A shorter single-ended interconnect or speaker cable performs better than a longer one because a longer run of unshielded conductor behaves more like an antenna, picking up more radio-frequency and electromagnetic interference along its length. This is the opposite of a marketing claim you'll sometimes hear, that a longer cable somehow sounds better. From a technical standpoint, there's no basis for that claim. There's only a reason to sell longer, more expensive runs.
Where this article is going: why length matters, how it connects to something you've likely already experienced with an old radio or an early mobile phone, why it matters even more with turntables, and why professional audio solved this problem decades ago with a cable type most home systems don't use, but should think about when a long run is unavoidable.
Why length turns a cable into an antenna
Any length of conductor can act as an antenna, and the longer it is, the more effectively it does. This isn't a cable-specific quirk, it's basic radio physics: an antenna's job is to pick up electromagnetic energy, and how well it does that depends heavily on its length relative to the frequency it's catching.
Think about an old FM radio. Those radios came with a telescopic antenna you'd pull out to full length to catch a weak station better. The longer you extended it, the more signal it captured. Early mobile phones worked the same way, they had a physical antenna you'd extend to improve reception. In both cases, length was the whole point, more conductor meant more captured signal.
A speaker cable or an RCA interconnect isn't designed to be an antenna. But electrically, it doesn't know the difference. Extend that single-ended conductor over a longer run, and it starts behaving the way that telescopic antenna did, capturing more ambient RF and electromagnetic noise along its length, not less. Longer doesn't mean quieter. It means more exposed conductor for interference to couple into. Geometry and shielding also play a role in how much of that interference actually reaches the signal, but length sets the baseline exposure regardless.
Why this matters even more for single-ended connections
Single-ended RCA interconnects are more vulnerable to this than balanced connections because they have only one conductor carrying the signal relative to ground, with no second conductor to cancel out what gets picked up along the way.
This is why, for RCA and most speaker cable runs, shorter is consistently the better choice. A shorter run simply gives interference less conductor to couple into in the first place. There's no length at which a single-ended cable magically improves by getting longer. The physics runs the other direction entirely.
Why this matters even more with turntables
The consequences get more serious with turntables, particularly with a low-output moving coil (MC) cartridge feeding a step-up transformer. A moving coil cartridge produces an extremely small signal to begin with, often a fraction of what a moving magnet cartridge produces, and that signal needs to travel from the cartridge, through the tonearm wiring, into the phono stage or step-up transformer, before it's amplified to a usable level.
At that signal level, any noise picked up along the way isn't a minor addition, it's a much larger percentage of what you're actually trying to preserve. A longer, more antenna-like signal path at this stage of the chain does proportionally more damage than the same length would do later in the system, after the signal has already been amplified. Keeping this path as short as practically possible isn't a nice-to-have with MC cartridges and step-up transformers, it's one of the more consequential things you can control.
How professional audio actually solved this
Professional audio solved the long-cable problem by switching to balanced XLR connections, which use common-mode rejection to cancel out interference picked up along the cable's length, rather than avoiding long cable runs altogether.
Live sound and studio environments frequently need long cable runs, sometimes tens of meters, from a stage to a mixing desk, for example. A single-ended cable that length would be a serious antenna problem. Balanced XLR cables carry the signal on two conductors instead of one, identical but opposite in polarity, plus a separate ground. Any noise picked up along the run tends to affect both conductors equally. Because the receiving equipment only cares about the difference between the two signals, that shared noise cancels out, while the actual audio signal, which is opposite on each conductor, doesn't. That's common-mode rejection, and it's specifically why professional audio can run long cables without the antenna problem single-ended connections face.
That's common-mode rejection, and it's specifically why professional audio can run long cables without the antenna problem single-ended connections face. The full mechanism behind balanced rejection is covered in more depth here, if you want the complete picture.
This is also the practical answer for anyone who genuinely needs a longer run at home. It isn't "buy a longer single-ended cable and accept the tradeoff," it's "use a balanced connection if the components support it," since that's the actual engineering solution to the problem, not a workaround.
The short answer
A longer run of single-ended conductor picks up more interference, not less, because it behaves more like an antenna the longer it gets. There's no technical case for a longer cable sounding better. Where length is unavoidable, a balanced connection, not a longer unbalanced one, is the actual solution.
Where length is unavoidable, a balanced connection, not a longer unbalanced one, is the actual solution. If you're weighing interconnect options for your own system, this guide walks through the practical side of choosing one.
FAQ
Does a longer RCA cable sound better than a shorter one?
A longer RCA cable does not sound better than a shorter one. A longer run of single-ended conductor picks up more electromagnetic interference along its length, behaving more like an antenna, not less like one.
Why do longer cables pick up more interference?
Longer cables pick up more interference because any length of conductor can act as an antenna, and antenna performance generally improves with length. This is the same principle behind a telescopic radio antenna or an early mobile phone antenna, extending the conductor increases how much signal, wanted or unwanted, it captures.
Why does cable length matter more for turntables with MC cartridges?
Cable length matters more for turntables with MC cartridges because the cartridge's output signal is extremely small before it reaches the step-up transformer or phono stage. Noise picked up along a longer signal path represents a much larger proportion of that small signal than it would later in the chain, after amplification.
Why don't XLR cables have the same length problem as RCA cables?
XLR cables don't have the same length problem because they carry the signal on two conductors with opposite polarity, plus a ground. Interference picked up along the run typically affects both conductors equally and cancels out at the receiving end, a process called common-mode rejection, while the actual signal does not cancel.