Zeppelin Design Labs VPM-1 Ready to Install (Mono)

The Zeppelin Design Labs VPM-1 Ready to Install (Mono) is a volume pedal mod: a module that replaces the string and potentiometer inside an Ernie Ball VP Jr with a magnet and a Hall-effect sensor¹. The treadle still moves like a normal volume pedal, but instead of dragging a string across a potentiometer, it moves a magnet past a sensor that reads its position. The audio path stays analog, while position, taper and gain are set digitally, so there is no scratchy pot and no string to break¹.

The mono version is the basic form of the mod. Zeppelin Design Labs also builds stereo and expression versions, covered below, and a Large Format Adapter for full-size Ernie Ball volume pedals².

How it works

A stock Ernie Ball VP Jr controls volume with a potentiometer turned by a string and spring arrangement. Those are the parts that wear out: the pot gets scratchy and the string stretches or snaps. The VPM-1 removes both. A magnet rides on the treadle and a Hall-effect sensor, a component that measures magnetic field strength, reads where the treadle sits. That reading sets the volume without anything mechanical touching the audio circuit¹.

Because the position sensing is electronic, the mod can do things a string and pot cannot:

• Five response curves: linear, logarithmic, and reverse-logarithmic. The curve you pick is saved and comes back at the next power-up¹.
• Heel and toe points can sit anywhere along the treadle, and the sweep can run in reverse¹.

The response curves matter in practice. A linear pot feels uneven for volume swells because the ear hears loudness logarithmically, so a logarithmic curve can make the sweep feel smoother, and a reverse-logarithmic curve suits players who want most of the change under the toe. Setting the heel and toe points anywhere along the treadle means the working range can be narrowed, for example to use only the top half of the sweep for subtle level control.

Fit and vintage pedals

The module fits the VP Jr. Full-size Ernie Ball volume pedals, models 6165, 6166, 6167 and 6168, need the VPM-1 Large Format Adapter, which is sold separately from the mod kit itself¹³.

The adapter can also be used with vintage Ernie Ball volume pedals that have the jacks on the side of the chassis, and Zeppelin Design Labs notes some mechanical modding may be needed for those³. The maker's guidance on the mod itself is the same: vintage pedals with side-mounted jacks sometimes need a small mechanical change¹.

Stereo and expression versions

The mono version is one of several configurations of the same mod:

All versions share the same core design: analog audio path with position, taper and gain set digitally, five response curves that are saved and restored at power-up, and heel and toe points that can sit anywhere along the treadle with a reversible sweep²⁴⁵. The stereo and expression versions are made to order, with about a week allowed before shipping²⁴.

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