What is a load box?

When using a tube amplifier, you should always connect it to a speaker cabinet before turning it on – or a loadbox. The speaker cabinet (2, 4, 8 or 16 Ohms) must always be connected to the corresponding speaker output of your amplifier. Not doing so can lead to partial or complete destruction of the output stage of the tube amplifier. Most tube amp designers protect their products with fuses etc, but some amps do not have sufficient protection in place. Our general moto is that “It is impossible to predict the behavior of all the amplifiers on the market in case of use without a load (a speaker cabinet or a load box)”.

The electronic term that describes the speaker cabinet with respect to the amplifier is the “load”: we say the cabinet “loads” the amplifier. The term “load box” fits any product that embeds an electronic load. The main parameter of the load box is its impedance, and that is rated in “Ohms”. An 8-Ohm load box must be plugged to the 8-Ohm speaker output of the amplifier.

When using a Torpedo load box, the power sent to the load is turned into heat, so please follow the cooling recommendation of the load box – failure to do so may cause overheating which can lead to damage, both to the load box and to the amplifier. The Torpedo Reload, Live, Studio, Captor and Captor X are load boxes. This term indicates that these products feature a load which can electrically replace the speaker cabinet while safely dissipating (transforming into heat) the power coming out of the amplifier.

The embedded load in the Torpedo products is reactive: it embeds a specific circuit to simulate the complex impedance of a real speaker. This kind of system is widely used in the industry to silently test amplifiers.

voltage test

The high voltage tester (also called dielectric strength test or hipot test) can be carried out using AC or DC. If the high voltage test is performed using DC, it is then combined with insulation; if the high voltage test is made using AC, this is more stressful for the sample and therefore carried out according to the sketch below.