For the transformer core coils BT125, BT140, BT180, T236, VT236, to VT390 Mundorf uses nothing but FERON which is extremely low in losses and distortions. This material is a grain-oriented silicon iron with a sheet thickness of 0.35 mm. This high quality initial material is subsequently heat treated in a special process. In this way, distortions in the material's crystal lattice structure, caused by rolling and stamping, are eliminated. In this way, FERON is provided with a crystal lattice structure which displays optimum magnetic properties. Such a core material is used for the manufacture of high quality audio transformers. It is very seldom used in "normal" transformers, except where very low power loss is important. In this construction type, coils can be manufactured with very low internal resistances and extreme load-bearing capacity. These are the preconditions for a precise deep bass. The ratios of inductivity to internal resistance achieved here can often not even be realised with pure air cored coils, or only at considerably greater financial cost. Technical Specifications: Tolerance: max. 3% core material: FERON Elektrolyte copper 99.99% pure Grain-oriented silicon iron 0.35 mm
In non-impregnated coils, vibration occurs as a result of the current flowing through the coil. The microphonic effect, i.e. the conversion of mechanical into electric oscillations, adds these oscillations back to the original signal as additional information. In this way, details of the original signal are overlaid and rendered unrecognisable. The music loses spatial quality and transparency. This process is prevented by vacuum impregnation.
In vacuum impregnation, the coil is first impregnated with a special lacquer under vacuum. Because of the vacuum, this lacquer flows right into the innermost windings. The lacquer is subsequently dried in an oven at 130 °C. Thus the whole coil is baked into a very solid unit. The individual windings are prevented from vibrating and the original signal remains uncorrupted. Coils treated like that start with the letter V, like VT236 Beside vacuum impregnated coils we offer the baked varnish air coil. The windings of baked varnish coils are made using a special wire. After the coil has been wound it is heated up causing an additional layer of varnish on the wire to melt, bonding the individual windings firmly together. The effect is similar to that achieved with vacuum impregnation, but this process is cheaper for small coils. Baked varnish coils are available with winding diameters from 0.71mm - 1.40mm. All series are identified with a "B" prefix.
Please note: The power values Pmax in the following tables were determined at 20 degrees Celsius ambient temperature and free convection. They are just a guideline and - since we are not the manufacturers - cannot be guaranteed by us.
L denotes inductance, R the DC resistance, D the diameter, Le the length, Wire-W the width of the wire, DxH the diameter and the height.
Besides the transformer core coils with baked wire treatment, we also offer them with copper foil.
The coils are available with the following wire cross sections: