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DB per Decade Formula:
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DB per decade is a measurement used in electronics and signal processing to express how much a signal's amplitude changes over a tenfold increase in frequency. It's commonly used to describe filter roll-off rates and amplifier frequency responses.
The calculator uses the DB per Decade formula:
Where:
Explanation: The formula calculates the logarithmic measure of amplitude change over a frequency range that increases by a factor of 10.
Details: Calculating dB per decade is essential for designing and analyzing electronic filters, understanding frequency response characteristics of amplifiers, and characterizing signal attenuation in various electronic systems.
Tips: Enter the amplitude ratio between two frequencies separated by one decade. The ratio must be a positive value greater than zero.
Q1: What is the difference between dB/decade and dB/octave?
A: dB/decade measures change over a tenfold frequency increase, while dB/octave measures change over a doubling of frequency. 1 dB/octave ≈ 3.32 dB/decade.
Q2: Why is 20 used in the formula instead of 10?
A: The factor of 20 is used for amplitude ratios (voltage, current), while 10 would be used for power ratios. Since power is proportional to amplitude squared, we use 20 log10 for amplitude measurements.
Q3: What is a typical dB/decade value for filters?
A: First-order filters typically have 20 dB/decade roll-off, second-order filters have 40 dB/decade, and so on, with each additional order adding 20 dB/decade to the roll-off rate.
Q4: How is this measurement used in audio equipment?
A: In audio equipment, dB/decade measurements describe how quickly frequencies outside the passband are attenuated, which is crucial for crossover networks and equalizers.
Q5: Can negative values be calculated?
A: Yes, negative dB/decade values indicate gain rather than attenuation over the frequency range, though this is less common in typical filter applications.