The capacitors C23 (100uF) and C15 (47uF) are bulk capacitance that stabilizes the power supply lines. note: If you are using the Mitsubishi M5223AL op-amp you will need a 1K pull-up resistor from the second op-amp output to +9V. Espero que disfrutis esta modificacin, por favor hacedme llegar cualquier mejora o error que podis encontrar. Si sois buenos guitarristas, grabad una demo y subidla a youtube. R3 is the emitter resistance, 10K is a pretty standard value for an Emitter Follower buffer. There are some popular mods to improve its tone making it thicker/stronger and more versatile (Tri-Gain / JHS / Keeley / Analogman). The 2SC2240 is a cheap high-gain transistor, a simple unity gain buffer does not have high requirements for the transistor. The Boss DS-1 has been around since 1978 and remains to this day one of the top selling guitar pedals ever. Some opamps are damaged, some will latch-up, most take time for the input stage to recover from being over-driven, and that screws up the sound. It was doing that when I had it outside the enclosure but inside the enclosure no signal passes either way now. The emitter feedback reduces the distortion. I may have to rebuild it back to stock and see if it still works that way or not and try again. R9 en el emisor de Q2 controla la ganancia de la primera etapa, previa al operacional. Power Supply Stage.4. Pensad en el Klon Centaur, por ejemplo (con los medios resaltados, por cierto). A stereo guitar input jack could be used as an on-off switch, connecting the battery (-) pin to ground when the guitar jack is plugged. Change). For mass production true bypass switches are difficult to mount and not cheap, some big pedal circuit manufacturers (like Boss) prefer to use complex but cheap JFET bypass circuits that also can carry other benefits like keeping always the input/output buffer in the signal chain (if desired). In total there are 5 capacitors, 3 resistors, 2 diodes, and 1 LED (make that 2 LEDs if you want to change the existing indicator LED like we did)Asides from these components you will also need a soldering iron, solder, and some tweezers or similar tool capable of prying the old components from the PCB. Hi! Also, C5 & R10 reduce harmonics below 23Hz at the limit of the audio spectrum that will help either way to reduce oscillation. The Boss DS-1 is a distortion guitar pedal released in 1978 by Boss. From now on, all the models are commonly called post '94. A bigger R9 applies negative feedback through the Q2 emitter and lowers the collector current. 4.1 Input Impedance Calculation. The capacitor C1 isolates the guitar from any pedal dangerous DC level and filters the inaudible low-frequency signals with a cut frequency of 7.2Hz (fc=1/2C. (LogOut/ Frequencies at 7.2Hz are attenuated -3dB with a roll-off or 6dB/oct. The circuit uses a single layer PCB with standard through-hole components which makes it easy and cheap to produce. Output Buffer.9. R39 will protect the input of the op-amp keeping the current limited on the + pin. Greatings from Argentina. Es naranja y se llama distortion, as que en este caso es fcil de clasificar. The 3PDT drives the guitar signal either through the effect circuitry, or straight input-to-output, the guitar signal does not even touch the input of the effect. 2.3 Circuit Layout. C14 and R23 form a high pass filter with an fc=1.6Hz below the audio spectrum. No se de qu ao es tu pedal, pero si es posterior a 2005 creo, lleva la R40 a la salida del operacional que lo convierte en un Class-A. The design idea is simple: The Input and Output Buffers will isolate the circuit, keeping the signal path clean and tone-sucking free. These are the key elements: In consequence, by replacing R9 for a 1K resistor, the signal gets boosted just 7 times (17dB), so any typical guitar input signal of 100mVpp after the transistor booster stage has a level of 100mVpp x 7 = 0.7Vpp a low level that will not clip the op-amp stage. at the notch the loss is about -20db (500Hz) but there is no problem with this because in the previous stage after the diode clipping the signal has a 1.4Vpp amplitude, with -12dB loss the resulting signal will be 350mVpp (1.4Vpp/4times) which is fine for an output level and won't distort the input stage of the next pedal on the chain or the guitar amplifier. The circuit consists of a simple fixed -6dB/oct low pass