QED Metal 4mm Banana Plug - Pair

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Airloc Metal

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AIRLOC is QED's award winning loudspeaker cable termination method using specialist equipment.

Put simply, this is the best termination method to use with QED loudspeaker cables. The science  and engineering of loudspeaker cable doesn't stop with the cable…


New strengthened plug

The new Forté plug pin section is designed to maximise contact area throughout the wide tolerance range encountered in 4 mm amplifier and speaker sockets. Here, some are quite tight whereas others are loose, so the spring loaded Forté blade is designed to fit into smaller and larger sockets with equal insertion force.

This means that the contact area is maximised and the connection remains uniformly tight.


24k Gold Plated

Plugs are gold plated to eliminate oxidization, ensuring a life-long low resistance connection


  • 24k Gold plated
  • High copper brass body
  • AirlocTM cold weld system
  • Fits 6 mm and 8 mm binding posts
  • Minimum cable size 0.75 mm2
  • Maximum cable size 5.5 mm2
  • Accepts entire QED cable range
  • Colour-coded metal barrels
  • Available in red, black



Airloc™ is a form of cold weld system that can be used to permanently attach QED Forté™ banana plugs or spade terminals to our entire range of speaker cables.

One of the main reasons for choosing a QED speaker cable is the superior d.c. resistance characteristics offered by our exclusive use of 99.999% oxygen free copper conductors. It seems a shame then to ruin all this attention to detail by neglecting the most vulnerable area of the speaker cable chain - that of the physical interface between cable and amplifier or speaker terminals.

Seen under a microscope the surface of a typical copper strand is very rough and so using normal screw type terminals - as found on binding posts or cheap banana plugs - electrical contact is only made in a relatively small number of places. Add to this a layer of oxidation - which is inevitable if copper is exposed to the air for even a short time - and the combined resistance of the cable and its termination can creep back up to levels present in a more inferior cable.

By using a cold weld crimp type termination Airloc™ plugs squash the conductors and plug together to improve contact area and reduce resistance.

As can be seen in the graph below, by the time the full pressure has been applied the resistance of the joint has reached a minimum value.

Now, because all the air has been removed from the joint there will be no oxidisation of the contact surfaces so the low resistance will remain for the lifetime of the cable. During the cold weld process the cable and plug become one solid piece of metal.