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Whether you are setting up a temporary or a permanent stereo system, knowing the basics about how your components communicate is essential to getting the best quality sound. This fact couldn’t be more true when it comes to the delicate signals produced by a turntable. So, knowing the proper gauge and turntable cable lengths are critical to maximizing your audio experiences.
Understanding the correct turntable cable length involves using the equations to calculate voltage drop. Depending on the turntable and whether or not a pre-amp exists within will significantly affect the length of cable necessary before noticeable audio signal degradation.
Okay, so you don’t really need to be an electrical engineer to figure this out, even if it may appear as such. Never fear; I am going to walk you through it, step by step. So, by the end of this article, you’ll sound like a geeky audio engineer spewing formulas and numbers until your heart’s content. Let’s take this for a spin, shall we?
Table of Contents
Turntable Cable Lengths – Start Here
As I mentioned, we need to apply some math if we are to figure out just how long a cable is required (and what gauge) for optimal audio performance. However, before we dive right in, I should note the difference between two types of signals you likely have heard of: PHONO and LINE.
PHONO SIGNAL
Back in the day, when vinyl records were being invented and innovated, there was an issue with how much audio you could fit on a record. So, the Recording Industry Association of America (RIAA) introduced a standard (still in use today). This standard they created boosted the higher frequencies while lowering the low ones. In essence, it allowed more audio to fit on a record. However, when reproduced, it sounded weird, so the record players needed a mechanism to undo the standard for playback. The RIAA preamp was born, and this internal device amplifies the frequencies, reversing the compression standard imposed to fit more audio on the vinyl. (source)
The signal is called PHONO before it reaches the preamp. Many turntables offer both PHONO and LINE outputs.
The voltage of the PHONO signal is very weak and delicate at only 0.004 to 0.005 volts compared to the 0.3 volts found on the LINE signal. (source)
LINE SIGNAL
The audio signal produced post preamp in a turntable with LINE output is the amplified and corrected frequency version of the PHONO signal produced by the record cartridge. As mentioned, the LINE signal is amplified and runs at the industry nominal standard of 0.316 volts, with a peak of 0.447 volts. (source)
When To Use PHONO Or LINE
If your turntable has a built-in preamp, then you use the LINE output to your amplifier’s AUX input. Do not plug a preamp line like LINE into a PHONO input. If you have a PHONO input on your amplifier, ensure that a)you’re using the PHONO output from the turntable and b) if the turntable has an output selector, ensure it’s selected PHONO before plugging into your PHONO input on your amplifier.
Also, it’s wise to do the wiring when everything is turned off unless you like frying your speakers (And your ears).
Voltage Drop
Okay, so we’re almost ready to discuss cable lengths. First, you need to understand why length matters. The reason length matters is because of a phenomenon called voltage drop.
Here’s how voltage drop works. So, you have a braided cable wire, and that wire is a specific size. The wire gauge or AWG rating measures its thickness.
The wire gauge, or thickness, determines how much metal area there is in any slice of the wire at any given time. As such, it determines the amount of electricity that can safely pass through each slice of the wire as the electricity travels along. If there is too much electricity and not enough wire, the wire will heat up and catch fire to the wire’s housing. If there is too much wire and not enough electricity, the electricity will weaken over distance and time as it disperses and slowly fades into the surroundings. Some even escape the wire as electromagnetic fields, further weakening the electrical charge.
Over distance, this loss of charge, or voltage drop as it is called, will continue until there is no electrical signal left in the wire. Now, in a common audio line voltage of 0.316 volts, the voltage drop will be relatively negligible in a setup where the turntable is only a foot or two from the amp. But if your turntable doesn’t possess a built-in pre-amp, then you need to send the tiny signal (0.0004 volts) from the cartridge to your preamp. That tiny signal is going to be the victim of voltage drop if you try to go too far with the cabling. The preamp should sit basically right beside the turntable with the shortest possible cable length.
So the question is now, how long can you send a PHONO signal down a wire before voltage drop really messes with your audio signal. And just how long can that cable be before we have a problem?
Voltage Drop General Formula
VD = IR cox0 + IX sin0
Where:
VD = Voltage drop, the line to neutral, in volts
I = Line current in amps (the line load)
R = Circuit Resistance, ohms
X = Circuit Reactance, ohms
Cos0 = decimal power factor of the load
Sin0 = decimal reactive factor of the load
Obviously, we’re going to need to know a few more things, and also we’ll need a scientific calculator. We already know cos and sin, as they are programmed into the calculator. We also know the voltage, but that doesn’t appear in our formula. We need to know the amperage, resistance and reactance.
To get the rest of our numbers, we can either get a decent multimeter and start metering things out, or look in the manual for your particular record player as well as cartridge and get the rest of the data.
In reality, no one is going to want to go to all the effort, so I’ve created some general rules, which you will find below.
Rules For Turntable Cabling Length And Gauge
I’ve got four basic rules I follow for my turntable cabling. Here is what has worked for me:
- Phono cables like those used in your tonearm to feed the cartridge should be at least AWG 33. There are reported issues with 34 and smaller, but it depends on the particular manufacturer. The insulation ought to be isolating because the weak signals are easily affected by surrounding electrical fields. The wires need to be small due to weight restrictions that can affect the quality of playback, so we keep them thin to keep them light.
- Phono out like from the back of your turntable generally follow the same rules as for standard audio cabling in terms of gauge. I like to use the usual RCA’s at 14 AWG for this, but there’s a catch:
- External phono cables at 14 AWG should not be longer than 3 feet.
- Line cables at 14 AWG should not be longer than 100 feet.
According to Techwalla, most RCA cables built with decent quality or “reasonably well with shielding” as they say, can effectively run up to 200 feet.
High-quality cabling might get you more distance, but you might need a step-up transformer amplifier to extend the signal.
Isn’t A Bigger Cable Always Better?
It isn’t just in the movie Star Wars where we find Rebels. In the world of electricity, the rebel is called resistance. No, not The Resistance, just resistance. Resistance is measured in ohms, represented by the Ω symbol.
Just to give you the quickest rundown on how it works: Electricity, represented by a bunch of flying electrons, travels down the conductive path that is the wire. However, the wire is a solid, and not a gas, so although great for conductivity, there are also a lot of atoms in the way, which the electrons have to fly around. Think of it like this: the wire is a road, but because it’s a road it’s a natural traffic jam.
The more traffic on the road, the more the jam gets worse. That slows down the traffic more and causes the flying electrons to slow and watch the traffic, carefully rubbernecking while their counterparts are honking their horns because they are late to lunch.
So, our wire has this ‘traffic’ built-in that causes the flying electrons to slow down. The slow down causes other electrons to get mad, which heats things up until someone melts the wire.
Anyway, if you are a Douglas Adams fan, I hope you enjoyed the metaphor, if not, then I apologize. The point is that all wires have resistance. The smaller the wire, the less the size road so the resistance is greater. The larger the wire, the larger the road, the more room for traffic, the less resistance.
However, when you have a very weak electrical signal, then a really big road is somewhere the signal can get lost, confused, and eventually pull over to the side of the road to contemplate its own existence. In other words, too large a cable and the signal dissipates faster from dispersion.
It applies to very weak signals like those coming from a cartridge. That and cartridge cable needs to be as small and lightweight as possible or it can affect playback, anti-skate, and more.
At the end of the day, follow the guidelines from the manufacturer for your particular equipment and you’ll do just fine. If you can’t find those, stick to my rules above and in most cases, you’ll have great sound.
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