Sound Recording Solutions
Sound Card Recorder
Powerful voice activated microphone recorder for Windows. Click here to learn more.Amplifier
An amplifier can be considered to be any device that uses a small amount of energy to control a source of a larger amount of energy, although the term today usually refers to an electronic amplifier. The relationship of the input to the output of an amplifier - usually expressed as a function of the input frequency - is called the transfer function of the amplifier, and the magnitude of the transfer function is termed the gain. How much an amplifier increases the signal level is called the gain. This is usually measured in decibels (dB). Mathematically speaking, the gain is equal to the output level divided by the input level. This is the range usually quoted in dB between the lowest useful output and the largest useful output level. Since the lowest useful level is limited by output noise, this is quoted as the amplifier dynamic range. The bandwidth (BW) of an amplifier is usually defined as the difference between the lower and upper half power points. This is therefore also known as the ?3 dB BW. Bandwidths for other response tolerances are sometimes quoted (?1 dB, ?6 dB etc.). As an example, a good audio amplifier will have a ?3 dB BW from around twenty hertz to about twenty kilohertz (the range of normal human hearing). The rise time of an amplifier is the time taken for the out put to change from 10% to 90% of its final level when driven by a step input. For a Gaussian response system (or a simple RC roll off), the rise time is given by: Tr = BW/0.35, where BW is in Hz and Tr is in seconds. Time taken for output to settle to within a certain percentage of the final value (say 0.1%). This is usually specified in oscilloscope vertical amplifiers and high accuracy measurement systems. Slew rate is the maximum rate of change of output variable, usually quotes in volts per second (or microsecond). The properties of amplifier circuits distort the signal. This distortion comes in several forms including harmonic distortion and intermodulation distortion. Harmonic distortion is fairly easy to measure. The amplifier output is connected to a spectrum analyzer, (a device which graphs frequency against amplitude). Then a pure tone is applied to the amplifier input. Typically a sinusoidal signal of 1 kHz is used. The largest signal on your analyzer should be the input signal at 1 kHz. You will sometimes see humps at even intervals along the graph at even multiples of that base signal. These are the harmonics. The total harmonic distortion (THD) is the sum of these components relative to the signal. How much noise is introduced by the amplification process? This is an undesirable thing that is the inevitable result of the electronics devices and components. It is measured in either decibels or the peak output voltage produced by the amp when no signal is applied. How much of the input power is usefuly applied to the amplifier's output? Class A amplifiers are very inefficient, in the range of 10-20% with a max efficiency of 25%. Modern Class AB amps are commonly between 35-55% efficient with a theoretical maximum of 78.5%. Commercially available class D amplifiers have reported efficiencies as high as 97%. The efficiency of the amplifier limits the amount of total power output that is usefuly available. Note that more efficient amps run much cooler, and often do not need any fans even in multi-kilowatt designs.
Phone Call Recorder
Must have software for voice modem. Record all phone calls automatically, watch Caller ID information, create you own powerful answering machine. Perfect sound quality. Click here to learn more.3d audio effect - 3gp - a-law - aac - acm - adc - aiff - aliasing - amplifier - amr-wb - amr-wb plus - amr - apev2 tag - asf - atrac - audio codec - audio compression - avi - bitrate - bitrate peeling - chord - codec - comfort noise - compact audio cassette - compact disc - compression - compression artifact - compression ratio - contact microphone - container format - dab - data compression - digital audio - digital camera - divx - dolby digital - dolby digital plus - dsp - dvd-audio - dvd - effects unit - equalization - ffmpeg - flanging - fourcc - frequency spectrum - hi-fi - high-end audio - hiln - id3 - joint stereo - laser microphone - line level - lossy - loudspeaker - matroska - mcf - microphone - midi - mixing console - mp2 - mp3 - mp3 surround - mp3 sx - mp3pro - mp4 - mpeg-1 - mpeg-21 - mpeg-3 - mpeg-4 - mpeg-7 - mpeg - mu-law - musepack - music - mxf - nut - osm - parabolic microphone - pcm - perception - phonograph - pink noise - pqf - psychoacoustics - qdesign - quadraphonic - radio receiver - ratdvd - realaudio - red noise - reverberation - rhythm - ribbon microphone - riff - rmvb - sbr - signal processing - sound - sound card - sound effects - sound recording - spdif - speech encoding - speech recognition - speex - stereo - subwoofer - surround sound - synthesizer - tape recorder - tdm - tweeter - video - video compression - vob - voice analysis - vorbis - wav - white noise - wma - woofer