I bought one because they are described as high gain and I thought it would sound good when I wanted extra distortion but it sounds like a cheap wore out tube. I'm gonna stay away from Groove Tubes as there are much better tubes on the market. Try a Tungsol, JJ, or a Electro Harmonic, they sound much better.

I put this in V-1 of my HiWatt. I noticed it right away.I run Tung-Sol in V-2 and V-3.It's a rich & smooth distortion when you overdrive it. Even the cleanest settings are warmer with "tube vibe" between notes. No one would regret putting this in their tube collection. Have fun!

On the scale of .5 to 5.0,I gave it a 3.0 for features because I need a tube that gives me both lots of gain and a nice crisp clean sound. This tube has a good clean old-style sound, but no gain whatsoever. It does not give my amp enough gain. I gave it a 5.0 for quality because these tubes have a long lifespan. I play every day and I had these for four years. I give this tube a 4.0 because there are tubes of the same quality at a cheaper price. Overall, its a good tube for classic rock and blues, but I don't recommend using it for metal.

I have put these in a few different amps over the last 5-10 years and have really had none of the problems anyone is talking about. They have always added to the sound of the amps I have used them in. They are high in price and there may be other tubes as good or better for less but these are easy to get and I will keep on truckin with these tubes until I have a problem.

Do not believe the warranty against microphonics or rattling -- you are better off to buy the competing tubes and test them yourself. Groove tubes' testing procedures must be nonexistent. I bought four these things and only one of them was better than a similar tube costing 1/2 the price. Combo amps shake rattle and roll these really bad -- unless you like that extra rattling noise you are best to avoid GT tubes !