Morch DP-6 User manual

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H. H. MØRCH
MORCH
DP-6 Fitting instructions
• Contents of the packing
In the packing of the tonearm you will find the arm base in which the bearings are
encapsulated in a heavy body. This is the link between the moveable part of the tonearm and
the arm pillar, which is to be mounted in a bush in the board of the turntable.
Further you will find one arm tube according to the choice that you have had from literature
about the tonearm or from advice of your dealer. There also will be 4 weights, finger lever with
screws, knurled nut, hexagon spanner, and a syringe with silicone fluid.
The tonearm usually is supplied with the arm rest mounted on the pick-up lifter, but if desired
a separate arm rest could be supplied instead.
• Mounting the bushes
First it has to be decided exactly where to place the bush in which the tonearm is to be
mounted. The center of the bush should be at a distance of 212 mm (8 5/16 '') from the center
of the turntable platter and there has to be room enough for the counterweight rod to move
freely. The counterweight rod is having a rear overhang of 70 mm (2 3/4 ") as to the center of
the arm bush. If separate arm rest is used, it should be placed so that the arm when resting
on it is at a suitable distance from the record.
The mounting template on the packing of the tonearm is showing the position of the arm base
and the arm rest as to the turntable spindle. It should be noted that the position of the
turntable spindle shown is just an example. In order to allow for the most convenient position
of the arm base the turntable spindle could have its center anywhere on the arc shown.
Mark the center of the arm bush and check that the distance to the center of the turntable
platter is 212 mm (8 5/16 "). Then drill a 20 mm (13/16 ") hole with center in this mark. Also, if
separate arm rest is used, drill a 10 mm (13/32 ") hole for the bush for the arm rest about 155
mm (6 1/8 ") in front the 20 mm hole.
Fastening the two bushes: In order to make it easy to adjust the height of the arm and the arm
rest with the accompanying hexagon spanner, the small screws for fixing the arm and the arm
rest should point to the right.
Then the arm base is fastened in the arm bush.
• Mounting the cable to the amplifier
Put the grey plug of the accompanying tonearm cable into the socket below in the arm pillar. If
the turntable has a floating sub chassis, the cable should not be restricted in any way, and it
should be arranged in a suitable arc, so that it can not limit the free movements of the
suspension. Remember that the Y-shaped ground terminal should always be connected to the
chassis (ground terminal) of the amplifier. The chassis of the turntable may also have to be
electrically connected to the arm bush.

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• Choice of weights and putting them on
In order to make it possible to balance all phono cartridges the tonearm is supplied with three
counterweights - large, medium, and small - having the hole excentrically positioned and with
a tracking force weight having a centrally positioned hole.
The weights that are to be chosen for balancing a cartridge depend on which arm tube that is
to be used and on the weight of the cartridge.
The weights to be used can be found in the below table (tf. means tracking force weight).
At first the counterweight/s is put onto the counterweight rod and then the tracking force
weight. To put on the counterweight/s and to displace them along the counterweight rod they
have to simultaneously be revolved to and fro.
Weight of counterweight in grams when using: Counterweight size: Note:
Light arm tube Medium Heavy Extra Heavy
“Green” “Red” “Yellow” “Blue”
1.2-2.4 small only 1
2.5-6.5 0.5-4.3 small + tf. 2
5.2-7.6 3.0-5.4 0-2.2 medium + tf.
7.6-12.7 5.4-10.2 2.6-8.2 medium + small + tf. 2
9.0-9.9 7.0-7.6 4.1-5.0 large + tf.
11.9-21.2 9.9-15.4 6.7-11.3 0-4.8 large + small + tf. 2
19.0-21.2 17.0-19.4 14.0-16.2 6.5-9.0 large + medium + small + tf. 2
Notes:
1. Here the small counterweight is used as tracking force weight.
2. Here both the tracking force weight and the small counterweight are used as tracking
force weights. Each of them gives 1/2 gram of tracking force when slid 1 indentation
forwards.
With heavy cartridges or if large tracking force is needed the medium or the large
counterweight should be used as tracking force weights as well. The medium
counterweight gives 1.2 g and the large counterweight gives 2 g when slid 1 indentation
forwards.
Thus a certain tracking force can be obtained by sliding more than one weight adding up
their shares of tracking force.
• Refilling the silicone fluid
The accompanying syringe contains about 0.6 ml of silicone fluid (60 units). At first the pick-up
lifter should be filled in. Pull the black piston out of the lift cylinder and place it in a completely
clean place. Then inject 0.1 ml (10 units) of the fluid behind the shaft inside the lift cylinder.
When doing this, the lift handle must be in "lowered" position. When the fluid is injected, the
tip of the syringe is "wiped off" on the shaft, and the syringe is pulled up with a little jerk there-
by preventing the fluid from getting in touch with the walls of the lift cylinder. Do not put the
piston back into the lift cylinder until the silicone fluid has merged down to the bottom of the

