SOWTER AUDIO TRANSFORMERS
MICROPHONE TRANSFORMER

9045 Exceptional performance transformer with low microphone loading.
NOTE new version uses different core so performance may be a little different to plots shown below.

9045 microphone input transformer frequency response

FREQUENCY RESPONSE measured using 200 ohm source and 25k0 ohm load and a damping network of 45k0 ohms in series with 25 pF.

9045 mumetal can with thhreaded grommet

APPLICATION

Exceptionally high 20 Hz level, high bandwidth 200 ohm microphone transformer. Minimal microphone loading. Suitable as replacement for original transformer in many vintage recording studio units. 100% geometric balance relative to the secondary centre tap ensures near perfect phase splitting for use with balanced amplifiers

FEATURES

Unusually large Mumetal laminated core for minimal distortion and even at very high levels. Two chamber bobbin provides full geometric balance and 4 internal electrostatic shields for the ultimate in noise rejection and phase splitting performance. The primary windings may be used in parallel for increased voltage ratio when used with 50 ohm microphones. Heavy Mumetal screening can to ensure immunity from hum fields. Phantom powering may be supplied in the 1:5 configuration using the primary center tap (Yellow + Grey). A damping network of 45k0 ohms in series with 25 pF across the secondary may be used depending on the input capacitance of the amplifier..
RATIO 1ct:5ct or 1:10ct
MAXIMUM LEVEL 0.5 % THD at 50 Hz (40 ohm source) +10 dBu
DISTORTION at 50 Hz (Source 40 ohms) 0.05% at +20 dBu
PRIMARY INDUCTANCE 10H approx
TOTAL DCR (Referred to primary) 21 Ohms approx
INSERTION LOSS 10k ohm source 10k ohm load 1.08 dBu
INPUT/OUTPUT BALANCE >60 dB
FREQUENCY RESPONSE 6k4 ohm source 10k ohm load +/- 0.25 dB 15 Hz to 60 kHz
9045 microphone input transformer connections
9045 microphone input transformer input impedance

INPUT IMPEDANCE measured with 25k0 ohm load

9045 microphone input transformer THD

TOTAL HARMONIC DISTORTION measured with 40 ohm source and 25k0 ohm load. Input Level +10 dBu.

9045 microphone input transformer phase response

PHASE RESPONSE measured using 200 ohm source and 25k0 ohm load