How to Match a Car Subwoofer and Amplifier

Need help knowing how to match a car subwoofer and amplifier? Tired of your friends constantly asking you to pair a sub and amp for them? Watch this video (or send it to a friend) and learn about the three major points of matching subwoofers and amps:

• The Total RMS of the System
• The Final Impedance of the System
• Types of Amplifiers

In this video we use the 750 watts RMS Kicker CVX (CompVX) subwoofer and the Kicker ZX750.1 amplifier (750 watts RMS @ 2 ohm) as an example of a perfectly matched subwoofer and amp.

Subwoofer Design Software

Bandpass Designer Software calculates 4th order bandpass theoretical enclosures and boxes.

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Input Parameters:

The following Theile Small speaker parameters are required for input. These values should be included with your speaker manual or can be found on the manufacture's web site. 

• Qts -  Total Q of the speaker
• Qes - Speaker electrical Q
• Fs - Free air resonance of speaker in Hz
• Vas - Volume of air equal to the speakers spring characteristics in liters
• Pmax - Maximum power of the driver in watts
• Diameter - The diameter of the driver in cm
• Xmax - The amount of cone movement in one direction in mm
• Dp - Diameter of the port(s) in cm
• Ports - Number of ports

The following speaker parameters are user defined inputs. These values should be inputted by user preference. 

Gain: dB increase of the system:

• S: Ripple
• S = 0.5 - Degraded response pronounced ripple
• S = 0.6 - Slightly degraded response slight ripple
• S = 0.7 - Best transient response no ripple

NOTES:

MAKE SURE THE UNITS MATCH (e.g. Vas is in liters not cubic feet).

Pmax, Diameter, and Xmax are not required for box calculation. They are used to determine the power response curve. Vf, Vr, Fl, Fh, Fb, and Lp will still be valid for Qts, Qes, Vas, Dp and number of Ports.

Ported designs require tuning. Bandpass Designer should give a good approximation of box parameters for most applications.

Use the largest diameter port as the design allows. Drivers greater than 10" in diameter can produce port noise due to the air movement.

Calculated Parameters

The following speaker box and enclosure parameters are calculated:

• Vf: Internal volume of front chamber (port goes into this chamber) in liters.
• Vr: Internal volume of rear chamber (sealed) in liters.
• Fb: Box resonance in Hz
• Fl: -3 dB frequency for the low end roll off
• Fh: -3 dB frequency for the high end roll off
• Lp: Length of port(s) in cm

Sealed Designer Software is for designing sealed or closed theoretical enclosures:

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Input Parameters:

The following speaker Theile Small parameters are required for input. These values, except Qtc, should be included with your speaker manuals or on the manufactures web site. 

• Qtc: Total Q of the speaker and box
• Qts: Total Q of the speaker
• Qes: Speaker electrical Q
• Fs: Free air resonance of speaker in Hz
• Vas: Volume of air equal to the speakers spring characteristics in liters
• Pmax: Maximum power of the driver in watts
• Diameter: The diameter of the driver in cm
• Xmax: The amount of cone movement in one direction in mm

Vented Designer Software is for designing vented or ported theoretical enclosures.

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Input Parameters: The following Theile Small speaker parameters are user defined inputs. These values should be inputted by user preference. Alignment: Choose desired alignment: SBB4: Good response, Large enclosure, Low tuning frequency QB3: Slightly degraded response, Small enclosure, Lower F3 SC4: Degraded response, Large enclosure, Low tuning frequency

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1 to 4 W audio power amplifier

General Description:

The TDA1015 is a monolithic integrated audio amplifier circuit in a 9-lead single in-line (SIL) plastic package. The device is especially designed for portable radio and recorder applications and delivers up to 4 W in a 4 Ω load impedance. The very low applicable supply voltage of 3,6 V permits 6 V applications. 1 to 4 W audio power amplifier

Special features:

• single in-line (SIL) construction for easy mounting
• separated preamplifier and power amplifier
• high output power
• thermal protection
• high input impedance
• low current drain
• limited noise behaviour at radio frequencies

Circuit Diagram:

1 to 4 W audio power amplifier circuit diagram

Datasheet for TDA1015: Download

4 W audio power amplifier with DC volume control

GENERAL DESCRIPTION:

The TDA1013B is an integrated audio amplifier circuit with DC volume control, encapsulated in a 9-lead single in-line (SIL) plastic package. The wide supply voltage range makes this circuit ideal for applications in mains and battery-fed apparatus such as television receivers and record players. The DC volume control stage has a logarithmic control characteristic with a range of more than 80 dB; control is by means of a DC voltage variable between 2 and 6.5 V. The audio amplifier has a well defined open loop gain and a fixed integrated closed loop. This device requires only a few external components and offers stability and performance. 4 W audio power amplifier with DC volume control

Features:

• Few external components
• Wide supply voltage range
• Wide control range
• Pin compatible with TDA1013A
• Fixed gain
• High signal-to-noise ratio
• Thermal protection

PINNING:

1. power ground
2. amplifier output
3. supply voltage
4. electronic filter
5. amplifier input
6. control unit output
7. control voltage
8. control unit input
9. signal ground (substrate)

Circuit Diagram

4 W audio power amplifier with DC volume control

Datasheet for TDA1013B: Download

Stereo headphone amplifier

General Description:

The LM4910 is an audio power amplifier primarily designed for headphone applications in portable device applications. It is capable of delivering 35mW of continuous average power to a 32Ω load with less than 1% distortion (THD+N) from a 3.3VDC power supply. The LM4910 utilizes a new circuit topology that eliminates output coupling capacitors and half-supply bypass capaci-tors (patent pending). The LM4910 contains advanced pop & click circuitry which eliminates noises caused by transients that would otherwise occur during turn-on and turn-off. Boomer audio power amplifiers were designed specifically to provide high quality output power with a minimal amount of external components. Since the LM4910 does not require any output coupling capacitors, half-supply bypass capaci-tors, or bootstrap capacitors, it is ideally suited for low-power tors, or bootstrap capacitors, it is ideally suited for low-power sumption are primary requirements.  Amplifier circuit

Features

• Eliminates headphone amplifier output coupling capacitors (patent pending)
• Eliminates half-supply bypass capacitor (patent pending)
• Advanced pop & click circuitry eliminates noises during turn-on and turn-off
• Ultra-low current shutdown mode
• Unity-gain stable
• 2.2V - 5.5V operation
• Available in space-saving MSOP and SOIC packages

Applications

• Mobile Phones
• PDAs
• Portable eletronics devices
• Portable MP3 players

Circuit diagram:

Stereo headphone amplifier

Amplifier circuit