“The Electro-Harmonix Hot Tubes “Amplifier Overdrive Simulator” distortion pedal. The Hot Tubes is one of the gnarleyist sounding distortions I have ever used and it is very versatile. This pedal goes from slightly overdriven tones to all out fuzz, with a wide range of very cool tones in between. It sags like an overdriven amplifier which is why they called it the “Hot Tubes.”
Perhaps made from 1978-1984. Here’s an example w/original packaging. They may have been designated the U-77.
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