Airloc™ is a form of cold weld system that permanently attaches QED Forté™ banana plugs 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 - such 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, 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 either 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. Since the copper contact has been effectively removed from the resistance equation we can concentrate on the plug to terminal resistance.
The plugs themselves are made of solid brass which has roughly twice the resistivity of copper. For this reason our 4mm banana plug was devised so that its crosssectional area would be at least double that of the cable to which it was connected effectively cancelling out the extra resistance of the plug material. QED then plates the connector with high purity gold which has a resistivity almost as low as copper but more importantly does not oxidise in air. The relatively smooth gold surfaces provide a larger contact area than the uneven copper strands in the cable and because the gold will never oxidise the contact surface remains clean and low resistance for life.
The new Forté plug pin section is designed to maximise contact area throughout the wide tolerance range encountered in 4mm amplifier and speaker sockets. Here some are quite tight whereas others are loose, so the spring loaded Forte 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.
QED Forté with Airloc technology; guaranteed low resistance and strength - for life.