Voici un best-off des mods pour BOSS DS1 :
Citation:
DS-1 Melanhead Mod.
C10, C11 ----------- .047uf
C2 ----------------- .68uf
C3, ---------------- .068uF
C4 ----------------- 470pf Silver Mica
C7 ----------------- 220pf Silver Mica
C8, C14 ------------ 1uf
C9 ----------------- .47uf
C12, C13 ----------- .1uf
R13 ---------------- 2.4K
R39 ---------------- 20K
R16 ---------------- 4.7K
R2 ----------------- 620K
D5 3mm LED
All caps are Panasonic Film unless otherwise noted and resistors are 1% metal film.
Boss DS-1 Mods
February 15, 2006:
The Boss Distortion is one of the oldest distortion units, dating back to the late 1970’s. This is the second unit I’ve owned. The first one was traded off before I started modding pedals. Good thing they have a good street price ($40 at the time of this writing). There are a few version differences throughout the years. The main change, around 1994, was that the Toshiba TA7136AP opamp was replaced with the Mitsubishi M5223AL.
There are many different mods out there for the DS-1. The two that I have decided to take on are by Robert Keeley and by Bob Melanson (Melanhead in the DIY world). There are some aspects of each that I like so rather than do one over the other, I combined them a little. The dual 3mm LED’s as clippers rather than one was my experiment. Most mods call for one but I like the sound of two for even more crunch, much like the old black Marshall Guv’nor.
0. C1, C10 - change to 0.047uf
0. C2, C8, C14 - change to 1uf
0. C3 - change to 0.068uF
0. C5, C12, C13 - change to 0.1uf
0. C9 - 0.47uf
0. C11 - 0.033uf
0. D4, D5 - change to Red 3mm LED
0. R13 - change to 2.2k
0. R14 - change to 1.5k
0. R16 - change to 4.7k
0. R39 - change to 22k
All capacitors are Panasonic metal film although silver mica or poly film would be fine too. Some of the caps are left the same value and just replaced with better quality caps (who knows how much difference it makes but what the heck …).
All resistor changes are 1% metal film but carbon film can be used as well and close-enough values are acceptable (i.e. 2.2k vs. 2.4k; 22k vs. 20k). Since my parts stock is missing some metal film resistors, I opted to use what I had and went with carbon film with little to no noise increase.
Play with the value of R13 as this controls the amount of distortion. Lowering this value increases the distortion. For D4 and D5, the combinations of diodes and LED’s that can be done are endless. Try series LED’s, series LED’s and diodes, series diodes. Let your ears decide.
Thanks to Robert Keeley and Bob Melanson for their mods.
August 29, 2006:
Changed R13 back to stock value of 4.7k. Changed D4 and D5 to 1N4001 and 1N4148 respectively.
May 14, 2007 (updated November 2, 2007):
Changed R14 back to stock value of 2.2k. Changed R39 back to stock value of 4.7k. Put back in stock caps that were replaced with same value. Reverted some other caps back to their stock value. Adjusted parts change list (below) to reflect actual part and value changes.
This is my minimal mod that really changes the sound of the pedal enough that it can be a standalone distortion through a clean channel with a good full sound.
0. C5 - change to 0.1uf
0. C11 - change to 0.047uf
0. C13 - change to 0.1uf
0. D4 - change to 1N4001
0. R16 - change to 4.7k
January 23, 2008:
Here is another low parts count mod that I call, Minimal Mod Part II. C5, C11 and C13 are back to their stock values, 0.47uf, 0.022uf and 0.047uf respectively. R14 was raised to increase the lows. R16 was lowered to increase the mids.
0. D4 - change to 1N4001
0. R14 - change to 4.7k
0. R16 - change to 2.2k
These three changes make the DS-1 in to a great sounding distortion. It sounds excellent with both single-coils and humbuckers.
January 25, 2008:
First, I need thank Brian Wampler of indyguitarist.com for this mod. He has a featured article in the February 2008 edition of Premier Guitar magazine and he shares some great info about modding the DS-1. By doing one of those mods, other than all the diode changes, it sounds fantastic. So, starting off with a stock DS-1, make the following changes.
0. C2 - change to 1uf
0. C3 - change to 0.033uf
0. C5 - change to 1uf
0. C9 - change to 1uf
0. D4 - change to 1N4001
0. R16 - change to 2.2k
0. R17 - change to 15k
Read the full article on premierguitar.com here: Boss DS-1 Mods
Boss DS-1 Mods / premierguitar.com
If you’ve been in a music store anytime since 1978, you’ve no doubt seen the ubiquitous orange Boss DS-1 Distortion pedal. Universally recognized as a good, inexpensive distortion pedal, you’ve probably even owned one or two in the past. Although it houses a simple circuit design, it produces a very good sound, particularly for a mass-produced pedal. Let’s look a little more closely at the circuit and check out some changes that are available to make this great pedal even better.
