[NOTE - This post includes projects for the BOSS DS-1, ProCo RAT, Electro Harmonix Big Muff Pi, the Electro Harmonix Small Clone Chorus and the Little Angel Chorus]
Kurt Cobain - arguably the last great Rock star. In 1991 Nirvana's Nevermind changed the face of guitar music for good. The sound was pretty much unstoppable with the aggressive roar of Kurt's overdriven tones softly complimented by the chorusy wobble and jangle of his clean licks. Kurt used a wide range of gear and it's nearly impossible to pinpoint exactly what gear he was using at what point during his career, however with a little research I've come up with a DIY guide to building your own Kurt Cobain pedalboard so you too can sound like the King of Grunge. The equipment I've chosen (FX pedals) were used mainly in Nirvana's Nevermind period...
Kurt used a range of guitars but by the time he came to record Nevermind he'd settled on the cheaper Fender models for his main sound; the Fender Mustang and Jaguar are now synonymous with Kurt but any guitar with a humbucker installed in the bridge position and a single coil elsewhere will be able to produce his tones.
His main preamp was a Mesa Boogie Studio .22, these were run into Crown Power Base 2 power amplifiers. Kurt used these to drive anything from a single stack to four 8x12 stacks (depending on the size of the venue). To get Kurt's tones you're going to at least need a closed back 4x12 cab, anything less and you just won't get the required air movement and low end thump. The preamp was set fairly clean, this allowed Kurt to use his distortion boxes to generate all of his signature aggressive distortion tones.
Here's an image of Kurt Cobain's stage rig from around 1992:
As you can see it's pretty simple - a BOSS DS-1 Distortion box into an Electro Harmonix Small Clone Chorus Pedal. However, it is also known that Kurt used a ProCo RAT and an Electro Harmonix Big Muff during the recording of Nevermind.
[One of the best album covers ever?]
In this guide I'm going to offer projects to build a BOSS DS-1 Distortion, a ProCo Rat and an Electro Harmonix Big Muff. I will also provide a project for the Electro Harmonix Small Clone but will also cover a project detailing the construction of a simpler Chorus circuit (some of the parts in the original Small Clone are now quite rare and hard to purchase).
So, first up is the BOSS DS-1 Distortion:
It's an age old classic and produces that pronounced nasaly distortion and clipping which became Kurt's go to heavy tone. There's a great project for the BOSS DS-1 Distortion over at tonepad.com here: http://www.tonepad.com/getFile.asp?id=78
And here's a schematic for reference:
Next comes the ProCo RAT. Personally I like the RAT more than the DS-1, it's got a slightly more open tone and isn't as nasal:
Again there is a great project on the tonepad site, check it here: http://www.tonepad.com/getFile.asp?id=89
And a great schematic taken from a tracing of a RAT produced in 1986 (About the right era!):
A massive part of the RAT sound is the diode type. You can change the 1N4148 for anything really, I like red LEDs in mine, Mosfets setup as diode clippers also sound decent. For the Nirvana tone go with the 1N4148s.
Next the Electro Harmonix Big Muff Pi. The Big Muff has been a firm favourite for distortion mongers since the 70s and it's one of my favourite pedals. It creates a smooth, compressed distortion sound like no other pedal I've heard before.
Once again we're off to tonepad.com for our project file: http://www.tonepad.com/getFile.asp?id=94
And a reference schematic:
Finally we're onto the choice of Chorus pedal. Kurt used his Electro Harmonix Small Clone chorus on nearly every record he made. Come As You Are gives you a great idea of the tones the pedal can create:
The Small Clone gives the guitar that watery almost liquid effect. Now the problem with building the Small Clone is the rarity of some of the parts, the key chip is the MN3007 which are now obsolete and very expensive. They are in stock at Banzai Music but cost over 8 euros a piece: http://www.banzaimusic.com/Delay-Chips-Clock-ICs/.
Once again tonepad hosts a great project file for the Small Clone, check it out here: http://www.tonepad.com/getFile.asp?id=97
I'm going to suggest something a little different though. The "Little Angel MKII" is a simple chorus circuit designed by Rick Holt and Mictester over at freestompboxes.org. It use the common and easily attainable PT2399 delay chip as it's heart. Here's the schematic, PCB transfer and PCB layout:
There is an even simpler version available that only uses a single dual op amp presented in the Little Angel thread on freestompboxes.org here: http://freestompboxes.org/viewtopic.php?f=13&t=10276
So there you go, put together your own Kurt Cobain / Nirvana pedal board! If you've got any questions, please email me or leave a comment :-)