1.
Set-up and assembly instructions:
Section 1: Introduction:
Welcome to the Omega, we hope you gain much pleasure from the tonearm, and appreciate the efforts we have made to provide you with this exotic and bespoke product.
Before attempting to mount the arm, it might be sensible to take a few moments to familiarise yourself with it. This is undoubtedly going to save some time later.
The Omega arm is very simple to mount and align, the total time taken should not be more than 30 minutes, but this is dependant to a large extent on the turntable.
To start with, your box should contain the following;
1)The Omega pick-up arm.
2)One small bag of screws and hexagonal keys.
3)One set of instructions.
4)An alignment protractor
5)A template for cutting the turntable arm board.
Should any of these parts be missing, please consult your dealer or contact us directly.
Firstly remove the arm from the box, comparing it with fig.1.identify the main features.
Starting with the Headshell, you will see a rib, or ridge, along one side. The cartridge must fit against the main flat surface, and not make contact with the rib in a such a way as to not sit flat.
The cartridge tags are colour identified but do not `pull-out’ any further than the front of the headshell.
Note also the location of the screw that adjusts cueing height.
The main counterweight is fixed as close to the bearings as possible, and is not adjustable. The mass has been determined to provide an almost zero balance of the arm, with no cartridge fitted, and without the additional secondary weight being present.
The counterweight design provides for both course and fine adjustment of the tracking downforce. This is unusual in tonearm design so you should note that the general principal is that the should slide the small weight into a position that gives a small but positive feeling of downforce, clamp it using the two grub screws, and then make the final fine adjustment using the knob at the very back of the arm.
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It should also be pointed out at this stage, that it will be very difficult, if not impossible to achieve a condition where the arm floats horizontally. Beyond the absolute horizontal, the arm will appear to `fall’ faster.
This is because of the dynamic balancing of the Omega, and is an intentional feature of how the Omega works.
The first stage in setting up the arm is to remove the base plate, this is fitted to the arm for transit purposes, but must be removed. Find the 2.5mm hexagonal key in the small bag, and loosen the screw shown in fig1. and slide the base plate off the arm and put the arm to one side for now.
If you look inside the base plate, you will see a sprung plate. When the clamping screw on the side is tightened, this plate will move outwards and secure the main pillar.
This method is far superior than providing a single screw to fix the VTA. ( Vertical Tracking Angle.)
Looking back at the arm, there are two more features to note before we address the counterweight adjustment in detail, these are bias adjustment, and cue height adjustment.
The bias, or anti-skate device, corrects the inward pull of the arm generated by the 4fact that the arm sweeps across the record in an arc. And this arc is not perpendicular to a radius drawn form the centre of the turntable.
The amount of bias required unfortunately varies, there is no `ideal’ setting. It not only changes according to the geometry of the turntable, but changes from the beginning to the end of a record ( the radial velocity decreases towards the centre). It is a force that is sensitive to the suspension settings of the turntable, if not exactly horizontal, the force will change. And to make things worse, it also varies according to the degree of modulation within the groove.
There are two points to note in relation to the Omega. Firstly, being a 10” ( 254mm) arm, the magnitude of the skating force is much lower than a conventional 9” arm.
Secondly, being dynamically balanced, damped by differential masses, and not having co-incident bearings, the arms behaviour is not conventional. It is subject to far more controlling forces than a conventional arm.
So the setting bias correction is always, at best, an approximation. Please note that it does not really adversely affect the sound quality that much. Ultimately, optimal setting only allows any particular musical performance to be tracked with a slightly lower downforce.
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Be careful in trying to set downforce too low, as you will be more likely to damage both the record and cartridge if you mistrack too often.
Traditionally, Helius arms have always built into the geometry of the design, a bias force sufficient to correct the condition without having to apply additional compensation.
The result was that most Helius arms could be played with no additional bias. This has now changed to avoid confusion. The zero position on the bias compensation dial literally means no bias is being applied.
The bias dial will turn through 300 degrees, not quite a full turn.
Please note that turning the dial ANTI-clockwise will INCREASE the bias force. Logically, the opposite is true and turning it clockwise in decrease the force.
We suggest you start by turning the dial to its half way position, i.e. to the end of the graduated scale.
You may turn it more, and will do not damage by doing so. Eventually the dial will hit its dead-stop and turn no further.
