Sowter 9762
DAC Interface Transformer

PACKAGE OPTIONS Part Number
Threaded grommet Coloured Leads 9762-E 

APPLICATION For use with most current out Digital-to-Analogue Converters.  Designed for and tested with AD1865N-J .  Should also work well with  AD1851, AD1852, AD1853, AD1861, AD1862 . Provides current to voltage conversion with approximately 22 dB gain.  Presents a low impedance to the DAC output for best frequency response. Provides significant sound quality improvement when compared to other interface methods. Ensures full isolation of digital noise in ground and supply rails.  An I/V resistor of 200 ohms is suggested but there is sufficient inductance for good quality operation with higher values.  Lower values may improve the souns but will reduce the output. Can be configured to drive 9335 attenuator without loss of bandwidth. Can be used driven from multiple parallel DAC's to increase output level.

The I/V resistor across the secondary of the transformer instead of the primary has yeilded the best result according to some customers.  The value of the resistor should be increased by the ratio squared.  The table below suggests values for rexperiment.

FEATURES Exceptionally large and high performance transformer.  Twin secondary windings for driving differential (push-pull) amplifier. These may be used in parallel to improve the bandwidth and reduce the output impedance to 8K which is suitable for driving our type 9335 attenuator.  Mumetal core for minimal harmonic distortion.  Mumetal can for magnetic shielding.
CAN DIMENSIONS 45 mm Dia. x 52.5 high
PRIMARY INDUCTANCE 2.3 H 
PRIMARY DC RESISTANCE 6.5  Ohms  approx.
SECONDARY DC RESISTANCE 1.25k Ohms approx
RATIO 1 : 6.4+6.4
SUGGESTED I/V RESISTOR  Across
primary
secondaries parallel 200 Ohms
secondaries series 100 Ohms
Across secondary secondaries parallel 4.2k Ohms
secondaries series 16k Ohms
FREQUENCY RESPONSE (Typical) Parallel secondary windings +/- 1.5 dB 5 Hz to 100 kHz
Series secondary windings +/- 1.5 dB 5 Hz to 50 kHz
  Sowter 9762 connections
E A Sowter Ltd
PO Box36 IPSWICH IP1 2EL England
Tel: +44(0)1473 252794
Fax: +44(0)1473 236188