How to set up a turntable as an integrator
In a previous article, Stephen Dawson looked at what was required in a turntable for decent playback. In this article, he looks at how to properly set up a turntable.
Properly setting up a turntable isn’t just about producing good quality sound, it’s also vital for preserving the most delicate of music media: the vinyl records themselves. It’s a skill that has dwindled in the decades since record-playing was the main method of music reproduction.
The music on a vinyl record is held in a single groove which spirals from the outside towards the centre. This groove wobbles side to side and (with stereo records) up and down, moving the stylus of a turntable. The cartridge converts this movement into an electrical signal which the rest of your system amplifies.
Sounds simple enough but remember: the stylus is diamond and the LP is vinyl. The groove is wobbling rather violently in places. Unless the turntable is set up properly, the stylus will inflict a lot of damage on the record and incidentally sound pretty poor.
Setting up is not rocket science but can be fiddly. And, as always, the internet is a source of both useful and thoroughly misleading information.
Does the turntable need to be set up at all?
Recognising some of these difficulties, several turntable manufacturers produce what might be termed ‘plug-and-play’ units. Although some require just a little more work than that.
Generally, these provide little in the way of adjustment, with everything like tracking weight pre-set. The cheaper models use a spring-loaded tonearm to provide the correct tracking weight and usually have a low-cost magnetic cartridge (variations of the Audio-Technica AT3600 or AT3600L are often used with these. This cartridge even appears – with the branding removed – in models from some relatively high-end brands). The cartridge is pre-installed. Turntable assembly at most consists of placing the platter over the spindle and placing the rubber belt, then plugging things in.
Higher-level ‘plug-and-play’ models from such companies as Rega and Pro-Ject use “proper” tonearms with counterweights to balance the arms. But the weight isn’t easily adjustable and provides the correct tracking weight only with the supplied cartridge. These typically have a fixed, pre-set anti-skating bias.
But here we’re concerned with the next level up in turntables. Setting up the rotating elements of the turntable is usually simple, and just a matter of following the instructions. But for proper playback, the tonearm must be adjusted correctly for the stylus to do its work in accurately tracing the groove and thus avoiding damage to the record while providing excellent sound quality.
All tonearms in this category provide three settings, and some add one or two more. The settings are:
- Tracking angle and overhang
- Tracking force
- In some cases, vertical tracking angle
- In some cases, azimuth
The first three are vital, the fourth is important and the last two… well, we’ll get to them.
Stylus overhang and tracking angle
An LP is made by the manufacturer cutting the groove into a master, which is then used to create a mould to stamp vinyl blanks, turning them into records. The original groove is cut using a tool that is driven in a straight line from the edge of the disk towards the centre while the disk rotates. The tip of the tool vibrates according to the signal, encoding the sound into the groove.
The important point here is that for perfect playback, the cartridge/stylus combination would also somehow be driven in a straight line. So-called linear turntables do exist, but they have their own problems. The vast majority of turntables, both old and new, use a pivoted arm. It’s secured at the plinth, swinging freely on low-friction bearings. So rather than following a straight line, the stylus describes a gentle arc as it is drawn across the surface of the record.
For reasons of geometry, this means that most of the time the stylus is at a slight angle to the perfect tangent that would be preferred. To minimise this error, the cartridge must be positioned so that at two points in its progress across the record surface the stylus is exactly at the tangent. Correctly set up, this keeps the maximum error to the minimum possible.
To complicate matters, the tracking angle error matters more the closer the stylus is to the centre of the record (it has to do with the linear speed of the track under the stylus). So, over the years various experts have weighed in on where those two exact points of tangent should be – they’re called the null points. Generally, they are around 66mm and 120mm from the centre of the spindle.
To achieve this your cartridge must be set to the correct angle in the tonearm headshell, and to the correct “overhang”. Overhang refers to the fact that if you lift the tonearm and move it in so that the stylus is in line with the centre spindle (you can’t do this with all turntables due to limited arm movement), it will actually be something like 15 to 20mm beyond the spindle, not directly over it.
Setting overhang directly is very difficult, even if your tonearm will move that far. My Thorens TD 1600 want it set to an impossibly precise 17.8mm.
But it works out that if you set the cartridge in the headshell so that it is exactly tangent at the two null points, the overhand will also be set correctly.
The correct cartridge angle can be using a tracking angle protractor (the one I use has them at 66.04mm and 20.99mm). The protractor isn’t that transparent plastic semicircular thing you may recall from school. It’s a rectangle around 150mm in length with a hole at one end, often made of cardboard.
The hole goes over the turntable spindle. Marked on it are two grids, with dots indicating the position of the stylus at the chosen null points. You carefully lower the tonearm and place the stylus in turn at each of those two points and adjust the cartridge until it is parallel to the marked grid lines at each spot. You do that by twisting the cartridge angle within the headshell and moving it backwards and forwards. Then you can tighten the mounting screws.
