Warm Up Device Oct 2021 Every now and then I find the need for a warm up device, or dummy load, to replace my Loud Speakers. Whether its to warm up my system prior to a demo, or run in some new parts or piece of equipment I purchased. The ability to run my set up silently, so as not to disturb others is a desirable feature. I  purchased a large pre used Heat sink of ePay and some big Arcol resistors that were in a sale. I need four channels as my semi active speakers are powered by two Stereo Amps. The resistors are all  6R8, 150W, 1%. I bought a 1U 19" rack case and proceeded to cut a large hole in the top. I made the hole smaller than the heat sink, leaving a 10mm strip all round, so I could bolt the heat sink to the case. This exposed the underside of the heat sink, so I could bolt the resistors directly to it, using some heat sink compound. Each resistor was wired to a pair of Binding posts The case has useful vents on the underside and I fitted some large feet, scrounged off another project. These will allow air to circulate freely. That's basically it, big resistors on a big heat sink. I just plug my speaker leads into this and let the gear warm up in silence. Tube amps in particular, need a load attached to the outputs when powered up, to avoid serious damage. This device replaces the load that the speakers provide.