filter (formed by R16 and C12 with an fc=234Hz) and a fixed -6dB/oct high pass filter (formed by C11 and R17 with an fc=1063Hz) using the VR3 pot to mix the two signals. This is the reason why a lot of mods like the'Vintage Ripper', the 'Fat Mod for DS-1' or the 'Huevos Grandes' increase the size of R9 from 22 to 1K, this makes the voltage gain of the Transistor Booster Stage to decrease from the default 35dB(56 times) to a more moderate value of 17dB (7 times). Asymmetrical Clipping - The stock DS-1 uses a pair of 1N4148 diodes in a hard clipping arrangement after the opamp. It buffers interfaces the previous Transistor Booster stage with the second half of the op-amp that will do all the magic. Dallas Rangemaster Treble Booster Analysis, Time Manipulator - Arduino Delay/Echo/Reverb, Tube Screamer Input Impedance Calculation. Teniendo en cuenta todas estas consideraciones, veamos mi ltima modificacin de pedal. U1 NJM3404A ( or equivalent M5223AL, BA728N), Although the circuit has been the same through the ages, the unusually SIL (Single in Line). The Transistor Boosting Stage has a huge amount of gain, it amplifies the incoming signal 56 times (35dB). The first half of the NJM2904L dual op-amp is a simple buffer, it won't add (or remove) anything to the guitar signal. For C11 and C12, any kind of capacitor will do, but the values are very important (test if possible). 1978 Original First Release using the Toshiba TA7136AP pre-amplifier (it is not an op-amp) with the circuit labeled as DS-1. The. 2.1 JFET Bypass Switching / True Bypass. This distortion stage is followed by a passive tone filter and level control. This remained unchanged for about 16 years. In 1994 the op-amp was replaced by the Rohm BA728N. but thats where I am at. This makes the user have a higher grade of control and variation; from a simple boosting to hard clipping. Maybe something was previously wrong or you have touched some other component inadvertedly. The components replaced in the tone stack are C11, C12, R15 and R16. R9 at the emmiter of Q2 controls the gain of the first stage, previous to the opamp stage. You need JavaScript enabled to view it. Or a mecanic problem, look for some dirt in the switch itself, or the battery cable not properly put in place. In an Emitter Follower the input impedance can be calculated as, If you want a further explanation of how to make all the numeric calculations, check the, The frequency response of this input buffer is dominated by the high pass filter created by C, This stage applies some frequency filtering and signal boosting before the op-amp stage. There is an obvious RC network (R14 & C10) with C10 in parallel with D4 and D5 clipping devices. Playing with the distortion potentiometer the edge of the waveform can be softened by in any case the overall look is pretty squared and distorted. One of the things [], [] I have to confess that it has only be used a few times, just because lately I am using my modified DS-1, BOSS OD-3 or Tim Pierce Overdrive. El resalte se produce a los 800Hz, que para m es el mejor punto para conseguir un tono agradable y capaz de ser odo en una mezcla en el contexto de una banda. During its life, the Boss DS-1 Distortion has had two schematic revisions due to components availability: a. La placa tiene sitio de sobra para poner dos condensadores en esa posicin. Thanks for the contribution and for sharing it! I think this is why people say that increasing R9 "flattens the frequency response". Simulando el circuito en LTSpice, encontr el punto en el que se resaltan los medios de la seal sin perder la capacidad de controlar el tono (aunque esta capacidad se ve algo reducida respecto al DS-1 original). Hard clipping seems to have usually a more dynamic overall response to the guitar touch than soft clipping, although it depends on the circuit design. A 3PDT switch. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); DS-1 vs modded DS1: frequency response electric-safari, https://electric-safari.com/2019/03/17/turn-a-boss-ds-1-into-a-nice-overdrive/, BOSS DS-1: modding my own mod electric-safari, BOSS OD-3 and J.Rockett Tim PierceOverdrive, Give it an asymmetrical clipping character, more pleasant to my ears and more valve-like distortion. With a value of 22 Ohms, the output is so high that the signal at the output of the operational is almost always clipped. Para reducir la distorsin, he hecho estos cambios: Para el resalte de medios, cambi varios componentes de la seccin de tono. The 3PDT drives the guitar signal either through the effect circuitry, or straight input-to-output, the guitar signal does not even touch the input of the effect. Con un valor de 22 Ohms, la salida es tan alta que la seal a la salida del operacional es limitada por los diodos prcticamente siempre. var addy5230ce14d5603ba6bd88484b4b0c40a7 = 'info' + '@'; Also since the bass frequencies dont get amplified quite as much at this initial stage it helps to keep the distortion tighter across its range. This distortion stage is followed by a passive tone filter and level control. Bipolar diodes have Vf=0.7V and LED have Vf > 1.5V, depending on the color. Somewhere between 2.2K and 4.7K would provide the best results. The CSGuitars modification aims to make changes to the following areas: Extend the clipping into lower frequencies, Reduce the overall gain and improve low end response. Si sois ricos, enviadme un Klon Centaur para compararlo con mi DS-1 modificado. Increasing this resistor will reduce the maximum opamp gain while attenuating less gain for lower frequencies. At max distortion, harmonics over 72Hz get the full gain of the distortion stage, and everything below it gets progressively less gain and distortion. The idea is to raise the signal levels so the next stage can work with acceptable levels although as we can see later, the signal is maybe too boosted after this stage. Increasing the value of R9 will further reduce the gain of the initial transistor boosting stage, allowing far more range for softer distortions at low drive settings. The Power Supply Stage is a simple resistor divider that provides the power (+9V) and bias voltage (+4.5V) to the pedal: The input buffer is a plain Emitter Follower (aka Common Collector) with unity gain and high input impedance that preserves signal quality eliminating tone sucking (high-frequency loss): The Q1 part is a 2SC2240 Toshiba transistor, cheap low-noise/high-gain (=200-700), nothing special here, it just does the job. The purpose of this filter is just to remove the DC levels from the final output signal. It controls it by allowing highs through the feedback loop. The previous TA7136AP integrated circuit was at the end of its stock life, so the whole circuit design was modified (re-labeled as DS1-A) to accommodate a standard easy to find and replace dual op-amp.This model is not very loud with a transparent drive. Put a compressor before and an equalizer that boosts the 100Hz frequency after it, and youll get the real sound of rock and roll. Gain reduction - Prior to reaching the opamp the signal travels through a transistor boosting stage where the signal level is increased dramatically, the gain in this stage is so high in fact that it drives the signal into soft clipping before it even reaches the distortion part of the circuit! Reducir la distorsin (cantidad de clipping), Darle un carcter asimtrico, ms agradable a mis odos y ms parecido a la distorsin de vlvulas, Resaltar los medios en la curva de respuesta de frecuencias. The last change was in 2006 when the New Japan Radio NJM2904L opamp was introduced. document.getElementById('cloak5230ce14d5603ba6bd88484b4b0c40a7').innerHTML = ''; Usad un medidor de capacidad si es posible para obtener un valor lo ms cercano posible. PPD: JAVIER from Argentina made some changes to this mod, he used a 47nF for C12 and a 15K for R15, getting very similar results. Bass notes are less clipped, so the distortion is frequency selective (similar to what happens in the Tube Screamer, but in that case, the freq limit is 720 instead of 72Hz). By reducing the values of C11 and R17 we drastically shift the cut off for the tone controls high pass filter, creating a flatter response in the neutral setting. The design idea is simple: The Input and Output Buffers will isolate the circuit, keeping the signal path clean and tone-sucking free. You need JavaScript enabled to view it. d. 2006 Forth Release when the New Japan Radio NJM2904L op-amp was introduced with the usual DS1-A circuit. (LogOut/ Normalmente los pedales basados en hard clipping, mucha distorsin y una curva de frecuencias mid-scooped (frecuencias medias rebajadas) son denominados distorsin, y aquellos basados en soft clipping y con resalte de medios son llamados overdrive. Tone / Level Stage. Como resumen, stos son los componentes reemplazados: Para C12, 82nF no es un valor muy comn, pero puedes poner 47nF y 33nF en paralelo para tener 80nF, suficiente dada la tolerances habitual de los condensadores. 