Topics: Playback Quality

Getting the best sound from your records is a long journey. Making correct choices for your future purchases and also setting up and adjusting the equipment you have now will help avoid damage to your records, and more importantly, give you a degree of detail, tonality and dynamic range that can only be called an epiphany. Many topics need to be addressed, and some jobs can be performed at minimal expense.

Cartridge Alignment.

To get top-quality playback and not damage your records, the ideal setup would have the stylus meeting the groove at a perfect tangent.  If the needle is twisted at an angle to the groove walls, it won’t travel smoothly, won’t read the signal as accurately, and will cause damage to the groove walls. Misaligned cartridges will remove some tones, add new, discordant tones, change tone character, and change some tones to noise.

Linear Tracking Tonearms.

Getting the needle to meet the groove at a perfect tangent at every point across the playing band is only possible with a linear-tracking tonearm.  Many companies have made them, and some work better than others.  But the main conceptual problem with linear tracking is that the force which propels the needle toward the center of the record is imposed on the needle itself, out at the end of the tonearm.  But the point where the linear tracking arm needs to slide is eight or so inches away, where it meets the lateral motion bearing.  The sideways force on the arm eight inches away comes to the linear motion bearing as torque; it wants to make the bearing bind up.  The cooking grill on a campfire ring at a public campsite works exactly this way; the grill has a horizontal arm with a sleeve-knuckle at the end which rides up and down on a vertical post, but the weight of the grill torques the knuckle and makes it bind on the post.  Relieve the weight of the grill and the arm will slide up and down on the post.  With a linear tracking tonearm you could solve this problem by using a screw to drive the arm back and forth, but the distance between the grooves, and therefore the speed at which the arm needs to travel, is not constant.  This is because the mastering engineer changes the feed rate of the cutter head on the lathe used to make the vinyl master: during quiet passages, the groove doesn’t deflect very far to the left and right, and a closer distance between grooves is possible.  But during loud passages, amplitudes are much higher, and the grooves need to be further away from each other to prevent crossover and interference.  By only feeding the lathe at the faster rate when necessary, the total number of minutes that can be recorded onto one side or a record is maximized without sacrificing dynamic range.  But it means that the speed of the tonearm as it moves across the playing band during normal playback will vary from one record to another, and from one point on the same record to another.  The system that allows the tonearm to move across the record needs to be led by the groove itself and allow smooth motion without binding or chatter.  Minimizing or eliminating the tendency of the arm’s lateral tracking bearing to bind up due to tracking forces is the challenge facing makers of linear tracking tonearms, and all of them have succeeded, to some degree.

Swinging tonearms don’t have this problem, but they have a problem of their own, which is that they will always have some amount of angular tracking error.

Minimizing Angular Tracking Error.

Mounting the cartridge on the headshell cannot be done correctly by naked eye alone.  You need an alignment protractor to ensure that the needle lands at the correct distance from the tonearm pivot, and that it sits at a perfect tangent at the two distances known as “null points.”  The mounting distance, null point positions and offset angle are all functions of the record size, or the beginning and ending radii of the playing band.  For this reason, Turntable Tuneup offers custom alignment tools for 7 inch singles, 10 inch EPs and 78 RPM records, 12 inch LPs and 16 inch transcription records.  Playing any of these formats on a turntable that’s set up for a different size record will result in unacceptable levels of angular tracking error, poor playback quality and possible record damage.

Alignment geometry is determined by the size of the record, specifically, the radii of the beginning and ending of the playing band; and also the effective length of the tonearm. The narrower the playing band, the more accurate the alignment can be.

Along the playing band range, there will be two “null points” where the cartridge alignment will be perfect, and along the rest of the playing band, the angular error will go up as the distance from the null points increases.

 

ErrorChart12

In the middle portion of the radius, between the two null points, the error is in the opposite direction of the error nearer the inside and outside of the playing band.  However, posing the numbers as positive instead of negative makes the above chart more clear.

