HOW TO GUIDE: Spin Doctoring
Analogue addict Neville Roberts explains how to inexpensively set-up and optimise your turntable for the best possible sound…
One of the joys – and the curses – of vinyl is that turntables need careful setting up. If you take the time to do this properly, you can wring far more performance out of your record player than you thought possible. The other side of this is that if you don’t set your deck up correctly, it’s going to sound much worse than it should.
The reason for this is that LP records – unlike other music sources – are very much physical storage media. The music is stored as complex undulations of a spiral groove, or to be precise, two spiral grooves – one on each side of a record! Together, the stylus and cartridge form a delicate measuring instrument to measure the deviations of both walls of the groove from a mean position and convert this to two electrical signals. The tonearm’s job is to support this measuring instrument and help it define the mean position in the groove.
As well as supporting the record being played, the turntable must also rotate the LP at precisely the correct speed. Therefore, a record deck must be correctly set up to faithfully reproduce the recordings stored on a vinyl disk. Fortunately, this is not as difficult as you might think, and there are a number of inexpensive tools available to assist in the process.
Turntables are effectively high precision vibration measuring machines, and so it’s hardly surprising that they’re sensitive to vibration. For this reason, the most important and basic thing you can do is to place it away from your loudspeakers and/or floor. The last thing they want is extra vibration coming into them when you pump up the volume on your amplifier. So I can’t understate the importance of correct placement on a good system support or wall shelf, one that’s designed not to transmit vibrations up into the deck’s plinth.
When you’ve got your deck correctly positioned in the room, then you next need to make it dead level. The stylus is held in the groove entirely by gravitational force, so any imbalance will mean that the downward force on the stylus will not be exactly perpendicular to the record, which is a potential source of distortion. Fortunately, most turntables are fitted with adjustable feet and levelling is easily accomplished with the use of a spirit level. It’s important to place the spirit level on the turntable platter, rather than on the body of the turntable itself.
Some record decks allow for the adjustment of the turntable speed. The easiest way to set this correctly is to use one of the many stroboscopic discs that are available. Simply place the strobe disc over the spindle, view the appropriate markings under a mains-powered light source, which in the UK will flicker at 50Hz, and adjust the speed until the marks are stationary. This should be carried out while actually playing a record so that any effect on the motor speed as a result of stylus drag will be taken into account.
Right, here’s where it gets a little more involved. Although many people will have purchased a phono cartridge prefitted into their record deck, there may come a time when you wish to consider a cartridge upgrade. So, at this point, I’ll mention the importance of matching a cartridge to the tonearm.
One of the physical properties of an arm is the effective mass, which is the mass of the arm as seen by the cartridge. Cartridges have a property called compliance, which, in simple terms, is the ability of the stylus to ‘comply’ with the groove and is measured in terms of the distance the stylus is displaced for a given sideways force applied (either X μm/mN, X mm/N, X x 10-6 cm/dyne or simply X cu for Compliance Unit – it is all the same value of X!).
Neither high or low compliance is necessarily good or bad, but generally speaking, a low compliance cartridge matches well with a high effective mass arm, and vice versa. It is this combination of effective mass and compliance that has an impact on the tracking ability and also results in a particular resonant frequency of the arm/cartridge combination.
Every combination of arm and cartridge has a natural resonant frequency, which should be about 10Hz. If it’s much higher than this, it will intrude into the low frequencies of the recording, such as low organ notes. If much lower, the harmonics of this resonant frequency could intrude into the audible spectrum. This is why cartridge manufacturers specify the compliance of their cartridges and why tonearm manufacturers recommend low, medium, or high compliance cartridges.
It’s not an exact science, but compliance is certainly a consideration when choosing a cartridge. As a general rule, a compliance of >20cu is high, <10cu is low, and anything in between is medium compliance. In terms of effective arm mass, 5g is low, 11g is about average and 17g is high. For example, the classic SME Series III tonearm (effective mass 5g) is ideal for high compliance moving magnets, whereas, say, a Zeta (effective mass 16g) is best for low compliance moving coils. Everyone’s benchmark, the Rega RB300 (and its derivatives, all around 11g effective mass) works best with both medium compliance moving magnet and moving coil cartridges.
