When buying power tubes for your amp it is always a good idea to purchase an extra set that is matched to the set you are buying. For example if you are buying a matched pair of tubes for your amp get a matched quartet. Once you set the bias for the first pair from the quartet the second pair do not need to have a bias adjustment. This can apply for amps with any number of power tubes. If your amp uses a quartet purchase two quartets that match each other. This is very helpful if you are on a gig and a power tube goes bad. You can just pull the bad set and put in the new pair without the bias adjustment that could take too much time during a performance. Having a leather glove or something to grip the hot tube is also a good idea if this needs to be done during a performance. 300Guitars Shop My shop is located at 1 Executive Dr Unit L Toms River, NJ 08755 Please feel free to email me if you have any questions or are in need of some tech work. Monday: 10am - 5pm Tuesday: 10am - 5pm Wednesday: Closed Thursday: 10am - 5pm Friday: 10am - 5pm Saturday 10am - 2pm. (I am in every other Saturday). I am also an Eminence, Mercury Magnetics, Mojo Musical Supply dealer. I do all the tech work myself so you deal directly with me. I am a one man shop and my hours can vary so please contact me to confirm that I will be open. Email me: firstname.lastname@example.org Call or text me: 848-218-0362 Shipping Info for all repair work: Please ship all repairs to: 1 Executive Dr Unit L Toms River, NJ 08755 I am currently offering all phases of guitar work which includes: Set-ups Fret dressing Re-fretting New hand cut custom bone nuts & saddles Electronics work And amplifier work which includes: Basic maintenance Bias adjustment Repairs and restorations Modifications And more.... Testimonials: David Nicholas - The 20watt amp is sounding fantastic! Delivered the goods at the gig and I'm finding cool tones all over the place with it. Love the cab w Emenince Tonkerlites too- perfect for my sounds! Makes the 12 string sound like a grand piano! Peter Lacis - I had an audition for something recently that was all about Led Zeppelin I -- my custom Pennalizer BLEW THE MINDS of the guys I was playing with. They couldn't believe the sounds coming out of that amp. That album was never in my mind when I came up with the idea....so that's yet another testament to the amazing work that you do. Scott Goldberg - I am very satisfied with the set-up, and the fast turn around. With the "lower" action it feels easier to play. I will definitely spread the word.