Audio Filters Circuits |
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An audio filter is a frequency dependent amplifier circuit, working in the audio frequency range, 0 Hz to beyond 20 kHz. Many types of filters exist for applications including graphic equalizers,synthesizers, sound effects, CD players and virtual reality systems. Filters are defined by their slope, which determines the attenuation of signals outside the ‘pass’ band. Most audio filters on mixing desks (and DAWs) will have a slope of 12dB or 18dB per octave, and in synthesizer filters the slope may be as steep as 24dB per octave. If an 18dB/octave high-pass filter is set to 80Hz, any audio an octave below that (at 40Hz) will be attenuated by 18dB, and an octave lower still, at 20Hz, it will be attenuated by 36dB... and so on.
For example, high-pass filters are often used in studio recording and sound reinforcement to attenuate extraneous low-frequency content like mechanical rumble or vocal plosives. By choosing a filter with a cutoff frequency below the fundamental frequency range of the program, a HPF can be used to differentiate between program signal and low-frequency noise. Low-pass filters can also be used to eliminate unwanted, counter-productive bandwidth. One common example is using a LPF to establish the limited bandwidth of a low frequency transducer, like a ‘sub’ mic on a kick drum. Other examples include the entire universe of subtractive synthesis.
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The amplifier drives the base of a common emitter PNP MPS6517 operating with a voltage gain of about 20. RL control varies the quiescent point of the transistor Q, so that varying amounts of signal exceed the level of V r, diode D 1 rectifies the positive peaks Ql output is only when these peaks are more larger than r V "'" 7. 0 volts. The...
The circuit input is taken from the terminal loudspeaker or amplifier output jacks. If the right channel is large enough to charge C1 to a potential which exceeds the breakdown voltage of the emitter of Ql, a voltage pulse appears in R7. Similarly, if the left channel signal is large enough to charge C2 to a voltage that is greater than the...
This circuit is selective for the tuning adjustment between two closely spaced tones audio. The frequency is dependent on the selective value capacitors and resistors in the feedback circuit between the collector and base of Q1. With the values shown, the frequency can be "tuned" to a hundred cycles or so-around 650 Hz Ri and R2 should be...
This preamplifier is requirement result of many friends to give a high quality preamplifier, capable to drive high quality power amplifiers with good sound, it`s not however difficult to making, it combines simplicity and handiness. It does not allocate a lot of facilities and various filters, but is drawn so the acoustic signal follows the... .
Another one unit of graphic EQ. five bands. The basic difference with the other circuits is, that I use instead of IC, transistor and the power supply, go up in +/- 24V DC, ensuring low distortion and bigger margins of overloading. With switch S1, we can isolate the EQ. inside or except operation, leaving the musical signal to pass without no... .
The circuit of graphic equalizer, allocates ten adjusting potesometer , that each one from them affects in a predetermined area of frequencies, the central frequency of which abstains a octave (double), from the central frequencies of her neighbouring regions. Each unit has common materials with remainder and it differs only in the capacity of... .
The composite lowpass filter uses interior constant-k full sections terminated by m-derived half-sections.The design technique is also applicable to highpass and wideband filters (references 3 and 4). Figure 1 shows a schematic of the composite lowpass filter. The filter uses four inductors of two different values and five capacitors of two... .
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