Electro Harmonix produce some of the funkiest, filthiest effects on the market - from the legendary Big Muff Pi to the funkalicious Q-Tron, if you've heard that unmistakable fat sound, it's probably an EHX!

They continue to push the boundaries for new generations, as they have done over the past 30+ years.

You might be looking for their official site, or how about the wikipedia entry?