The circuit is a buffered bypass circuit with electronic switching, as are all Boss pedals. The circuit comes in through R1, a 1K resistor, and then travels through C1, a .047 microfarad, or µf, capacitor into the first buffer. This buffer goes out through C2 and then into a JFET (junction gate field-effect transistor), which is part of the switching. If the pedal is off, the signal goes out to the switching circuit and through the output through Q7, which is the other JFET. These JFETs act as a switch, allowing the signal to either go through the distortion circuit or out through the buffers, producing a clean signal.
When the pedal is on, signal travels to Q6, through C3 and into a transistor gain stage. R7 controls the gain of this circuit by changing the voltage bias, consisting of a 470k resistor which you can increase or decrease in value to adjust gain before the next stage. Increasing the value increases gain, while decreasing it will give you a little less gain overall but will tighten up the DS-1’s low-end response, ridding it of the flubbiness many people dislike. We can also decrease C3 to get this same effect by not allowing as much bass to come through. I like to change its value to either .022µf or .033µf if I’m looking for a less flubby tone. To clarify, to me “flubby” means a deeply compressed tonality. C4, which has a value of 250 picofarads (pF) also filters out some highs. Changing this won’t do too much, although you may be able to coax a little more brightness by changing it to a 100 pF capacitor.
The signal then goes out through C5 into the opamp. This opamp is used in a unique way to clip the signal. R11 controls the gain in combination with the distortion knob, R13 and C8. The gain control is set up this way to enable the clipping of higher frequencies as you turn the distortion up. When it’s turned down, it allows lower frequencies in – giving it a muddy sound since the signal is clipped beforehand through the transistor gain circuits, then clipped again when the distortion control is turned down. The first stage clipping is still occurring and as a result, the pedal doesn’t sound as clear and articulate as many would like. R13 and C8 are part of this “non-inverting” opamp circuit which provides negative feedback to ground. This is important for several reasons. The resistor value of R13 and the capacitor value of C8 basically provide a frequency range where the signal is made to clip. In this case all frequencies above 33hz is being clipped. To contrast, a Tubescreamer only lets frequencies above 728hz clip. This means that none of the lower bass frequencies are being boosted and/or clipped in the Tubescreamer.
The signal goes out through R14, which is a 2.2k resistor, through C9, which is a .47µf capacitor running across two diodes – D4 and D5 – and then to ground. All the usual diode tricks can be done here to allow more asymmetric clipping or different clipping flavors. Here C10 is also in parallel with D4 and D5 and is used to filter out highs in conjunction with R14. R14 and C10 form a low pass filter, cutting out high frequencies.
Go to indyguitarist.com/filter.htm and scroll to the bottom. Plug these values into the corresponding fields to determine which frequencies are being filtered. With the current values you will find it’s filtering everything above 7k, which helps to smooth things out a little bit. If it’s too bright, replace R14 with a resistor valued at 3.3k, allowing more highs to be filtered out, or try a 4.7k resistor to filter out everything above 3.3kHz.
After traveling through the diodes and the capacitor, the signal goes through a Big Muff - inspired tone control. There are many things we can do to manipulate the tone here, and a great resource is the Duncan Tone Stack calculator, available at duncanamps.com/tsc/. Experiment with different values to find the tone you’re looking for. In the stock version of the pedal, the tone is a bit “scooped,” meaning that there is little mid frequencies allowed through making the tone a little “thin” sounding. We can change that quite easily however. Check out the suggested changes in the charts below to get a warmer tone, a scooped mid tone or simply less highs.
After the tone control the signal travels through the level control and then out through R18, which is a 10k resistor, and then on to Q7, which is the other side of the JFET switching circuit. In its on state, it goes past Q7, through C13 – which is a .047µf capacitor – through yet another output buffer and then a resistor, a capacitor and finally through the output.
Let’s look at some modifications that will have your DS-1 doing your bidding in no time.
Classic JCM-type Marshall Tones:
LOCATION CHANGE TO:
C3 .033µF
R17 15k
C2 1µF
D4 1N4148 Connected in Series to another 1N4148
D5 1N4001 Connected in Series to another 1N4001
C5, C9 1µF
R13 OPTIONAL - Change to 1k for tons of gain, if you do this, also change c8 to 1µF
Modern distortion tones
LOCATION CHANGE TO:
R16 1k
R14 10k
C10 .001µF
C5, C9 1µF films caps (in addition to R15 3.3k)
D4 LED
Vintage distortion tones
LOCATION CHANGE TO:
D5 LED
C3 .033µF
R16 1k
C11 .001µF
If you like the general sound of the DS-1 but are looking for less highs and more of a tonal range change C10 to a capacitor with a larger value. Stock is .01ìF for a frequency roll-off of 7.2kHz.
Less shrill highs
LOCATION CHANGE TO: FREQUENCY ROLLOFF:
C10 .015µF 48kHz
C10 .022µF 3.2kHz
C10 .027µF 2.6kHz
C10 .033µF 2.1kHz
C10 .047µF 1.5kHz
All in all, the Boss DS-1 Distortion is an inexpensive pedal that can rival many of the best boutique pedals simply by changing the circuitry a little. While this may seem difficult, technical and out of reach, it really is very simple if you know what to change and where to change it. I hope that I’ve given you the knowledge and courage necessary to change your pedal from a mouse into a monster. Happy soldering!
Brian Wampler
