The DZ4 Preamp is based on the Diezel VH4 pedal, first released in 2016 as an adaptation of the classic amplifier of the same name. The pedal version was intended to capture the feel of the VH4 amplifier’s third channel, called “Mega”. It’s intended as a true preamp, with suitable output level to drive a power amp directly, but can also be used as a traditional drive pedal in combination with others.
The DZ4 is an exact adaptation of the audio path of the VH4, but with some minor convenience & usability tweaks to the overall circuit. The first is the power supply, which has been updated to support a 9V input while reliably delivering +/-12V as in the original circuit. (More on this in the build documentation.)
The second minor change is the handling of the two outputs. The original pedal had two output jacks, one for using it as a standard pedal (with some attenuation and tone shaping) and one for connecting straight to a power amp. This has been changed to a toggle switch so you can select between the two types of outputs without having to unplug anything.
The third change is to the bypass. The original unit was buffered bypass only, but we’ve added a true bypass/buffered bypass slide switch if you’d rather keep the buffer out of your signal path when the pedal is disengaged.
The end result is a faithful adaptation of the VH4 pedal, but with a few quality-of-life tweaks so it integrates better with the rest of your rig.