The **JT-111-R** is a high-performance, chassis-mount line input transformer manufactured by **Jensen Transformers**. It is widely considered an industry standard for high-end audio equipment, particularly for balancing unbalanced signals or isolating ground loops. --- ### 1. Key Technical Specifications Below are the primary electronic characteristics of the JT-111-R: | Parameter | Specification | Notes | | :--- | :--- | :--- | | **Turns Ratio** | 1:1 | Unity gain transformer | | **Impedance** | 10 kΩ / 10 kΩ | High input impedance | | **Frequency Response** | 0.25 Hz to 100 kHz | Extremely flat response | | **Max Input Level** | +19 dBu @ 20 Hz | High headroom for pro-audio | | **THD** | < 0.001% @ 1 kHz | Minimal harmonic distortion | | **Shielding** | Mu-Metal Can | Superior EMI/RFI protection | --- ### 2. Core Electronic Components & Construction The internal architecture of the JT-111-R is designed for maximum transparency: * **Core Material:** Uses a specialized high-permeability nickel alloy (Mu-Metal) core. This reduces hysteresis distortion and allows for high signal levels at low frequencies without saturation. * **Faraday Shield:** Features an internal electrostatic shield between the primary and secondary windings. This significantly improves Common Mode Rejection Ratio (CMRR), typically around **107 dB at 60 Hz**. * **Windings:** Precision-wound copper coils designed to minimize leakage inductance and capacitance, which preserves high-frequency phase linearity. * **Enclosure:** The "R" suffix indicates a round Mu-metal housing with wire leads, providing magnetic shielding from nearby power transformers or motors. --- ### 3. Application Circuits The JT-111-R is typically used in the following electronic configurations: 1. **Isolation Transformer:** Placed between two pieces of gear to break ground loops (eliminating hum and buzz). 2. **Unbalanced to Balanced Conversion:** Converting a consumer RCA signal to a professional XLR balanced signal. 3. **Input Stage:** Used as the front-end for high-quality preamplifiers or mixing consoles to provide "galvanic isolation." --- ### 4. Wiring Diagram (Lead Colors) | Lead Color | Function | | :--- | :--- | | **Red** | Primary (+) Input | | **Brown** | Primary (–) Input | | **Orange** | Secondary (+) Output | | **Yellow** | Secondary (–) Output | | **Black/Clear** | Case Ground / Shield | ---