Audio Circuits & Microphones Study Guide PDF

### **Equalization Circuits** - **Passive Equalization:** - No power needed. - Simple, natural sound. - Limited range and gain. - **Active Equalization:** - Requires power (e.g., batteries or phantom power). - More flexible, can boost/cut frequencies. -...

### **Equalization Circuits** - **Passive Equalization:** - No power needed. - Simple, natural sound. - Limited range and gain. - **Active Equalization:** - Requires power (e.g., batteries or phantom power). - More flexible, can boost/cut frequencies. - Common in professional audio gear. ### **Quality Factor (Q) in Peaking Filters** - **Q Factor:** - Measures filter sharpness. - High Q = narrow bandwidth; useful for precise adjustments. - Low Q = wider bandwidth; smoother tonal shaping. ### **Bandpass Filter** - **Function:** - Allows a specific frequency range to pass. - Attenuates frequencies outside that range. - Combines high-pass and low-pass filters. ### **Speech Intelligibility Frequency Range** - **Range:** 300 Hz to 3 kHz. - **Importance:** Critical for clear understanding of spoken language. ### **High-Pass and Low-Pass Filters** - **High-Pass Filter:** - Passes frequencies above a cutoff. - Attenuates low frequencies (e.g., wind noise). - **Low-Pass Filter:** - Passes frequencies below a cutoff. - Attenuates high frequencies (e.g., hiss). ### **Main Frequency Bands in EQ** - **Sub-bass:** 20-60 Hz (warmth). - **Bass:** 60-250 Hz (fullness). - **Midrange:** 500 Hz - 2 kHz (clarity). - **Presence:** 4 kHz - 6 kHz (detail). - **Brilliance:** 6 kHz - 20 kHz (sparkle). ### **Microphone Mechanics** - **Dynamic Microphones:** Durable, good for high SPL, no power needed. - **Condenser Microphones:** Sensitive, requires power, wide frequency response. - **Ribbon Microphones:** Warm sound, fragile, good for high frequencies. ### **Directional Response** - **Definition:** Sensitivity to sound from various directions. - **Types:** - **Omnidirectional:** Captures sound equally from all around. - **Cardioid:** Most sensitive from the front; rejects sides and rear. ### **Transient Response** - **Definition:** Ability to capture rapid changes in sound. - **Importance:** Crucial for clarity in percussive sounds. ### **Microphone Sensitivity Rating** - **Measurement:** Output voltage for a given sound pressure level (mV/Pa). - **Higher rating = better for quiet sources.** ### **Microphone Equivalent Noise Rating** - **Definition:** Inherent noise level of the microphone (dB SPL). - **Lower rating = quieter operation.** ### **Balanced Audio Line** - **Wires:** - **Hot (Positive):** Carries the audio signal. - **Cold (Negative):** Inverted signal for noise cancellation. - **Ground:** Common reference point, reduces interference. ### **Microphone Frequency Response Curve** - **Definition:** Shows sensitivity across frequencies. - **Importance:** Helps in matching microphones to specific applications. ### **Polar Patterns** - **Common Types:** - **Omnidirectional:** Equal sensitivity from all directions. - **Cardioid:** Heart-shaped response focusing on the front. ### **SPL Handling of Dynamic Microphones** - **Typical Levels:** Handles SPL above 140 dB; suitable for loud sources. ### **Microphone Impedance** - **Definition:** Resistance to electrical current (ohms). - **Low Impedance:** Better for professional use; lower noise. - **High Impedance:** More prone to noise; used in consumer applications. ### **Overload Distortion** - **Definition:** Occurs when input exceeds microphone capacity. - **Effects:** Results in clipping and distortion of the audio signal.