After carefully fitting your cartridge to the headshell with the stylus guard on, and connecting up the four wires from the tonearm, the next step is to carry out an initial setting-up of the tracking force. At this stage, it only needs to be set approximately to allow other adjustments to be made, which will have an effect on the final tracking force. This is usually accomplished by setting both the tracking force adjustment and the bias adjustment on the tonearm to zero, and then moving the counterbalance weight so that the arm is perfectly horizontal. Make sure, of course, that you have removed the stylus guard before you do this, as it will affect the weight of the cartridge. Now set the tracking force adjustment on the tonearm to the value recommended by the cartridge manufacturer. This is good enough to enable the other adjustments to be made before the tracking is set more accurately later.
Now you’re ready to align the cartridge, essential for getting your cartridge to perform at its best across the whole playing surface of the record. This involves setting the azimuth or vertical alignment, the overhang and the angle of the cartridge in the headshell. Setting azimuth simply involves ensuring that the stylus is perpendicular to the record when the cartridge is viewed from the front. Placing a small mirror on the platter and gently lowering the stylus onto it will highlight any misalignment. If your headshell does not have an adjustment for this, fitting a small paper shim between the cartridge and the headshell will allow for any slight adjustment, should this be required.
The overhang and the angle of the cartridge in the headshell are set using an alignment protractor, sliding the cartridge forwards or backwards and twisting it in the headshell so it lines up with the calibration marks on the gauge. The overhang is the difference between the distance of the tonearm pivot from the centre spindle (which is fixed for a given tonearm) and the distance of the tonearm pivot to the stylus (which is known as the effective length).
This is important because although the groove of the record is cut using a cutter that is tracked straight across the radius of the record, it is played back with a cartridge that tracks in an arc across the record since the tonearm is pivoted at one end. The calculations required to work out the optimum positioning of the cartridge are therefore not straightforward. Fortunately, there are a number of alignment protractors out there that make the job easy (including some free ones that you can download from the internet, such as The Vinyl Engine, once you have registered on the forum). If you use a downloaded protractor, ensure that you print the PDF ‘Actual size’ instead of ‘Shrink oversized pages’ from the print options of your PDF reader, otherwise the scale of the protractors will be wrong!
There are several different cartridge alignment calculation models available, each with their own particular strengths, but all are aimed at minimising tracking errors and distortion at different points across the record. Although the Baerwald (or Löfgren A) method seems the most popular, you will achieve very satisfactory results with any of the models, provided that you follow the instructions on the gauge. Needless to say, vinyl geeks disagree about which is best, but most normal people will lose the will to live hearing them discuss the subject!
Now that the cartridge is exactly where it should be in the headshell, it’s time to set the tracking force accurately. The markings on a tonearm are notoriously unreliable for setting the tracking force, so the only way to do this properly is to use a stylus balance. Again, there are a number of balances on the market, but I prefer modern digital gauges as they are very accurate and easy to use.
The cartridge manufacturer will usually specify a range for the tracking force and you should set the force to a value within that range – but what value should you use? A test record is very useful for deciding this, but not essential. These records usually have a tracking ability test consisting of a tone recorded at increasing amplitudes, which can assist in setting the tracking weight and bias. Too low a tracking weight will result in poor tracking and do more harm to your records than erring on the high side, but don’t overdo it!
Tracking ability isn’t everything and will very much depend on your tonearm and cartridge combination. At very high levels of the test tone, your cartridge will start to mistrack, which is indicated by a buzzing sound. If you don’t have a test disc, just get one of your favourite records and play a really highly modulated section, and listen for any sign of distortion from mistracking. If you’re still not sure, set the tracking force to just under the cartridge maker’s recommended maximum setting.
