11/27/2023 0 Comments Speaker wire for car audioShould you use 18-AWG speaker wire with your subwoofer? Probably not. For the mids, at full power, maybe there is a minute loss that might affect the balance of the system. For your tweeters, it just doesn’t matter. What happens if we run 14- or 18-AWG wire instead of 12-AWG? The chart below shows the reduction in output at the most extreme cases with test tones being played. With the dynamic characteristics of music, it’s safe to assume the average required power is 1/10 of the maximum. At even one notch down, those reductions diminish significantly. In short, these differences aren’t going to be audible at anything other than when the volume is turned up all the way. The voltage drop in the wire will be 0.314, 0.181 and 0.026 volts which, if my math is correct, represents a reduction in output of 0.157, 0.091 and 0.018 dB, respectively. If the speaker wire is full AWG spec and is made from pure copper, the 10-foot length will have a total resistance of about 36.3 milliohms. Let’s use a piece of 12-AWG speaker wire with a length of 10 feet for our benchmark. Current in Car Audio Speaker Wireįor our example, our 300-, 100- and 4-watt power levels translate to 8.66, 5 and 1 amp of current flowing through the respective speakers. We’ll also maintain the simplicity of the example by assuming all the speakers in the system have a nominal impedance of 4 ohms. To keep our example simple, let’s use 300 watts, 100 watts and 4 watts for the math involved in calculating how much power is lost due to the resistance of speaker cabling. As such, we need to look at an average level. Music isn’t a single constant sinusoidal waveform. An AC sine wave of, say, 10 volts RMS can do the same amount of work as 10 volts DC. For pure sine waves, this with where the Root Mean Square (RMS) value comes in. Power in Alternating Current SignalsĪ commenter in that thread wrote, “Yeah, but it’s AC, not DC,” as if to imply that an AC signal wouldn’t deliver as much current to the speaker. With nearly 5 dB more output required, the subwoofers would need 316 watts, assuming they had the same efficiency as the midrange speakers. So, you need about 4.1 watts for those tweeters if the mids are getting 100 watts. In this example, the average amplitude of the signal going to the mids compared to the tweeters is 13.9 dB louder. If you had 100 watts going to the door speakers, your tweeters would only need 1 watt of power to keep up. In fact, it’s about 20 dB less at the highest level. It’s clear to see that the tweeters are receiving a lot less energy than the midrange drivers in the doors. In this graph, we show the audio energy going to the subwoofer (red), the midrange drivers (orange) and the tweeters (yellow). The graph below shows the energy fed to the subwoofers, midrange drivers and tweeters using these crossover points. If you have a typical car audio system, then you may have a subwoofer or two to handle reproducing audio frequencies below 80 Hz, midrange drivers to handle the sounds from 80 to 3,500 Hz and tweeters for those frequencies above 3,500 Hz. The green line is the energy content in Daft Punk’s “Get Lucky” averaged over the entire length of the track. The blue line in the graph above shows the frequency of pink noise. If you analyze the energy in a pink noise waveform, you’ll see that its amplitude attenuates at a rate of -3 dB per octave or -10 dB per decade as frequency increases. Why do higher frequencies need less power to reproduce? Most of the sounds we hear follow the same approximate shape as pink noise. In that case, your amplifier will produce significantly less power than it would take to reproduce the lowest notes of a synthesizer or bass, even at the same perceived volume level. Suppose you’re listening to a recording of an electric guitar. The amount of voltage produced by your amplifier is dependent on the volume setting and the frequency content of the audio signal. So, to help as many people as possible understand the subject, we put together this article to explain why you don’t need 12-AWG wire for your tweeters. The comments on the post were prime examples of how little some audio enthusiasts understand about the signals going to the speakers in their car audio system. Not too long ago, we stumbled across a discussion about the need for large-gauge car audio speaker wire to be connected to a high-power amplifier.
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