Building a tone arm

How often do you read headlines like: 'Build your own high-end turntable', 'Build your own high-end DA converter' or 'Build your own high end loudspeaker system'. 

I never trust the promises of the authors of those articles and of most hobbyists on the world wide web. There is no such thing as a high end turntable built from all sorts of old parts or from the spare parts that you have to order and will be delivered by a special supplier, unless you have full knowledge of the subject and a vast experience. 
There is no such thing as a high-end DAC that is based on a low bit converter in a standard aluminum case if only attention was paid to the quality of resistors, opamps and capacitors. Far more important are the physical properties of the unit, the elimination of resonances and getting a balanced construction that makes a stereo image and maximum harmony possible.

DIY tonearm on DIY turntable with a trial of the Universal Record Stabilizing Ring

Building a high end loudspeaker system requires a well calculated network and above all that you understand the effects of damping, the effects of the materials used in constructing the cabinet, and have knowledge through experience regarding the optimum shape.
Using a small low mid unit on a small baffle is very fashionable but only one large unit or two smaller ones on a relatively large baffle will give you the basis for harmonious sound. On top of it many hobbyists think that a well structured and harmonious sound will be achieved with expensive units only. If you cannot design a system that works well with cheap stuff, cables included, than there is no need to buy a $ 250 or $900 tweeter.  

There is no such thing as a high end tone arm that is built from all sorts of parts and materials bought in the ironware shop if you do not have knowledge of materials, mass, resonances, etc.

So I do not promise you a high end tone arm. If it will be high-end or at least very good, depends on you alone. What I show and describe is how I made my tone arm. I will tell you what the special features are of this fabulously working piece. Maybe it will inspire you to have a go at building a tone arm. And if you read and look very well, you may well be surprised by the excellent quality of the arm you finally may have built yourself. But that will only be the case if you have very good hearing.

HIGH END
High end? The parts may be O.K., but it is putting them together that makes the difference.
If high end was that easy you would not have to pay at least $2500 for a top quality deck (motor and arm) and another $2500 for a cartridge. You would not have to pay at least $5000 for a high end convertor built in a CD player like an Accuphase.
A high end tone arm? Maybe not, but if you have knowledge of the sonic properties of materials (preferably through experience) and you have the proper ears to scan the effects that you achieve by using and combining the materials and in the way you construct the arm you can perform great feats. You may even reach a very high degree of performance as regards to both mechanical aspects and sound quality since these are linked. And do not forget that there can be a lot of fun in constructing too.

MONITOR
First of all it is important that you have quality loudspeakers with a very good frequency response that goes deep down and extends well in the upper regions of the audio band. At the same time it should give a very neat yet open reproduction of the mid frequencies.  A bad loudspeaker system will make you easily compensate for poor bass response, bad renounces and standing waves in the system and/or in the room. So your loudspeaker system should be dependable and also well positioned.

COMPENSATING
When I told a friend that I had built a pick up arm that was working well, he said to me: "So all these high end tone arms are either not as good as reviews may say or they are far too expensive for what they offer."
I momentarily use a loudspeaker system that I have built/assembled myself using among other things an electronic crossover (Luxman 2003 which works with 8 x 12AU7). This crossover facilitates the adjustment of level and crossover frequency. My friend added: "And you are compensating for the weak points of the speaker system and vice versa".
His reaction of course was understandable. But he was not right because my speaker system works well with various CD players and standard turntables and arms.

THE BEST IN THE WORLD
The existence of the best pick up arm in the world (and all these other high quality tone arms: Graham, Goldmund, a.o.) does not mean that you should not enjoy the fun and the seriousness of the learning process when building a tone arm or a turntable yourself.
I have built various turntables myself, the first one in 1980. I have done the final mechanical fine-tuning of Denon CD players originally costing $1500 and that put them very close to the category of Krell, Levinson, Theta, a/o.
I always had the desire to try my luck in tone arms. It never came to materializing several ideas because I was too busy writing and doing other important things. Life is all about priorities. But after talking to a veteran in audio, a rather old man who had spent his life at building his own arms and cartridges, I decided to try my luck.

PRELIMINARY EXERCISE
This man had built a tone arm of balsa wood with a length of 40 cm (about 17.7 inches). So I started off with a tone arm of balsa wood with an effective length of 32 cm (12.5 inches) because I did not have more space for a longer arm at the time. As you know balsa wood is very light and you do not reach easily the limits of arm mass in relation to the compliance of the cartridge. So I combined the wood with strips of thin aluminum to improve the sonic properties of the balsa and to heighten the effective mass of the arm in order to be able to mount a Denon DL 103 cartridge. That arm performed rather well and provided a fabulous and lifelike transient response.
Although visitors liked the sound of it, I myself thought that some coloring was evident. I was more suitable for a lightweight moving magnet cartridge à la Shure.

