Buyer and Engineering Guide

This section contains information, recommendations and applicable data for the professional buyer and engineer.

Choose Your Sound Objectives

AUDIO

Before you purchase any sound system components, you must decide what kind of sound you want to reproduce. Understanding which objectives are most important will keep development focused on achieving those goals.

For Example:

  • A public address system requires high sensitivity and intelligibility to ensure understood messages in a noisy environment.
  • A home theater system requires both high performance full range audio and attention to eye-catching cosmetics.
  • Aerospace requires flame retardant parts, high intelligibility and reliability.
Tips for Purchasing

Loudspeakers are arguably the most critical system component. From vocal clarity to thundering bass lines, it's the speaker that shapes the sonic quality of the source material. Knowing the sound you want guides every other aspect of purchasing the audio system for your application. Knowing the basics of sound system components means you'll have more knowledgeable conversations with audio consultants and manufacturers -- and you'll make smarter buying decisions. That's what this guide is all about. The MISCO team has deep experience in a broad range of audio markets from Aerospace to Theme Parks. Our diverse knowledge is a critical factor in helping you get the specific sound you want. It gives us insights for designing, engineering and manufacturing every audio application you can imagine.

Typical MISCO Loudspeaker Applications

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Loudspeaker Basics

Tips for Purchasing
BASICS!

A loudspeaker is where the electrical signal becomes sound. It breaks down into four subsystems:

  1. Motor Magnet and voice coil. When an electrical signal is applied, the magnetic fields interact and create mechanical movement.
  2. Diaphragm Cone and dust cap. The cone couples to the air to create soundwaves, according to the movement of the motor, to create sound waves and audible sound.
  3. Suspension Spider and surround. Keep the voice coil centered in the magnet's gap, and returns the cone to a neutral position after moving.
  4. Frame The speaker basket provides the rigid chassis that precisely holds everything together, and often acts as a heat sink for the voice coil.
 

Loudspeaker Design Process

Designing a loudspeaker to achieve specific performance goals is a complex process; a lot of physics and engineering with a bit of "black magic" thrown in. But the basics are easy to grasp and essential to know if you're going to get the sound you want.

1. Establish target parameters

  • Performance: Frequency response, sensitivity, power handling, impedance, are the primary specifications
  • Mechanical & mounting requirements based on the space available especially speaker diameter, depth, and weight.
  • Environmental factors: Indoor, Outdoor, Temperature, Chemical resistance, flame resistance are typical factors.

2. Establish cost and delivery requirements

  • Forecasted annual quantities and target cost are important factors. They drive many engineering considerations and decisions and are best discussed early in the project.
  • Things which tend to increase the cost of a speaker
    • Larger frame or magnet size
    • Higher power handling
    • Light weight and compact Neodymium or Alnico magnets.
    • Cone body materials such as composites or special blends of paper. Cone edge materials such as natural or synthetic rubbers.
    • Special treatments for more difficult environments
  • Consider the total landed cost not just the piece price.
    • High quality vendor reduces costs of inspection, scrap, or field defects
    • Does cost include VMI (vendor managed inventory) or Kan Ban?
    • Shorter lead times allow quicker time to market for customer
    • Complete assemblies and pre-assembled units allow lower installation costs.
  • Consider Near-sourcing: Using vendors close to point of use reduce costs
    • Shorter lead times improves customer service and competitiveness
    • Reduced freight & duty costs over
    • Reduced delays due to customs or shipping delays
    • Reduced risk due to long supply chain management
    • Quick and easy communications
    • Intellectual Property production. Keeping confidential information, confidential.

3. Design and engineering

  • Project plan - Overview of how the speaker will be designed along with timeline and key milestones.
  • Final agreement on performance specifications and acceptance criteria.
  • Quoting any development costs. If the product requires extensive engineering there may be costs associated with created performance simulations and drawings.
    • Common tools in loudspeaker design are FEA, magnetic modeling (e.g. SpeaD, FineMotor, Magnet)
    • Solidworks to create 2D or 3D models.
     

4. From Plan to Prototype

  • Engineering drawings and bill of materials (BOM), is the shopping list of all the parts (both custom made and "off-the-shelf") that go into the speaker.
  • Quotes -- the drawings and BOM are sent to vendors who respond with quotes on their parts of the project for both samples an production.
  • Functional prototypes -- once the customer approves the quotes, samples are ordered, inspected, built into prototypes and tested.

5. Performance Testing

  • Complete testing is done on the samples to ensure that the target specifications are met. Initially this acoustical performance testing.
  • Power testing may be completed to the customers exact performance criteria and use.
  • More advanced testing may include long-term reliability as well environmental testing to various Military or FAA standards.
  • Prototypes are sent to the customer for their evaluation, test and measurement.

6. Production

  • Once the product is approved, parts are ordered and pre-production builds and testing assure the production will meet the approved samples.
  • To verify that every manufactured product meets its specs, every one undergoes performance testing; test such as frequency response, impedance, distortion, and other parameters. It;s the final pass/fail check before a speaker goes to work delivering the sound you want.