The bias (or anti-skating) adjustment exerts a small outward force to the tonearm to counteract the tendency of the arm to swing towards the centre of a record when playing. Usually, the tonearm’s bias adjuster has markings on it, and you set the bias to the mark corresponding to the tracking force applied. However, if you have a test record, you can set the bias more accurately by using a tracking ability test: when the cartridge starts to mistrack, there should be the same level of buzzing on both channels. Some people try and set the bias by using a smooth disc ‘record’ with no groove and adjusting the bias so that the cartridge does not move in or out when the disc is rotated. This does not work in practice as the forces on the stylus are different when it is actually sitting in a groove. What’s more, the tip of the stylus will tend to cut a fine groove in the vinyl after the first revolution, rendering the disc unusable!
The last adjustment to make is the tonearm height to set the Vertical Tracking Angle (VTA), which sets the Stylus Rake Angle (SRA) of the cartridge. The VTA is the angle of the cantilever to the record surface (usually around 20 degrees), which in itself is not that critical. However, the SRA, which is the angle of the stylus in the groove, is very critical and has a major impact on sound quality. The closer the SRA can be adjusted to match that of the original cutter head, the more information the stylus will retrieve from the groove. The VTA will vary depending on the tracking weight, so it is essential to set this before attempting to adjust the VTA. This is adjusted by altering the height of the arm and the correct point is best determined by ear.
A good starting point is to set the arm height so that the arm is parallel to the record when it is playing and to choose a well-known record with some bass and either a solo violin or a female vocalist. If the arm is too high (VTA too great), the sound will be harsh and thin with poor imaging. If set too low, the sound will be dull with ‘boomy’ bass, lack detail and again have poor imaging. The correct point is unmistakable – the instruments and vocals snap into focus and everything sounds clear.
DO IT CLEAN
Now that everything is perfectly set up, it’s important to keep everything as clean as possible. If you’re lucky enough to own a proper record cleaning machine, then wet clean your record at least once – and then when dry, put it back into a new polythene inner sleeve so the old paper one doesn’t scratch the disc and/or recontaminate it with tiny particles of dirt. This goes for brand new LPs too if possible, because they come with sound-degrading ‘mould release agent’ in the groove that’s effectively a by-product of the manufacturing stage. Wet cleaning removes this, and will also likely make the disc sound cleaner and more dynamic. Once you’ve got your LP records super-clean, you then need to keep them that way. As such, you’ll need to clean off any dust before every playing. There are many cloths and brushes available, but my personal preference is a carbon fibre brush.
It’s amazing how quickly fluff can accumulate around the stylus from airborne dust after only playing a couple of sides – even with scrupulously clean records. A carbon-fibre or fine hair stylus brush can be used, and the way to clean a stylus is to gently brush from the rear of the cartridge forwards towards the front. I personally like to use a stylus cleaning putty or cleaning substance where the stylus is gently lowered into the medium to remove the dirt.
The final things to mention are the turntable main bearing and belt (if you’re using a belt drive deck). Many bearings require some form of lubrication and they will also require occasional cleaning and an annual re-lube. A special high-performance oil of the correct viscosity for your bearing should be used, and there are some excellent oils specifically blended for this purpose available from your turntable manufacturer or audio accessory suppliers. As modern bearings are high tolerance, a lint-free piece of cloth should be used to avoid any risk of leaving debris in the central bearing or around the spindle. Some bearings have a small ball bearing inside, so do be careful if you plan to turn your deck upside down to clean it!
Belt drive turntable owners should periodically clean their belts with a 50/50 mixture of isopropyl alcohol and distilled water – what we used to call “tape head cleaning fluid”, back in the day. Every six months or so, take the belt off and give both sides a wipe with this to remove contaminants, and also clean all the surfaces that the belt touches, like the outer circumference of the inner platter for example. If the belt feels even slightly loose, then get a new one.
If you work through the above steps in a calm, considered and methodical manner, you’ll end up with a very enjoyable sounding turntable – regardless of how expensive it is. The other bonus is lower wear and tear to your precious vinyl collection – so what’s not to like? It’s never a bad time to clean up your vinyl act!
A Chartered Scientist, Chartered Engineer, Chartered Physicist and a Fellow of the British Institution of Engineering and Technology, Neville has worked as a Director of the British National Health Service, for the Ministry of Defence and in private industry. He’s a lifelong audio enthusiast and regular contributor to British hi-fi magazines, with a passion for valves and vinyl.
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