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Boss DS-1 Ultra Distortion
Keeley Mod


DS-1 distortion pedal has a lower noise level than a stock pedal! Metal film and poly capacitors are used in the coupling sections to provide the true mid-range and high frequency transparency your guitar tone needs while increasing the bass response of the pedal. It goes without saying that the note definition has been improved. The result is a pedal that provides more gain and volume while losing no note definition. Perfect for driving Marshall stacks and other high-powered gear. This pedal has been modified to have asymmetrical clipping. This mod gives you 2nd order harmonic distortion, which has a very musical sound. At very high saturation levels it almost becomes an octave type of effect. DS-1 Ultra Distortion Pedal has been modified to have the Seeing Eye LED. There is an LED located in the “O” of the word TONE. This LED is not just a visual effect. It is in fact fun to watch but it is part of the secret weapon in our reworking of this pedal. The LED is part of the circuit that clips the signal and gives it that full, distorted sound.
Recommended starting point: Try setting the Tone Control at about 10 o’clock and the Level and Distortion controls at 12 o’clock noon. Most modern amps are a little bright sounding so this should sound good for a starting point. For a crisp yet really heavy sound driving a tube amp, we like to set the Tone Control to noon and then set the Distortion and Level control to about 2-3 o’clock. Stand back and enjoy!
What you get with the Keeley DS-1 Ultra Mod!
  • 1. Better bass response along with true mid range and high frequency transparency
  • 2. More gain and volume without losing note definition
  • 3. "Ultra" switch to go between a louder, clear distortion to a thicker, more saturated distortion
  • 4. All of these mods result in a true "Marshall in a box" distortion pedal!

All modifications are warranted for you, the original owner, for one year. If you have any problems at all please email Mammoth Electronics at If you are happy with this product, please let everyone know and tag us on Instagram and Facebook with #mammothelectronics. If you are not happy with this product for any reason at all, please let us know within 48 hours and we will refund your order. The entire Keeley and Mammoth team thanks you for your business. You’re keeping the good tones alive! If you like this product, there’s more where it came from, check out the rest of our products on

Mod development times are between 3-5 business days from the day that we receive your pedal(s).

Please ship to the address below:

Mammoth Electronics
Attn: Mods Department
3203 Broce Dr
Norman, OK 73072

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