Ideal for medium amps like early Super Reverbs or Band Masters. This tube can also substitute a 5Y3 to enhance dynamics and power output!

Ideal for medium amps like early Super Reverbs or Band Masters. This tube can also substitute a 5Y3 to enhance dynamics and power output. Some users have swapped the 5AR4 in their Vox AC30 with a 5U4, noting a reduction in heat development and an extension in the lifespan of the power amplifiers. Additionally, this tube is recommended as a "stability guarantee" for those who can tolerate a minor reduction in performance.