil.
    In the frequency domain, clipping produces strong harmonics in the high frequency range. The extra high frequency weighting of the signal could make tweeter damage more likely than if the signal was not clipped. However most loudspeakers are designed to handle signals like cymbal crashes that have even more high frequency weighting than amplifier clipping produces, so damage attributable to this characteristic is rare.
    The greater area under the curve is damaging to amp, tweeter and woofer. The tweeters have an additional problem caused by clipping. The crossover element that functions as a high pass filter effectively shielding the tweeter from higher power bass freqencies is a capacitor. Capacitors allow current to flow while the voltage is changing and (depending on the value of the capacitor) their impedance drops as the voltage changes faster. So, a high frequency is passed on to the tweeter (since it's voltage is changing rapidly) and impedance rises to block current from a voltage that is changing slowly - and they completely block DC. At the point of clipping, instead of the usual smooth sine wave, there is a sharp angle - a fast (nearly infinite) rate of change (calculus freaks - what is dV/dt right at the corner? - This is where the harmonics come from - the sharp corner). So, when clipping occurs, the crossover sees it as a high frequency, and allows the full output of your amplifier to reach the tweeter.
    [edit]Digital clipping

    In digital signal processing, clipping occurs when the signal is restricted by the range of a chosen representation. For example in a system using 16-bit signed integers, 32767 is the largest positive value that can be represented, and if during processing the amplitude of the signal is doubled, sample values of 32000 should become 64000, but instead they are truncated to the maximum, 32767. Clipping is preferable to the alternative in digital systems wrapping which occurs if the digital hardware is allowed to "overflow", ignoring the most significant bits of the magnitude, and sometimes even the sign of the sample value, resulting in terrible modification of the signal.
    [edit]Sources of clipping

    In analogue audio equipment, there are three common causes of clipping.
    An integrated circuit or discrete solid state amplifier cannot give an output voltage larger than the voltage it is powered by (commonly a 24- or 30-volt spread for operational amplifiers used in line level equipment).
    A vacuum tube can only move a limited number of electrons in an amount of time, dependent on its size, temperature, and metals.
    A transformer (most commonly used between stages in tube equipment) will clip when its ferromagnetic core becomes electromagnetically saturated.
    Some audiophiles believe that the clipping behavior of vacuum tubes is superior to that of transistors, in that vacuum tubes clip more gradually than transistors, resulting in harmonic distortion that is generally less objectionable.
    Manoni Productions
    Pass me another beer...You are still ugly!

  3. #3
    Over view of Sub groups

    IO5-D/c
    Inline Module 5MT Series D

    Stereo Master, Pan Pot's and Sub Groups

    The main stereo master MIX is assinged to the tape chain. The input of the MIX PAN is driven by the tape chain fader output. Its output drives the stereo mix bus.

    In addition, there is a second pan pot, the RT-PAN, that is driven by the output of the record chain fader.

    Both Pan Pots are rotary controls with center detend. The center attenuation is 3 dB, which maintains are pure direction control that does not change the level.

    While the mix pan is always in the signal path of the tape chain, the RT pan can be switched into the signal path from the record chain fader to the input of the routing matrix by the PAN switch, next to the pot. Since in most cases, the routing is used for mono recordings, the pan is only needed for a stereo recording. When active, it controls the level relation between the odd and the even routing busses.

    It is possible to rout the output of the record chain fader to the mix bus. This very important feature makes it possible to use the channel for two independent input signals while mixing. The MIX switch routs the record fader to the main stereo bus. In differenc to the routing matrix, the RT-Pan is always active if the record fader feeds the mix bus.

    TO RTG

    The TO RTG (to Routing Matrix) switch next to the Mix Pan rerouts the output of the mix pan from the mix bus to the input of the routing matrix. This switch overrides the default signal flow from the output of the record chain fader to the routing matrix.

    This function makes it possible to arrange audio sub groups on the fly without the need to consider the level relations and the pan settings. By pressing TO RTG, exactly the level that was sent to the mix bus now drives the input of the routing matrix. If a pair of routing busses is selected, that are not otherwise needed, these busses become a subgroup that mirrors level and pan settings exactly. This principle offers the choice to arrange any number of audio subgroups up to a maximum of 12 stereo at any time.

    Sub Group Master Chains

    Of course, an audio subgroups needs a master channel. The IO5-D/c inline modules offer the choice to use either the tape chain or the record chain of any channel as audio sub group master. While one of the chains is used as master, the other chain can still be used for another signal. The INP switch selects the output of the channel's routing bus amp as tape chain input signal. If SUB is pressed, the record chain becomes a sub group master. This method requires no patching but the channels of the selected routing busses must be used as master. In addition, it is possible to get the bus output signal from the patchbay. In this way, of course, any channel, including stereo channels or stereo returns of the master section can be used as subgroup master.

    The audio subgroup system of the 5MT Series D mixing consoles is not limited to one level only. Since every subgroup master can be routed to another routing bus, it is possible to build up very complex grouping areas, from a simple one level only group to a system that can use up to 12 levels.
    Manoni Productions
    Pass me another beer...You are still ugly!