UNIPIVOT
The balsa arm has a uni pivot with no play at all. If you pull the arm towards you in the vertical plane you can feel that there is no play. That is one explanation for that incredible transient. So a very important goal when building the second arm was to achieve an excellent transient.
Hobbyists always have parts and stuff from ancient times. They keep it because it can be useful some day (mostly never). I had an old Lenco (Goldring) turntable with tone arm. The platter was meant to serve in a record cleaning machine which I intended to build myself. The intention vanished when I bought a real professional Keith Monks machine. The arm of the Lenco could have parts that I could use. But I discovered that the vertical bearing had enormous play and this would kill any transient drastically. As you know the tiniest amount of play is disastrous. 

The horizontal bearing was not a perfect construction either. It consisted of two triangular shaped "knifes" that rested in tiny rubber blocks on top of the vertical bearing. These rubber blocks had at one side a v shaped cut in which the two horizontal knifes rested. The knifes I could use of course. But the rubber v shaped beds were too soft so I had to construct beds that were firm and not sloppy as the ill Lenco construction showed (mostly as a result of ill treatment over the years by the user). I not only had to make the beds but also I had to find a vertical bearing that I could use. It appeared that it was impossible to extract the knives from the original arm tube. That is why I decided to use a small part of the existing arm tube.

BEARINGS
I had a few 'old' tone arms from Thorens turntables (TD 160 and TD 166). I found that I could use a vertical bearing of one of them if I took out the existing arm part and if I put it upside down. I mounted it on an acrylic base plate. Mounting it upside down means that there must be enough room underneath the mounting plate (the base plate). My home made turntable has sufficient space for that part that originally was the top. The other end of this vertical bearing ends with a shaft with a small diameter. It needed more mass and also reinforcement.
A craftsman turned the needed part: a cylinder of 30 mm in diameter and 21 mm high and drilled a hole of 5.85 mm in the center. The cylinder is bolted with two screws on the thin vertical axis.

DYNAMICALLY BALANCED
There are two ways of applying the vertical pressure (downforce) of a cartridge in an arm. With a statically balanced tone arm the down force is achieved by means of weight. By precisely sliding the counterweight towards the pivot the desired amount of down force is attained. This method has a drawback. Not every record is completely flat. The slightest warp causes an up and down movement of the cartridge and this movement can be translated into swinging. If the tone arm is well constructed measures are taken in order to minimize these effects. For instance: by making a construction where the counterweight is at the same horizontal level as the needle tip. The dynamically balanced tone arm does not suffer from this anomaly because the vertical down force is applied by means of a spring. The down force does not vary as much as is the case with a statically balanced arm because the cartridge is held down by the spring at all times.

Click on the arm to view a larger image.

CONSTRUCTION
So on top of the cylinder I mounted a strip which is bent at two points (s shape) marked in the drawing of spare parts as "strip for the attachment of the spring". At the lower end which is close to the arm base there is a hole so a spring can be attached.
On top of this bent strip I mounted a u profile with v-shaped cut outs that forms the support for the arm tube. The top of the cylinder has two holes at the same distance and with the same diameter as the holes in the aluminum strip and the u profile. The width of this u profile is 16.4 mm and is a standard size. It can be bought in the iron ware shop. The horizontal bearing will only function well if the knifes rest in a this shaped bed which was precisely cut out. The v must have a wider angle than the angle of the knifes. The bottom of the V has to be very sharp so that sliding of the knifes is impossible. The cutting of the V is a difficult affair and needs special tools and quite some practice before the right V shape is achieved.

With household scissors I cut from aluminum sheet a strip of about 8 centimeters long and 2 centimeters wide. Halfway I bent the strip around the short tube far enough behind the knife bearing so it does not interfere with movement. The strip has to get fully around the tube and should than have a flat section where 2 holes should be drilled. After that the strip should be bent again, but now around the arm tube ending in a flat section again with 2 holes for tiny screws so that the arm tube as well as the short tube with the knives can be tightened and secured.

