Download Fuzz Face Pedal And Distortion Analysis Robert Lemiesz

 Fuzz Face Pedal And Distortion Analysis Robert Lemiesz For my Physics 406 project I created a Fuzz Face pedal. I used this schematic (http://www.tonepad.com/getFileInfo.asp?id=82) from tonepad. Tonepad is a popular resource for DIY music projects. The pedal is called “Pelusa” Face. However it is very similar to the original fuzz face design. Figure 1: Basic Fuzz Figure 2: Pelusa Face As can been seen for Fig 1 and 2. The differences between the original fuzz and the one I built are very minor. Main differences being the grounded 2.2MΩ resistor after the input, and the tone loop in the original has terminals 1 and 2 of the 1K potentiometer grounded; the pelusa face only has the 1 terminal grounded, and the capacitor is connected to both. Brief History of Fuzz Face The fuzz face was original developed by Dunlop, and was not really anything “special”. It wasn’t until Jimmi Hendrix started using them to create his characteristic sound that the fuzz face became somewhat of a classic sound. The original Fuzz Face used AC128 Germanium transistors. These were not terribly good transistors, even for Germanium (which is already really leaky). The AC128s however led to a very inconsistent sound amongst the early Fuzz Faces; leading to some artists ordering them in bulk and picking out their favorite ones. Later the AC128s, were replaced with NK275s as the standard transistors for the fuzz face. The fuzz face works by inputting signal through a DC blocking resistor driving a transistor one, transistor two is directly coupled with transistor one. This is called a “voltage biasing circuit”. The final non-­‐
polar capacitor blocks the Fuzz Face from saturating any device that follows it, also it determines the lowest frequencies that are let through. As such a higher capacitance would give you a lower tone. (most information on this page summarized from http://www.geofex.com/article_folders/fuzzface/fffram.htm to serve as background information) Figure 3: My Final Circuit (pots detatched) Distortion Analysis Aside from building the Fuzz Face circuit I also analyzed the effects of distortion on a couple different distortion pedals, including the one I build. I.
Robert Fuzz Face Silicon Transistors a. Max Tone b. Min Tone Figure 4: Harmonic Analysis of Silicon Fuzz II.
Robert Fuzz Face Germanium Transistors a.Max Tone – Indistinguishable from Silicon Fuzz Face b. Min Tone – Indistinguishable from Silicon Fuzz Face Figure 5: Germanium Fuzz Face Harmonic Analysis From these we can see that the Germanium and Silicon versions of my pedal were virtually the same. With some harmonics being more/less prominent in each version of the pedal. However we may have seen more of a difference if I had used NKT275 Germanium transistors rather then random T.I. transistors that I found laying around in an ECE lab. Also, I ran these tests while my pedal was still on a breadboard, creating interference from the local radio frequencies, especially in the noise floor tests. III.
Delta Labs Tube Overdrive a. Tone Min Figure 6: Delta Labs TO min tone b. Tone Max From this data we can see that the tube overdrive works by layering on even harmonics. As you increase the tone knob the even harmonics get more prominent, as well as adding small amount of odd harmonics for a harsher tone. IV.
EMI Fuzz Face Ultra a. 40% Drive b. 100% Drive This data is from the Fuzz Face built by Professor Errede. It includes potentiometer to control the amount of current driving the main transistor. Allowing for a much more variable tone, as seen in the above graphs.