Tonearm geometry explained: overhang, azimuth and VTA for serious vinyl playback

A cartridge costing three thousand dollars, mounted on a tonearm set up by someone who eyeballed the overhang and called it done, will consistently be beaten by a cartridge costing six hundred dollars that's been properly aligned. I've heard this play out at shows more times than I can count, and I see it every time I visit a system that the owner considers finished but is, quietly, a mess. The geometry of a tonearm is not a set-and-forget afterthought. It's the foundation everything else sits on.

This is the article I wish existed when I first started taking vinyl seriously. Not a primer for beginners — if you're here, you already know a stylus traces a groove — but a proper account of what each alignment parameter actually does to the sound, where the meaningful tradeoffs are, and what tools and methods are worth your time at the serious end of the market.

Why tonearm geometry matters more than most audiophiles think

A pivoting tonearm traces an arc across a record, not a straight radial line. Because of that arc, the cartridge body is never perfectly tangent to the groove — except at one or two specific points on the record surface, depending on the alignment standard you choose. Everywhere else, there is a small angular error called tracking angle error, which generates distortion. The goal of alignment is to distribute that error across the playing surface in the most tolerable way possible.

That's the job of overhang and offset angle together. But there are three other parameters that operate independently and are, in my experience, more often wrong: azimuth, vertical tracking angle (VTA), and stylus rake angle (SRA). Each one does something different to the signal. Get one wrong and you're leaving real resolution on the table, regardless of what you paid for the cartridge or the phono stage.

Incidentally, if you've already sorted your phono stage gain and loading — covered in our DACs and streamers guide and addressed in detail in our dedicated piece on the Rega Planar 3 setup (check price) — come back to geometry next. They compound each other in ways that are hard to unpick if you haven't isolated the variables.

Overhang: the number everyone knows, often set incorrectly

Overhang is the distance by which the stylus tip extends beyond the spindle centre when the tonearm is positioned directly over it. It's measured in millimetres and, combined with the offset angle built into the headshell, it places your two null points — the spots of zero tracking angle error — at specific radii on the record.

The three common alignment standards each define different null-point pairs. Baerwald (also called IEC) places them at 66mm and 120.9mm. Löfgren B places them at 70.3mm and 116.6mm, which biases the correction toward the inner grooves where distortion is worst. Stevenson places one null point very close to the label area and accepts more error in the midband. There is no universally correct answer. I tend toward Löfgren B for modern pressings with programme material close to the lead-out, and Baerwald for older LPs cut with more conservative inner-radius practices.

Setting overhang accurately requires a protractor. There are two categories: arc-based protractors, which you align by tracing an arc through a single reference point, and two-point protractors, which check the cartridge body and stylus position at both null radii simultaneously. For serious work, two-point is the only method I trust. The Feickert Protractor and the Dr. Feickert Adjust+ software (used with a USB microscope) are the reference tools at the top end. For most of us, a well-made printed two-point protractor from the likes of Conrad Hoffman's downloadable templates — calibrated for your specific effective tonearm length — is entirely adequate and costs nothing.

One practical note: headshell slots are rarely uniform in their markings, and the difference between 1mm of overhang error at the cartridge body and zero is audible on dense inner-groove material. Take the time.

Azimuth: the most overlooked parameter in any setup

Azimuth describes the rotational angle of the cartridge on the horizontal plane — whether the stylus sits perfectly vertical in the groove when viewed from the front. When azimuth is off, the two channels of a stereo cartridge generate different output levels and phase relationships from the same groove modulation. The result is a narrowed, slightly smeared stereo image and audible crosstalk between channels.

The conventional advice is to set azimuth visually: look at the cartridge from the front and make sure the stylus looks vertical. This is better than nothing. But it's not sufficient for a serious cartridge, because the generator itself (the coils and magnets inside) may not be perfectly aligned with the stylus body. Visual alignment of the body tells you nothing about the generator geometry.

Proper azimuth setting requires measuring crosstalk. The correct tool is a test record with a dedicated azimuth track — either a signal recorded on only one channel, or the Analogue Productions test tones — and either a voltmeter or, better, a spectrum analyser app on your phone. You're aiming to minimise the signal appearing in the channel that should theoretically be silent. Some people also maximise channel separation as a proxy; the two approaches aren't identical but for most cartridges they converge close enough.

Honestly, this step is where I see the biggest gains in systems that were already considered well set up. A cartridge with 30dB of crosstalk spec that's been properly azimuth-aligned sounds dramatically more precise in its stereo presentation than the same cartridge set by eye to 40dB nominal but with 2° of rotational error in the generator.

VTA and SRA: what they are and why people confuse them

Vertical Tracking Angle (VTA) is the angle of the tonearm tube relative to the record surface. Stylus Rake Angle (SRA) is the angle of the stylus shank — and ultimately the contact line of the stylus on the groove wall — relative to vertical. They are related but not the same thing, and conflating them causes a great deal of confusion.

