As the volume goes lower (blue line), the graph shows a steeper slope with more high content. During its lifetime the pedal went through some minor cosmetic but major sonic changes. It creates a high pass filter together with RVOL that will determine the lowest frequency that gets out of the pedal. 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. 1.1 The transistors.2. Just in time for the holidays. 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. New comments cannot be posted and votes cannot be cast. This is due to the RC filter created by C1 and the input impedance (5KΩ approx. Initially designed around a pair of Germanium transistors, the first’s output feeding into the second’s input and, in turn, having its bias controlled by the output of the second transistor in a series feedback circuit. The price for the RM mod is the same as the … This gain variation is crucial in the design, the best match uses a low gain in the first stage (β=70-80 approx.) There are two main possibilities: Germanium transistors are considered to have an overall better sounding to this effect with some drawbacks: germanium manufacturing is not as consistent and controlled as silicon and they have shorter lifespan and more. As the volume goes lower (blue line), the graph shows a steeper slope with more high content. -A low passed feedback loop, closed by either a momentary footswitch or a simple toggle switch. A: With this mod, you get an additional knob ("Level") to control the amount of input signal that gets through to the Fuzz. The earliest models were covered in red, light or dark gray Hammerite paint with the Fuzz Face logo in white or black, the text in the smile reveals the pedal's age. Update 1/03 : We can offer our mod on the ROGER MAYER blue rocket "The Fuzz Face" pedal, using the existing circuit board. The voltage gain (AV) can go from 8.2 to as high as the transistor's basic internal gain (when RFUZZ is maxed out). Turn it down and the fuzz is milder. Today, both the, The earliest models were covered in red, light or dark gray Hammerite paint with the Fuzz Face logo in white or black, t, The transistors are the most sensitive part of the design with a whole mythology. The Long Story. B = Feedback constant (not to be confused with the transistors, When the fuzz control increases the attack, the 20uF C, The FF frequency response is shaped by the three capacitors C, All harmonics below 31Hz will have 6dB/oct of attenuation, The plot below represents the total frequency response of the fuzz face, the different lines show the effect of the volume potentiometer. It is important to select the right transistor from the whole batch in order to archive the best effect performance. Shipped From. 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 bias resistors of both transistors can be set by a trimpot, but a switch puts this control on the outside, by using pots. The problem is what you end up with is not a Fuzz Face, it's just what you decide to call a Fuzz Face. The FUZZ pot used is a little higher so it can get a little crunchier and more fuzz. Discussion Paper About Fuzz FAce Batteries by DingoTone.com Arbitrer Fuzz Face by Fuzzcentral. Making this cap bigger will let more low frequencies out. Fuzz Face Circuit. In any lot of raw stock, there are always only so many parts in the 70-85 and … Its uncanny ability to add harmonic richness and “hair” around … The balance of Q1 & Q2 and just as … Part of the output current is taken from Q2 emitter and introduced as current in Q1 base, so the feedback resistor R4 is shunt connected with the input and in series connected with the output. Free Shipping. 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). The Fuzz Face is a distortion guitar pedal designed in London by Arbitrer Electronics Ltd in the autumn of 1966. The Fuzz Face is an extraordinarily simple design that uses a mere eleven components. I shall see. The value of the output impedance can be calculated using the formula: Zout = RVOL//470ΩZout MAX = RVOL//470Ω=500K//470Ω = 469Ω. In amplifier design the degenerative (negative) feedback is used to: The properties above are obtained at the expense of a reduction of gain. One is in a feedback loop and the other is for the tone control. You need JavaScript enabled to view it. Turbo boost as in extra clipping/gain? Control the input/output impedance: raising or lowering their values. When the input signal has a higher level, the input stage will soft-saturate in both semi-cycles like in the image below. The Fuzz Face low input impedance will load the guitar pickups. So, basically I'm looking for some whacky mods to implement into a Si Fuzz Face circuit. So, basically I'm looking for some whacky mods to implement into a Si Fuzz Face circuit. 