ZXY-EI16 Fly-Lead Microphone Transformer, Audio Isolation Type, 50 Hz - 20 kHz, Turns Ratios 1:5 and 1:6, EI16 Laminated Steel Core, Dimensions 16.5 x 14.5 x 14.5 mm

1. Product Name

ZXY EI16 fly-lead audio isolation microphone transformer, model B2456 for the 1:5 version or model B2577 for the 1:6 version. EI16 laminated steel core, insulated bobbin, coil wrapped externally with protective tape, four color-coded leads, frequency range 50 Hz to 20 kHz, dimensions 16.5 mm length, 14.5 mm height, and 14.5 mm depth.

Overview. The core is an EI16 laminated stack; the coil is wound on an insulated bobbin on the center leg and finished with tape wrapping. This product has no pins; four leads are provided: blue and yellow for the primary, red and green for the secondary.

Fly-lead devices offer flexible routing to the microphone housing, cable harness, or assembly interior once the mechanical design is finalized, whereas pin-type transformers require PCB changes. Two standard turns ratios cover common step-up needs, and custom windings are only required when neither fits.

2. Features

EI16 laminated steel core. The core uses an EI16 laminated stack rather than a solid block, wound on an insulated bobbin with the coil wrapped in protective tape.

50 Hz to 20 kHz frequency range. Covers the entire audible band, suitable for microphone lines or coupling stages without becoming a bandwidth-limiting factor.

Voice and data coupling. Windings are designed to couple voice and data signals between circuit stages and across isolation barriers, not to transfer power.

Two standard turns ratio versions. 1:5 model B2456 and 1:6 model B2577, allowing the step-up ratio to match circuit requirements without custom design.

Low distortion, wide bandwidth design. Windings are designed for speech clarity while preserving audio playback fidelity.

Dielectric withstand voltage 1500 V. Tested at a 1 mA leakage current limit for 60 s, this is the barrier specification on which isolation performance relies.

Four color-coded leads. Primary is blue and yellow, secondary is red and green, with the dotted polarity mark for each winding shown on the wiring diagram, enabling correct connection without a multimeter.

Compact EI16 footprint. 16.5 mm length, 14.5 mm height, and 14.5 mm depth, small enough to fit inside a microphone housing or beside a connector.

The side view shows a laminated stack rather than a potted block: two outer laminated side legs, the bobbin flange between them, and the tape-wrapped coil end face. Leads exit from the bobbin at the flange, keeping solder points outside the winding window.

3. Advantages

Protects front-end equipment. As an isolation transformer, it prevents the output stage of upstream equipment from being damaged by abnormal conditions on the other side of the barrier.

Eliminates ground loop hum. Resolves AC hum caused by multiple ground points in a system—a common source of noise in audio chains with independently powered units.

Bidirectional interference suppression. Reduces external interference pickup in both balanced and unbalanced transmission, with a single device covering both wiring schemes.

Installation flexibility. The fly-lead design adapts to various mounting and routing scenarios, including cases where no solder pads are available.

Balanced audio quality maintained. Low distortion with wide frequency response preserves speech clarity without compressing the audio band.

Custom production and stock availability. Custom designs are available, while standard versions are factory-direct and kept in stock.

Wire according to the wiring diagram, not the physical lead order. Blue is the primary phase lead, yellow is the primary return; red is the secondary phase lead, green is the secondary return. Dots mark the phase end of each winding, allowing both windings to be connected with the intended polarity without trial and error.

4. Applications

Professional audio equipment. Lavalier microphones, camera microphones, instrument microphones, microphone preamplifiers, and audio isolation modules.

Audio systems. Signal isolation and noise elimination in high-end speakers, home theater systems, and automotive audio.

Communication equipment. Signal coupling for telephones, fax machines, VoIP terminals, and modems, requiring isolation between the line side and equipment side.

Industrial and broadcast systems. Audio signal isolation and transmission in public address and conference systems, including wiring between rooms and racks.

Both views capture the same body from the lead side, illustrating layout considerations: leads exit upward from the bobbin, so the component requires clearance above the flange rather than mounting area below it. This is why the design was chosen for microphone cavities and cable harness assemblies.

5. Application Specifications

The following specifications are the declared data for this model: general data, electrical parameter tables for each type at 25 °C, physical dimensions, and lead definitions.

5.1 General Specifications

5.2 Electrical Specifications, Both Turns Ratio Versions, 25 °C

Inductance is measured at 1 kHz with a 0.3 V test signal and is a minimum value; DC resistance tolerance is ±15%; dielectric withstand voltage is 1500 V with a 1 mA leakage current limit for 60 s. Winding 1 is the primary, i.e., the microphone side; winding 2 is the secondary, i.e., the mixer side.

5.3 Physical Dimensions

5.4 Lead and Winding Definitions