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Keeley Java Boost CV7003 Booster Pedal. The Ultimate Rangemaster Clone

Keeley Electronics

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The Keeley Java Boost is a germanium based TREBLE BOOSTER, it is not a clean boost. It is designed to give you classic tones from the 60's and 70's. It must be used with a cranked amp that is overdriven or distorting a bit already. The more the amp and pedal are cranked, the more the creamy, beautiful, sustaining distortion there will be.

What makes this one raise an ears and eyebrows is that it has the REAL DEAL, no joke Mullard OC44. Yup, Made in Holland. There is only a small number of the OC44 and CV7003 transistors, so this will be a limited edition pedal. Looking for the Ultimate in Boosters? The Perfect Boost for your main overdrive pedal? From Surf to FUZZ...the best cutting and biting tone from a pedal!

The Java Boost is NOT AT ALL related to the TS9 or Blues Driver, OR ANY distortion or overdrive pedal. Boss or Ibanez don't make anything like it! It is a Treble Booster by design, not a typical overdrive or distortion pedal. That means, the higher the note played, the more it gets amplified... and then, by your amp, distorted. Bass Notes get cut in two of the modes on the java boost!

It is most widely used with a tube amp set to a bit of overdrive or clipping. That is the key to getting a great sound from this pedal. For example, setting the java boost in front of a very clean amp with the volume on 1-2 will surely result in a fairly weak guitar tone!

Set the amp for some breakup, then click the java on. There, you'll have a fantastic sound and see why people rave about the Java Boost.

Another way to run it is before an overdrive pedal. This is the pedal to get if you want a two pedal overdrive setup. Couple this in front of a TS9 or BD-2 and the results are simply amazing. This will add sparkle and life to your solos like no other pedal can. Check out the full-length web site www.javaboost.com!


  • Modern Dallas Rangemaster Circuit.
  • 3 way switched treble-booster, Stock Vintage Rangemaster(center), Mid-boost(to the Right), and Full Range(to the Left)
  • The switch is a very expensive locking 3 way switch so your setting is not moved.
  • Metal film parts for low noise.
  • BEST PART, The ULTRA RARE MULLARD OC44 !!!!!!!!!!!!!!!!
  • This is the transistor used in the mid 60's and only the best survive Keeley's critical testing. Low leakage of 150uA or less and Hfe of 80-110 are minimum requirements for the transistor to be used in this circuit.
  • Second best part, DC jack and Negative ground system so it will work with your other supplies and effects and no smoking! BATTERY power is really the best way to power this device. Because of its simple nature, ANY POWER SUPPLY WILL CAUSE NOISE. Keeley has designed in measures to reduce this noise, but it will still appear even with the best supplies. Batteries will last 48 hours of continuous use in this unit.
  • (A useful analogy...a 65 Vette had higher compression needing a specific power source... High Octane gas to deal with the compression ratio... Well... this Vintage gear (came out around '65) has a special power source requirement BATTERIES, not modern DC supplies. Yes, the Vetter will move down the road on 85-87 octane gas, but you'll hear some noise...KNOCK AND PING! Just like with a DC supply with the Java Boost, you'll hear noise!)
  • Violet LED.
  • Each unit is perfectly dialed in...internal potentiometers let us fine tune each of the tested and passed OC44's for optimum operation.
  • Tone Control!!! Yes Keeley's Java Boost has a second way to control the frequencies of the boost made, plus the Standard Level Control.
  • True-Bypass, Switchcraft jacks.
  • Powder Coated case.
  • Stamped serial number.
  • THE Benchmark for all other Dallas Rangemaster pedals.