30+ Joined Reverb. If you alter every value within that same basic circuit you can get virtually any decent randomly selected pair of transistors to work. The gist of the Fuzz Face remains in the simple circuit that uses eleven components (2 transistors, 4 resistors, 3 caps and 2 pots) and the astonishing tones created with them; delivering a soft asymmetrical clipping that changes to hard clipping in both semi-cycles under the fuzz pot action. PsPice models used for AC128 Fuzz Face simulation: .MODEL GERPNP_LOWGAIN PNP(IS=85.8N BF=85.000 NF=1.000 VAF=102.207 +IKF=9.981M ISE=0.435N NE=1.200 BR=20.000 NR=1.000 VAR=20.000 +IKR=1.248M ISC=120.8N NC=1.200 RB=173.312 IRB=5.000U RBM=43.328 +RE=20.000 RC=60.000 CJE=6.000P VJE=0.400 MJE=0.400 TF=0.150U+XTF=9.996 VTF=2.000 ITF=9.983M PTF=1.000 CJC=3.750P+VJC=0.600 MJC=0.330 XCJC=0.650 TR=2.865U+CJS=0.0 VJS=0.700 MJS=0.500 XTB=1.000 EG=0.670+XTI=4.000 KF=5.000F AF=1.000 FC=0.750).END, .MODEL GERPNP_HIGHGAIN PNP(IS=120.8N BF=120.000 NF=1.000 VAF=102.207 +IKF=9.981M ISE=0.435N NE=1.200 BR=20.000 NR=1.000 VAR=20.000 +IKR=1.248M ISC=120.8N NC=1.200 RB=173.312 IRB=5.000U RBM=43.328 +RE=20.000 RC=60.000 CJE=6.000P VJE=0.400 MJE=0.400 TF=0.150U+XTF=9.996 VTF=2.000 ITF=9.983M PTF=1.000 CJC=3.750P+VJC=0.600 MJC=0.330 XCJC=0.650 TR=2.865U+CJS=0.0 VJS=0.700 MJS=0.500 XTB=1.000 EG=0.670+XTI=4.000 KF=5.000F AF=1.000 FC=0.750).END. 3.2 Voltage Gain.4. AC128 Transistor datasheet 1 pdfAC128 Transistor datasheet 2 pdf. The output capacitor C3 blocks the DC level from saturating any device following the Fuzz Face. The value usually does not get as low as -5.5dB, the series resistor of the battery should be taken into consideration and will raise the output level. When the gain goes high the feedback is smaller and the high pass filter influence is less important. Between that, adjustable bias, and switching between caps where it makes the most impact (B-C on Q2 or input cap), you'll have quite a versatile fuzz. Fuzz Face Frequency Response. The pot should be wired like this: Lug 1 … Make an Offer. In the picture below you can see the original enclosure (left) compared with the new compact Dunlop box (right): The original Fuzz Face uses single layer PCB with through-hole components. ): \[fc=\frac{1}{2\pi R C}=\frac{1}{2\pi \cdot Z_{in}\cdot  C_{1}}=\frac{1}{2\pi \cdot 5K \cdot 2.2uF}= 14Hz\]. About This Listing. The current flowing into the base of the first transistor is proportional to its collector voltage. The devices can be returned for credit or refund as long as they are not soldered and have full leads. 2.2 Components Part List / Bill of Materials. 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). var prefix = 'ma' + 'il' + 'to'; For fuzz, I usually reach for a Foxx Tone Machine, Shin Ei Companion or Mosrite Fuzzrite before a Fuzz Face, but I love the Fuzz Face circuit all the same. Dial it Back. var path = 'hr' + 'ef' + '='; Dennis Cornell: "All the transistors worked in a very similar way and all did the job, but they did give a slightly different tone. Note that the output signal is not completely flat when it clips (it is slightly tilted), this feature adds more character to the sound . This voltage divider created by R2 and R3 will greatly reduce the output level. Reduce the noise: minimizing the contribution to the output of unwanted electrical signals. Whatcha planning here? e-mail us at This email address is being protected from spambots. Pete's Pedals, St … As simple as that! During its lifetime the pedal went through some minor cosmetic but major sonic changes. This Fuzz Face Distortion is constructed to vintage specs, featuring the original Germanium PNP transistor design for a rich, creamy fuzz sound. Arbitrer Electronics manufactured the pedal from 1966 to 1975, Dallas Music Industries did a final batch in 1975-77, after that the production stopped. The variable power supply is a good idea. The cut frequency of this HPFilter is: \[fc=\frac{1}{2\pi R C}=\frac{1}{2\pi \cdot R_{vol}\cdot  C_{3}}=\frac{1}{2\pi \cdot 500K \cdot 0.01uF}= 31Hz\]. In the above image, the output voltage at Q2 is shown under the action of the RFUZZ potentiometer (the volume is set to max). As a rule of thumb, Zin should be at least 1 MΩ. 