There comes a time in every guitar players life where they have stared at the back of their amplifier, speaker cable in hand puzzling over which setting to put their impedance to. What is impedance? Why does it matter? More important than that, does it affect my tone? Let’s dig into the often misunderstood and sometimes confusing world of impedance.
What is impedance?:
An amplifier is a complex circuit that consists of capacitors, resistors and inductors and other various components to ensure the amplifier maintains proper voltage and function. Simply put, once a signal is applied to each component, the component will produce its own capacitance, inductance and/or resistance based on the respective component type. The sum of all of their collective resistance is what is known as impedance (Z). The unit of measurement for impedance is referred to as Ohm (Ω).
What is Ohm Ω?:
German physicist and mathematician Georg Ohm is who we have to thank for the discovery of well, Ohms. After much research, Mr. Ohm discovered and created a theory known as Ohm’s Law which states that the current running through a conductor between two points is directly proportional to the voltage across the two points. Basically, if you increase voltage in a circuit with a fixed resistance, the current goes up.
What is the difference between 4Ω vs 8Ω vs 16Ω?:
Now that we have discussed impedance and ohms the mystery behind 4Ω vs 8Ω vs 16Ω should quickly disappear. Essentially, the difference between them is the level of impedance! (not as exciting of an answer I know, but stick with me here). What this translates to is that each one of these settings provides a different impedance path for your speakers to connect to your amplifier. This is where all the fun of understanding speakers, parallel and series wiring and their tone all come into play.
Speakers in Series and Parallel:
Have you looked at the speakers in your amp and wondered why each speaker in your 2X12 was rated 4Ω, but is connected to the 8Ω setting? That is because the speakers are wired in series! A simple way to remember how series works is that “series stacks”. What this means is that the Ω rating of each speaker is added together to produce that group impedance rating. In this example:
4Ω + 4Ω speakers wired in series = 8Ω
However, the disadvantage of series wiring is if one of your speakers goes out the other will as well due to the way both speakers are connected. In a parallel circuit, only the failed speaker will stop producing sound.
Let’s take a look at another example. Your 2X12 speakers are both rated at 8Ω each, but now you’re tuning into the 4Ω setting on your amp. That is because your speakers are wired in parallel. In parallel wiring the rating is halved. If we look to our example now:
8Ω + 8Ω speakers wired in parallel = 4Ω
Now that you are armed with this knowledge you never have to worry about plugging your amp into the wrong impedance channel again. Simply look at the speakers and see how they are wired and either add or divide the two to get your ohm rating. Make sure to look and see how the speakers are wired. The handy dandy charts below will help clear up which you are looking at.
The tonal difference between series and parallel is also something worth discussing. While it is a subtle difference series wired speakers tend to have more “umph” and power to them while parallel wired speakers tend to be smoother and a bit more tame. This is a classic example in tonal debate where, in theory, rearranging wires that inevitably equal the same values should not affect the tone, but when using your ears instead of math you can, in fact, hear a difference.
The disadvantage of series wiring is if one of your speakers goes out the other will as well due to the way both speakers are connected. In a parallel circuit, only the failed speaker will stop producing sound.
This is all great, but what does impedance do for tone?
An amplifier will be at its best (maximum power to the speaker) when all impedance is matched evenly (i.e 4Ω speaker to 4Ω amplifier setting). While other combinations such as an 8Ω amp setting into a 16Ω speaker will produce more mids, while the opposite will reduce them.
Keep in mind the tone your speakers produce, the tone of the amp and the wiring are all factors that come into play when creating the ultimate tone.
For another example, in an amplifier with Celestion Greenbacks, if you compare an 8Ω speaker vs a 16Ω speaker with all things being equal, the 8Ω will sound much fuller while the 16Ω will have a perceived thinner tone.
***** Do not connect a speaker with more than double the output impedance of that of the amp. Bad things will happen and you will not only not like the sonic results, but you will not like the amp repair bill either!
The Biggest Factors of Impedance Tone:
While the wiring does make a difference with the tone the most important aspects to consider are the ohm rating of the speakers, the amplifier’s impedance setting and the type of speakers. In my next article I will go into detail on speakers and how everything connects for sweet, sweet tones.
As always, use your own ears, experiment and create the ultimate tone for yourself that will inspire you to never put your guitar down!
If you have any questions I am available at ZacDelVecchio@gmail.com and @ZacDelVecchio on Instagram