Looking at the chart, the first question that comes to mind is, why is the error so much higher in the opening of the playing band than the maximum error between the null points, or the error at the inside of the playing band?  Why not set the alignment model with a definition of the beginning of the playing band being further out from where it actually begins, at a radius of 5.75 inches, in order to lower the angular error at 5.75 inches?  This would even things out more, and reduce the maximum error at the beginning of the band.

The answer is that if you did change the mathematical model to make the three maximum errors more equal to each other, the average error across the entire playing band would go up by quite a bit.  Tweaking the numbers to make the angular errors at the beginning and end of the playing band roughly equal would bring the average error up from 0.7725 degrees to 0.8942 degrees.  The maximum error in the middle of the playing band would come up from 1.127 degrees to 1.5209 degrees, and the error at the start of the playing band would only come down from 1.9 degrees to 1.09 degrees.  Bringing down the error at the beginning of the playing band isn’t worth the sacrifice of higher playing errors everywhere else on the record.

The Lofgren-B model goes the other direction.  Instead of seeking to lower the three maximum errors, or get them closer together in severity at the cost of a greater average error, Lofgren-B results in maximum errors that are greater in difference from each other (low in the middle, higher in the beginning and end of the playing band) and a lower average error when compared with the Baerwald geometry outcomes.

Tracking Errors.

The needle is supposed to meet the groove at a perfect tangent.  When it does, the needle meets the groove wall with the highest amount of contact area.  This spreads the tracking force and the forces which move the needle back and forth across a wider contact patch, reducing contact pressure and minimizing groove damage.  Permanent groove damage happens through a process called ablation; when the surface of the groove wall is compressed under pressure and then released, small bits of the wall blast away, much like road pavement on a hot summer day.  It heats up and wants to expand outward but there’s no room for it to move into.  It can’t absorb the pressure internally, so it deforms and breaks up outward to above the surface instead, resulting in a pothole and a small pile of concrete or asphalt chunks lying on the road surface.

The Skating Force.

Skating forces tend to propel the tonearm quickly to the inside of the record’s playing band.  If you have a record with one blank side, try playing it.  The needle will fly straight in to the middle.  When the record is being played, the needle is held in place by the cartridge body and tonearm while the groove is sliding past underneath it.  The groove walls make the needle travel left and right, which means that the needle is being propelled in one direction or the other by the changing position of the groove wall on one side or the other.  When it’s moving to the right, it’s being pushed from the left, and when it’s moving to the left, it’s being pushed from the right.  The total amount of left and right motion comes out to a zero sum, in one sense.   However, the groove wall on the outside is moving faster than the groove wall on the inside, because the radius is slightly higher.  This is why the undulating sine wave expressed in the groove imposes more net force moving the needle toward the inside than toward the outside.  It’s exactly like the Coriolis Effect.  A sink full of water that is allowed to drain from the bottom will form a spinning whirlpool, and the direction it rotates in depends on whether you’re on the planet’s northern or southern hemisphere.  What causes the rotation of the water is the fact that the side of the sink closer to the planet’s nearest pole is spinning faster than the side of the sink closer to the equator.

Anti-Skate Mechanisms.

Skating force impedes proper signal tracing, causes a tendency to skip grooves toward the inside, and causes an imbalance in signal strangth between the left and right channels.  Anti-skate mechanisms are used to counteract the skating forces and reduce these effects; there are a few different designs.

The degree of skating force has several variables: distance of the needle from the spindle center; angular error of the needle (which not only varies across the band, but also switches direction); the shape of the needle; cartridge compliance; tracking force; composition of the vinyl material; signal amplitude; and others.  The degree of acceleration depends on the mass of the tonearm, and the tendency to skip can depend on the depth of the groove.  What this means is that you’re never going to get skating forces down to zero all the way across; you can only get them closer to zero.

Friction-Driven Anti-Skate Mechanisms.