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. The fuzz face has a negative feedback called shunt-series feedback (Current Controlled Current Source CCCS). If we take into consideration the feedback network, once again the second stage will not reach values as 18dB. The circuit is deceptively simple: two transistors, four resistors, three capacitors and two pots. There are two main possibilities: Germanium transistors are considered to have an overall better sounding to this effect with some drawbacks: germanium manufacturing is not as consistent and controlled as silicon and they have shorter lifespan and more temperature sensitivity. 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. 4.1 Output Impedance. My sincere appreciation for D.Clark support. This is the reason why t, The above graph shows a high pass filter with a cut-off frequency of 14Hz (18.6 -15. Page 1 of 3 1 2 3 Next > vintagevoltage351 Well-Known Member. 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. The tone control works better (not as fierce either side of center), and overall better sound to my ears. Very Good. 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. Fuller mod. Have you heard of the ZVex Fuzz Factory? 2017. The effect became very popular because Jimi Hendrix played it and there were not many distortion pedals around at that time. Resources. You need JavaScript enabled to view it. This gain variation is crucial in the design, the best match uses a low gain in the first stage (β=70-80 approx.) BUT the output of the pedal is not directly taken from Q2 collector, there is a voltage divider created by R2 and R3 (the power supply is effectively at AC ground). The 20uF is so big that almost all the frequencies get full amplification. Warranty Information. Electrical Engineering Thesis by William E. Overton focused on the Fuzz Face. The graph also shows a general roll off of the bass harmonics under 14Hz, this is due to the high pass filter created by C2 and Zin (input impedance of the pedal). The single layer PCB with through-hole components fits without problems inside the oversized cast iron enclosure. The earliest ones were Arbiter-England, then they … But when we look at the circuit: Fig.1 Fuzz face circuit, classic 60s original schematics (made with Fritzing) Not so easy to understand, isn't it? I guarantee that your pair will sound "like a Fuzz Face" if used with the resistor values I recommend. It was based on the Tone Bender circuit but had its own sound completely. It can be broken down into three parts: Input Stage, Output Stage and Feedback Network. I don't think the FF output is large enough for this. These are the most important DC bias points of the circuit.note: The input stage is a Common Emitter (Collector Follower) PNP amplifier, it provides a high voltage gain with low input impedance and high output impedance. Also, in a subsequent build of a Silicon Fuzz Face, I tried high-gain 2N5088 transistors rather than searching for the low gain 2N2222 I had used earlier. It produces a characteristic high distorted sound called fuzz.Ivor Arbiter took the round shaped enclosure idea from a microphone stand and it was the first pedal including a DPDT stomp-switch. That combo always works great. Other fuzz pedals like the, Big Muff Pi have a more distinctive frequency response. What I currently already have planned:-Variable power supply (4-9V).-The bias resistors of both transistors can be set by a trimpot, but a switch puts this control on the outside, by using pots. 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. 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. Is equal to the input impedance of a common emitter stage. note: The hump originated when the fuzz control is set to minimum (the lowest dark green trace) is due to the C2 bypass capacitor which creates also filter (C2 - RFUZZ). 