Loudspeaker Examples

EXAMPLES

GAMING

Gaming Loudspeaker

Model # BJ21-01B

  • Sub-woofer with 2.1 channel, class-D amp with 110Hz 18/dB Octave Crossover Subsonic Filter on Subwoofer Channel Optimized Mid-Range and HighFrequency Active Equalization

Specs:

  • Size: 5-1/4" Long-Throw Woofer with
  • Poly Cone and Rubber Surround
  • Sensitivity: 100 dB SPL
  • Frequency Range: 45 to 20kHz

PRO SOUND - Concert & Stage

Concert & Stage Loudspeaker

Model # WC21W-4A

  • 21" (533 Mm) Subwoofer, 4 Ohm Edge Wound Coil 800 Watts, Ferrite Magnet, Treated Paper Cone With Accordion Cloth Edge, Dual 8" Spider Suspension, Round Cast Aluminum Basket.

Specs:

  • Size: 21.0 inch / 533 mm
  • Impedance: 4 ohms
  • Sensitivity: 95 dB SPL
  • Frequency Range: 20-500 Hz
  • Qts: 0.56
  • Rated Power: 800 watts

PRO SOUND - Musical Instruments

Musical Instruments Loudspeaker

Model # J10PA-8D

  • A 10 inch, round, guitar speaker, 8 Ohm sdesigned with a 7 oz ALNICO magnet and vintage magnet housing along with a vintage seamed paper cone. The basket is black powder coated armorstyle with a 1" Voice Coil.

Specs:

  • Size: 10.0 inch / 257 mm
  • Impedance: 8 ohms
  • Sensitivity: 97 dB SPL
  • Frequency Range: 70-6000 Hz
  • Qts: 1.95

Auto/Motorcycle

Automotive Motorcycle Loudspeaker

Model # MX65-4B

  • 6.5" (165 mm), 4 Ohm, Extended Range Coax for Music and Voice, 40 Watts, Ferrite Magnet, Black Talc Filled Polypropylene Cone With Natural Rubber Surround, Dome tweeter.

Specs:

  • Size: 6.5 inch / 165.0 mm
  • Impedance: 4 ohms
  • Sensitivity: 91 dB SPL
  • Frequency Range: 30-20000 Hz
  • Qts: 0.31

OUTDOOR

Outdoor Loudspeaker

Model # ATS-360

  • These outdoor speakers are designed Omni-directional (360) for applications where hidden audio and smooth coverage, without loud or dead spots, is desired. Rugged and built to be buried in any terrain. Mushroom® Speakers provide the music source that blends.

Specs:

  • Size: 8.0 inch / 200.0 mm
  • Impedance: 8 ohms
  • Sensitivity: 93 dB SPL
  • FO: 70-8000 Hz

TRANSIT

Transit Loudspeaker

Model # N9870-WP

  • 6" (156mm), 8 Ohm, Voice Range, 12 Watts, Ferrite Magnet, Black Acrylic Treated Cloth Cone With Pre Treated Black Cloth Sound built for high reliability and intelligibility.

Specs:

  • Size: 6.0 inch / 156.0 mm
  • Impedance: 8 ohms
  • Sensitivity: 92 dB SPL
  • Frequency Range: 100-8000 Hz
  • Qts: 2.53

MILITARY

Military Loudspeaker

Model # MP-1103

  • This product is designed for voice communications and includes a phenolic cone for outdoor or difficult applications. The use of a piezo ceramic driver reduces the problems caused by size, weight and stray magnetic fields of conventional speakers. They are resistant to normal humidity variations and unaffected by a variety of external shock, vibration and stress conditions.

Specs:

  • Size: 4 inch / 100 mm
  • Impedance: 1000 ohms
  • Sensitivity: 80 dB SPL
  • Frequency Range: 450- 20,000 Hz

SIGNAL/ALARM

Signal Alarm Loudspeaker

Model # N9113-D

  • This 3", 8 Ohm speaker uses an acrylic impregnated cloth cone to make it waterproof. This speaker uses a sealed frame design to provide maximum output at 1100 Hz.

Specs:

  • Size: 3.0 inch / 77.0 mm
  • Impedance: 8 ohms
  • Sensitivity: 107 dB SPL
  • Frequency Range: 900-3000 Hz

COMMERCIAL

Commercial Loudspeaker

Model # JC8PA-5T2570-8WB

  • 8" (205mm), 8 Ohm, Full Range speaker, with Ferrite Magnet, Paper Cone. Includes 5 watt, dual 25/70 voltage transformer. Both are mounted on a 13” round decorative steel grille, painted white.

Specs:

  • Size: 8.0 inch / 205 mm
  • Impedance: 8 ohms
  • Sensitivity: 97 dB SPL
  • Frequency Range: 40-14000 Hz
  • Qts: 0.8

AEROSPACE

Aerospace Loudspeaker

Model # EN4FR-1000A

  • A light weight, 4" speaker with an aluminum basket and high energy neodymium magnet. An innovative circuit board design allows the speaker to be used in a 70 volt system without the need for a heavy transformer.

