Sowter Type 1990
Configurable 1:10 or 1:20 Transformer 3 to 50 ohm Phono Cartridges
|PACKAGE OPTIONS||Part Number|
|APPLICATION For matching moving coil Phono cartridge to balanced or single
sided solid state or valve pre-amplifier. Ensures appropriate loading of
the cartridge and correct matching to pre-amplifier. Ideal for use with
low output cartridges.
Suitable for most cartridges with a dc resistance in the range 3 to 10 ohms. In order to get the correct HF roll off it is recommended to use a Zobel network consisting of 330 pF in series with 9.2k ohms. The loading seen by the cartridge mat be adjusted by means of a secondary load resistor.See the table below. If the cartridge does not require loading just omit the resistir (R)R altogether. Two transformers are required for a stereo system.
|FEATURES Mumetal (76%Nickel) laminated core for minimal harmonic distortion and exceptional bandwidth. 4 separate electrostatic screens for rejection of hum and noise in the cable connecting between the cartridge and transformer. Multiple interleaved windings ensuring exceptionally good bandwidth with a wide range of cartridge impedances. As shown above the bandwidth improves with lower cartridge resistances. The high bandwidth and very low phase shift ensures excellent transient response. Mumetal can for magnetic shielding. Available with colour coded leads or international octal plug for a small extra charge. Available wound with OCC wire as an option. This transformer replaces types 7136 and 9575|
|RATIO||1:20 (26 dB)|
|TOTAL HARMONIC DISTORTION at 20 Hz (6 ohm source) typical||0.05%|
|FREQUENCY RESPONSE 5 Ohm source 100K load with Zobel network (330pF in series with 9.2 k ohms)||+/- 1.5 dB 3 Hz to 100kHz|
|NOTE The transformer should be connected as shown below. The Black (ground) lead is normally connected to the signal ground of the amplifier. You may need to experiment with different connection points to minimize hum.|