MOUNTING THE CARTRIDGE
Make with a file a flat side on the 8 mm tube at one end. The cartridge will be mounted on a small piece of Plexiglas. Plexiglas has a distinct sound that differs from that of aluminum or carbon (if you have the ears), but unlike aluminum and carbon it has a far better rigidity and rigidity is one of the most important features of a good pick up arm, especially of the headshell.
Drill three holes in this small base plate as is seen in the drawing. This piece of acrylic is to be mounted on the arm tube with one screw which is located a bit off center (refer to drawing). This screw makes it possible to adjust the horizontal angle of the cartridge when changing the effective length of the arm tube and finding out which length (effective mass) is the best. The way this mounting plate is connected to the arm tube has an audible effect. In general it is advised to tighten screws very well in order not to create a bending mode which results in a noticeable frequency that will repeat itself throughout the audio band and can be heard in coloration of the sound, a sloppy bass and ill defined highs.
When much later when the arm is tried out and you had all opportunity to determine the effective mass of the arm which gives the best sound, you have to glue the arm tube and Plexiglas mounting plate together with 2 component polyurethane glue (in some countries available under the name Bison Nite) or any other quality glue (but even all purpose household glue probably will do the job). However do not put the glue in between the Plexiglas and the flat side of the arm tube, but just on the sides of the tube in order not to obstruct the flow of energy (sound) from the cartridge into and in the arm tube..
The optimum arm mass will make the bass tight and will result in an even and extended frequency characteristic and  will bring perspective in the sound image. Too much mass will make the sound heavy and restrained. If the arm is too light, a distortion free tracking of heavy passages will be impaired. Remember that the arm/cartridge resonance must be 8 to 12 Hz. which is well below the audio band which starts at 20 Hz. The turntable's resonance should be in the vicinity of 2 to 4 Hz. so it cannot interfere with the cartridge/arm resonance.)

WIRING OF ARM AND CARTRIDGE
For wiring the cartridge you can use all sorts of wire as long as it is light and of small diameter. Better use some wire from an old arm or buy a special wire which is available from certain specialized dealers. The kind of wire you choose however plays an important role as regards to sound quality as you know. Especially the longer wire that you use inside the arm tube. Sound quality of an arm may sometimes be attributed to the construction and the materials, but in many cases it is also the wire that puts an arm in a higher category of quality.
The inner arm wire can vary. The 12" arm of the Sony TTS-3000 (a turntable from 1969) has a very thin wire. Early Thorens arms have very supple wire as the later Thorens arms have more sturdy wire. Nowadays many designers use special wire from Cardas (USA), Van Den Hul (Holland), Scheu (Germany).

SILVER AND COPPER
For the inner arm tube I used silver plated copper wire with a green Teflon insulation. That kind of wire is quite sturdy and can only be used in the arm itself and not at the spots were more supple wire is required: at the beginning of the arm for connecting the cartridge and the end of it (pivot) where a transition without torsion is necessary. At that end I soldered 4 very supple and rather long wires from another (old) tone arm so that the arm can move freely. These wires should be connected to 2 cinch connectors (female) that you can mount on a support which is to be bolted on the general base (not on the sub chassis) close enough to the pivot of the arm. To this support with the cinch connectors a phono cable of your choice can be connected which leads the signal to the (pre-)amplifier.
You can use an ordinary phono cable or special van den Hul phono cable that leads the signal to an external preamp as in my case and from there you can use a more heavier interconnect of a quality brand. Adjusting the arm and fine tuning its mechanical capabilities is as exciting as choosing the interconnect cables that delivers the best harmonics, dynamics and a wide frequency band. There are numerous vintage records that will let you hear the best sound of strings, brass and percussion for instance.

DAMPING OF THE ARM
Although I started of by damping the arm tube with some long snips of balsa wood which made the music sound controlled, I found that the damping is very critical and can inhibit the speed of the musical signal especially when moving coil cartridges are in use. The idea of damping is not bad altogether but if you use some damping the amount of balsa that you would apply also could depend on the nature of the cartridge but foremost on the sonic properties of the aluminum arm tube. I did not try a paddle in a bath of a damping liquid with a certain viscosity as in the SME arms.
Arm resonances are probably already suppressed to some extend if you use a more sturdy inner wire. In any case: the wire should not lay too loose so it can not pick up vibrations and amplify resonances. The way to go about it is by putting thin strips of balsa in the rear of the tube (1 or 2 long strips of say 15 cm, but very, very thin). These will damp the arm tube and the wire over a certain length. The effect of the balsa is easily discernible by ear (and by measurement, if you are an expert in that field). Since your loudspeaker system has told you before what the qualities are in conjunction with a turntable (or several turntables), the loudspeakers will tell you exactly what the sonic qualities of this new arm are and how you can optimize them. Too much balsa is disastrous for any transient response and openness of the sound pattern. No balsa will tell you immediately if the low frequencies are uncontrolled and the high frequencies are unclean.

