When it comes to correlating how the parameters of a speaker translate into music reproduction, well, the details are often somewhat sparse. One speaker characteristic that’s often overlooked when searching for new subwoofers or woofers is Q. This unitless number is a key component in describing how the suspension and motor work to control and damp cone oscillation at its resonant frequency. Different Q values affect efficiency, frequency response and, ultimately, sound quality. It’s not an intuitive topic, but understanding Q factor is crucial to picking the best bass solution for your car audio system. This is a full-propeller-beanie discussion, but it’ll be time well spent.

What Is Speaker Q?

If you’re an audio aficionado, then you may have heard of speaker specifications called Thiele/Small parameters. These specifications can be used to simulate and predict the low-frequency performance of a loudspeaker. Three of the specifications relate to a topic called Q. Q (or quality factor) is a unitless number that describes how underdamped an oscillating circuit is. A higher Q value means that the circuit or system has low damping and will ring or resonate for longer.

Here’s an analogy that might help you understand. Do you know those springy little door stoppers that kids like to play with? They go boing when you flick them. In the right setting, they’re somewhere between entertaining and amusing. After a few dozen flicks, they become annoying. They have a high Q factor. They bounce back and forth for a few seconds after the initial input (a flick of your finger) is applied.

If you were to apply a piece of electrical tape to the top of the door stopper, it would act to damp the vibrations. The effect would lower the Q of the spring system, and the resonances (vibrations) would stop faster.

For most mechanical or electrical circuits, a Q of 0.5 is considered to be optimally damped. A Q of 0.3 would be over-damped, and a Q of 0.7 would be under-damped. A tuning fork, for example, has a Q of roughly 1,000.

Speaker Q Factor

For the purposes of this discussion, we are going to look at a typical door woofer (6.5-inch) to evaluate how different Q factors affect frequency response. The perfect speaker would have a flat frequency response that’s determined by its Thiele/Small parameters. It would look like this:

Qts is the Thiele/Small parameter that defines the total Q factor of a speaker. The value takes into account both the mechanical and electrical Q factors of the driver, equally.

Most car audio speaker manufacturers don’t fully understand the relationship between Q and frequency response, or they choose to ignore it to deliver a certain “sound.” Unfortunately, when it comes to truly high-end speakers, tailoring the frequency response of the system should be left to an equalizer built into a digital signal processor, and not a characteristic built into a speaker.

Here are the benefits of using a higher-Q door woofer: They are more efficient in the upper bass and midbass region. The extra energy stored in the suspension is released and adds to the output, typically in the region focused around 140 to 160 Hz. If you’re designing an audio system without a subwoofer, the extra bass can be of some help in making the system sound fun.

The drawback is that the extra energy that is stored and released by the suspension is distortion. It’s sound that wasn’t in the original recording. Remember, the suspension of the speaker is a spring. You don’t want it to continue to resonate back and forth after the signal goes away. That back and forth motion not only affects the frequency domain but the time domain. Sounds continue to ring out after the original input is gone. In subwoofers, this is often what’s described as being boomy. In a door woofer, it’s sloppiness. Conversely, a properly damped speaker is often described as sounding “tight” or “fast.” Since speed can’t change, these descriptions are limited in their accuracy.

Shopping for Great Woofers

If your car audio system includes a subwoofer (and it really should), then you’ll want to search for a door woofer that has a low Q. Some 6.5-inch woofers like the Audison Thesis TH 6.5 II and Audiofrog GB60 have Qts values under 0.5. The Morel Supremo MW6, Hertz MP 165P.3, and Focal ES 165 KX3 woofers also have relatively low Qts values. Lower values (0.4 to 0.5) are better, and you’ll want to avoid anything above 0.6 if you have a subwoofer and want properly damped midbass performance.

Drop by your local specialty mobile enhancement retailer and talk to them about how best to upgrade your car audio system to deliver amazing bass and midbass performance and accuracy.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

One trait that has come to be universally expected among luxury vehicles is the quietness of their interior. Once exclusive to such premium vehicles as Mercedes, Audi, BMW and Rolls-Royce, companies like Hyundai and Kia are delivering startlingly quiet interiors. In addition to minimizing road and wind noise, the drone of an exhaust system and the hum of the tires, a quiet cabin lets you hear more of your music and makes your hands-free Bluetooth calls sound better. Let’s take a look at how your local specialty mobile enhancement retailer can make your vehicle more luxurious.

How Automakers Create Quieter Vehicles

Automakers use technologies like Active Noise Cancellation (ANC) that combines information from microphones placed around the interior with signal processing that uses the sound system speakers to cancel out low-frequency road noise. So far, this technology isn’t available in the aftermarket.

Another popular noise control solution are tires that are lined with polyurethane foam to reduce noise. Michelin suggests that tires equipped with its Acoustic Technology can be as much as 20% quieter than a conventional tire.

Automakers also fill voids in the chassis with special closed-cell foam to reduce noise transfer and increase vehicle rigidity. The foam also reduces noise transfer into the vehicle.

