NOTE: THESE ARE ALMOST 4" TALL SO CHECK TO BE SURE YOU HAVE ENOUGH SPACE.

These have indirectly heated cathodes like 5AR4s and 5V4s. This means that it takes a minute or so for this tube to supply B+ voltage to the rest of the tubes in your amp, thereby allowing them to preheat and prolonging their life. Prefect in all amps without standby switches. The few extra bucks you spend on one of these will save you lots of money by extending the life of the other tubes in your amp.

NOS in original boxes. Labeled and boxed as International Service Master. The most durable, overdesigned, 5Y3 you'll ever see. These have indirectly heated cathodes which means that they turn on (very) slowly like GZ-34/5-AR4s. This feature helps to extend the life of the other tubes in your amp.

Mike,

I wanted to thank you.

This tube sounds great in my Victoria 518. It really is built like a tank and really brings out the sound of the amplifier.

Thanks again.

Christian