CARTRIDGE
We all know that the turntable, the arm and the cartridge interact in a very delicate way. The diamond tip picks up the tiniest information. The analogue source has far more bits than the digital formats! The minute movements are transformed into electrical signals by the coils in the cartridge and send to the amplifier.
Turntable-arm-cartridge should be seen as an entity. That is why one commercial arm performs better than another in conjunction with the same turntable (motor unit) and why a given cartridge does not always deliver as pure a signal with certain arms and record players.
I designed this arm with a Denon DL 103 cartridge in mind and in practice. The DL103 is a very fine cartridge not only if one takes the price into account. There are many audiophiles and music lovers who have been frustrated by the use of some expensive and fragile cartridges that prevented them form relaxed listening because of the constant worrying about the fragile cantilever, the expensive thin shaped diamond tip and in some cases the collected dust in an open cartridge. That is not to say that the high quality and high end cartridges need to be a pain in the neck. They perform extremely well if the owner takes care and has the right equipment in order to display the virtues.

EFFECTIVE MASS
A cartridge performs best with a specific tone arm. Not only because of the sonic qualities of the arm, but also because of the effective mass of the arm. The effective mass should be perfectly suited to the cartridge that you want to use. The first SME was built at the beginning of the stereo era for the new Shure lightweight pick up. Fidelity Research have built cartridges that had to be adopted by arms with an effective mass as high as 30 gr. And they built the arms to go with these cartridges.
For the Denon DL 103 the English magazine Hi-Fi Choice states 16 gr. as the maximum effective mass of the arm. To those 16 gr. the weight of the cartridge has to be added. That means that more than the 16 gr. (without counting the weight of the cartridge) will put the resonance too low. The sound will then have a lumpy quality and impair speed. On the other hand too little mass will mis track the groove and blur mid and high frequencies, and will give the sound some vagueness at the same time because of the fact that the fundamental frequencies of instruments are not well controlled and thus not well transmitted. Just to remind you once again.

ADJUSTMENT
With this DESIGN you can find out and adjust the effective mass of the arm tube without the need of adding weight as is usually done by means of a sliding metal ring or screwing some weight in between the cartridge body and the head shell. At the same time you will keep the arm as long as possible. My impression is that the 'unused' part of the arm tube at the other end of the pivot has a significant influence on the sonic properties notwithstanding the fact that the tube will be secured above the pivot and the propagation of sound waves will be stopped to a certain extend because of the tight connection with the short tube with knife bearings.
For every 10 mm of the aluminum tube that I used I had to calculate a weight of 0.6 gr. For the screws used to fit the cartridge and the small acrylic mounting plate some 2 gr. should be added. The result was that an effective mass of the arm of 16 gr. could be calculated as follows: 16 - 2 = 14 : 0.6 = 23.3 cm.
N.B. A friend of mine told me that I had not calculated the effective mass according to the appropriate equation. Therefor I will recalculate it later and write in this section about it.
The total length of the arm tube used by me was 38 cm. I tried the arm at 28 cm which gives a mass of 16.8 gr. without counting screws, mounting plate (and of course the cartridge). At first hearing the sound was well controlled but was lumpy and muddy. So I had to experiment and detect a more suitable mass. (See at the end of this article.)

ARM LIFT, CALIBRATION AND SPRING
As arm lift you can use an existing arm lift or you can think up something as I did. My lift works as a lift but is not suitable for positioning the cartridge on the right spot.
For calibrating the arm (overhang, horizontal tracking angle) you should use a template from a manufacturer, a shop or you make one yourself. Be sure to firmly secure the arm at the base after alignment. Also the arm tube should be secured very firmly so that a swinging mode can not occur and an accentuation of some frequencies is impossible.
Now it is time to calibrate the vertical pressure. I use the arm in its dynamic version. That is the version with the spring. That spring has to be very supple but at the same time not too long. A long spring has to be shortened when you have shifted the tube to the back, that is when you have shortened the effective length of the arm tube. You will notice that. If you do not do that the spring and the ring n the arm tube are likely to touch the platter and record.
When calibrating the tracking weight first of all the sliding ring on the arm tube to which the spring is attached should be close to the pivot so that the spring does have no influence and the weight of the ring (little as it may be) has no significance either. Balance the arm with the counterweight. Than move the ring in the direction of the cartridge and the spring will get some tension. Use a tracking weight balance of Nagaoka, Shure or any other make and move the ring so far that the scale indicates 2.25 gr. for the Denon; if you use another cartridge you will have changed for another effective arm mass and you will have to use the proper tracking force indicated by the manufacturer.
All moving parts that are not well secured and thus can vibrate have an influence on the sound. In order to eliminate any resonance provoked by the ring and the spring you should take a tiny bit of balsa wood or a very small part of a match and push that in between the arm and the ring so that the ring cannot move or vibrate. Originally I had damped these resonance by means of tape. But when a collector from abroad came to visit me and we listened to various records we decided that the sound was too well damped and the mid band was not open enough, which as I discovered later was caused by the small pieces of black plastic insulation tape in combinations with the mass of the arm which was too high. So finally I adjusted the arm and reduced the effective length of the arm tube to 25 cm.
In time you will also discover that the tracking force needs adjustment as well as the side thrust (bias).

