By the way you typed your query, you're not even close to being qualified to touch the insides of your amp. It took me 5 years and countless hours of dabbling with DIY electronics to finally gather enough confidence to fiddle with the insides of my amp, and I almost broke the amp/electrocuted myself on the first try.
Each tube draws a certain amount of electricity different from others, even of the same type or brand. You need to bias each and every new set of power tubes you plug into the amp. Preamp tubes are plug and play.
I'll at least tell you what I used on my personal amp:
1. Digital multimeter
2. 1 ohm, 1 watt, 1 percent metal film resistor (one per each power tube on your amp)
The method I used on my amp is called the cathode resistor method. This involves desoldering the ground wire on all power tube sockets (the things your power tubes plug into, usually pin 8 on 8-pin tubes) and soldering a 1 ohm, 1 watt, 1 percent resistor between this pin and chassis ground. It's very important to get 1 ohm, 1 watt (or higher), 1 percent (or better) resistors or the measurements will not be as accurate. You will measure the so-called plate voltage of the amp from pin 3 of any of the power tubes, get that value, then find out how much current your tubes need to perform at optimum conditions, which can then be measured via the resistors we soldered earlier. Adjust the bias pot (small square/circle thing in the amp with a screw head that can be turned) until you get the optimum current as per the calculated range. Below are some websites that might help you.
http://www.duncanamps.com/technical/lvbias.htmlhttps://robrobinette.com/Tube_Bias_Calculator.htmBefore attempting any of these, please read up on
draining filter capacitors,
using a multimeter, and
general electronics safety guidelines.
Please take note that I am only sharing you knowledge I got via the Internet. I will NOT be responsible for any damage or injuries you sustain should you decide to try this yourself.