When the cutting head cut the lacquer that became your record, the cutter stylus was raked at approximately 92° from the groove floor (slightly back from vertical). To replay the groove accurately, your playback stylus should ideally present the same angle. For a modern line-contact or Shibata stylus, that typically means the stylus shank should be somewhere between 91° and 93° from vertical, measured at the contact point.

VTA affects this because raising or lowering the tonearm pivot changes the angle at which the stylus approaches the groove. Most tonearms let you raise the arm pillar — loosening a locking collar and sliding it up or down — to adjust VTA. The relationship between arm height and SRA depends on your specific cartridge geometry, so there is no universal rule like "the arm should be level" or "the back should be slightly raised". Those rules of thumb are shortcuts that may or may not apply to your cartridge.

What you're listening for when dialling VTA is, put simply, tonal balance and resolution. Too low (arm rear elevated) tends toward brightness and hardness in the upper midrange. Too high (arm rear depressed) tends toward warmth and slightly veiled treble. The correct position is where the recording sounds most natural and the top end has both extension and ease simultaneously — not a small ask, but repeatable once you know what to listen for.

Record thickness complicates this further. A 180g pressing sits higher than a standard-weight record, which changes the effective VTA. Some audiophiles adjust for every record. I'll admit this is more effort than I think most systems reward, unless you're running a high-compliance cartridge on a unipivot arm that's genuinely sensitive to the change. For most setups, find a setting that works well on the pressings you play most often and leave it there.

The interaction between parameters — and why order matters

These four parameters are not fully independent. Changing VTA can shift the effective tracking force slightly. Adjusting azimuth on a tonearm that uses the counterweight as the adjustment point (twisting the counterweight to rotate the arm tube) can alter the horizontal balance and therefore the effective anti-skate force. Overhang adjustments shift the stylus forward or back in the groove, which changes the moment arm and therefore the tracking force microscopically.

The correct order of operations is: set overhang and offset first (requires dismounting and remounting the cartridge if you need significant adjustment), then set vertical tracking force using a quality stylus gauge, then set anti-skate, then azimuth, then VTA/SRA last because it's most easily adjusted in situ and you'll be revisiting it as the cartridge beds in.

Anti-skate deserves a brief mention here: almost every tonearm's anti-skate mechanism is a crude approximation. The skating force varies continuously across the record surface and varies again with groove modulation. No fixed anti-skate setting is correct at every point. For a starting position, set it equal to your tracking force in grams and then experiment. Most cartridges are more forgiving of slightly too little anti-skate than too much; excess anti-skate introduces its own form of distortion on loud passages.

Tools worth buying at the serious end

A quality digital stylus gauge is non-negotiable. The Riverstone Audio or Ortofon DS-3 gauges are accurate to 0.01g and cost relatively little. Avoid the cheap acrylic scales — at the price point where you're agonising over VTA, the tracking force error from a bad scale matters.

For azimuth, the Analogue Productions' "Ultimate Analogue Test LP" is available through a handful of Australian distributors and includes dedicated azimuth tracks alongside frequency sweeps and other diagnostic material. It's a better investment than most cables.

For overhang, as mentioned, a well-printed two-point protractor matched to your arm's effective length is adequate. If you're running a statement-level arm like a Graham Phantom or a Kuzma 4Point, the manufacturer usually supplies a dedicated alignment jig — use it in preference to anything generic.

A USB microscope for SRA measurement is, I'll grant, deep into the obsessive end of the hobby. The Dino-Lite range (available through various Australian scientific suppliers) starts at around AU$200 and lets you photograph the stylus in the groove and measure the rake angle directly in software. If you're running a cartridge north of AU$4,000, it's genuinely worthwhile. Below that, careful listening is probably sufficient.

Statement cartridges and the limits of self-adjustment

A note worth making: some reference-grade moving coil cartridges — and I'm thinking of things like the Audio-Technica AT-ART1000, the Ortofon Anna Diamond, or any of the top-line van den Hul builds — have tolerances in their manufacture that make published specs less reliable guides than you'd expect. Each sample is, to some extent, its own animal. The measurement-based approach to azimuth (rather than trusting the nominal crosstalk spec from the datasheet) becomes even more important, not less, as you move up in price.

I'd also say this: if you're in Sydney and running a serious table, the team at Audio Connection in Crows Nest have a setup rig including an oscilloscope-based crosstalk measurement station and they'll do a proper alignment service for a reasonable fee. Having your work checked by a different set of hands is a valuable reality test, particularly if you've been adjusting the same arm for months and your ears have started to normalise whatever you're hearing.

Tonearm geometry doesn't reward the one-time setup and forget approach. It rewards obsession — moderate, methodical obsession. The record collection you've spent years building deserves nothing less.