6.2 Op-Amp Gain Frequency Response. The image below is only applicable to the case where the signal is so small (below clipping) that the diodes don't conduct, where theresistor R14 and C10 form a low pass filter with fc=7.2KHz that will mellow the signal, but most of the time D4 or D5 are conducting Generally speaking, the C10 cap makes thedistortion less grainy, making a rounder-pleasant distortion. Quera experimentar estos conceptos con un BOSS DS-1 que compr averiado y que arregl. Al simular su circuito conseguimos una curva muy similar pero ms suave, menos pronunciada en los 800Hz, y tambin aparentemente ms atenuada en las altas frecuencias: Probad esto si la modificacin suena muy nasal, o si obtenis algo de fritanga en el amplificador. The R1 input series will protect the base of the transistor from surge currents (electrostatic discharges from the guitar jack tip). The aim of this stage is just to buffer the signal and remove the DC level. var path = 'hr' + 'ef' + '='; 6.3 The effect of the C10 Capacitor.7. fcmax = 1/(2C8R13) = 1/(2*3.14*0.47u*4.7K) = 72Hz, fcmin = 1/(2C8(R13+VR1)) = 1/(2*3.14*0.47u*104.7K) = 3Hz. I hope you enjoy this mod, please let me know of any improvements or mistakes you may find. If you want to read more about the switching circuit operation, check the TubeScreamer pedal explanation, this part of the circuit is exactly the same: On the other hand, true bypass switches (3PDT) are considered to give a clean and transparent path for the bypassed signal. It is the loudest among all the models, at higher gain settings the distortion is fizzy (poorly made fuzz) with some noise. The output buffer has exactly the same circuit as the input buffer, its task is to keep a low output impedance for better signal integrity in the guitar-pedals-amp chain. There is however a twist to this tale; very few of the greats used the stock modelWith the DS-1 being such a common pedal, modifications for the circuit proved popular, allowing players the ability to tailor this distortion to their own sonic desires.While there are many well documented modifications out there you could choose from, we present to you the CSGuitars mod: a selection of some of the best ideas from other mods, with a unique spin on the values to dial in a deep, dynamic distortion thats a bit more user friendly than the stock unit. The resistor divider (R24, R25) generates +4.5 volts to be used as a virtual ground (bias voltage). While this is generally a good idea as distorting low frequencies can make the distortion slow or muddy, we felt that dropping the cut off frequencies for these filters slightly (by increasing the values of C2 and C3) would add some extra body to the distortion, while not compromising its aggression. Modders will unbalance the D4-D5 network to make their clipping even more asymmetric. Reemplazar solo uno de los diodos (D5 por ejemplo) por un LED rojo deja ms espacio para la seal, y al mismo tiempo cumple con el otro propsito de tener clipping asimtrico. DS-1 tone stack is based on the Big Muff tone stack. I tried with different values and for me 100 Ohms gave the sweet spot for having the right amount of distortion with the gain control at 12 oclock, for both single coil and humbucker pickups. This first model had some inconveniences like momentary LED and the need for an external power supply. Engineer working for a big company and amateur musician. This transistor overdrives the signal from the early stages of the pedal and will condition the behavior of the whole effect. At the beginning of the stage, there is an RC network (C5-R10) that creates a high pass filter with a cut frequency of 23Hz (fc=1/2RC). Mejora mucho el sonido final. The circuit presented here is adapted to be used with a 3PDT switch, simplifying the circuit for DIY. var addy_text5230ce14d5603ba6bd88484b4b0c40a7 = 'info' + '@' + 'electrosmash' + '.' + 'com';document.getElementById('cloak5230ce14d5603ba6bd88484b4b0c40a7').innerHTML += ''+addy_text5230ce14d5603ba6bd88484b4b0c40a7+'<\/a>'; In terms of sound, it gives the warmest distortion, offering glints of