Tubes

Can anyone tell me is there a difference between a 5y3 tube and a 5y3gt tube, also should i get N.O.S. or just get new ones. if so what kind

If your unit calls for a "GT", you should not use a "plain" 5Y3. If your unit calls for a 5Y3G, you may use the "GT"--In other words, the newer tubes have suffix numbers, and usually can be sub'ed for the older tubes. I believe the "G" stands for "glass"--don't know what the "T" is for---As for NOS, vs. new--that's a "toss-up", I never worry about, with the exception that I won't purchase tubes made in China.-- Ron Rich

Thanks so much, Tubedepo here i come....

Ron Rich wrote:If your unit calls for a "GT", you should not use a "plain" 5Y3. If your unit calls for a 5Y3G, you may use the "GT"--In other words, the newer tubes have suffix numbers, and usually can be sub'ed for the older tubes. I believe the "G" stands for "glass"--don't know what the "T" is for---As for NOS, vs. new--that's a "toss-up", I never worry about, with the exception that I won't purchase tubes made in China.-- Ron Rich

You'll never catch a chinese tube in any of my sets either, Ron.

Oh and Ron, perhaps this might help:

A 5Y3G is a glass-encased "shoulder style" tube.
A 5Y3GT is a glass-encased "straight tubular" version.
The 5Y3GTA or "B" is an improved version - better power rating.

Matt,
Thanks--I had forgotten what the "T" was--BTW-- I think --if memory serves me well--a 5Y3, is a metal envelope, if my great, but not too long memory, serves me well-- Ron Rich

The GTA and GTB series are tubes built with a fixed warm up time.

In the old sets with tube filaments wired in series, if the tubes warmed up at different rates, the tube that warmed up first would get an overvoltage until the other tubes warmed up. That tube would burn out more frequently than the others. So they started designing tubes with a fixed warmup time: 11 seconds.