This is a fiddly process, made more difficult by the many cartridges with elaborate casings which aren’t easy to align visually. When done, though, the angle of the cartridge within the headshell will be correct, as will be the overhang.
Alignment protractors are available for a few dollars at most quality turntable retailers (or you can download several from vinylengine.com). If you do that, be very careful with your printer settings to make sure the print isn’t “scaled” to a different size. And then measure the distances carefully afterwards, just to make sure. Unless you have a particular preference, it’s generally best to go for the Baerwald protractor, which is the first one, under the heading “Stupid Protractors”. Some of the other protractors can help with unusual arms.
Some turntables don’t have slots to adjust the cartridge, but fixed holes on the headshell. They may or may not offer an arm-length adjustment at the pivot end. They are likely designed for cartridges of a particular type. You should follow the turntable maker’s recommendations.
Different cartridges work most effectively at different down-force settings. Back in the 1970s, companies such as Shure led the way to lighter forces – some of theirs were said to perform well at just three-quarters of a gram (I was using turntables in those days but couldn’t afford those high-end cartridges).
These days, settings of 1.5g to 3.5g are more the norm. Whatever cartridge you have, you should set it to the manufacturer’s recommendation. If a range is specified, try the mid-point to start.
To set the tracking force, first install and align the cartridge. Changing the position of the cartridge may change the tracking weight. Then set the anti-skating to zero and remove any stylus guard. Now, without a record on the turntable, carefully move the tonearm out so that the stylus is above the turntable mat and lower the queuing level. Hold the arm up so the stylus remains clear of the mat.
Now, rotate the tonearm counterweight so that the arm is perfectly balanced. That is, the arm stays horizontal with the stylus hovering just slightly above the turntable mat. When you’ve achieved that state, the arm is set for a downforce of zero grams.
The counterweight will typically have a freely spinning calibration ring marked in grams. Rotate this – but not the counterweight – so that it reads zero. Holding the arm still, turn the counterweight slowly so that it moves in towards the pivot. When the calibration ring reads the selected tracking weight, you’re there. Put the arm back in the rest and put the queuing lever back up. A small number of tonearms use a different system, perhaps involving a simple dial for setting the weight. You’ll need to follow its instructions.
If you’re setting up tonearms professionally, or don’t fully trust your turntable’s calibrations, you may wish to invest in a turntable tracking force scale.
The geometry of turntables with pivoted arms causes a surprising and unexpected force on the tonearm, called skating. This is a force that pushes the stylus towards the centre of the record. It can lead to increased wear in the inner side of the groove and distortion.
Anti-skating mechanisms apply a force that pushes the arm gently in the other direction, towards the edge of the record. The amount required to perfectly match the force varies on a range of things, such as the degree of modulation of the groove, the shape of the stylus used and even the formulation of the vinyl. Plus, most importantly, the amount of tracking force. Most of those aren’t known and some vary from moment to moment, but the tracking force is known.
The anti-skating mechanism can use a spring or a magnet or a weight on a string. In many cases, there’s a control dial with markings. This should be set to match the tracking force. The turntable instructions should provide advice on the settings for other systems. But if they don’t (such as my Thorens TD 1600 turntable), you may need to experiment. If there is insufficient anti-skating, you’ll find when you start playing a record, the stylus may jump a few seconds into the start of the song. If this happens repeatedly, increase the anti-skating.
Likewise, if the stylus, carefully placed in the lead-in section of the record, tends to jump backwards, perhaps off the record entirely, then reduce the anti-skating.
Vertical angle and azimuth
Some turntable tonearms allow you to adjust the vertical stylus angle, and some allow you to adjust the “azimuth”. The latter is simply whether the cartridge, looked at from the front, is perfectly vertical, not leaning to the left or right. In general, there’s no need to intervene unless it’s obviously off.
Vertical tracking angle is the angle, looked at from the side, that the stylus sits at when playing a record. This is sometimes specified, and if so, the figure will be 25 or so degrees.
There is a very wide range of opinions on this. At one extreme, the founder of the Rega brand of turntables says that an adjustment for this isn’t necessary. He argues that the angle of the cutting device was never standardised and varied over a wide range, so trying to replicate this is pointless.
In the middle, it seems sensible to adjust the height of a tonearm – if it has such an adjustment – so that it remains horizontal with different cartridges of different heights.
At the other extreme, some audiophiles swear that subtle tweaks to the angle can change how things sound. Some use test records and equipment to tweak this and azimuth to minimise measured distortion.
Of course, LPs come in a range of thicknesses, which changes the angle. I’m unsure whether they adjust on a record-by-record basis.
It’s all about the sound and your precious vinyl
These adjustments can be fiddly, but unless you’ve got a factory-fitted cartridge they are well worth doing to ensure that the thin wobbly groove in the spinning vinyl both delivers the most accurate signal and is spared from the harm that will degrade further enjoyment.