Simple Boss Pedal Mods: Changing from Stock to Rock

Boss pedals’ ruggedness and reliability have made them staples on professional pedalboards for decades now, and the Boss DS-1 Distortion pedal and the SD-1 Super Overdrive are often among the first pedals aspiring players buy.

New In Box Boss DS-1 & SD-1

Featured on the pedalboards of heavy-weight musicians like Steve Vai, Joe Satriani and Kurt Cobain, the DS-1 is synonymous with crunchy rock sounds, while the SD1 emulates the smooth breakup of a naturally overdriven tube amp. It also can be used to push an already overdriven amp into punishing distortion, as Zack Wylde does.

But what if these tones could be improved upon by switching only a few components to unleash the best possible characteristics of each pedal? If you're handy with a soldering iron, these mods can be accomplished in just a few minutes, and you’ll have your friends and fans envying your tone.

Boss DS-1 Modifications

Stage one of this mod involves changing the clipping diodes, which are responsible for all of the distortion characteristics of the pedal. The stock DS-1 uses a pair of 1n914 silicon diodes. These are by far the most common clipping diodes, as seen in almost every other Boss pedal, as well as Tube Screamers and Pro Co Rats.

To completely unlock amp-like distortion, we'll be changing these to IRF520 MOSFETs. By soldering the drain and gate pins together, MOSFETs act similar to diodes. The tonal differences, however, are night and day. This mod really opens the pedal up to a whole new tonal spectrum and removes the harsh frequencies associated with it in its stock form.

Boss DS-1 circuit board

D4 & D5 1n914 Silicon Diodes that need to be replaced

To start, de-solder the diodes from D4 and D5. Laying the MOSFET on its back (metal tab down), twist the middle pin over the left pin and solder. This combines the drain and gate as stated above. Once both MOSFETs have been soldered this way, you are ready to install. Since the clipping diodes in this pedal are wired in parallel, orientation does not matter as long as they are facing opposite each other. Orient the MOSFETs in the holes vacated by the old diodes so that they are facing opposite directions. This means that if the drain/gate combo is in the left hole of D4, the source pin will be in the left hole of D5, or vice versa. Resolder, trim the excess leads and box it back up. Plug in and you'll immediately notice a bold, amp-like saturated distortion with clear note separation.

IRF520 Mosfet

IRF520 with drain and gate pins soldered together

IRF520 Mosfets Soldered onto circuit board

Stage two is much simpler but equally as powerful. The capacitor in C12 is responsible for the overall EQ curve. I used a polyester box capacitor, but a regular polyester capacitor would also work. Ceramic caps are not recommended at this value, as they have a somewhat harsh tonality to them. This removes the inherent tubbiness while bringing the mids to the forefront. The curve is now much more useable, and harmonics leap from the fretboard.

Stock DS-1 0.1uf Capacitor in C12

0.022uf Capacitor in C12

Boss SD-1 Modifications

Contrary to the DS-1, this set of mods will focus more on overall tonality vs. gain. Stage one of this mod involves changing the stock JRC4558 IC to a much cleaner, higher efficiency opamp. I have selected the NE5532, but OPA2134, TL072, or TL062 would all work as well.

De-solder the eight lugs from the original chip and remove it. Adding a socket is highly recommended, both to protect the incoming IC from heat and to allow for easy swapping to dial in whatever tone you're seeking. Once the socket is installed where the old IC was, snap the new IC into the socket with the orientation mark facing the DC jack. This cleans up the overall character of the pedal and slightly reduces gain and noise, which gives it a much better boost, especially in front of an already dirty amp.

Stock JRC4558 IC in SD-1

New Socket and NE5532 Chip installed

Stage two once again involves clipping diodes, note D5 and D6; these come stock with 1n914 silicon diodes. To get a slightly bolder clip, change these to either 1n4148 or 1n4001 silicon diodes; the tonal differences will be subtle but noticeable. To drop the gain slightly, 1n34a germanium diodes can be added. It is important to note, however, that germanium diodes will slightly lower the output. Either of the aforementioned diodes will work very well. When installing diodes, it is important to note orientation. All diodes have a stripe on one end denoting polarity. For most aforementioned diodes, the stripe is black. Any 1N400x diodes will have a silver stripe. Printed on the space vacated by the stock diodes, you will notice a diode symbol that looks similar to ->|-. The stripe MUST be on the end with the |. This denotes directional current flow.

Stock 1n914 Silicon Diodes in D5 & D6

1n34a Germanium Diodes installed in D5 & D6

Tone for Days

Boss pedals are highly mod-able, making them the small block Chevy's of the pedal world. With these simple mods on an SD-1, you can get tones that are of higher quality than a Tube Screamer at nearly half the cost. Whether mild breakup tones are what you’re looking for, or if you're pushing an already dirtied up amp, this pedal will always have your back.

By nature, the DS-1 is fizzy and inarticulate, making the tone stack unusable in most live situations with its stock scooped midrange. Adding the aforementioned mods turns it into a fire-breathing, high-gain pedal that sounds more amp-like and can turn any clean amp into a gained out monster. Parts for these mods can be acquired at online electronics stores like Mammoth, Mouser, Jameco, or Small Bear Electronics, and really turn these underdogs into go-to pedals.

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