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cylinder, and hereafter the piston must not be pulled up again, as the silicone fluid would then
easily stick to the walls of the lift cylinder. If this happens the piston will "go down" much too
slow.
The tonearm is supplied with damping for the horizontal movement. Damping the vertical
movement is not always an advantage. If desired, silicone fluid is filled into the well of the
tonearm base. This is done through the hole, which is seen in the plexiglass on top of the arm
base, when the arm tube is not on. Resting like this the tip of the syringe can just reach the
well through this hole. Inject 0.2 ml (20 units) of the silicone fluid into the well, and carefully
"wipe off" the tip of the syringe on the edge of the well, before pulling the syringe up with a
little jerk. The plexiglass over the well must not be unscrewed.
The damping of the vertical movement of the tonearm is obtained with the screw, to which the
arm tube is attached.
It goes all the way down into the silicone fluid. When the tonearm is supplied this screw is in
its lower position, and if silicone fluid is injected, it will give maximum damping. The damping
is reduced as the said screw is turned some revolutions up with the hexagon spanner. For
further adjustment it should be noted, that the screw should not be forced down into the bot-
tom of the well. This will make the tonearm rock in its bearings. Be careful if you want to
increase damping again. The screw must be at least one revolution above the bottom of the
well. (If measured the screw must protude minimum 11.5 - 12 mm (about 15/32”) above the
surface of the plexiglass).
• Mounting the cartridge
Using the accompanying finger lever the cartridge now can be mounted on the arm tube. If
possible, use the accompanying aluminium screws. Provided that the tonearm is mounted, so
that the distance from the pivot to the centre of the turntable is as indicated on the mounting
template, the position of the stylus - to obtain correct overhang - should be: with standard arm
tubes right under the front edge of the black plane of the arm tube - with PRECISION arm
tubes 4 mm (5/32”) behind the front edge. Also the cartridge should be in parallel to the said
black plane. Carefully push the terminal jacks of the wires unto the pins of the cartridge with a
pair of tweezers. Do not squeeze the thin wiring too hard. Red and green are signal and
ground of right channel. White and blue are signal and ground of left channel. Then fasten the
arm tube on the arm base with the accompanying knurled not, which should be tightened well
with two fingers. Check that the overhang is correct - 18 mm (23/32”) - and adjust if
necessary.
• Adjusting the tone arm
First make a coarse adjustment of the weights. The tracking force weight - and where marked
2) also the small counterweight - should be back at the end of the counterweight rod, while
moving the counterweight/s backwards or forwards until the arm tube is balancing in about
horizontal position.
Apply tracking force by sliding the tracking force weight and may be also the small
counterweight forwards. Both of these weights will give ½ gram for each indentation that they
are moved forwards. Thus together they will give 1 gram.
If one of the counterweights is going to be used to apply tracking force, the tonearm should be
balanced with the weights arranged in such a way that there is room enough to move the
counterweight in question.
It is an advantage to use as large or as many counterweights as possible.
And by coarse adjustment of the weights it appears that the counterweight can not get far
enough forwards to obtain balance, the tracking force weight can be slid forwards until
balance is obtained. This place then will be zero point for the tracking force calibration. If the