Next is the adjustment of the cueing height. This being the height above the record surface that the arm will lift when you lift the cue lever.
Turn the arm upside down. The bias dial will appear on the left of the arm, but close to the pillar ( see fig 3) you will notice an adjustable screw head.
Screwing this inwards ( so that moves deeper into the platform ) will increase the height the arm lifts off the record. It is factory set to lift between 5mm and 10mm above the record surface, but this may be adjusted to suit yourself.
Be warned however, that this cannot be adjusted insitu, once the arm is mounted in the turntable, it is not possible to adjust. The arm will have to be removed from the turntable to change.
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Finally, the counterweight adjustment.
Referring to fig.3, please note that the `slide’ onto which the small weight is fitted must be in its out-most position, otherwise you will not be able to fit the weight.
Offer the weight into its slot and lock either one of the two small grub screws to hold the weight temporarily in place, roughly in its half way position. ie, so it can still be moved backwards or forwards.
For now, the weight can be left in this position.
Looking at the very back of the arm, you will see a small grub screw fitted into the Fine Adjustment knob. Although the knob will turn by hand, it is easier to fit Allan key into the grub screw, and use this to make the fine adjustments.
We suggest you turn this knob to see how it works, gently moving the counterweight backwards and forwards to set the weight.
Please note that we can supply any one of 3 minor weights to cover a wide range of cartridges. It is therefore not possible to provide a graduated scale against which the downforce can be adjusted.
Now we come to fitting the arm and setting it up on the turntable.
Section 2: Mounting Instructions:
If you have purchased a turntable arm board suitable for Omega, then please skip this section and move directly to the text from the red asterix on page 6 of these instructions.
However, if you have to cut your own arm board, identify the arm / turntable template. The objective is to cut a large central hole into which the Omega base plate will fit, followed by 3 smaller holes for the screws that will bolt the arm’s base plate and the turntables arm board together. Fig 4 provides basic dimensional information to enable you cut the base plate hole.
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a)Use a small pin to pierce the small dark green circle labelled ‘Bearing centre’.
b)Place the 6mm hole in the template over the turntable spindle, then use a pencil inserted into the pin hole you’ve just made, to scribe an arc on the arm board.
c)The Omega may be mounted at any point along this arc, but obviously needs to be positioned centrally within the arm board. Due attention also needs to be
d)given to the orientation on the arm with respect to the turntable, visually, the arm should be parallel with the side of the turntable.
e)Use a pin to fix the template to the arm board, then remove the other end of the template from the spindle. It should now be free to rotate about the pin. Ensure the image of the Omega is oriented parallel to the side of the turntable.
Use another pin to piece the other 3 small red holes that identify the M4 screw locations, and more importantly, the hole identified as the `Base Plate centre’.
Note that the arc you just marked is not the centre of the base plate, but the centre of the arm bearings, and the centre of the base plate lies 5.5 mm in front of the bearing centre. It is this second point that is to be drilled for the base plate, not the bearing centre point.
f)Remove the template from the turntable / arm board. At this point you should have 4 points marked on the arm board.
g)Cut the large central hole between 43mm and 45mm in diameter.
h)Drill the 3 screw holes 5mm in diameter.
i)Insert the base plate into the cut-out, and bolt it into place using the three M4 screws found in the plastic bag. Depending on the thickness of the arm board, ( the materials will vary from wood to metal to plastic.) select the corresponding 4mm diameter screw length from the bag of screws provided. Two lengths are provided with the arm.
Before cutting the holes, it might be helpful to use a pair of compasses to draw a circle 54mm in diameter from the `Base Plate centre’ point, to identify the circle on which the M4 screws will be drilled, and secondly, a circle 43mm in diameter to mark the main base plate hole. Note that the 54mm diameter circle should superimpose the 3 base plate screw holes. See fig 2.
It would help also if you further scribed a line from the same `Base Plate centre’ directly down (towards the front of the turntable) so it intersects with the 54mm diameter hole. This establishes the exact position of the first hole. Likewise, scribe two other parallel lines nearly 23.5 mm immediately to the left and right.
Before cutting the holes, first note the location of the 4mm grub screw that locks the height of the arm. Although the rotational position of the base plate is not critical, it remains convenient that this screw is accessible from the right hand side of the arm. In much the same position it was when you separated the arm from the base plate.