This type is hidden below the turntable plinth, and controlled by a knob near the base of the tonearm.  The dial may be marked with number from 0 to 4 (or some other number); or it may have symbols for spherical and elliptical diamond needles.  Turning the dial up will increase the friction force imposed on the tonearm’s lateral motion.  This type is least preferred, first because it complicates the tonearm design with a mechanical linkage from the tonearm hub and bearing down to the hidden friction wheel, and second, because it uses solid mechanical friction which will impose chatter; it makes the lateral movement much less fluid.  It’s a source of vibration in the tonearm shaft, which will cause signal interference at the cartridge pickup.  The best approach with this system is to leave it at zero and only begin turning the dial upward if the turntable displays a tendency to skip forward that can’t be fixed with proper cartridge alignment and tracking force.  You can also adjust its setting and try to detect any change in signal balance, the clarity of single high notes (like a horn or a bell).

Gravity-Driven Anti-Skate Mechanisms.

While friction-drive anti-skates are most often found in factory-installed tonearms, gravity-driven anti-skate mechanisms are most common on aftermarket arms.  All of its parts are above the plinth, which simplifies installation; however, it has small, removable and easily-lost parts, requires consumer setup, and is therefore less mass-market consumer-ready.

Gravity-driven systems use a small weight (usually about 5 grams) suspended by a monofilament string (like a lightweight fishing line) which goes around one or more pulleys and finally attaches to a notched post which extends from the tonearm’s moving hub.  The notches in the post are at different distances from the tonearm’s pivot point; by attaching the string to notches further out or closer in, the lateral torque (which counteracts the skating force) upon the tonearm is increased or reduced.  Because the gravity system imposes motive force upon the tonearm instead of friction, it’s possible to set the anti-skate so high that it will cause backward skipping.  One way to tune such a system is to find the point where it starts to cause back-skipping, and the point where it fails to prevent forward-skipping, then set the position of the cord on the shaft halfway between those two points.

Fluid-Based Motion Damping Systems.

Many aftermarket tonearms also have a motion damping/anti-skate system which use a thick silicone oil in an arc-shaped trough mounted close to the tonearm base, and a vertical paddle attached to the tonearm wand which extends downward into the trough, beneath the surface of the silicone fluid bath.  As the tonearm moves laterally across the playing band of the record, the paddle has to displace the thick fluid as it rides through the trough, and the force required to do so depends on the width of the paddle, its depth beneath the surface of the oil bath, the viscosity of the silicone fluid, and the speed of the paddle’s motion.  At very low speeds, the silicone will absorb chatter in the arm’s motion but allow the arm wand to travel smoothly toward the end of the playing band.  More rapid motions and accelerations, such as a sudden skip of the needle to an adjacent groove, are inhibited with proper fluid damping.  Turntable Tuneup offers three different thicknesses of silicone fluid for use in motion damping troughs; you can mix them together to achieve custom thicknesses; they will not separate from or react with each other.

Vibration Damping.

Your turntable is a mechanical playback system.  The phonograph cartridge transforms vibrations in the stylus and cantilever into an electrical signal which goes to the amplifier.  To read the cleanest signal possible, vibrations in the turntable itself, and particularly in the tonearm, should be held to a minimum.  Vibrations can be transmitted from the floor and cabinet, from the sound waves in the air, or from noise in the drive motor.  There are many steps you can take to dampen these vibrations and improve the quality of signal playback.

Every material vibrates.  However, different materials vibrate at different natural frequencies.  Some materials tend to absorb vibrations.  These tend to be elastic materials like rubber, loose materials like sand, or soft metals such as lead.  By layering materials that vibrate at different frequencies, the transmission of vibrations from one material to another can be minimized.  You can also minimize transmission of vibrations by resting the turntable on a tiny surface area, through the use of tiptoe mounts.

You can use a thick slab of stone underneath the turntable base, rubber mounting feet, rubber or neoprene pads between the stone slab and the shelf to dampen vibrations from underneath.  There are also pointed tiptoe mounts, vibration-damping mounting feet, and bags or boxes full of sand.

