Before You Start

A cartridge install is not delicate work in the sense of requiring a steady surgeon's hand. It is delicate in the sense of being unforgiving: one slipped screwdriver can shear a cantilever, and a misaligned cartridge will wear grooves unevenly for as long as it stays on the arm. The antidote is preparation and patience, not talent.

What You Need

Lay everything out before you touch the cartridge. You want the cartridge itself, the headshell or tonearm mount, a small screwdriver (usually M2.5 for the mounting hardware, occasionally a Phillips or a hex), the four headshell wires (often supplied pre-attached to the headshell), a two-point alignment protractor, and a stylus force gauge. A bright light and a magnifier help more than most people expect.

Leave the stylus guard on for the entire installation. It comes off only when you are ready to play a record.

The Wire Colors

The industry convention, used by nearly every manufacturer, is four color-coded leads that connect the cartridge pins to the tonearm (Shure):

  • White — Left channel positive (L+)
  • Blue — Left channel negative / ground (L−)
  • Red — Right channel positive (R+)
  • Green — Right channel negative / ground (R−)

A few cartridges use slightly different conventions, and the pin layout on the cartridge body is not always labeled. Always check the manual before connecting. If you get a channel reversed, the soundstage will be mirrored; if you get a polarity reversed within a channel, that channel will be out of phase with the other and the image will collapse.

Installing the Cartridge

1. Wire First, Then Mount

Clip each of the four leads onto its matching pin on the cartridge. The clips should slide on with light pressure — if one feels loose, gently pinch it closed with tweezers before it is on the pin, never while it is. Leaving the cartridge loose while you do this gives you room to work from any angle.

2. Mount the Body Loosely

Thread the mounting screws through the headshell slots and into the cartridge body, but do not tighten them. You need the cartridge to slide forward and backward freely in the slots, because that is how you set overhang.

3. Set Overhang by Sliding

Place your protractor on the platter (spindle through the center hole), and lower the stylus onto the alignment point. Slide the cartridge forward or backward in the headshell slots until the stylus tip sits exactly on the point. Overhang — the distance the stylus extends beyond the spindle — is typically 15–20 mm, but the exact figure depends on your tonearm's effective length. The protractor handles the geometry for you.

4. Set Zenith (Rotational Alignment)

With the stylus on the alignment point, look straight down at the cartridge body. The long axis of the cartridge should be parallel to the grid lines printed on the protractor. Rotate the body in the headshell slots — small amounts — until the sides of the cartridge run parallel to the grid. This is zenith, and it is easier to judge with a loupe than with the naked eye.

5. Check the Second Null Point

Move the tonearm to the second alignment point on the protractor and check parallelism again. It will probably be slightly off. Return to the first point, nudge, then re-check the second. Two or three iterations is normal. When the cartridge is parallel to the grid at both points, the geometry is correct across the record (Vinyl Engine).

6. Tighten Evenly

Snug the mounting screws in small alternating turns — left, right, left, right — the way you would tighten a wheel on a car. Even pressure prevents the body from shifting out of alignment as the screws come down.

7. Balance, Tracking Force, Anti-Skate

With alignment set, the last step is the counterweight. Balance the arm so it floats level with the stylus guard still on, zero the tracking-force ring, then dial in the force specified by the cartridge manufacturer. Set anti-skate to the same numeric value as tracking force as a starting point. This is standard tonearm procedure and applies to every cartridge.

What Alignment Actually Means

A pivoted tonearm swings through an arc. A record groove is a spiral. The stylus can only be perfectly tangent to the groove at two specific radii on the record — everywhere else, there is some tracking angle error. Alignment is the practice of choosing where those two perfect points (the "null points") fall, so that error is distributed intelligently across the playing surface.

Get it right and distortion is low and even from the outer edge to the label. Get it wrong and distortion rises — especially toward the inner grooves, where the groove velocity is lowest and the stylus is most sensitive to geometry errors.

