MISCO Loudspeakers 101

MISCO Speakers

A leading audio industry company that focuses on using advanced technology, design, and testing to enhance audio products and educate customers.

Loudspeaker

A transducer that converts electrical energy into mechanical energy to produce sound, with different types such as dynamic, electrostatic, and piezoelectric speakers.

Sound

A variation in atmospheric pressure that we can hear, with objective attributes like amplitude and frequency, and subjective attributes like loudness, pitch, and quality.

Dynamic Loudspeaker

The most commonly used type of loudspeaker that operates based on electromagnetic principles, with components including the motor, diaphragm, suspension, and chassis.

Electrodynamic Driver Systems

The four main systems of an electrodynamic driver include the motor, diaphragm, suspension, and basket/frame, each playing a crucial role in the speaker's operation.

Direct Current (DC)

Electric current that flows in one direction, often provided by sources like batteries, with a fixed polarity and no waveform.

Alternating Current (AC)

Electric current that changes direction periodically, corresponding to the compression and rarefaction of air in an acoustical signal, with a waveform that alternates above and below a line.

Waveform

Patterns of sound vibrations described by audio engineers, visualized using an oscilloscope, showing voltage changes over time, with complex waveforms representing various frequencies and amplitudes.

Frequency

The rate at which the air is alternately compressed and rarefied, measured in Hertz (Hz), representing how many "cycles per second". High frequencies correspond to high pitch.

Wavelength

The distance between two consecutive crests of a wave, measured in meters (m), inversely related to frequency.

Voltage

The measure of electrical "pressure" in a circuit, analogous to the force pushing water through a pipe, stated in Volts (V).

Current

The measure of the quantity of electric charge flowing through a circuit, analogous to the diameter of a water pipe, stated in Amperes (A).

Power

The product of voltage and current in a circuit, measured in Watts (W), representing the total amount of energy delivered.

Resistance

The opposition to the flow of current in a circuit, measured in Ohms (Ω), described by Ohm's Law.

Impedance

The opposition to current flow in AC circuits, similar to resistance but specific to alternating current, measured in Ohms (Ω).

Amplitude

The measure of the size of a wave, not to be confused with frequency, with units varying based on the context (e.g., Volts, Amps, Watts in electrical terms).

Decibel (dB)

A unit for expressing amplitude on a logarithmic scale, commonly used in audio and acoustics to describe sound pressure levels.

Dynamic Range

The ratio between the largest and smallest signals in a system, often expressed in decibels (dB) in the context of human hearing.

Sound Pressure Level (SPL)

The measure of sound pressure in decibels (dB SPL), indicating the intensity of a sound relative to a reference pressure of 20 micropascals.

Midrange

A driver that handles middle frequencies, typically from around 250 Hz up to 4 kHz - 5 kHz, requiring a frequency response free of irregularities.

Tweeter

A small driver intended for high frequencies, usually above 2500 Hz to 1500 Hz, with minimal diaphragm motion and different types like Horn, Dome, and Electrostatic.

Frequency Response

A measure of output uniformity at various frequencies, often graphed with amplitude response in dB SPL on the vertical axis and frequency on a logarithmic horizontal axis.

Sensitivity

A measure of sound pressure produced by a loudspeaker for a specified input, typically stated in dB SPL at a certain voltage or wattage at 1 meter distance.

Efficiency

The ratio of acoustic power produced to the input electric power, often confused with sensitivity, with direct-radiator dynamic speakers having low efficiency.

Resonance (fo or fs)

The natural frequency of a moving system like a loudspeaker, crucial for enclosure calculations and indicating proper driver construction.

Voice Coil Impedance

The varying impedance of the voice coil in a loudspeaker, especially near resonance, specified with tolerance, frequency, and input level.

Rated Power (watts)

The ability of a loudspeaker driver to withstand input power, rated using standards like EIA RS-426B and IEC 60268-5, different from amplifier power ratings.

Closed (Sealed) Box

An enclosure with no major openings except where the driver is mounted, also known as an infinite baffle.

Vented Box

An enclosure with two openings, one for the driver and the other connecting the air volume inside to the outside, aiming to utilize energy at low frequencies.

Helmholz Resonator

A vented box with a vent that turns it into a resonator, coordinating the resonant frequency with the driver's fs for a flatter frequency response.

Passive Radiator

A box similar to a vented box but with a passive radiator instead of a vent, using the mass of the radiator's diaphragm to substitute for the air mass.

Motor

The system in a loudspeaker that converts electrical energy into mechanical energy or force, producing reciprocating motion.

Magnet

The source of power in a loudspeaker driver, made from materials like ferrite, alnico, or neodymium, and providing the magnetic energy needed for operation.

Magnetic Structure

Consists of the front plate, back plate, and pole piece in a loudspeaker, providing a path for magnetic flux and concentrating it in a narrow gap for interaction with the voice coil.

Voice Coil

A coil of wire in a loudspeaker that generates a magnetic field when current passes through it, causing the coil to move back and forth in response to the audio signal.

Diaphragm (Cone)

The part of a loudspeaker that converts the mechanical force from the voice coil into acoustical energy, producing sound.

Suspension

The component in a loudspeaker that holds the cone and voice coil centered laterally while allowing them to move axially, consisting of the surround and the spider.

Dust Cap

A protective cap glued onto the center of the cone in a loudspeaker to prevent dirt and dust from entering the gap while allowing for better high-frequency performance.

Frame (Basket)

The supporting structure of a loudspeaker that holds the motor parts, cone, and suspension in the correct relationship, typically with terminals for connecting to external wires from the amplifier or crossover network.

Gasket

A component in a speaker made of chipboard, plastic, or rubber that serves various purposes such as clamping the cone in place, preventing vibration noise, acting as a spacer, or for cosmetic reasons.

Adhesives

Critical materials used in speaker assembly to attach various parts like the magnet structure, spider, voice coil, cone, gasket, dust cap, and more, with different types such as Cyanoacrylates, epoxy, structural acrylics, and solvent-based glues being commonly used.

Rivets and Eyelets

Rivets are used to attach terminal strips, while eyelets are used for solder lugs in closed basket speakers and as a junction point for joining voice coil wires and tinsel lead wires.

Workmanship

Precision workmanship is essential in speaker assembly due to close tolerances of the voice coil travel, variety of materials used, and high expectations regarding sound quality and appearance from users.

Common Manufacturing Defects

Various issues that can arise in a loudspeaker such as broken voice coil lead wire, bad soldering, off-center magnet assembly, glue issues, shorted leads, bent basket, torn cone or gasket, and more, affecting performance and quality.

Small Signal Parameters

Fundamental physical properties of a loudspeaker used for designing enclosures for low frequencies, often referred to as Thiele-Small parameters, accurate at small inputs but not suitable for high input levels, with examples like free-air resonance and voice coil DC resistance.

Small Signal Parameters

Parameters used to describe the behavior of a loudspeaker system under small signal conditions.

DC Resistance (Re)

The DC resistance of the voice coil, measured carefully, which is crucial for accurate calculations of Q.

Quality Factor (Q)

Describes the lossiness of a resonant system, with Q being the inverse of damping (d = 1/Q).

Mechanical Q (Qm)

Represents the damping of the fundamental resonance by mechanical energy dissipation in the speaker parts, mainly the suspension.

Electrical Q (Qe)

Represents the damping of the fundamental resonance by the braking action of the motor when driven from an amplifier with constant voltage output.

Total Q (Qt)

Represents the damping of the fundamental resonance by all causes and is the parallel combination of Qm and Qe.