How Can You Make Your Vehicle Quieter?

As interesting as it is to know how automakers make cars quieter, you might be interested in a simple solution to increase the comfort of your vehicle. The answer is sound deadening. Companies such as SoundShield, Dynamat, Stinger, Wirez, Hushmat, Resonix and many more offer products that can be affixed to the flat surfaces of your car or truck to reduce the noise that transfers into the vehicle. These damping mats, also known as constrained layer damping material, reduce the ability for the metal panels that make up the doors, roof and floor of your car to vibrate and pass sound into the interior.

Steps To a More Luxurious Vehicle

When it comes to blocking noise, the first step is usually to have your installer treat the outer door skins with constrained layer damping mats. These panels are often large and relatively flat, making them a prime source of noise.

The next step is to seal up any openings in the interior door skin. Not only do these openings allow sound to enter the vehicle, they dramatically reduce the performance of any speakers in the doors. Even factory-installed woofers will perform much better once the doors are sealed up.

Once the doors are quiet, you will want to turn your attention to the floors and fenders. Tire, exhaust and mechanical noise from the engine and transmission can be reduced significantly with a layer of quality deadening.

As you can see from the photo of the red Porsche 911 (courtesy of Matt Schaffer from Sound FX Off-Road and Car Audio in Lewes, Delaware), not every square inch of the vehicle needs to be covered for deadening to do its job.

Last and certainly not least, treating the roof with proper noise control will cut down on wind noise. Make sure the sound deadening material you have chosen can withstand being installed upside down. Not all of them have an adhesive that is strong enough to defy gravity for years and years.

How Much Quieter Will My Vehicle Be?

Many customers ask how much improvement a layer of sound deadening will make. It’s difficult to provide an exact number because it depends on how much deadening already exists and the design of the vehicle. Treating an entire interior (doors, floor, fenders and roof) can easily reduce background noise by 10 to 15 dB, even on relatively new vehicles.

To find out how much quieter your vehicle can be, drop by your local specialty mobile enhancement retailer today and ask them about treating your vehicle with sound deadening. We can guarantee the improvement in luxury and comfort will be worth every penny you invest.

Over the years, many car audio enthusiasts have complained that while new speakers made their car stereo systems sound better, the new speakers didn’t make the systems any louder. In fact, the more you work to upgrade your speakers, the more you often find that you have traded efficiency for smooth frequency, accuracy and clarity. This article explains a bit of the physics behind this phenomenon and provides a solution to make your audio system sing.

Speaker Efficiency Versus Bandwidth

The speakers that are installed in cars and trucks on the assembly line are designed to play loudly with minimal power. This efficiency is achieved by using lightweight cone materials and voice coils. The drawback of this design is a trade-off in power handling (small coils handle less heat) and bandwidth (lighter speaker cones typically produce less bass).

The image above compares the output of two high-quality 6.5-inch coaxial speakers from Audison. The trace in green is the Prima APX 6.5 and the trace in blue is the Voce AV X6.5. You can see that at most points across the frequency graph, the APX 6.5 is more efficient by 2 to 3 decibels. In this case, the rated efficiency numbers of 94 dB and 91 dB correlate well to the information provided by the graph.

It’s worth noting that the Voce produces 3dB more bass output at all frequencies below about 80 Hz. This output is due, in part, to having a cone mass of 16.1 grams compared to the 11.5 grams of the Prima.

Is one speaker better than the other? No: They are each designed for specific applications. The lighter Prima driver is intended to be used with low- to mid-power amplifiers. The Voce is a little less efficient overall, but can handle more power and offers 50% more excursion capability. When paired with an appropriate amplifier, the Voce has the ability to play louder than the Prima.

These speakers highlight the typical scenario that happens when someone upgrades to a speaker solution that offers smoother frequency response and more bandwidth. The audio system will sound better, but isn’t as efficient. When provided with the power they need, the better speakers can play louder.

How to Make Your Car Audio System Play Louder

It should come as no surprise, based on the information above, that the key to being able to crank up your music is to have adequate power from the amplifier in your car audio system. If you are using a standard aftermarket radio or your vehicle has an entry-level audio system, then each speaker in the car or truck might only see around 20 watts of power.

If you’ve got a high-power radio like a receiver from Sony, or you’ve added an ultra-compact amplifier, then roughly 45 to 50 watts are available to drive each speaker. If you opt for a larger amp that will have to be mounted under a seat or in the cargo area, you may have 85 to 150 watts available to crank your tunes to 11. Much more than this will probably result in damage to any conventional high-frequency speaker (not a subwoofer) designed for a car audio system.

Great Car Stereo Speakers Need Power to Play Loud

If you are upgrading your car stereo system to play louder, then you need a combination of speakers that have good excursion capabilities and amplifiers powerful enough to drive them. If your system design falls short on either count, it might not play as loudly as you want. Your local specialist mobile enhancement retailer can help you plan your upgrade so you’ll have the performance and reliability you want.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.