On the turntable itself, it may be possible to mount the tonearm with a sheet of lead in between the tonearm base and the plinth, or to mount the cartridge with a lead shim between the cartridge and headshell.  Using lead must be done with great care, for it is a dangerous neurotoxin.  All scraps and shavings must be collected and disposed of (recycled with alkaline batteries), and small pieces must be kept away from children, who might ingest it.  Lead melts at relatively low temperatures and can easily be cast into shapes; however it will emit dangerous fumes (containing arsenic, among other things) when melted, so this job must be done outdoors or in a very well ventilated area.  Substantial research and preparation must be performed before embarking on any project involving toxic materials or dangerous temperatures.  The benefit of lead is that it’s particularly heavy, and has no crystalline structure.  This makes it particularly soft and malleable, and resistant to the transmission of vibrations.  Another metal which shares these properties, but costs substantially more, is pure gold (but not gold alloys).  Lead sheet can be obtained online; just google “lead sheet.”  Lead shot can be purchased from any gun shop which sells reloading supplies, or muzzle-loading gear.

 Choosing a Better Tonearm.

To minimize angular error, longer tonearms are best.

Tracking errors are more significant with shorter tonearms.
This chart shows what happens when you use shorter or longer tonearms with your 12 inch records. Longer tonearms produce significantly less error.

This chart shows what happens when you use shorter or longer tonearms with your 12 inch records. Longer tonearms produce significantly less error.

P-Mount vs Half-Inch Mount Headshells and Cartridges.

Tonearms with p-mount cartridge fitments should be avoided, as the selection of cartridges with p-mount bodies is limited, and usually have low-quality needles.  Also, there is no way to adjust the cartridge alignment with p-mount systems.  Tonearms with H-4 headshells are a very good idea, as new headshells are commonly available.  Having interchangeable headshells allows you to run multiple setups, for different size records, or special cartridges for 78 RPM records or mono pressings.  You also want to look for a tonearm that has an adjustable vertical tracking angle, meaning you can raise and lower the tonearm base.  This will allow you to mount the tonearm on any turntable and compensate for variations in platter height, platter pad thickness, cartridge height, and even record thickness.

Platter Speed Stability.

Think of your platter as a perpetual-motion machine.  We all know that perpetual motion isn’t real; there are always forces which conspire to slow an object down.  Still, we do our best to minimize these forces, such as friction.  Also, we want to lend the object as much kinetic energy as possible, to minimize the effect of friction upon its speed.  With a spinning platter, instead of mass, we look at its moment of rotational inertia.  The platter is a flywheel.  To give it maximum rotational inertia, we want to give it as much mass as is practicable, and to locate that mass as close to the outer rim as possible.  Mass at the outer rim has a greater effect on rotational inertia than mass at the center, because the tangential speed of mass at the outside is far greater.  With greater rotational inertia, the same friction force will have a lesser effect on the platter’s speed.

Reducing friction in the platter is a matter of servicing the platter bearing.  Better turntables will have large-format bearings than can be re-oiled.  That bearing should have no play and no lash, and also be able to withstand substantial axial and radial loads.

Phono Cartridges and Needles.

The most important consideration to go into your decision on which cartridge to run on your turntable is that you shouldn’t run cartridges with cheap needles.  Conical or spherical diamond needles meet the groove on a very small surface area, which means that the pressure along that area between the needle and the groove is far greater than it needs to be.  The needle doesn’t just rest on the groove; the walls of the groove move the needle back and forth, and up and down.  If the force required to move the needle around is concentrated in a small area, then the vinyl material becomes much more stressed and compressed, raising the likelihood and seriousness of damage to the record groove.  Pops and ticks and scratching on a record surface aren’t caused by friction or drag; it’s caused by a process called ablation.

Think of a road surface on a very hot day in direct sunlight.  The heat causes the concrete to expand, but it’s a big surface and there’s no room for the material to travel laterally.  Instead, pressure ridges build upwards and large chunks of concrete get blasted off of the underlayment by the pressure of expansion and of tires transferring weight loads on and off of them repeatedly.  Small bits of vinyl get blasted away from the walls of the record groove in a similar fashion when the record needle passes along it at high speeds and pressures.

