In spite of the slender appearance, the MØRCH tonearms have an amazing mechanical strength and stability. They are the result of the best precision mechanics, the finest craftsmanship, and realize technical and tonal claims without compromise.
What has been achieved with the MØRCH tonearms enables the cartridge to accomplish its task with extraordinary motional ease while maintaining a very high degree of stability.
The proof of their superiority lies in the listening! The MØRCH arm have received high acclaim from both critics and sceptics, simply because their sonic superiority can be easily demonstrated.

Above in this picture is model UP-4 with standard 9" armtube. Below is model DP-6 with PRECISION 9" armtube.

The MØRCH tonearms consist of an arm base with its mounting facilities, bearing assembly, balancing rod and weights, and the arm tube for the cartridge. One appealing feature of the MØRCH design is the arm tube, which can be separated from the arm base by removing a nut. Three arm tubes, each one different mass (from ultra light to extra heavy), are available for specific cartridge requirements.

The standard armtubes are being phased out and replaced with armtubes called narrow. They differ from the standard 9" armtube in that the plexiglas flange has been replaced with a metal flange.

  Green dot: Effective mass 4 g

  Red dot: Effective mass 7.5 g

  Yellow dot (discontinued)

  Blue dot: Effective mass 14 g

Standard 9" armtubes

The fundamental tonearm resonance (present in all arms) is partly determined by the compliance and the weight of the cartridge that is to be used and partly by the weight of the arm, known as the “effective mass”. However, the frequency of the fundamental resonance can be moved up or down by altering the mass of the tonearm. Thus, by choosing the correct arm tube out of 3 available, the fundamental resonance can be moved to a frequency where it does not interfere with the audio signal.

Typical DP-8 lateral resonance. Be aware that at very low frequencies where the modulation is horizontal, there is no fundamental resonance.
The amplitude just rolls off downwards. The graph was taken from this document, which contains more DP-8 examples

With the lightest of the arm tubes you achieve the lowest effective mass, and with this particular arm tube the MØRCH tonearm is the lightest available today. This arm tube is designed for cartridges using a low tracking force, since they have a high compliance. For cartridges requiring a high tracking force (usually low compliant) one of the heavy arm tubes should be chosen. Users that own more than one cartridge can mount each of them in its proper arm tube. Changing cartridges then becomes a simple swap between arm tubes. Thus the mass of the arm is always optimized for its cartridge.

A cavity in the central body housing the bearings is off-centered in the forward direction, providing an asymmetric mass distribution for the prevention of symmetrical barrel resonances. Both the rod with its balancing weights and the arm tube are rigidly attached to the arm’s central body. The body itself is solid and very heavy. Thus vibrations originating in the cartridge are efficiently damped before they reach the bearings, their stability being assured.

In addition three counterweights of different size, and one tracking force weight contribute to the ideal concentration of the arm’s mass close to the fulcrum. The lateral balance is adjusted by way of the counterweights, which are eccentrically positioned on the counterweights rod.

The bearing assembly in the above mentioned cavity is in height located as an extension of the horizontal plane of the record surface. Therefore with warped records the motion of the stylus will remain vertical when bumps” are negotiated and warp wow will not be heard.

The antiskating force is applied by a watch spring. Its tension is adjustable for maximum accuracy even while a record is playing. The tension is transferred via a nylon string which is attached to the outside wall of the arm’s central body. As the arm tube moves over the record, the correct geometry between the spring/filament assembly and the central body’s rotation provide for the exact variation of skating compensation over the entire playing surface of a record.

The tonearm is adjustable for the vertical tracking angle as well as the azimuth.

A Special version of the 9" arm tube called PRECISION is supplied with a wide cartridge mounting platform having the underside precision ground for perfect contact with especially wide cartridges.

Also 12" armtubes are available. They are available only with the narrow headshell such as the one on the narrow 9" armtubes. PRECISION armtubes and 12" armtubes are available only with red and blue color codes.

Top: Model DP-6 with the Precision armtube. Bottom: Model UP-4 with regular armtube.

Copyright © 2012 H.H. Moerch

Moerch DP-8/DP-6/UP-4 Patents: United States No. 4,257,615, United Kingdom No- GB 2 035 656 B