When it comes to car audio amplifiers, people often mistake quality with high power ratings. This misperception has led to manufacturers coming up with every angle or trick possible to measure as much power as possible from their designs. Many manufacturers publish both continuous low-distortion specs as well as maximum power ratings. Are the high numbers useful or relevant? Spin up your beanie propeller for a close look.

How Car Audio Amplifier Power Is Measured

There are lots of wrong ways to measure power from a car audio amp. The worst is to make an assumption about the load impedance of a speaker and measure the voltage being produced by the amp. The voltage measurement is used in a simple equation to supposedly calculate power. The problem is, the impedance of a speaker changes depending on the frequency being played, so the math simply doesn’t work.

An ever-so-slightly better method is to use a voltmeter and an ammeter. These tools are used to measure current and voltage. There are two problems with this method. Most users leave both tools in peak-hold mode and perform math on the resulting numbers. As the voice coil of a subwoofer heats up, its impedance rises and current flow decreases. Maximum current will often be present at the beginning of the measurement, then maximum voltage a few seconds later as the current draw from the amp power supply reduces. The second problem is that voltage and current aren’t in phase through a voice coil because the coil has inductance. This gets into somewhat complicated alternating current theory. Just know that the two measurements have to be taken at the exact same instant – much faster than typical meters can produce – for them to be accurate.

During amplifier development, power is measured with a purely resistive load bank and calculated based on voltage. This provides an accurate lab number, but may not translate perfectly into real-world performance when driving highly reactive loads (woofers with high inductance). That said, the numbers are repeatable and consistent.

For real-world measurements, D’Amore Engineering developed the Amp Dyno AD-1. This rack-mount device not only measures current and voltage simultaneously, it also analyzes the audio signal for distortion and can stop the measurement when it reaches 1%. The handheld AMM-1 Audio Multimeter offers the same functionality in a device that can be used with subwoofers and speakers in a vehicle.

What About Distortion?

Determining how much power is available to drive your speakers needs to take into account distortion in the audio signal. If the amp is pushed into clipping, the power it is producing no longer matches the original waveform. Back around 2004, the Consumer Electronics Association (now called the Consumer Technology Association) developed a standard for car audio amplifier power testing called CEA-2006. The standard specifies the supply voltage to the amp (14.4 volts), the load impedance (4 ohms) and the maximum amount of distortion and noise allowed in the output signal (1% THD+N). Manufacturers can include lower-impedance measurements for subwoofer amplifiers designed to produce maximum power into 1- or 2-ohm loads, but they are to be separated from the CEA-2006 (now called CTA-2006) specification.

What About Maximum Power Ratings?

Maximum power ratings, like those provided with most radios, are basically useless. Let’s look at a high-quality multimedia receiver like the Sony XAV-AX5000. Sony rates the radio as capable of producing 20 watts of power from each of the four channels. Total noise and distortion are below 1%, as per the CTA-2006 specification.

If you were to continue to turn up the volume on the radio past the point that the amp reached 1% distortion, the little amplifier IC would keep trying to produce more voltage. The limiting factor is that the amp can only work with the voltage provided by the battery and alternator – about 13.5 to 14.0V in most cases.

This voltage limit means that the most voltage we can apply to a 4-ohm speaker is about 13 volts from the highest peak to the lowest dip.

If we push the output to a level that would contain roughly 1% distortion, the result would look similar to the following waveform.

If you were listening to this, you’d start to hear the waveform turn sour because of the addition of unwanted harmonic content.

If we find a way to continue increasing the signal going into the amp, without increasing the maximum voltage the amp can produce, the waveform starts to look like this:

What Is Power?

When looking at the above three waveforms, the power is calculated by analyzing the area under the curve for each half of the waveform. For a pure sine wave with no distortion, the equation is (Peak-to-Peak voltage x 0.707)^2 / R. For our 13-volt peak-to-peak waveform with a nominal resistance of R=4 (a 4-ohm speaker), that works out to 21.12 watts. As we introduce more clipping, the rest of the waveform increases in amplitude. There isn’t a simple formula to calculate power in a distorted waveform. Once we get to a square wave, where the voltage swings from our maximum positive to our maximum negative limits, the formula is (Peak-to-Peak Voltage)^2 / R. For our example, this is 42.5 watts.

The graph above tells the tale of clean power versus dirty power. Any output signal that falls into the green area should be reproduced accurately and with minimal distortion. Because of the power supply voltage limits of our amplifier IC, we can get more power from the amp, but it will be distorted and sound garbled.

Are Peak Power Ratings of Any Use?

If an amplifier manufacturer wants to publish the largest possible “power” number on an amplifier, and it is capable of producing a square wave output, then the peak power rating should be roughly double that of the RMS, continuous or CTA-2006 compliant rating. Can we use this power to listen to our music? Not really. It sounds terrible. Drop by your local specialty mobile enhancement retailer today and let them help you choose an amplifier that produces the power you want without adding unwanted distortion to the signal.

This article is written and produced by the team at www.BestCarAudio.com. Reproduction or use of any kind is prohibited without the express written permission of 1sixty8 media.