Specs:

  • Size: 4.0 inch / 100.0 mm
  • Impedance: 1075 ohms
  • Sensitivity: 92 dB SPL
  • Frequency Range: 200-6000 Hz

HOME THEATER

Home Theater Loudspeaker

Model # OOC12WF-4-4B

  • 12" (304mm), Cast Aluminum, Dual 4 Ohm, Woofer, 100 Watts, Ferrite Magnet, Paper Cone With Foam Surround, Tinsel Leads Sewn Into Spider, Parameters Shown Are Coils In Series, RoHs Compliant.

Specs:

  • Size: 12.0 inch / 304.0 mm
  • Impedance: 4 ohms
  • Sensitivity: 90 dB SPL
  • Frequency Range: 20-200 Hz
  • Qts: 0.36

Glossary of Terms

BL: Speaker force factor or strength of the motor. Higher BL values mean larger forces are generated by electrical current flowing through the voice coil. It is the product of B (magnetic gap field strength) x L (Length of voice coil wire in the magnetic gap field). It is often stated in Tesla-Meters (T-M). Typical speaker BL ranges from 2 T-M to 20 T-M.

Cms: Mechanical compliance of the driver suspension of stated in mm/N

dB: Decibel. A unit of signal strength, actually the ratio or difference between two signals. The decibel is a logarithmic (rather than linear) measurement. For example, doubling the output of an amplifier yields a 3 dB increase in signal strength. See: SPL.

Driver: A term often used to describe the unenclosed speaker. Other terms used are transducer, loudspeaker, or speaker.

DCR (Re: The DC (direct current) electrical resistance of the voice coil (Also known as Re) measured in Ohms. A speaker rated with an 8 ohm impedance will have a D.C.R. of about 6 - 7 ohms.

Fo (Fs): Resonance frequency of a driver when the maximum amount of energy is stored in the moving mass and suspension. Coincides with maximum impedance (Zmax). A sub-woofer may have an Fo of 20 Hz while a tweeter may have an Fo of 3,000 Hz.

Frequency Response: A range of frequency that a speaker produces, expresses in hertz and often given with a tolerance. Typical ranges are: Sub-woofer: 20-100Hz; Woofer: 40-500 Hz; Mid-range: 200-3,000 Hz; Voice range: 300-3,000 Hz; Tweeter range: 3,000-20,000 Hz; Full range: 20-20,000 Hz

Impedance: A type of resistance which includes the inductance of the voice coil during operation and is measured in ohms (Ω). According to Ohms Law, it's the ratio of voltage (E) to current (I in an AC circuit. (E/I = R)

Most speakers are categorized as either 4Ω or 8Ω. Matching the load impedance of a speaker to the source impedance of an amplifier (4Ω to 4Ω, for example) helps maximize power transfer. Using a speaker with a lower impedance rating then the amplifier can damage the amplifier. Using a speaker with a higher impedance rating then the amplifier will not damage the amplifier but will produce less output from the speaker.

Mms: Mechanical mass of diaphragm cone assembly, including air load and is stated in Grams. Typical Mms are 0.3 grams for a tweeter to 120 grams for a sub-woofer.

Power Rating: A complex and often mis-stated specification. It is stated in Watts (W) and often referenced to an industry standard, such as EIA-426B or AES. The best ratings are created using the type of signal or program material used in the actual application. Ratings can be defined relative to a maximum distortion, mechanical bottoming (soft parts hitting hard parts), power compression (when more power in does not create more sound out), or when the speaker "blows" (stops working altogether). Power ratings can vary from 0.1 watt for small speakers to over 1000 watts for large speakers.

Qts: Q of driver at Fs considering all driver losses. Combination of mechanical (Qms) and electrical (Qes) damping that occurs in a loudspeaker. Most loudspeakers have a Qts from 0.3 to 1.0.

Sd: Surface area of the speaker cone stated in cm². A 4" (100mm) speaker has an Sd of approximately 55 cm²

Sensitivity: The measurement of output for a given input, usually expressed in decibels (dB) SPL with 1 Watt input measured at 1 Meter distance. This approximately correlates to the efficiency of the loudspeaker's ability to turn electrical energy (signal) into acoustic energy (sound). Most speakers have a sensitivity of 75 - 100 dB SPL with 1 watt / 1 meter.

Sound pressure level (SPL): Technical term for what your ears interpret as loudness or volume. Expressed in decibels (dB) above the threshold of hearing at 0 dB. Background music or a nearby conversation could have an SPL of 50-60 dB. A rock concert could get up to 120 dB.

Tolerance: Most speaker parameters are typically I0 -20% or +/- 5 dB per frequency response and sensitivity.

Vas: The volume of air having the same acoustic compliance as the driver suspension. This relates to the compliance of the speaker suspension (Cms) and the size of the speaker cone (Sd). It is expressed in units of ft³ or Liters. This is an important specification in determining loudspeaker enclosure volume. A small 2" speaker may have a Vas of 0.2 Liters while a 12" woofer may be 150 Liters.

Xmax: The Maximum excursion of a speaker usually stated in Millimeters (mm). It is roughly equal to the amount of voice coil wire above or below the front plate of the speaker. It can vary from 0-25mm depending on the speaker type.