var path = 'hr' + 'ef' + '='; The minimum cut frequency is 31Hz, it goes higher when RVOL goes down. and a high gain in the second stage (β=110-130 approx.). If you fancy building your own fuzz face, our good friend Doctor Tweek also sells a nice range of silicon transistors (including BC108’s and 9’s). This feature of giving soft asymmetric distortion to small signals and clipping harder in both semi-cycles on big input signals (strong chords) gives a nice touch sensitivity which enhances the expressive possibilities. It's the "middle" voltage, the spot where a waveform is centered on. Schematic diagram of a Fuzz Face adapted with a trimpot. In the Fuzz Face the Q1 collector voltage sits around -1.6V,  so the voltage swing on the positive semi-cycle is much bigger than in the negative semi-cycle. This analysis covers the first Arbitrer Fuzz Face model equipped with PNP germanium transistors from the first releases. FF Sound Signature II: Soft Clipping - Hard Clipping: As the second stage is driven harder, it can reach hard clipping in both semi-cycles of the signal. Using a smaller resistor, the filter will cut more lows out (fc=160Hz) which will result in a brighter sound. There is some controversy of when and where the 2-transistor topology appeared: the Tone Bender MK1.5 is similar to the Dick Denney designed Vox Distortion Booster circuit, nearly identical to the Italian made Vox Tone Bender circuit, and the Arbiter Fuzz Face circuit. Desensitize the gain: make the gain value less sensitive to transistors (i.e component variation caused by temperature). The Fuzz Face Models. The main difference is that the Fuzz Face is biased slightly colder, making it more usable in warm environments. Easiest To Use Fuzz Pedal. Electrical Engineering Thesis by William E. Overton focused on the Fuzz Face. In a Common Emitter transistor the voltage gain can be calculated following the equation: note: The gm value of a transistor is defined as: In the real life, the input stage will not reach 49dB of gain, the feedback network will reduce this levels to 18.6 dB approx. Fuzz Circuit Guitars Image Guitar Vintage Guitars. Increasing this impedance will reduce the gain. Germanium transistors tend to have high leakage current and an inconsistent gain value. During its lifetime the pedal went through some minor cosmetic but major sonic changes. Synthrotek-MDIV-Eurorack-Clock-Divider-Multiplier, window.dojoRequire(["mojo/signup-forms/Loader"], function(L) { L.start({"baseUrl":"mc.us4.list-manage.com","uuid":"38f29b26bad12e4a62cf41410","lid":"99f032f6ee","uniqueMethods":true}) }). The effect became very popular because Jimi Hendrix played it and there were not many distortion pedals around at that time. How does the feedback work in the Fuzz Face? Is equal to the input impedance of a common emitter stage. Go right ahead. 4.2 Voltage Total Gain. Great Germanium Fuzz Face-alike with 3rd Bias dial - not in wide circulation at all, best to buy from site - mjmguitarfx.com. 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You need JavaScript enabled to view it. var addy_text0bbee1a085a5092a78cb1fa82c758b68 = 'info' + '@' + 'electrosmash' + '.' + 'com';document.getElementById('cloak0bbee1a085a5092a78cb1fa82c758b68').innerHTML += ''+addy_text0bbee1a085a5092a78cb1fa82c758b68+'<\/a>'; \[\\r_{\pi } = \frac{(\beta +1)\cdot Vt}{I_{EQ}}=\frac{(\beta +1)}{gm}= \frac{(70+1)}{0.0088}= 8K\], \[A_{V}=-g_{m}\cdot R_{C}= -g_{m}\cdot R_{1}= 0.0088 \cdot 33K = 290\: (49dB)\], \[g_{m}=\frac{I_{e}}{V_{T}}= \frac{0.22mA}{25mV}= 0.0088\], \[A_{V}=\frac{R_{C}}{R_{E}}= \frac{R_{2}+R_{3}}{R_{pot1}}\], \[A_{V}min=\frac{470+8K2}{1K}= 8.2\: (18dB)\], \[f_{c}=\frac{1}{2\pi R C}=\frac{1}{2\pi \cdot R_{pot1}\cdot  C_{2}}=\frac{1}{2\pi \cdot 1K \cdot 20uF}= 7.9Hz\], The Fuzz Face is a distortion guitar pedal designed in London by Arbitrer Electronics Ltd in the autumn of 1966. 