DYNAMICALLY VERSUS STATICALLY BALANCED
Applying the maximum of mass for a given cartridge will especially be of benefit to the reproduction of recordings from the nineteen fifties en sixties, the era when tone arms were much more heavier. All of a sudden I became aware of the fact that Samson François must have been playing on a grand piano manufactured by Erard (or Pleyel?) when recording the Four Ballads of Chopin (Columbia FC 1041, 10"). And it is amazing how good the piano tone was captured in those days. Also you can notice that Jorge Bolet probably plays a Baldwin on his Remington recordings.
Using a spring for the vertical down force has the advantage that the pressure is practically always the same. There is just a slight variation when warped records are played. As said earlier the variations in pressure when using a statically balanced arm are much greater because of the swinging of tube and counterweight, while with a spring this movement is suppressed, (better controlled).
If you use a gimbal bearing as in the Thorens arms in combination with the spring, the arm will play records in whatever position the turntable is in. Nevertheless you should however always adjust the turntable so it is level.

POSITION OF TIP AND COUNTERWEIGHT
In the proposed design you will see that the pivot is at the same horizontal level as the diamond tip. On top of that the counterweight is positioned underneath that horizontal plane. So this arm can also be used as a statically balanced arm and will perform well.
I de-coupled the counterweight by means of a few centimeters of rubber insulation (shaft) taken from an old, yet supple interconnect. I put this insulation over the bolt which holds the counterweight. The amount of play between counterweight and bolt depends on the tightness of the insulation and the sort of rubber or plastic.

SOUND
The performance of a tone arm depends also on the sonic virtues of the turntable itself and if they match the arm's behavior. The sort of turntable mat is of great significance. If you use an acrylic mat (à la Goldmund) on a rather heavy platter you need high quality amplifiers that perform extremely well in the top end of the audio band. If you use a rubber mat distortion will be increased. If you use a turntable mat of glass the top and bottom ends of the audio band will be much cleaner but also "lighter" in nature.
I must say that I am very pleased with this arm. The sound has weight and transparency, nevertheless the audio curve appears very even and straight. Transient response is very good. The soul of the music is conveyed in a very realistic way.

UPDATE
My aim was to have a long tone arm in order to minimize the horizontal tracking angle. But also I wanted a long tube as would be possible for reasons of sound. At the same time I wanted to have the possibility to find the optimum effective mass for a specific cartridge without adding weight in the form of blocks or little plates between the cartridge and the head shell (mounting plate).
This article is meant as an inspiration to those who want to try building a tone arm themselves; not necessarily in the same way and with the same parts as I did.
It is possible to use lighter aluminum tube but it has to have enough rigidity to avoid bending (it easily does even if you do not see it).
Eventually I will try to improve my arm by finding and using a higher grade of tube which is used in medical equipment for example or I will try to get hold of a carbon fiber tube; even though I am a fan of aluminum more so than of carbon fiber.
If you have questions and/or comments send an e-mail.
Comments and suggestions from readers will be included in these pages.
So this article is to be continued.

© December 1998 R.A.B.

UPDATE 2
Since 1998 the turntable has not altered and the arm and cartridge are still functioning extremely well and give with - the Denon DL-103 - a very harmonious build up, an open stage, depth and tangible sound. The only upgrade I have made is exchanging the arm wires for Cardas phono wire (Cardas 4x33 AWG Shielded Tone Arm Cable) and the many (10 !) interconnects in my active system are all terminated with Bullet Plugs and the connecting cables are are all Cardas Crosslink ordered at http://www.diycable.com. The only exception is the interconnect of the electronically and mechanically!!! modified Denon DCD 2560 CD-Player, which is connected via a Cardas Cross Link.

31-12-2003

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