An elliptical needle will fit inside the groove with a much larger contact area.  This means that, with the same tracking force (usually 1.5 grams), the pressure between the needle and the groove wall is greatly reduced.  Aligning the cartridge to minimize angular tracking error across the entire playing band is also very important for maximizing the contact area.
Preamplifiers and Power Amps.
Cables.
Speakers.
The Room.

Playing Monophonic Records.

Record collectors don’t need to be told that there’s good music that was made in decades prior to the current one.  We also know that good music doesn’t age; it is timeless.  Recordings made long ago should not be consigned to the dust bin just because they didn’t have an accompanying Video on MTV, weren’t produced with Auto-Tune, or, because they weren’t recorded in Stereo.  The LP format was invented in 1948 by Columbia; the process of recording Stereo signals (both Left and Right channels simultaneously in the same groove) onto Vinyl records came along ten years later, in 1958.  Stereo grooves have two signals; both waveforms modulate at a 45 degree angle from the horizontal surface of the record and at a 90 degree angle to each other.  Signals with higher amplitudes have to be cut more deeply into the record surface.  When producing the master disk off of a tape, this requires a cutter head with substantial power, to move the cutter needle further down into the acetate and remove more material.  Early stereo cutter heads didn’t have much power compared to units produced in the late 1960s, and stereo records didn’t have very much dynamic range compared to the audiophile records being produced today.  Mono records, on the other hand, have a single groove that modulates to the left and right.  The cutter head moved the needle back and forth as the master disk spun beneath it, but the depth of the cut never changed.  For this reason, cutter heads didn’t need to use a lot of power to make a recording with a lot of dynamic range.

Record producers were accustomed to producing records with the Mono version as the Reference Original; the Stereo version was produced as an afterthought, up through the mid-1960s at least.  Many record collectors seek out mono versions of Rock LPs from the 1960s; it is widely believed that with Beatles records, the best sounding copies are the British Mono pressings, at least up through Rubber Soul.  These Mono versions have recently been reissued.  I have some original Mono Bob Dylan records that I think sound fantastic.

All radio broadcasts were in Mono up until 1961 when FM Stereo broadcasts began.  FM Radio receivers made up until that time would need a decoder to create a stereo signal; Mono remained the broadcast standard for AM radio and Television until the advent of Cable TV.  For this reason, record producers needed to produce Mono versions of all their recordings until the last couple of decades.

So, if you run across Mono records, what to do?  The most common answer is that with a stereo audio system, the preamp should be set to Mono, or A+B, so that the two signals coming from your stereo phono cartridge are combined in the preamp and played the same on both speakers.  If you play a Mono record on a stereo system, it’s likely for an incomplete signal to be created on each of the two circuits.  The distortion will be subtle but real.  Mono cartridges are made for collectors of Mono LPs and 78 RPM records, but making the adjustment on the preamp is good enough for most stereo systems.

Playing “Re-Channeled for Stereo” Recordings.

When Stereo came into vogue, many older recordings were reissued for the new format.  One recording I have is of Hank Williams Greatest Hist on the MGM label.  The original recordings were in Mono, but the new pressings were prominently labeled, “Re-Channeled for Stereo.”  What they did was put the original mono signal on the left channel, and then took that signal, delayed it slightly, and also re-equalized it to emphasize the higher frequencies, and recorded that version onto the right channel.  The delay gave some amount of three-dimensionality, and the different equalization made it sound like the bass notes were coming from the left and the treble notes were coming more from the right.  Traditionally on a stage, the upright bass player would be on the left side of the stage and the guitar players on the right; re-creating this effect was the purpose of emphasizing higher notes on the right channel of re-channeled recordings.

However, if you listen to the right channel of these records only, it sounds off.  The signal has been messed with and will never be as clean and pure as the mono original.  So, when you run across re-channeled recordings, the thing to do is set your preamp to play the Left (A) channel alone, on both speakers, or if that option is not available, leave the system in stereo mode and push the balance all the way to the left, giving the right speaker no volume at all.  Of course, if you can find the original Polydor Mono Hank Williams records, that’s even better yet.