** The combined base plate / arm board should now be fitted to the turntable.
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Before the arm can be inserted into the base plate, and onto the turntable the cartridge must now be fitted, this is delicate, and care must be taken to protect the stylus from damage.
It is academic at this stage whether you fit the cartridge tags first, or mount the cartridge in the headshell first.
At Helius, we generally find it easier to plug the gold tags into the cartridge before bolting the cartridge into the headshell, but you chose the opposite.
Connect the gold tags from the arm to the cartridge. These are usually colour coded, the convention being that
Red is Right +
Green is Right -
White is Left +
Black/Blue is Left -
Position the cartridge body centrally with respect to the slots in the Headshell and use the two screws that invariably come with the cartridge, to secure it in place. Do not over-tighten the bolts at this stage as the alignment has not been verified.
Before mounting the arm onto the turntable, slacken the locking screw indicated in fig 1, for the small counterweight to allow the weight to slide back and forth
Mount the Omega / arm board onto the turntable.
Before placing the stylus on the record check the vertical height. The arm tube needs to clear the record, but note it is tapered. The headshell itself slopes backwards by a commensurate amount , so the underlying line of the arm tube should be parallel with the record surface. The height of the arm can be set by tightening the 5mm grub screw in the side of the base-plate.
Once you are satisfied that height is correct, the cartridge must be properly aligned within the headshell. Identify the alignment protractor and place it over the turntable spindle. Place, in turn, the stylus on each of the two points shown.
Twist the cartridge in the Headshell, and adjust its position in the slots, until the body of the cartridge remains parallel with the lines on the protractor, in both positions on the protractor.
Tighten the Headshell screws, and return to the job of adjusting the tracking down-force.
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This is subject to both a course and fine adjustment. You will already have noted that secondary weight slides front and backwards.
Please recall at this stage that an M4 grub screw is fitted into the end of this knob expressly for the purpose of making the adjustment more easy through the use of an allen-key. This might be particularly useful when heavy cartridges are used and the small weight extends beyond the point where adjustment by hand is easy.
You may chose to simply turn the knob by hand, but it is quite small and the shape is aesthetic rather than practical.
If your cartridge falls within the normal weight range, you should find that since the weight is quite far back, that it must be moved forward to achieve a positive downforce.
Start by adjusting the down force knob so the whole assembly moves forward, noting the `balance ‘ of the arm while to adjust it.
Once the downforce becomes positive, return to the small weight and move it backwards or forwards to achieve a downforce of roughly 2g. Finally, clamp either
( or both ) of the M3 grub screws to lock the weight in place.
Turn the down-force adjusting knob anti-clockwise, and the tracking force will increase by moving the weight closer towards the bearing fulcrum.
Use a set of stylus scales to check that the down-force matches the manufacturers specification.
Once the correct force has been established, a tracking record can be used, if available, to verify the result. If such a record is not available, then select a highly modulated record…… an orchestral crescendo for instance, and listen for any break up of the music.
If there is none, they leave the down-force as it is, otherwise, increase move the counterweight inwards slightly to increase the force.
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The system is nearly ready, just one last job of adjusting the bias compensation force. As previously described, this area is a little grey in terms of a precise adjustment. Since the Omega arm is a 10” (254mm effective length.) The extent of the lateral force is much lower than that needed with a 9” arm.
As a rough guide, set the dial about half way aroundthe scale shown..The marking only indicates the direction the dial should be turned in order to increase the force.
The only reasonable guide for optimal setting is to suggest that if a record can be found that offers a reasonable space between tracks, then place the stylus on the disk, but not in the groove. Adjust the bias force until the arm appears to float before `catching’ the groove. Without any bias, or without sufficient force, the arm will want to float inwards towards the centre of the record. Excessive bias, and the arm will pull outwards.
In ultimate terms, the bias will only allow the cartridge to track with a down-force a little lower than it would otherwise require. In extreme cases, it might influence the left-right balance of the music.
Finally, the arm is set–up as far as the cartridge in concerned, and the system is now nearly ready to play. However, there is a final task to perform, and this is with respect to the cables.
Since the choice of cables is a personal and sometime controversial choice, we have chosen to leave you with the option of changing these if you wish.