  4. #4
    Audio feedback

    (also known as the Larsen effect) is a special kind of feedback which occurs when a feedback loop exists between an audio input (for example, a microphone or guitar pickup) and an audio output (for example, a loudspeaker). In this example, a signal received by the microphone is amplified and passed out of the loudspeaker. The sound from the loudspeaker can then be received by the microphone again, amplified further, and then passed out through the loudspeaker again. This is a good example of positive feedback. The frequency of the resulting sound is determined by resonant frequencies in the microphone, amplifier, and loudspeaker, the acoustics of the room, the directional pick-up and emission patterns of the microphone and loudspeaker, and the distance between them.
    More specifically, the conditions for feedback follow the Barkhausen criterion, namely that an oscillation occurs in a feedback loop whose delay is an integer multiple of 360 degrees and the gain is equal to or greater than 1 (both at the given feedback frequency). If the gain is greater than 1, then the system can start to oscillate out of noise, that is to say: sound without anyone actually playing.
    Most audio feedback results in a high-pitched squealing noise familiar to those who have listened to bands at house parties, and other locations where the sound setup is less than ideal this usually occurs when live microphones are placed in the general direction of the output speakers. Professional setups circumvent feedback by placing the main speakers a far distance from the band or artist, and then having several smaller speakers known as monitors pointing back at each band member, but in the opposite direction of the microphones.
    Audio feedback is usually undesirable. However, electric guitar players such as Pete Townshend and Jimi Hendrix have used it as an audio effect, and was used extensively after 1965 by the The Monks, first played onstage by The Who and first commercially recorded by The Beatles on the single "I Feel Fine" released November 26, 1964 in the UK. Used in this fashion, the artist has some control over the feedback's frequency and amplitude as the guitar strings (or other stringed instrument) form a filter within the feedback path and the artist can easily and rapidly "tune" this filter, producing wide ranging effects. Artists can even manipulate feedback by shaking their instruments (in the style of Pete Townshend) in front of the amplifier, creating a throbbing noise. More recently, Audioslave guitarist Tom Morello (formerly of Rage Against the Machine) has employed feedback in conjunction with a "killswitch" on his guitar and heavy use of the whammy bar to create inventive hip hop-influenced solos.
    Also note that desirable feedback can be created by an effects unit by using a simple delay of about 50 ms fed back into the mixing console. This can be controlled by using the fader to determine a volume level.
    To avoid feedback, automatic anti-feedback filters can be used. (In the marketplace these go by the name "feedback destroyer" or "feedback eliminator".) These electronic devices are a multi-band parametric equalizer combined with a spectrum analyzer which applies a notch filter to frequencies with a very high peak compared to the rest of the audio spectrum. This can also be accomplished by an audio engineer using either a parametric equalizer (normally found on a mixer's input channels) or a graphic equalizer (commonly connected between the mixer's outputs and the amplifier inputs to correct acoustical problems in a room or to address feedback issues).
    Manoni Productions
    Pass me another beer...You are still ugly!

  5. #5
    Manoni Productions
    Pass me another beer...You are still ugly!

  6. #6
    Fading and Panning

    Audio mixing consists of two primary tasks: fading and panning. Fading audio adjusts its gain level, or volume. Fading up audio increases its volume; fading down decreases it. Fading helps you match the audio levels of different clips, as you would with dialogue. Or you can create audio transitions or effects, such as making a car sound more and more distant.

    Panning affects how a clip's audio is distributed between the left and right audio speaker. Panning audio can imply an apparent position for a sound.

    Starting with Premiere 6, you can mix audio by using either the timeline controls or the audio mixer. In the timeline, you can manipulate lines that represent fade and pan levels. The line is sometimes referred to as a "rubber-band," and manipulating it is called "rubber-banding" (Figure 8). Adjusting the slope of the lines affects the clip's volume and distribution. This method is precise and visually clear. On the other hand, it doesn't provide simultaneous audio playback.

    Figure 8 In the timeline, you adjust panning and fading by using "rubber-band" controls.

    The Audio Mixer window resembles a traditional audio mixing board (Figure 9). It controls fading and panning in real time, using more conventional-looking fader controls and pan knobs. This method favors simultaneous audio response to precise graphical control.

    Figure 9 In the Audio Mixer window, you adjust panning and fading by using controls similar to those of a traditional mixing board.

    Another important distinction between the two methods is the context in which they're used. The timeline controls are clip-oriented, whereas the audio mixer is track-oriented. In other words, you manipulate the fade and pan lines for each clip in the program in the timeline; you use the audio mixer to mix entire tracks of the program. You can switch between methods at will, depending on your preferences and the task at hand.

    Percentages versus dB

    In previous versions of Premiere, audio levels were measured strictly in terms of percentages. Though this was meaningful in relative terms, it didn't correspond to conventional sound measurements.

    Fortunately, Premiere can now display levels in terms of decibels, or dB. A decibel is the standard measure of acoustical power used by audio professionals everywhere. To double the volume, increase the level +6dB.

    Technically speaking, a decibel is one-tenth of a bel, which measures the ratio of two audio power levels--usually, an audio signal and a reference (such as the threshold of hearing). And yes, it's bel as in Alexander Graham Bell, the telephone guy.
    Manoni Productions
    Pass me another beer...You are still ugly!

  7. #7
    as far as drum kits. I have a 10 piece pearl with 5 symbols and a high hat (double bass) I like it alot. you really need to go to the store and sit behind a set and see what you are comfortable.

    And as far a setting up live events.......that is a totally different lesson. there are TONS of great sites to get good PA advice. here is one to wet your whistle

    http://www.epanorama.net/documents/g...pa_advice.html
    Manoni Productions
    Pass me another beer...You are still ugly!

  8. #8
    Padding has to do with cutting a level by chunks, measured in db's, usually with the purpose in mind to limit an input to a range the equipment is designed to operate at. Pads are usually found at the front end of an input channel of a mixing board, with numbers like -4db, -15 db. What it does is attenuate the incomming signal by that amount. High gain mics and direct-boxes are typical candidates for input padding.

    Inline padding is another type, this one in the form of a small device or box that plugs in between two devices, and is used where padding is needed but not offered on the equipment. The function is the same as above.
    'I think my intimate relationship with electronics started as a child when I was playing with a screwdriver and a wall plug, Doc, and...'

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