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Roll-off is also significant on audio loudspeaker crossover filters: here the need is not so much for a high roll-off but that the roll-offs of the high frequency and low-frequency sections are symmetrical and complementary. An interesting need for high roll-off arises in EEG machines. Here the filters mostly make do with a basic 20 dB/decade ...
Modern systems have far wider potential bandwidth. An essential feature of all cutting amplifiers—including the Neumann cutting amplifiers—is a forcibly imposed high frequency roll-off above the audio band (>20 kHz). This implies two or more additional time constants to those defined by the RIAA curve.
The roll off frequency sets what is specified as the RIN bandwidth. RIN is sometimes referred to as a kind of 1/f noise otherwise known as pink noise. Relative intensity noise is measured by sampling the output current of a photodetector over time and transforming this data set into frequency with a fast Fourier transform. Alternatively, it can ...
Cutoff frequency is the frequency beyond which the filter will not pass signals. It is usually measured at a specific attenuation such as 3 dB. Roll-off is the rate at which attenuation increases beyond the cut-off frequency. Transition band, the (usually narrow) band of frequencies between a passband and stopband.
The cutoff frequency is the critical frequency between propagation and attenuation, which corresponds to the frequency at which the longitudinal wavenumber is zero. It is given by ω c = c ( n π a ) 2 + ( m π b ) 2 {\displaystyle \omega _{c}=c{\sqrt {\left({\frac {n\pi }{a}}\right)^{2}+\left({\frac {m\pi }{b}}\right)^{2}}}} The wave equations ...
The filter does not attenuate all frequencies outside the desired frequency range completely; in particular, there is a region just outside the intended passband where frequencies are attenuated, but not rejected. This is known as the filter roll-off, and it is usually expressed in dB of attenuation per octave or decade of frequency. Generally ...
Low frequency equaliser section with compensation for inductor resistance. The resistance r represents the stray resistance of the non-ideal inductor. The resistance r' is a real resistor calculated to compensate for r. Occasionally, a low-pass section is included to compensate for excessive line transformer roll-off at the low frequency end.
High-frequency roll-off that is not fully compensated in the replay channel may be offset by pre-emphasis during recording. [29] Lower replay time constants decrease the apparent level of hiss (by 4 dB when stepping down from 120 to 70 μs ), but also decrease apparent high-frequency saturation level, so the choice of time constants was a ...