Many of you reading this will have heard of clipping diodes before, but how much do you really know about them? In this guest blog, Alex Millar of Zander Circuitry explains what clipping diodes are, where they are found and why they are used in guitar pedals...
All about clipping diodes
Diodes can serve quite a few purposes in a guitar pedal circuit but in the vast majority of cases they’re used to create either hard clipping or soft clipping in overdrives and distortions, so that’s what we’re going to take a look at.
Clipping is a type of waveform distortion that occurs when a signal is pushed into a circuit with more output voltage/current than the circuit can handle. Probably the most recognisable example of this is when you turn up a tube amp to the point when it starts to distort on its own. Obviously, that requires a lot of volume and not everyone is able to play at those levels, and that's where pedals come in.
In many cases, overdrive and distortion pedals allow us to create distorted tones at any volume - without needing to crank the amp. A common way of creating clipping with a guitar pedal is with diodes.
One of the biggest factors affecting the performance of a clipping diode in a guitar pedal is it’s forward voltage (FV). All diodes will have differing FV values, but generally they can be grouped by type: Germanium (~0.3), Silicon (~0.7), Red LED (~1.7-2.0).
The 3 listed above are the most commonly used diode types for this application, although you can use other components such as transistors and MOSFETs as clipping diodes when configured correctly. So what does the forward voltage do? Well, in short it sets the clipping threshold for your signal. A typical guitar signal can range from 1-4 volts depending on the type of pickup and the rest of the circuit in any pedals you have on.
When a signal hits the diode, anything that peaks that voltage will be clipped. So if you have a pedal with both germanium and red LED clipping options, you’ll find the germanium mode will be quieter and more distorted. Which brings us quite nicely onto...
Hard Clipping vs Soft Clipping
Hard clipping refers to diode configurations that are tied to ground on one side. This creates a "hard" cut off point where your signal (a nice smooth sine wave) is chopped off and given flat peaks (closer to a square wave). This creates a very aggressive and ‘obvious’ effect and is typically used in effects that are advertised as distortion pedals.
Famous hard-clipping diode pedals include: Boss DS-1, Proco RAT and the MXR Distortion+ / DOD 250.
Soft clipping refers to clipping diodes that are added inside a feedback path, typically in op-amp based circuits. Placing diodes here softens the edges of the clipped signal and offers what people usually refer to as a smoother, tube-like tone. These pedals are often marketed as overdrives, although the lines are a little blurry on that. Without doubt the most famous soft-clipping diode pedal has to be the Ibanez Tubescreamerand its many clones/variants.
Symmetrical vs Asymmetrical Clipping
Diodes are polarised parts, meaning they have a positive and negative side, like a battery. They are often found placed in back to back pairs in a circuit, facing opposite directions. This is known as symmetrical clipping, because you have the same number of diodes on each side. This means that the signal is clipped evenly on both the positive and negative sides of its waveform.
Asymmetrical clipping is where you have more diodes (in series) on one side than the other, or if you are using more than one diode type (i.e one germanium and one silicon), which throws the balance of the clipping off.
When using the same type of diode for both configurations, it is generally considered that asymmetrical clipping tends to sound louder, clearer and crispier, whereas symmetrical clipping is quieter, smoother and more distorted. One of the reasons asymmetrical clipping tends to sound louder and clearer is because placing diodes in series increases the effective forward voltage (i.e if you have two 0.3FV germanium diodes in series, the total FV would be 0.6; three diodes would be 0.9FV and so on…)
Clipping diodes: Summary
Personally, I love hard clipping setups because of the dramatic difference they make to the way a circuit sounds and reacts. At Zander Circuitry we place a clipping diode rotary switch on almost all of our dirt pedals to give the player a quick and easy way to experiment with them.
The Big Muff, which our American Geek (transistor) and Siva(op-amp) pedals are based on, is technically a couple of soft clipping stages chained in series, even though it is commonly advertised as a fuzz. Most traditional fuzz circuits do not use diodes for clipping, which explains why the Big Muff is often referred to as sounding very smooth with plenty of sustain compared to something like a Fuzz Face.
We could quite literally talk all day to the Nth degree about clipping diodes and their almost infinite configurations, but I think this is a good signing off point that gives you a good overview of the basics.
Live music is gradually returning to venues large and small following a hellish 2020 and 2021 for the music and events industries. Whether gigging is a hobby or a full-on career path, things have changed and musicians have had to adapt...
I spent an obsessive amount of time checking out univibe pedals. I'm so glad that I purchased this one from Boost. It is simply fantastic! If you don't believe me, then check out some video demos. Thanks Jim! + JG
This is a fantastic drive pedal. There’s plenty of Plexi style pedals out there and I’ve owned a few, this one stood out for the switchable A/B-B/A switch. The boost side is nice and simple, much like an LPB-1. Not overly clean but a perfect partner to the drive side. The Plexi side is again nothing revolutionary but very good all the same and sounds great, on a par with far more expensive pedals.
The build quality is also top end, very neat and tidy. Squeezed into the single enclosure and with a lifetime warrantee I couldn’t ask for more. I don’t think this’ll be leaving my pedal board any time soon!
Lots of great sounds in this relatively-compact delay / reverb
I’m only just starting to scratch the surface of the KMA MACHINES Cirrus, but absolutely loving it so far. Very responsive to pick attack which means can really control the “ambience” with playing style. Really looking forward to exploring further.
Had a few vibes, absolutely loving this one, check the YT demos, lovely satisfying vibe with all the swirly goodness you could hope for. Beautifully made and reasonably priced. Highly recommended - and Jim at Boost is a top guy
I came across the Formula B Fuzz Rangers via online demos on Youtube, and they all sounded so good that I had to get one. Looking online I found the Boost Guitar Pedals website via the Formula B website as a listed UK stockist. Jim was excellent and the pedal arrived when he said it would and it was perfectly packaged. I would have no hesitation in buying any other product from Boost.
As for the Fuzz Rangers, it is a great pedal. I had to work at it a touch to get the sounds I liked from it, but it seems to react really well to different guitars and different amps with adjustments to volume and tone on the guitar and different amp settings. I found it works best into a slightly cranked amp, and volume roll-off on the guitar offers a great variety of sounds from clean to classic fuzz. Thoroughly enjoying the pedal. Well done Jim, great website and a great selection of interesting brands and pedals..... Which one next????
Having used a number of univibe clones over the years this one truly nails the sound for me, it comes with some clever additions in a pedal board friendly size and is excellent value for money. If you want the true sound of the original this pedal delivers.Special thanks to boost Guitar Pedals for putting this deal together so quickly..
I'm still working my way through all the sounds, but so far I'm loving them all.
Each time I think I've got a fav sound I flip the diode switch and there's another one. Great value for a four-in-one fuzz pedal!!
Both modes really useable. The first can get a wooly or starved/wolly sound or more nasally raw sound depending on how you dial it in.
Mode two can be more mid focused and with both switches down it's just a real nice deep, warm wall of fuzz. Great stuff.
Awesome pedal. Does everything from short slaps, to long endless delays, or echo-verb. The infinite delay feature on the button hold is interesting, though if you need a certain sound out of it like that, you have to be okay with the sound that those settings create when the infinite hold feature is off. I’m sure it will be great for recording some interesting textures, but I don’t think I’d use it live, as the infinite hold sounds glitchy and cuts off very quickly at some of the shorter, more subtle delay settings that I use. The art on the pedal is nice, and the build quality is solid. Comes with a carry bag, for some reason, but I can’t complain. A great unit by any standard, but especially good quality and features for the ticket price.