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Air Core Foil Inductors
Precision copper foil air-core inductors engineered for high-fidelity loudspeaker crossover networks. Lower skin effect, higher dimensional stability, and cleaner sonic performance than conventional wire-wound designs.
Leading Edge Technology for Loudspeaker Crossover Networks
Bridgeport Magnetics manufactures precision copper foil air-core inductors designed specifically for high-fidelity loudspeaker crossover networks. Using advanced laminating technology, high-purity copper or silver foil is tightly wound onto a Lexan polycarbonate tube under high tension and vacuum-fused for exceptional dimensional stability.
These foil-wound air-core inductors deliver measurable advantages over conventional wire-wound designs, including negligible skin effect below 100 kHz, perfectly linear inductance with zero core saturation, and significantly lower stored charge and power loss. The result is cleaner signal transfer, reduced distortion, and cooler operation even under prolonged high-power conditions—making them ideal for state-of-the-art crossover designs where sonic accuracy and long-term reliability are critical.
Mounting options include a single polycarbonate screw through the central bore, silicone elastomer, or hot-melt adhesive for flexible integration into crossover boards.
Air Coil Foil Inductor Specifications
- Negligible skin effect below 100 kHz — many orders of magnitude lower than conventional wire-wound inductors
- High winding tension and vacuum fusing lock the conductors rigidly in place, eliminating relative motion and the FM distortion caused by reactance modulation in wire-wound designs
- Flat inductive reactance from 5 Hz to 50 kHz
- Zero saturation distortion thanks to true air-core construction with no magnetic materials
- Highest space factor (ratio of conductor cross-section to total cross-section), delivering lower DC resistance in comparable dimensions
- Negligible power loss from skin effect and extremely low stored charge
- Cooler operation under prolonged high-power conditions due to superior heat dissipation from high winding density
Air coil foil inductor core (Lexan polycarbonate tube)
Leads: 0.010 x 0.321 inch
Conductors: 99.99% pure copper
Dielectric: 0.0015” thick polypropylene film
Gauges: 12,14, and 16 AWG
Inductance Tolerance: +/- 2.5%
| Inductance (mH) | DCR #12 AWG (ohms) | DCR #14 AWG (ohms) | DCR #16 AWG (ohms) |
| 0.05 | 0.013 | 0.026 | 0.031 |
| 0.08 | 0.027 | 0.042 | 0.065 |
| 0.11 | 0.032 | 0.05 | 0.078 |
| 0.15 | 0.034 | 0.054 | 0.086 |
| 0.2 | 0.043 | 0.068 | 0.108 |
| 0.22 | 0.045 | 0.071 | 0.112 |
| 0.27 | 0.049 | 0.078 | 0.124 |
| 0.3 | 0.052 | 0.082 | 0.129 |
| 0.33 | 0.053 | 0.083 | 0.13 |
| 0.39 | 0.06 | 0.095 | 0.15 |
| 0.47 | 0.07 | 0.11 | 0.173 |
| 0.5 | 0.075 | 0.12 | 0.19 |
| 0.56 | 0.083 | 0.13 | 0.204 |
| 0.62 | 0.09 | 0.142 | 0.225 |
| 0.68 | 0.098 | 0.154 | 0.242 |
| 0.82 | 0.111 | 0.175 | 0.276 |
| 1 | 0.12 | 0.188 | 0.295 |
| 1.1 | 0.132 | 0.204 | 0.32 |
| 1.2 | 0.141 | 0.22 | 0.343 |
| 1.3 | 0.15 | 0.235 | 0.368 |
| 1.5 | 0.16 | 0.251 | 0.394 |
| 1.8 | 0.191 | 0.3 | 0.471 |
| 2 | 0.202 | 0.318 | 0.497 |
| 2.2 | 0.211 | 0.332 | 0.522 |
| 2.7 | 0.235 | 0.37 | 0.583 |
| 3.3 | 0.268 | 0.421 | 0.661 |
| 3.9 | 0.304 | 0.477 | 0.748 |
| 4.7 | 0.348 | 0.547 | 0.86 |
| 5 | 0.362 | 0.565 | 0.882 |
| 5.6 | 0.392 | 0.612 | 0.955 |
| 6 | 0.415 | 0.648 | 1.012 |
| 6.5 | 0.422 | 0.658 | 1.026 |
| 7 | 0.431 | 0.672 | 1.048 |
| 7.5 | 0.44 | 0.686 | 1.07 |
| 8 | 0.451 | 0.704 | 1.099 |
| 8.5 | 0.462 | 0.72 | 1.122 |
Through our precision copper foil air-core inductor designs, we’re delivering the ultra-low skin effect, exceptional dimensional stability, and uncompromising sonic accuracy that today’s highest-performance loudspeaker crossovers demand.
High-end and reference loudspeaker crossovers
Maximum transparency and lowest possible distortion for critical listening.
Critical midrange and tweeter filter sections
Where skin effect and microphonics most affect perceived clarity.
No-compromise DIY and commercial speaker designs
Preferred by builders who refuse to settle for wire-wound coils.
High-power amplifier and studio monitor crossovers
Cooler operation and superior heat dissipation under demanding conditions.
Precision audio filtering where core saturation and magnetic distortion cannot be tolerated
True air-core performance with zero magnetic distortion or hysteresis.
Precision-Tested Copper Foil Air Core Inductor
Every Bridgeport Magnetics copper foil air core inductor is designed and manufactured in the United States at our facility in Shelton, Connecticut.
Each unit is individually tested for inductance and DC resistance to confirm it meets the specified values and tight ±2.5% tolerance. This unit-by-unit verification, combined with controlled high-tension winding and vacuum fusing, delivers consistent high-tolerance performance from one inductor to the next.
Let's build yours to spec.
Custom magnetics engineered and manufactured in the USA. Tell us your requirements and our engineers will help.
Frequently Asked Questions
What are air core foil inductors?
Air core foil inductors are precision coils wound from flat copper (or silver) foil instead of round wire, with no magnetic core. This design delivers lower skin effect, higher dimensional stability, and cleaner performance in high-fidelity loudspeaker crossover networks.
Why choose copper foil inductors over traditional wire-wound inductors?
Copper foil inductors (Air Coil Foil Inductor) offer significantly lower skin effect, higher space factor, better heat dissipation, and reduced microphonic distortion compared to conventional wire-wound designs – making them the preferred choice for critical audio crossover applications.
Do air core foil inductors reduce skin effect?
Yes. Because the conductor is a flat foil rather than round wire, copper foil air core inductors exhibit negligible skin effect below 100 kHz—many orders of magnitude lower than standard wire-wound inductors.
What are the main advantages of foil-wound air core inductors in speaker crossovers?
Foil-wound air core inductors (Air Coil Foil Inductors) provide flat inductive reactance, zero core saturation, extremely low stored charge, and superior mechanical stability. These characteristics result in lower distortion and more accurate sound reproduction in loudspeaker crossovers.
Are copper foil air core inductors suitable for high-power applications?
Yes. The high space factor and dense winding of copper foil inductors improve heat dissipation, allowing them to operate cooler under prolonged high-output conditions while maintaining stable inductance and low power loss.
Are Bridgeport Magnetics air core foil inductors made in the USA?
Yes. Every copper foil air core inductor from Bridgeport Magnetics is designed, manufactured, and individually tested for inductance and DC resistance at our facility in Shelton, Connecticut to ensure consistent high-tolerance performance.