The Three Common Geometries

Different people, over the decades, have proposed different answers to the question of where the two null points should sit. The three you will see on almost every protractor are (Analog Planet, Le Son):

  • Baerwald (Löfgren A) — null points at 66.0 mm and 120.9 mm. Equal peak distortion at the inner groove, the outer groove, and the middle. The default choice for most tonearms and most music.
  • Löfgren B — null points at 70.3 mm and 116.6 mm. Lowest average distortion across the record, at the cost of slightly higher distortion at the extreme outer and inner grooves.
  • Stevenson — null points at 60.3 mm and 117.4 mm. Pushes the inner null point to the innermost groove, minimizing distortion at the end of the side. Common on Japanese tables (including Technics) and a reasonable pick for classical listeners with long, densely cut sides.

None of these is wrong. They are different priorities. Baerwald is the safe default if you have no reason to prefer otherwise.

Azimuth: The Other Angle

Zenith is the rotation of the cartridge when viewed from above. Azimuth is the rotation when viewed from the front — the stylus should be perfectly vertical, not tilted left or right. Most modern cartridges mount square to a flat headshell and need no adjustment. If yours looks visibly tilted when you face it head-on, the headshell (not the cartridge) is usually the problem.

Common Misconceptions About Cartridge Installation

MYTH

“Alignment is optional if the cartridge sounds OK.”

Reality: a misaligned cartridge causes inner groove distortion, channel imbalance, and accelerated groove and stylus wear — even if it sounds fine at first. The damage accumulates on every record you play.

MYTH

“I just use the alignment mark on the headshell.”

Reality: headshell alignment marks are approximate manufacturing references, not precision alignment tools. They will get you within a few millimeters of correct, which is not the same as correct. Use a protractor.

MYTH

“Tighter screws mean better cartridge coupling.”

Reality: over-torquing cracks plastic cartridge bodies and can strip the threads in the headshell. Snug is enough — fingers plus a quarter turn, not full torque.

Frequently Asked Questions

Do I need a torque-limiting screwdriver?

No. A small jeweler's screwdriver with a comfortable handle is fine. The whole point of the "fingers plus a quarter turn" rule is that you do not need a calibrated tool to avoid over-tightening.

How do I know which alignment geometry my tonearm expects?

Check the manufacturer's setup guide. Rega, for example, specifies its own geometry via the headshell hole position. Technics tables are typically aligned to Stevenson. If there is no specification, Baerwald is the standard default and will work correctly on almost any pivoted arm.

The cartridge won't slide far enough forward in the slots. Now what?

You are running out of overhang adjustment. Confirm that the cartridge is mounted in the correct headshell holes (some headshells have multiple sets), and confirm that your tonearm's spindle-to-pivot distance matches its specification. If both are right and you still can't reach the null points, the cartridge and tonearm may not be geometrically compatible — an uncommon problem, but it happens with unusually short or long arms.

Do I need to re-align when I replace the stylus?

If you replace only the stylus (user-replaceable styli on many MM cartridges), the cartridge body has not moved, so alignment is preserved. If you replace the whole cartridge, you start over from step one.

How often should I check alignment on a cartridge that is already installed?

Once a year is plenty for a cartridge that does not get disturbed. Check it any time you remove and reinstall the headshell, bump the tonearm hard, or notice new distortion on inner grooves.

Put this into practice

Ready to apply what you just learned? These guides will help you make a smarter buying decision.

References

  1. [1]ShureColor code for phono cartridge wiring (white/blue/red/green convention) ↑
  2. [2]Vinyl EngineProtractor user guide: Baerwald, Löfgren, Stevenson null points and iterative alignment procedure ↑
  3. [3]Analog Planet (Michael Fremer)Null point positions for Löfgren A (Baerwald), Löfgren B, Stevenson, and UNI-DIN geometries ↑
  4. [4]Le Son InternationalCartridge alignment protractor overview and geometry comparison ↑