Do Speaker Cables Make a Significant Difference? Science Weighs In!

The Results May Surprise You

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Speaker cables and their impact on audio can be a highly contentious subject that pops up in conversation time and again. When mentioning speaker cable tests to Allan Devantier, the manager of acoustic research at Harman International (makers of Harman Kardon receivers, JBL and Infinity speakers, and numerous other audio brands), we got into an in-depth discussion. Would it be possible to demonstrate from a technical standpoint that – at least in fairly extreme circumstances – speaker cables can make a detectable difference in the sound of your system?

Some Background Information

First, a disclaimer: we don't have a strong opinion about speaker cables. We've done blind tests (for Home Theater magazine) in which panelists developed consistent preferences for certain cables over others. Yet we rarely concern ourselves with it.

Some people can feel dismayed by both sides of the speaker cable argument. There are publications that belligerently insist that speaker cables make no difference. And on the other side, you can find some some high-end audio reviewers' long-winded, elaborate, effusive descriptions of the differences in the "sound" of speaker cables. It seems to many that both sides are defending entrenched positions rather than engaging in an honest, open-minded effort to seek the truth.

Just in case you're wondering, here's what we use personally: some pro speaker cables made by Canare, some generic in-wall 14-gauge, four-conductor cables for longer runs, and a few other random cables sitting around.

We should add that in more than 20 years of speaker reviewing, and testing speakers from under US$50 to over $20,000 per pair, we've only ever had one manufacturer express concern about what cables were being using.

Allan's Analysis

What got Devantier interested was when we began talking about how a speaker cable might, in theory, change the frequency response of a speaker.

Every speaker is basically an electrical filter – a combination of resistance, capacitance, and inductance tuned (one hopes) to deliver the best possible sound quality. If you add extra resistance, capacitance, or inductance, you change the filter values and, thus, the sound of the speaker.

A normal speaker cable doesn't have significant capacitance or inductance. But the resistance does vary somewhat, especially with thinner cables. Because with all other things being equal; the thinner the wire, the greater the resistance.

Devantier continued the conversation by citing research from Floyd Toole and Sean Olive, colleagues at Harman, who were at the time working at Canada's National Research Council:

"In 1986 Floyd Toole and Sean Olive published research on the audibility of resonances. They found that listeners are particularly sensitive to low-Q [high-bandwidth] resonances. Midrange peaks of just 0.3 decibels (dB) were audible under the correct conditions. Since loudspeaker impedance varies with frequency, the DC resistance of the cable becomes very important. The following chart shows the maximum allowable cable length to ensure that amplitude response variations caused by cable resistance are kept below 0.3 dB. This chart assumes a minimum speaker impedance of 4 ohms and a maximum speaker impedance of 40 ohms and that cable resistance is the only factor; it does not include inductance and capacitance, which can only make things less predictable."

"It should be clear from this table that under some circumstances the cable and the loudspeaker can interact to cause audible resonance."

cable gauge

(AWG)

resistance ohms/foot

(both conductors)

length for 0.3 dB ripple

(feet)

120.003247.23
140.005129.70
160.008018.68
180.012811.75
200.02037.39
220.03234.65
240.05132.92

Brent's Measurements

"You know, you could measure this," Allan said, pointing his finger in a way that implied a command more than a suggestion.

We've been doing frequency response measurements on speakers since 1997, but we've always just used a nice, big, fat speaker cable to connect the speaker under test to the amp – something that wouldn't affect the accuracy of the measurement.

But what if we substituted a crummy, cheap little generic speaker cable? Would a difference be measurable? And would it be the kind of difference that would also be audible?

To find out, we measured the frequency response of a Revel F208 tower speaker by using a Clio 10 FW audio analyzer with three different 20-foot cables:

  1. the 12-gauge Linn cable we've been using for speaker measurements for the last five years or so
  2. a cheap 12-gauge Monoprice cable
  3. a cheap 24-gauge RCA cable

To minimize environmental noise, measurements were performed indoors. Neither the microphone nor the speaker nor anything else in the room was moved. We used an extra-long FireWire cable so the computer and all people could be out of the room entirely. We also repeated each test a few times to make sure that environmental noise wasn't appreciably affecting the measurements. Why so careful? Because we knew we'd be measuring subtle differences – if anything could be measured at all.

We then took the response with the Linn cable and divided it by the response of the Monoprice and RCA cables. This resulted in a graph that showed the differences in frequency response caused by each of the cables. We then applied 1/3-octave smoothing to help ensure no residual environmental noise snuck through.

It turns out that Devantier was right – we could measure this. As you can see in the chart, the results with the two 12-gauge cables were only subtly different. The biggest change was a boost of maximum +0.4 dB between 4.3 and 6.8 kHz.

Is this audible? Maybe. Would you care? Probably not. To put it in perspective, that's about 20 to 30 percent of the change typically measured when we've tested a speaker with and without its grille.

But switching to the 24-gauge cable had a huge effect. For starters, it reduced the level, requiring normalizing of the measured response curve by boosting it +2.04 dB so it could be compared with the curve from the Linn cable. The 24-gauge cable's resistance also had obvious effects on frequency response. For example, it cut bass between 50 and 230 Hz by a maximum -1.5 dB at 95 Hz, cut midrange between 2.2 and 4.7 kHz by a maximum -1.7 dB at 3.1 kHz, and reduced treble between 6 and 20 kHz by a maximum of -1.4 dB at 13.3 kHz.

Is this audible? Yeah. Would you care? Yeah. Would you like the sound better with the skinny cable or one of the fat ones? We don't know. Regardless, past stereo upgrade recommendations of using 12- or 14-gauge cables is looking pretty wise.

This is a fairly extreme example. While there might be a few exotic high-resistance speaker cables out there, almost all speaker cables of at least 14-gauge or so have low-enough resistance that any sonic anomalies introduced should be at least minimal (and probably inaudible). But it's important to note that we measured slight and repeatable response differences, even with two cables close in size and structure. Also, note that the Revel F208 speaker has an average impedance of 5 ohms (as measured). These effects would be more pronounced with a 4-ohm speaker and less pronounced with 8-ohm speakers, which are by far the most common types.

So what's the lesson to take away from this? Mainly, don't use skinny cables in any system where you care about the sound quality. Also, maybe don't be so quick to judge those who say they hear differences among speaker cables. Sure, many of them are obviously exaggerating these effects – and the ads from high-end cable companies often grossly exaggerate these effects. But the calculations and experiments performed suggest that people really are hearing a difference between cables.