Isolation & Special-Duty Transformers
OBK Ring (Toroidal) Transformer
Audio transformer specs get inflated more than almost any other electronics component — a unit stamped “1000W” often only holds that figure at a brief peak, not as a continuous rating. The OBK ring transformer is built the other way around: copper and core are sized to actually deliver the VA printed on the label as a continuous rating, not just survive it for a few seconds. Its toroidal, ring-shaped core keeps stray magnetic flux low, which matters directly for hum and interference in amplifier and audio-equipment builds, and the compact ring profile runs cooler and mounts more easily into a chassis than a comparable EI-core transformer of the same rating. Double-layer QZ-2 enameled copper winding plus a copper-foil shield between primary and secondary add an isolation barrier beyond the base insulation. The range runs from a compact 150VA unit to a 2000VA model, wound to whatever input/output voltage a specific amplifier, audio chassis, or cabinet installation calls for.
Key Features
Rated for What It Actually Delivers, Not What It Peaks At
The OBK series is built around continuous, honestly-rated power output and a low-noise toroidal core, not inflated peak specs.
True Continuous Power Rating
Copper and core sized to deliver the labeled VA continuously, not just at a brief peak, so the rating on the box matches real-world use.
Low-Leakage Toroidal Core
The ring-shaped core keeps stray magnetic flux low, reducing hum and interference in amplifier and audio-equipment builds.
Double-Layer Insulation
QZ-2 double-insulated enameled copper winding with a copper-foil shield between primary and secondary.
Compact, Easy-Mount Profile
Smaller footprint than an equivalent EI-core transformer, with a base plate for straightforward chassis mounting.
Low Temperature Rise, High Efficiency
Smooth, tightly-wound core construction keeps operating temperature and noise down while holding efficiency high.
150-2000VA Range
Sized and wound to the voltage a specific amplifier, audio chassis, or cabinet installation requires.
OEM & ODM Capabilities
Built-to-Order for B2B and System Integrators
Capacity, voltage, and lead configuration are wound to the specific amplifier, audio device, or cabinet application.
Configurable Capacity
Standard range 150-2000VA, with smaller or larger custom windings available on request.
Input/Output Voltage Customization
Primary and secondary voltages wound to the exact requirement of the amplifier or audio device being powered.
Lead Configuration
Lead length, wire gauge, and color coding configurable to match your chassis wiring layout.
Mounting Customization
Base plate size and mounting hole pattern adapted to your enclosure or cabinet design.
Application-Specific Configuration
Wound and shielded for audio equipment, power amplifiers, or general cabinet-mount electronics.
Small-to-Large Batch Production
From prototype quantities to volume production runs for OEM audio and electronics manufacturers.
Technical Specifications
Core electrical parameters are shared across the OBK series; capacity, dimensions, and weight scale by model.
| Product Name | Ring (Toroidal) Transformer |
|---|---|
| Core Type | Toroidal, high-permeability wound core |
| Frequency | 50/60Hz |
| Dielectric Strength | 2500V withstand |
| Input Voltage | AC220V (base configuration; customizable) |
| Output Voltage | AC12V (base configuration; customizable) |
| Input Leads | L: Blue, N: Red |
| Output Leads | L: Green, N: Yellow |
| Insulation | Double-layer QZ-2 enameled copper wire with copper-foil interlayer shield |
| Capacity Range | 150-2000VA |
| Dielectric | 2500V |
|---|---|
| Frequency | 50/60Hz |
| Capacity | 150-2000VA |
| Core | Toroidal |
| Rated Capacity | Height | Diameter | Weight |
|---|---|---|---|
| 50-100VA | — | — | — |
| 150VA | 55mm | 107mm | 4.1 jin (≈2.05kg) |
| 200VA | 57mm | 108mm | 4.9 jin (≈2.45kg) |
| 250VA | 67mm | 107mm | 5.6 jin (≈2.8kg) |
| 300VA | 60mm | 125mm | 6.2 jin (≈3.1kg) |
| 350VA | 63mm | 127mm | 6.7 jin (≈3.35kg) |
| 400VA | 65mm | 129mm | 7.1 jin (≈3.55kg) |
| 450VA | 66mm | 130mm | 7.3 jin (≈3.65kg) |
| 500VA | 68mm | 134mm | 8.5 jin (≈4.25kg) |
| 550VA | 70mm | 134mm | 9.1 jin (≈4.55kg) |
| 600VA | 72mm | 136mm | 9.3 jin (≈4.65kg) |
| 650VA | 75mm | 137mm | 9.5 jin (≈4.75kg) |
| 700VA | 76mm | 138mm | 9.7 jin (≈4.85kg) |
| 800VA | 77mm | 140mm | 11.5 jin (≈5.75kg) |
| 900VA | 73mm | 143mm | 13.5 jin (≈6.75kg) |
| 1000VA | 75mm | 145mm | 14.1 jin (≈7.05kg) |
| 1500VA | 85mm | 182mm | 21 jin (≈10.5kg) |
| 2000VA | 90mm | 185mm | 22.5 jin (≈11.25kg) |
Construction & Configuration
A toroidally-wound core sits under a double copper-foil shield, with color-coded leads and a base plate for chassis mounting.
Toroidal Wound Core
High-permeability ring core with a smooth, tightly-wound profile that minimizes gaps, noise, and interference.
Double Copper-Foil Shield
A copper-foil shielding layer sits between primary and secondary windings, adding isolation beyond the base insulation.
QZ-2 Enameled Copper Winding
Double-insulated enameled copper wire wound throughout, for consistent electrical performance under continuous load.
Color-Coded Lead Wires
Input leads (L: blue, N: red) and output leads (L: green, N: yellow) for straightforward wiring identification.
Mounting Base Plate
Bolted base plate with mounting holes for direct chassis or cabinet installation.
Compact Ring Profile
Height and diameter scale together across the range, from a 55mm-tall 150VA unit to a 90mm-tall 2000VA unit.
Standards & Test Documentation
Every unit is tested for dielectric withstand; further documentation is available for procurement and design review.
Dielectric Withstand Test
Every unit is tested to a 2500V withstand voltage to confirm insulation integrity.
Double-Layer QZ-2 Winding
Double-insulated enameled copper wire with a copper-foil interlayer shield between windings.
Datasheets & Dimension Drawings
Full parameter sheets and dimensional drawings available on request for design and procurement review.
Need a Transformer Wound to Your Amplifier or Chassis?
Tell us your capacity, input/output voltage, and lead configuration — we'll wind an OBK unit to match.