If you’ve ever been confused about the difference between series and parallel wiring then you’re in the right place! You might have come across these terms shopping for a new guitar, or looking to build your own, so today we’re going to demystify the science and expand on the sounds you can achieve with each.
Series vs Parallel Explained
Series and parallel circuits aren’t just a thing of the guitar world, the theory applies to all electrical circuits. You might have done the lightbulb experiment in school, but that also might have been a long time ago! So here’s a basic definition to get us started:
A parallel circuit features components connected along multiple paths, with each component having the same voltage running through it.
A series circuit features a single path of components, where each component has the same current running through it.
If you remember your school experiments, a line of bulbs in series will result in total failure of the circuit if one of the bulbs should fail. Whereas a line of bulbs wired into individual loops, i.e. a parallel circuit, will continue to function even if one of the bulbs fails.
Guitar Wiring Circuits
Moving away from your science lessons, lets look at how series and parallel circuits relate to our guitars. You might be surprised to learn that the vast majority of guitar circuits will feature some form of parallel wiring, particularly with Stratocasters and Strat-style guitars. Series circuits are far rarer, but despite this they are an incredibly powerful tonal tool.
We should clarify before we continue however, none of these terms apply to individual pickups, for a series or parallel circuit to come into effect, you must be connecting more than one pickup!
In parallel wiring, both pickups have their ‘hot’ and ‘ground’ connections sent separately to the output jack. Typically you’ll find this happening in the 2 and 4 positions on a standard Strat switch, as well as in the middle position for an LP style guitar. The signal will usually be passed through the guitar’s tone controls separately and you might have noticed that the tone controls on a Start work differently depending on which position the pickup selector is in.
How does parallel wiring sound?
The resultant tone is often described as ‘crispy’ and ‘quacky’ and parallel wiring results in a lower overall output, which can give great clean tones that don’t hit the front of your amp too hard. Depending on the type of pickups used, this can also result in a slightly anaemic tone, making some positions sound a little thin for certain tastes.
How does parallel wiring work?
This is because when wiring pickups in parallel, you’ll lose around 3/4 of the output when combined with the other. So instead of getting two pickups operating at 100%, you’re getting two pickups operating at a combined 50%, delivering that lower output tone. This is why the dual pickup combinations on a Strat don’t sound as loud as the single pickup positions.
In series wiring, the signal passes from one pickup’s ‘ground’ wire, straight into the second pickup’s ‘hot’ wire. By doing this we create one large pickup, essentially combining the output of both together. Typically you’ll find this kind of wiring on LP and SG style guitars, but there are plenty of examples on single coil guitars too. Many modern Fender guitars feature series switching, and Brian May’s ‘Red Special’ famously featured all three single coils wired in series.
How does series wiring sound?
Series circuit tone adds a boost like quality to your guitar, vastly increasing the output of the pickups for extra loudness when engaged. With two single coils you’ll find it delivers a beefier tone that’s much more like a humbucker or an overwound single coil. Unfortunately as is the issue with many overwound and humbucking pickups, you’ll inevitably lose some of the high end with a series circuit.
How does series wiring work?
This is due to the impedance created by the longer pickup wire. The further a signal has to travel, the more high end you’ll lose which is the same effect you'll see with extra long cable runs. For some players this can actually be a benefit, particularly with treble-heavy guitars like Telecasters, the extra beef from a series circuit can add some lovely warmth to your tone. Theoretically with a series circuit you’re getting two pickups operating at 100% each, however that doesn’t mean you’re actually getting a 200% sound when you engage the circuit. This comes down to the way the human ear perceives volume which you can read more about in our Guitar Potentiometers article.
So there you have it, series and parallel circuits demystified! To recap, parallel circuits offer a ‘quacky’ sound with a lower output and more highs, whereas series circuits deliver a thick sounding guitar tone with an emphasis on the mids and lows. There are plenty of ways you can utilise these in your own guitar circuits and you can often come up with some awesome results when combined with other Guitar Wiring Mods.
Check out our Guitar Wiring Guide to get started on your guitar wiring journey.
Our Guitar Wiring Mods article is sure to give you some inspiration!
Take a deep dive on a powerful tonal tool with Resistors in Guitar Circuits.