My all time favorite band is Black Sabbath and my all time favorite album is Paranoid. Back in 1970, if you wanted a distorted guitar sound, you had to max out your amp. To help with this, guitarist began using boosters and other pedals to get more gain into the amp before the preamp section. The muddier sound of vintage tube amps was greatly brightened with the help of treble boosters. The Dallas Rangemaster is a treble booster that Black Sabbath guitarist Tony Iommi used for the first few albums until it was accidentally thrown away. I wanted something close to the original design of the Rangemaster, which wasn’t a guitar pedal, it was a box that set on top of the amp.

I’ve added an input potentiometer that controls the amount of signal entering the circuit, similar to the guitar’s volume knob.

For the PCB, I used perfboard/prototyping board to connect the components together.

The enclosure I made using sheet metal. I cut the shapes out of metal and used metal brake to form a small enclosure. I made an extra piece on the back that fastens using a long bolt for the battery compartment. And the space above the battery compartment can hold the audio cable when not in use. The front panel has a simple toggle switch for power with an LED.

The smaller form factor enclosure meant that a 9V battery wasn’t really an option, generally I prefer to have the option for a battery just in case. For this pedal, power is provided entirely from the DC jack.

I didn’t stop there however, I also made a pedal version of the nearly the same circuit. I removed the input gain control and instead, added a toggle switch that controls the input capacitor. When in the Iommi position, the capacitor value is slightly smaller allowing more mids/lows to pass.

I wasn’t sure when I made this if I was going to like the smaller form factor, so I didn’t put much effort into the face design. I actually ended up using this pedal the 2nd most, right behind the Tube Crunch.

This circuit has an amazing sound running into my Peavey 100W tube amp. Since I’ve modded my amp’s preamp section to be very close to a Laney amp (same as Tony Iommi), running this treble booster gets me pretty close to that early sound.