There is always a lot of interest in the topic of silicon vs germanium fuzz and overdrive pedals. Below we talk about:
- What this actually means
- How the two types of pedal came about, and
- How the Silicon and Germanium pedals actually sound.
What do we mean by “Silicon Fuzz” or “Germanium Fuzz”
When we talk about a germanium or silicon based pedal, what we are referring to is the type of material from which the pedal’s semiconductors are made.
These semiconductors can be:
- Diodes – used for clipping circuitry and for power regulation
- Transistors – used to amplify the signal and match to the amplifier load
- Integrated circuits- packages of transistors and diodes. These are always silicon based, and appear in later pedals.
Clipping
We mentioned clipping above, and this is fundamental to all things relating to fuzz and overdrive.
Specifically, it is the clipping circuits and the exact manner in which the signal is clipped that makes a huge difference to the sound. Using silicon or germanium components sublty alters the clipping characteristics.
So, what’s clipping?
This is where the top of a pure signal is chopped off electronically. This can be by design or, probably in the case of the first boost pedals, where an amp was being unintentionally overdriven!
The picture below shows a pure signal going into either an amplifier or pedal, and coming out with the top chopped off! This is the sound of overdrive fuzz!
This can happen in two fundamental ways:
1. Clipping occurs in the amplifier
- The signal is amplified in the pedal. Then it is output to the amplifier, which cannot cope with the boost in the signal. As it cannot reproduce the waveform, it chops off the top of the pure guitar signal.
- This is typically what happens when an overdrive pedal drives an amplifier. The pedal drives the amplifier beyond its intended capability producing that classic sound.
2. Clipping occurs in the pedal
- Diodes are configured in the circuit of the pedal such that when the signal gets beyond a certain level, it will get chopped off and produce the clipped waveform
- This this is typically what happens in a fuzz pedal.
What’s The Story?
(Topical Oasis reference)
Fundamentally, there are two types of semiconductor material used in overdrive and fuzz pedals. Germanium is the “original” material used in classic boost and fuzz pedals, such as the Rangemaster and Fuzz Face.
Germanium
This was the original material used for transistors and diodes. It was in use up until the mid 70s. It was relatively expensive, less reliable and quite difficult to work with. It was very easy to burn out a germanium transistor with the touch of a soldiering iron!
Silicon
Silicon semiconductors became increasingly popular from the mid 70s and were cheaper, more reliable and had a much greater tolerance to being manhandled.
At the time silicon components became widely available and popular, most engineers and musicians thought that germanium would be completely obsolete- and for a period it appeared that way. Little did we know, but more later.
There is also a third semiconductor worth a mention, which is Selenium. This was typically used in high power circuits back in the 1930s but has very recently seen a resurgence of interest and specifically is included in the Cusack Music Project 34. But for the purposes of this article, we’ll just stick to looking at silicon and germanium.
The resurgence of Germanium
Despite all the technical benefits, musicians started to notice that silicon pedals sounded a bit different and were becoming interested in the “old” pedals. This was actually quite similar to what was happening in the valve versus transistor debate in amplifiers- but that’s for another day!
Also in a similar way to amplifiers, we have seen original vintage pedals become very collectable.
Manufactureres have for a while made germanium pedals that are exact replicas of the classics from the 50s, 60s and early 70s, as well as new designs. Examples are replicas of J Mascis pedals.
Indeed some newer designs, such as the Pharaoh and Hoof, switch between germanium and silicon clipping diodes. There are also pedals, like the Your Face 60 with a strong nod to the past, but built with small improvements for todays market.
Of course, the “classic pedal” status is not just held by products with germanium circuitry. Builders are also replicating and seeking to both replicate and improve their silicon counterparts. For example, Wren and Cuff produce an exact replica, in the Caprid, of a silicon Muff.
There are many excellent manufacturers that continue to innovate.
Silicon vs Germanium: Why and how they sound different
Both diodes and transistors are components that switch on, switch off, and can also occupy states in between where they partially conduct (hence semiconductors).
Germanium
Germanium switches on more quickly (we are only talking micro-seconds here!) than silicon and so changes the nature of the way the guitar signal is clipped, and hence the sound.
It also tends to be lower gain and gives a softer, vintage style sound at the expense of increased cost and being less tough.
Silicon
Conversely, silicon switches slightly later than germanium and, as a generalisation, has a wider frequency response.
Silicon sounds more aggressive and “tight”, is more physically robust, and less expensive.
In the end
Silicon and Germanium components change the characteristics of the clipping, which is what impacts the sound quality.
Softer retro sounds tends towards Germanium transistors and diodes.
A more “modern” sound tends towards Silicon, either in discrete component format (transistors) or hybrid integrated circuits (IC’s) such as the 1979 or Evil Filter.
As always, it’s horses for courses, depending upon the sound that you wish to achieve.
