![]() ![]() I’ve shown the impedance curves of two different 6.5-inch car audio woofers in the graph above. Impedance curves of two different 6.5-inch car audio woofers. If you’re shopping for a door speaker that will be used with a subwoofer, then a low-Q design will prevent a bump in the midbass region that’s associated with sloppiness and muddiness. If you need a driver for a small enclosure, then you’ll want something with a fairly low Qts value to hit a critically damped target Qtc around 0.65 to 0.7. Why might you want an over-damped driver? If you are using it in an enclosure, the compliance of the air in the enclosure combines with the compliance of the cone to create a new Q value – Qtc. A low-Q driver (Qts < 0.65) is considered mechanically overdamped, but this helps to bring the cone back to rest quickly after a signal is removed. A higher-Q speaker (Qts > 0.85) will store and release more energy, which causes the woofer cone to continue to move after the current is removed from the voice coil. We can sum it up in a few short statements. The two values create a “total Q” value called Qts.Ī while back, we wrote a detailed article on why you would want to choose low-Q woofers for your door speakers. The electrical Q is defined by Qes and is the ratio of the driver’s reactance to its resistance. The Qms value is the mechanical Q of the suspension. In the context of Thiele/Small parameters, speakers have three Q values: Qms, Qes and Qts. If you’ve been following the articles we’ve published about speaker specifications, then you’ll recall that a speaker includes two springs (the spider and the surround) that work to bring the cone back to rest after the electrical current is removed from the voice coil. When a technician is working with an equalizer to calibrate the output of a speaker, they will look at the frequency response measurement with an RTA, then choose a filter frequency and Q to boost or cut the signal to compensate for variations in the acoustic response. Three EQ filters are set to add 6 dB at 500 Hz: blue has a Q of 20, yellow is 4.31, and pink is 0.1. Here’s the same graph, with the second band set with a Q of 0.1 and the third band set with a Q setting of 20. The ARC Audio software is quite flexible, allowing for Q values from 0.1 to 20. ![]() Three EQ filters are set to add 6 dB at 500 Hz: blue has a Q of 8.6, yellow is 4.31 and pink is 2.2. I’ve overlaid two additional plus 6 dB filters on this equalizer response graph, one with a Q of 2.2 and a second with a Q of 8.6, to demonstrate the change in bandwidth. However, you need to know this: High Q values result in a narrower bandwidth and lower values in broader bandwidth. ![]() It’s unlikely that we will take the time to calculate Q values. Looking at the screenshot of the ARC Audio PS8 Pro software’s frequency response plot, we can see that boosting 500 hertz by 6 dB using a filter with a Q of 4.31 gives us -3 dB values of about 442 and 558 hertz. Frequency response of a +6 dB boost at 500 hertz using a filter with a Q of 4.31 For example, you might want to boost or cut frequency content at 500 hertz but not affect the output at 400 or 630 hertz. If you had a 30-band graphic equalizer in your vehicle, you’d want each band of adjustment to not overlap with an adjacent band (by default, at least). So if we divide the center frequency (F) by the bandwidth (B), we get the Q. Two values are important to the calculation of the filter Q: the center frequency of the filter and the bandwidth of the waveform at the point that it’s 3 dB down from the peak. Let’s look at the frequency response chart of a single band of equalization. Yeah, I know, more gobbledygook, right? The chart below helps to make everything much clearer.Ī graphical representation of how equalizer filter Q is calculated. So, in this context, what exactly does Q mean? In short, it’s a unitless comparison of the -3 dB bandwidth of the filter to the center frequency. We call this a parametric equalizer when frequency, cut/boost and Q are all adjustable. Your installer can dial in a certain amount of boost or cut at a specific frequency and turn the Q knob or enter a value that defines the frequency range the level adjustment affects. Many car radios and equalizers include adjustable bandwidth settings. When talking about equalizers, the Q of a filter describes its bandwidth. For speakers, proper cone control requires carefully calculated damping. The Q factor describes the damping characteristics of a resonant system. This EQ provides powerful features in a compact size.Car audio enthusiasts will run across the term Q, Q factor or Quality factor when discussing car audio speakers, subwoofer enclosures or parametric equalizer configuration. The Massive EQ 9 is a half din 9 Band Graphic EQ that will correct peaks and dips in sound characteristics associated with most vehicles' interior that dampens and limits both speaker output and imaging. ![]()
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