VPI 10 Inch Fatboy Tonearm - Unipivot

The Fatboy 10-Inch Unipivot — VPI's Heaviest Armwand, Balanced on a Point

A 10-inch 3D-printed tonearm turning on a single pivot. The armwand is the thickest VPI builds, printed in epoxy resin and Delrin with steel, copper and aluminum, and wired internally with Nordost Reference Wire.

A unipivot rests the whole arm on one point. That removes the friction of a conventional bearing almost entirely, and it makes azimuth adjustable — because an arm free to rotate about its pivot can be balanced to sit the stylus square in the groove.

Design and Engineering

Why a Thicker Armwand

An armwand has to carry what the stylus reads to the bearing without adding to it. Printing the tube rather than extruding it lets VPI build a shape that is stiff without being resonant, and the Fatboy takes that further than the arms below it in the range.

The printing is not a single material. VPI describes it as “3D Technology Consisting of but not limited to Epoxy resin and Delrin materials, steel, copper, and aluminum,” which is a structure rather than a molded part.

Three Ways to Set Azimuth

This is where the unipivot earns its keep. Azimuth can be set with the setscrews on the side of the arm tube, with the adjustable side weights, or with the dual pivot supplied in the box — which converts the arm to a two-point bearing if you would rather it did not rock.

Counterweight, VTA and azimuth are all adjustable, and the arm terminates in a Lemo connector rather than a captive lead — so the run to your phono stage is a separate cable that you choose, and one you can change later without touching the arm.

Geometry and Fit

The Numbers

Pivot to spindle is 258 mm and effective length 273.4 mm, giving 15.4 mm of overhang at an offset angle of 19.98°. VPI quotes average RMS distortion of 0.31%. Effective mass is 10.7 g, which sits in the medium band and suits the great majority of moving coil cartridges an arm at this level is likely to carry.

The 258 mm pivot-to-spindle distance is the number to check. The Fatboy is built around VPI turntables and their armboards; fitting it to another make means an armboard drilled at 258 mm and a base that will take the VPI mounting.

What Reviewers Are Saying

Positive Feedback called it "a simply stunning accomplishment and could easily be many audiophiles' final tonearm." Its verdict: "There's absolutely no question that one would need to spend significantly more money to get better performance."

Who Is the Fatboy Unipivot Best For?

• You own a VPI turntable — the armboard geometry is what this arm was designed around
• You want azimuth adjustment — three separate methods, including the dual pivot in the box
• You change cartridges — azimuth and VTA are both adjustable, so each one can be set properly
• You want the Nordost wiring — Reference Wire internally, to a Lemo connector
• You would rather not balance an arm on a point — a unipivot rocks until it is set, and the gimbal Fatboy is the same arm on a fixed bearing

How Do You Install It?

Mount the base so the pivot sits 258 mm from the spindle, then hang the armwand on the pivot and connect the Lemo. Fit the cartridge, set overhang with VPI's jig, then balance the arm and set tracking force. Azimuth comes last, using the side weights or the dual pivot, with the turntable leveled first — a unipivot depends on that.

Pairs Well With

What most VPI owners fit alongside a new arm.

• Phono cartridges — the arm sets the range of cartridge that will work
• Cartridge alignment tools — for setting the cartridge up once the arm is mounted
• Stylus force gauges — set tracking force once the arm is back in service
• Tonearm cables — the run from arm to phono stage

Frequently Asked Questions

Will it fit my turntable?

It needs 258 mm from spindle to pivot and a base that takes VPI's mounting. On a VPI turntable that is already the case; on anything else it means an armboard cut for it.

What is the difference between this and the gimbal version?

The bearing, and nothing else in the specification. Both are 10-inch Fatboy armwands with the same geometry and the same wire. This one balances on a point and offers azimuth by balance; the gimbal version runs in a fixed bearing.

Do I need to level the turntable?

More than usual, yes. A unipivot finds its own vertical, so a turntable that is not level puts the stylus into the groove at an angle.

Is anti-skating needed?

VPI's long-standing position on its unipivot arms is that they need very little anti-skating force, if any. The manual is the authority for the arm you have.

What is the dual pivot for?

It converts the single point to two, which stops the arm rocking and fixes azimuth mechanically. It is supplied in the box, so you can run the arm either way.

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