3.2 Voltage Gain.4. Trademarks, brand names and logos are the property of their respective owners. ).However, there are some other options, for a more compressed sound you can use β=90-120 for Q1 and β=150-190 Q2.There are some circuits that help to measure the transistor gain. Fuzz Face Output Stage. In terms of design, the bypass capacitor C2 should have a reactance, at the lowest frequency you are interested to amplify, less than the value of RFUZZ. This gain variation is crucial in the design, the best match uses a low gain in the first stage (β=70-80 approx.) Add to Wishlist. I’ve tried a Rat, Boss DS2, Fuzz Face, Red Witch Fuzz God, Big Muff, and enjoyed them all but couldn’t get along with any of them long term. Want to reduce the input voltage so the pedal breaks up into oscillation? Emitter degeneration capacitor C2:Any impedance between C2 emitter and ground (RFUZZ) will reduce the gain of the output stage, it is a form of local negative feedback. Fuzz Face: bias vs voltage sag. We choose optimum gain for Q1 and Q2 to make sure that proper biasing is possible. The Fuzz Face has a very low input impedance that will change with the position of the RFUZZ potentiometer (between 5.2KΩ and 8.4KΩ in the simulation). During its lifetime the pedal went through some minor cosmetic but major sonic changes. This effect is more noticeable when the gain of the pedal is low because it has more signal feedback coming from the output through R4. With this emitter resistance added, the Common Emitter PNP major parameters (ignoring by the moment the feedback network) can be determined by the ratio between the collector resistors (R2 + R3) to and the emitter resistor (the portion of RFUZZ not shorted to ground through the 20uF cap). This divider reduces the gain by a factor of R2/(R2+R3) = 470/(470+8K2) = 0.054 (-25dB), so the real gain of the output stage is: GVTOTAL = GVPEDAL - Attenuation of R2/(R2+R3)= 19.5 - 25 = -5.5dB. The last block (the Feedback Network) will affect the rest of the analysis because it will influence the most important parameters: voltage gain, input impedance, output impedance and frequency response. It can be calculated as: For this math calculation the feedback network is ignored but in practice, it will lower the input impedance to 5KΩ approx. The second amplifier stage can make the clipping harder, with sharper, For component economy, the power supply does not include any capacitors to remove ripple from the power line which is something common in, Amplifiers use current or voltage as input or outputs, you can check the. It's useful to adjust with germanium transistors because the bias can change with temperature. 2.3 Fuzz Face Circuit Bias: These are the most important DC bias points of the circuit. Q1 BIAS 22K Trimmer Q2 BIAS 10K Trimmer Q1 MP39B Q2 GT308V FUZZ 1KB (2KB) VOL 500KA BOM Adjust bias trimmers until it sounds sweet. All you need to do is connect your leads to a ground on the PCB and the collector of Q2 to get this reading. In the image below the voltage gain of the input stage is shown varying the fuzz potentiometer. You will need a multi-meter that reads DC voltage to accomplish this, which can be found very inexpensively at places like Harbor Freight Tools. Don’t Forget to check the additional notes on the Tone stack Section . Today, both the Dallas Arbiter and Fuzz Face trademarks are owned by Dunlop Manufacturing Inc. Fuzz Face Input Stage. I’m looking for pedal that works well both for leads and for rhythm. Fuzz Face: This is the classic Fuzz made famous by Hendrix and others. If the level goes down, the 500KΩ resistor will be reduced and the filter will remove more bass. 2.2 Fuzz Face Components Part List / Bill of Materials: This is the reduced list of components needed to build a Fuzz