ZXY-6731 Audio Isolation Transformer - 150:600 / 600:600, 40Vrms, 4000VAC, 20-Pin Dual-Row Solder Pins, Multi-Fin Industrial Enclosure

1. Product Name

ZXY-6731 audio isolation transformer. 40 Vrms, dual-row solder-pin terminal array, multi-fin industrial enclosure. Supplied as Model A (150:600-40Vrms) or Model B (600:600-40Vrms).

Identification. The faceplate is printed ZXYAUDIO / TRANSFORMERS, then the impedance configuration, then the model code ZXY-6731. The configuration printed on the label is what distinguishes the two variants: 150:600-40Vrms is Model A, 600:600-40Vrms is Model B. Nothing else on the body differs, so the label is the only external way to tell them apart once they are out of the carton; check it before installing.

Both variants are passive and encapsulated. There is no supply pin, no bias and no active stage: the signal enters the primary, crosses the magnetic path, and leaves the secondary isolated from the primary side. That is the whole function, and it is why the part has no quiescent current and adds no noise of its own.

2. Feature

Two impedance configurations on one platform. 150:600 for impedance matching and 600:600 for 1:1 line isolation, so one qualified design covers two circuit roles.

40 Vrms high-level voltage rating. Rated for high-level audio with strong overload capability, which is what separates it from a line-level-only part.

150 Hz - 600 Hz linear transmission band. Optimised for voice and low-mid frequency audio, the band that telemetry, intercom and paging actually occupy.

Galvanic isolation. Breaks ground loops and suppresses common-mode noise between the two sides.

Low insertion loss, stable phase. Signal level and timing stay consistent across the specified band.

Multi-fin industrial enclosure. Convective cooling ribs move heat away from the encapsulated core and windings.

Flame-retardant moulded body. Heavy-duty housing with epoxy resin potting to UL94 V-0.

4000 VAC dielectric strength. Primary-to-secondary withstand well above the 40 Vrms working level.

Operating range -40 °C to +105 °C. Industrial temperature coverage for outdoor and enclosed equipment.

20-pin dual-row solder-pin array. Primary 1-5, secondary 1-10 and auxiliary 1-5, wired out for direct chassis harness connection.

The heat path is worth a note, because it is unusual in a signal transformer. Audio levels of 40 Vrms are well above line level, and a part handling them continuously dissipates more than a line-level transformer would; the fins give that heat somewhere to go, and the epoxy potting conducts it from the winding to the housing. The result is a body that stays inside its temperature range in an enclosure without airflow.

3. Advantage

Wide impedance options from one design. Requalifying a second circuit role does not mean a second qualified part, which shortens project time.

Signal integrity with minimal loss. Low insertion loss and phase shift keep level and timing intact through the transformer.

Low distortion. Accurate transmission at professional grade rather than a deliberately coloured sound.

Rugged industrial construction. Resists thermal stress and mechanical vibration, so it survives where a bench-grade part would not.

Sealed epoxy potting. Environmental protection and consistent performance over the service life.

Built for critical environments. Suited to professional and industrial systems where a failure is not a routine event.

The 4000 VAC primary-to-secondary figure matters more than the 40 Vrms working rating suggests. A barrier that holds four kilovolts is not there to survive normal operation; it is there so that a fault on one side - a shorted supply, a lightning surge on a telemetry line, a mis-wired mains feed - does not put hazardous potential on the other. In broadcast and industrial installations that separation is a safety requirement as much as a noise measure.

4. Application

Broadcast and telemetry audio. Clean balanced audio transmission in broadcast consoles, remote broadcast units and telemetry systems.

Voice and intercom transmission. Impedance matching and isolation for clear, reliable voice communication in intercom and paging systems.

Studio signal routing and preamps. Balanced audio routing, preamplifiers and mix consoles, maintaining signal integrity and reducing noise.

Industrial audio isolation and grounding. Electrical isolation and ground loop elimination in industrial audio systems and control environments.

The common thread is a long cable between two pieces of equipment on separate earths. Telemetry lines run between buildings, intercom runs between rooms on different distribution boards, and industrial audio runs past drives and contactors. In each case the transformer is placed at the boundary, and the pair of impedance options lets the same part either match a low-impedance source into a 600 ohm input (Model A) or sit transparently in a 600 ohm line (Model B).

5. Application Specifications

5.1 Performance characteristics

5.2 Specification table

5.3 Terminal assignment (20-pin dual-row array)

6. Quality & Testing Assurance

Every unit is produced under a controlled manufacturing process and verified before shipment. Each one is tested for audio signal isolation and for 40 Vrms integrity, so a part that fails the barrier or the voltage rating does not leave the line.

The product carries CCC, CE, RoHS and UL compliance. The enclosure is flame-retardant and the epoxy potting is rated UL94 V-0, which is the flammability classification the UL claim rests on.