FoilQ - Copper Foil Coil

* click here for a certification of compliance

PURITY GUARANTEERoHS Compliant

FoilQ – “Absolute Transparency and Neutrality with Zero Distortion”

Perfect Quality with Zero Distortion, the Ideal Inductor. ERSE’s FoilQ line of coils are an upgrade to the well revered XQ line of coils. ERSE’s FoilQ coils offer the most extreme performance of any air core coil on the market today. The FoilQ line of coils offer improved bass dynamics, reduced microphonic distortion and uncomrimising musical neutrality. ERSE’s FoilQ coils offer our purity guarantee (99.99% pure copper ). This level of purity guarantees maximum sonic quality and performance. FoilQ’s sonic excellence is maintained through ERSE’s proprietary low constant tension devices. This process maintains the crystalline structure of the copper foil and the orientation of the BOPP film, once again insuring maximum fidelity and performance.

ERSE’s 0.003 inch thick high purity copper foil reduces all skin effect from 0Hz to 50kHz. This reduced skin effect allows for a more linear inductance and ESR verses frequency then any other inductor including litz coils. ERSE’s high purity BOPP film is up to 33% thicker then the competition, which correlates to lower interwinding capacitance and improved sonics. The large surface area and thinness of the copper foil and BOPP film significantly reduce microphonics.

Long term reliability is maintained of these FoilQ coils through ERSE’s vacuum fusing of the BOPP to the copper foil. This fusing process removes all oxygen and seals the copper foil from any outside contamination. Get the best sound for your money, today install ERSE’s copper foil coils.

All FoilQ inductors are lead free (RoHS Compliant)

  • Zero Saturation
  • Zero Skin Effect
  • Extremely Low Vibration
  • Sealed to Prevent Oxidation
  • Low D.C.R.
  • Very High Quality
  • RoHS Compliant
  • Tolerance: ± 2.5% centered on nominal value
  • Insulation Temperature: 200°C
  • 99.99% High Purity Copper
    PURITY GUARANTEE

  erseaudio logo Mundorf Jantzen Solen Intertechnik Result
Trade name XQ coils BL140 Perfect Lay Air Coils CU 1.4mm  
Wheeler formula Yes No Yes No No Higher DCR and lower Q factor
Varnish Impregnated Yes Yes Yes No No Varnish impregnated coils offer the lowest possible microfonic distortion
Hysteresis tension devices Yes No No No No Inconsistent winding factor and DCR’s
Precision Orthocyclic tooling matched to .001” Yes No No No No Improved matching of coils. Lower inductive tolerance.
Computerized layer winding Yes No No No No Improved layering and lower DCR.
Purity Guarantee
Click here for details		 Yes No No No No Unknown purity and conductivity can result in smeared sound

Tolerance

 1% 3% 1% 3% 3% Lower tolerances can assure your coil is closer to the advertised value
1.0mh #14AWG coil DCR CLAIMED 0.208 Ω 0.30 Ω 0.21 Ω NA 0.28 Ω Higher DCRs result in increased power loss and reduced performance.
1.0mh #14AWG coil DCR MEASURED 0.211 Ω 0.306 Ω 0.215 Ω NA 0.293 Ω Higher DCRs result in increased power loss and reduced performance.
  erseaudio logo Mundorf Jantzen Solen Intertechnik Result
Trade name EQ coils L100 Air coils NA CU 1.0mm  
Wheeler formula Yes No No NA No Higher DCR and lower Q factor
Bonded coil Yes Yes
optional		 Yes NA No Bonded coils offer lower microphonic distortion
Hysteresis tension devices Yes No No NA No Inconsistent winding factor and DCR’s
Precision Orthocyclic tooling matched to .001” Yes No No NA No Improved matching of coils. Lower inductive tolerance.
Computerized Orthocyclic layer winding Yes No No NA No Improved layering and lower DCR.
Purity Guarantee
Click here for details		 Yes No No NA No Unknown purity and conductivity can result in smeared sound

Tolerance

 2% 3% 3% NA 3% Lower tolerances can assure your coil is closer to the advertised value
1.0mh #18AWG coil DCR CLAIMED 0.471 Ω 0.49 Ω 0.55 Ω NA 0.60 Ω Higher DCRs result in increased power loss and reduced performance.
1.0mh #18AWG coil DCR MEASURED 0.482 Ω 0.531 Ω 0.572 Ω NA 0.581 Ω Higher DCRs result in increased power loss and reduced performance.