2.3 Circuit Bias Points.3. This is the reason why they do not respond well when they are placed after other pedals. I think the Arbiter-England one didn’t use the NKT275 germanium transistor; in those days we used the AC128. I bought this pedal in the 90's, played it once and threw it in the cupboard cause it sounded CRAP!!! var path = 'hr' + 'ef' + '='; Both are important to make the circuit work correctly, especially the one in the feedback loop. We are currently working on an impressive, if we can be so bold, tweak of the famous Fuzz Face pedal. ).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. The R3 and R4 resistors are a voltage divider that is reducing the signal level going to the output. Fuzz Face JHF2 mod Today I came across a fuzz face (supposedly from -93). addyf2cdf60638434545208c32de59f274e6 = addyf2cdf60638434545208c32de59f274e6 + 'electrosmash' + '.' + 'com'; It exhibits an attenuation in the low frequencies (high pass filter) with a fc=14Hz inherited from the input stage. The Technology of the Fuzz Face by R.G Keen.Fuzz Face Description by ScreaminFX. Notoriously a hit or miss production pedal, we have done some fiddling around and come up with a highly customizable and quite dependable mod. As I worked … FF5 PNP Germanium with … The Fuzz Face Models: The earliest models were covered in red, light or dark gray Hammerite paint with the Fuzz Face logo in white or black, t he text in the smile reveals the pedal's age. You will not be disappointed when you swap them. Watch. 3.1 Input Impedance. Capacitors present an impedance that decreases with frequency, the bias (DC) points will remain the same but high guitar (AC) signals will get higher voltage gain. The Fuzz Face Models. This is due to the RC filter created by C, The output stage is again a PNP Common Emitter Amplifier, this time with a variable emitter degeneration resistor (R, The value of the output impedance can be calculated using the formula, The fuzz face output impedance is affected by the feedback network and has a real value of 15K, The minimum cut frequency is 31Hz, it goes higher when R, With this emitter resistance added, the Common Emitter PNP major parameters (ignoring by the moment the feedback network) can be determined by the, If we take into consideration the feedback network, once again the second stage will not reach values as 18dB. … We can change that to our standard FUZZ pot for an additional $10. 8.1 Datasheets. It is not the ideal input stage for signal integrity but the best for simplicity and fast high gain. My favourite is … I know it has a feedback loop, from Q2 emitter to Q1 base, but I'm thinking of connecting the output back into the input for some howling noises. AC128 PSpice simulation model, check the last part of this article, physics.mcgill.ca/~grant/Stuff/fuzzface.txt, Electrical Engineering Thesis by William E. Overton, Discussion Paper About Fuzz FAce Batteries. We can use the formula: All the frequencies over 8Hz get full amplification. Sales. PNP transistors to try. I know the feeling…It’s very tempting to run your distortion pedals at max gain, … 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. The big amount of gain will clip the signal easily creating large amounts of higher harmonic content. Jack in, Jack out, battery clip, DPDT foot-switch. The usual solution in guitar pedals is to add some power filtering by placing 47~100uF cap together with a 100nF from the +9v to ground. We're only going to use the first lug and the wiper lug of the pot since it only needs to act as a variable resistor. The basic fuzz face is finished and will fit into a smaller enclosure if you prefer. This is the basic schematic of a PNP germanium fuzz face. The fuzz face was re-issued from 1986 to 2000. Fuzz Face PNP Germanium Transistor With Charge Pump Version. My sincere appreciation for D.Clark support.Thanks for reading, all feedback is appreciated  This email address is being protected from spambots. document.getElementById('cloakf2cdf60638434545208c32de59f274e6').innerHTML = ''; This is about 2V for LEDs, 0.7 for silicon and 0.4 for germanium, which is why there's always a booster stage before the diodes in distortion pedals. var addy_textf2cdf60638434545208c32de59f274e6 = 'info' + '@' + 'electrosmash' + '.' + 'com';document.getElementById('cloakf2cdf60638434545208c32de59f274e6').innerHTML += ''+addy_textf2cdf60638434545208c32de59f274e6+'<\/a>'; Some Rights Reserved, you are free to copy, share, remix and use all material.