grittiness and smoothness at the same time. Perhaps even add a switch to toggle between silicon diodes and LEDs, or between symmetric to asymmetric. By simulating the circuit with LTSpice, I found the spot where the signal is mid boosted without loosing the ability to control the tone (although it is somewhat reduced compared to the original DS-1 design). The clipping stage defines the distortion signature sound, it is built using 2 back to back diodes that shunt the signal to AC ground (4.5V), this kind of clipping technique gives a hard-clipping sound also used in the MXR Micro-amp or the RAT opposed to the soft-clipping style created by placing the diodes on the feedback loop of the op-amp and used in other pedals like the Tube-Screamer. On the other hand, true bypass switches (3PDT) are considered to give a clean and transparent path for the bypassed signal. The Boss DS-1 uses a passive Big Muff Pi style tone control, which scoops the mids and attenuates the lows or highs, depending on which way you turn the knob. var path = 'hr' + 'ef' + '='; This modification works incredibly well when used with Single Coil and P90 type pickups. Change), You are commenting using your Twitter account. Tone Control - The DS-1 features a passive tone control with both high and low pass filters which form a mid frequency notch in the centre position. addy5230ce14d5603ba6bd88484b4b0c40a7 = addy5230ce14d5603ba6bd88484b4b0c40a7 + 'electrosmash' + '.' + 'com'; Como podis ver, slo se han reemplazado seis componentes. From now on, all the models are commonly called post '94. [], [] my previous post https://electric-safari.com/2019/03/17/turn-a-boss-ds-1-into-a-nice-overdrive/ I converted the DS-1 distortion pedal into something very close to an overdrive. ste es, por cierto, uno de los cambios del famoso Keeley Ultra Mod. In the Op Amp Clipping Stage, the diodes (D4 & D5) are back to back connected to AC ground (+4.5V), so the clip is harder and as a hard knee giving a strong character. Replacing only one of the clipping diodes (D5 for instance) by a red LED yields more headroom and at the same time serves my second purpose of having asymmetrical clipping. At the beginning of the stage, there is an RC network (C. high-value resistor that biases the input of the op-amp to 4.5V. When an op-amp input is driven beyond the rails, bad things happen. Input Stage. voltage gain in this topology is collector resistance divided by the emitter resistance (R, The maths behind this topology so-called Shunt Feedback resistor are a bit complex and if you want to see the full numeric development check the. Marshall JCM & Octave Fuzz Mods by pedalheaven. The value of C5 has been increased as a result of this to couple the transistor stage to the opamp gain stage. Yo en alguno he cambiado el operacional por un TLC2272 adaptando patillaje, y quitando esa resistencia. The bump happens at 800Hz, which for me is the best point to get a nice tone that is capable of cutting through the mix in a band context. This is not an intentional filter, just a cap is needed to couple the previous transistor gain stage and a moderate-high value resistor is needed to bias the + pin of the op-amp at virtual ground (+4.5V). A 3PDT switch (Triple Pole Double Throw) will also allow you to light a power-on LED at the same time, which is pretty convenient. 6 year later, in 2000 the opamp was again changed by the Mitsubishi M5223AL. It is important to mention that by the time this diode is conducting, the opamp is already clipping. It is versatile; almost clean at lower gain setting with a serious edge at high gain (slight hiss is noticeable at higher gain settings). At the beginning (1978), the DS-1 was using the Toshiba TA7136AP opamp. C1,C3 47nC2,C8,C9 0.47uC4 250pC5 68nC7 100pC10 0.01uC11 0.022uC12 0.1uC13 0.047uC14 1uC15 47uFC23 100uFD1 1N4004D4,D5,D8 D1N4148Q1,Q2,Q3 2SC2240R1,R22 1KR2,R7 470KR3,R8,R18,R21,R24,R25 10KR4,R5,R10,R11,R23 100KR9 22R13 4.7KR14,R15 2.2KR16,R17 6.8KR39 47KR19,R20 1MU1 NJM3404A ( or equivalent M5223AL, BA728N)VR1,VR2 100KBVR3 20KBJ1,J2 6.35mm Jacks. This all-time classic Boss DS1 design has a lot of subtle things going under the radar that even the original designers do not fully grasp, in my opinion, the Klon Centaur is the pinnacle of this factor. Its really all about what you want the maximum setting on the drive control to do.