SOWTER AUDIO TRANSFORMERS
SOWTER TYPE 9990

1:20 Transformer for Moving Coil Phono Cartridge BUY

9990 frequency response

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 1 to 15 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 resistor (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 side leads,PCB pins or threaded grommet . This transformer replaces types 7136 and 9575
RATIO 1:20  (26 dB)
PRIMARY INDUCTANCE 350 mH approx
DC Resistance (primary) 1.96 Ohms approx
DC Resistance (secondary) 1230 Ohms approx
FREQUENCY RESPONSE 5 Ohms source (-3 dB points) 5Hz to 80 KHz