Face: 1    C1:    2.2 uF1    C2:    20 uF1    C3:    0.01 uF1    R1:    33KΩ1    R2:    470Ω1    R3:    8.KΩ1    R4:    100KΩ1    Rvol:    500KΩ (Audio tap)1    Rfuzz:    1KΩ (Linear tap)2    Q1, Q2:    AC128     Jack in, Jack out, battery clip, DPDT foot-switch. var prefix = 'ma' + 'il' + 'to'; The Fuzz Face has asymetrical clipping designed into it! Even though we do this, it is important to know how to do this on your own, as Germanium transistors are very sensitive to temperature changes and will need to be re-biased now and again. Fuzz Face Frequency Response.7. Fuzz Face Circuit. Feed the output from one block back into itself? e-mail us at This email address is being protected from spambots. The earliest ones were Arbiter-England, then they became Dallas-Arbiter England sometime in 1968 since then there have been a variety of words in the smile. A lot less saturated, it could be described as softer, warmer and rounder. The Fuzz Face low input impedance will load the guitar pickups. Dallas Rangemaster Treble Booster Analysis, Time Manipulator - Arduino Delay/Echo/Reverb. Synthrotek is now testing and bias testing all of the Germanium transistors that we send with kits and completed units. I’m not looking to copy a specific sound, just to use something for original music not to copy other people’s tone. They are common technologies still easy to find nowadays. Making this cap bigger will let more low frequencies out. It exhibits an attenuation in the low frequencies (high pass filter) with a fc=14Hz inherited from the input stage. Ivor Arbiter took the round shaped enclosure idea from a microphone stand and it was the first pedal including a DPDT stomp-switch. The trimmer resistor can be dialed in by ear to suit the desired tone if you so desire. The voltage gain (AV) can go from 8.2 to as high as the transistor's basic internal gain (when RFUZZ is maxed out). 2.3 Circuit Bias Points.3. The Fuzz Face Resistors: The original models use 1/2W carbon film resistors. Thanks for reading, all feedback is appreciated. Unless you know what you're doing and have a positive ground PSU, you should use all these components, otherwise omit them and solder a jumper between J1 and J2. However, there are some other options, for a more compressed sound you can use β=90-120 for Q. AC128 Transistor datasheet 1 pdfAC128 Transistor datasheet 2 pdf. The fuzz face output impedance is affected by the feedback network and has a real value of 15KΩ (measured at 1KHz with RVOL=500KΩ). The general amount of gain is considerably reduced due to the feedback network. This voltage divider created by R2 and R3 will greatly reduce the output level. The first-stage device is a regular Fuzz Face Q1, and I did not need the stabilizing capacitor. This last image below shows in red color the typical output signal, characterized by an asymmetric waveform and a hard-clipping when the fuzz potentiometer is maxed. The Fuzz Face circuit has 9 components. The cut frequency of this HPFilter is: \[fc=\frac{1}{2\pi R C}=\frac{1}{2\pi \cdot R_{vol}\cdot  C_{3}}=\frac{1}{2\pi \cdot 500K \cdot 0.01uF}= 31Hz\]. However, it can be considered as a bad output impedance, it is too high and can carry problems when it is placed in the pedal chain. So, like all Deep Trip pedals, the BOG takes the usual 9V, center negative power supply, as most standard pedals do. This value varies with the volume control level and the fuzz control position. This gain variation is crucial in the design, the best match uses a low gain in the first stage (β=70-80 approx.) This email address is being protected from spambots. It's a great sounding Germanium version - sizzles in all the right place. Fuzz. Who wouldn't like to tweak their Fuzz Face bias on the fly? In this video I will set the trimpots of my Dunlop Fuzz Face JDF2Hope you find it useful