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distance from here to the counterweight is not large enough to give the correct tracking force
a smaller counterweight should be used.
The height of the tonearm now should be adjusted. With the stylus resting on a record the
arm base is moved downwards or upwards until the arm tube is in parallel to the
record, and the arm base is turned so that the pick-up lifter can always support the arm tube.
The screw in the arm bush then is tightened with the accompanying hexagon spanner.
If the tone arm rest is mounted on the pick-up lifter, it should - when adjusting the position of
the arm base - be considered that the arm rest should allow the arm tube to rest in a suitable
distance from the record.
The height of the pick-up lifter is adjusted so that the stylus is about 4 mm (5/32”) above the
record, when the pick-up lifter is in "raised" position.
If separate tone arm rest is used, it is adjusted in a height, so that the arm tube rests on it,
when the pick-up lifter is in "raised" position.
• Cartridge azimuth
Azimuth (inclination of stylus as seen from the front) may have to be adjusted. When the
stylus is resting on a record, the stylus - and so the cartridge - should stand at a right angle as
to the record. If it does not, note the direction in which the cartridge should be tilted, and take
off the arm tube.
On top of the arm base in the left side there is a red dot. In the right side - opposite to the red
dot - there is a sunk screw in which the hexagon spanner will fit. By turning the hexagon
spanner clockwise the arm - and so the cartridge - will be tilted to the left. Opposite by turning
counter clockwise. 1/4 - 1/2 turn may be enough.
Put back the arm tube and check if further adjustment is necessary.
• Lateral balance
The direction of the counterweight rod extended to the stylus should be the line of lateral
balance. Coarse adjustment can be done by turning the counterweights on the counterweight
rod, so that their center of gravity is pointing downwards or upwards and about 30° to the right
as seen from the end of the rod.
Fine adjustment can be done by raising the moveable part of the tonearm at the
counterweight rod. The hexagon spanner could be used holding it horizontally under the
counterweight rod as close to the body of the arm base as possible and using it to raise the
moveable part of the tonearm about l mm off its bearings.
When doing this the arm tube should rest on the raised pick-up lifter, and the anti skating
spring should be pushed, so that it does not pull the tonearm.
When raising the moveable part of the tonearm as described above, both sides of the arm
base should raise simultaneously. If one side is too light and comes up first, the "heavy end"
of the counterweight/s should be turned a little in the direction of the side, where the arm is too
light. Then try again to raise with the hexagon spanner, a.s.o. until both sides comes up
simultaneously.

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• Anti-skating
The anti-skating force is adjusted with the little black handle next to the pickup lift. The amount
of antiskating force required depends on the tracking force and the shape of the stylus. Thus
no calibration is possible.
Coarse adjustment can be done with the stylus running between the grooves next to the label
of the record. Correctly adjusted, the stylus should move slowly towards the center of the
record.
Fine adjustment could be done by reducing the tracking force a little whilst listening to a
critical passage. If for instance distortion occurs in the right speaker, the handle should be
turned clockwise. (The best result is obtained with a test record). The adjustment is not
critical. It is better giving too little than too much antiskating force.
The range that the antiskating handle can move, will cover most cartridges. The tension of the
spring, however, can be altered by loosening the screw in the center of the round black pulley.
By rotating the pulley with two fingers, you can set to a new tension.
• Special about PRECISION arm tubes
PRECISION arm tubes are supplied in "red" and "blue" versions only. They have a wide and
very precisely ground mounting plane to assure a good mechanical contact to cartridges
which have a similar large and accurate mounting plane. The PRECISION arm tubes are 4
mm (5/32”) longer than the standard ones in the forward direction.
• Special about 12” armtubes
In the section mounting the bushes it is described how the position of the 20 mm (13/16 “)
hole is found. For 12” armtubes the distance from the center of the hole to the center of the
turntable patter should be 294.1 mm (11 9/16”).
If the arm bush is mounted exactly at above distance from the center of the turntable platter,
the stylus should be positioned just under the front edge of the black plane of the arm tube.
After mounting, check that the overhang - 13.3 mm (17/32”) - is correct and adjust if
necessary.