Don't attempt to do this unless you understand the safety precautions you must take to prevent yourself from being electrocuted. These amps have upwards of 500 volts DC running through them and if you put your hands in the wrong place, it can kill you. The number one rule is to never touch the chassis with both hands at one time. That completes a circuit through your heart. I do it several times in the video but I am very careful where I touch the chassis. Never touch the wires inside. This is my process of biasing my amps. I had to learn on my own so there are probably better ways of doing it but this works and I have used this method on all of my amps for years. You only need a decent Digital Multi-Meter and either a single or dual bias probe. The dual is much faster and convenient. You can make your own probes but I have never looked into it. There are other products out there like the Weber Bias Rite but I have never used it. Some people bias by ear. I prefer to have a number range that I can work with. I tend to bias on the cold side which preserves tube life. The tube plates can glow red if you bias them too high. That will damage them. It turns out it is not that easy to find two tubes that bias within 5% tolerance and it can be a real pain and expensive trying to find two tubes that are matched. There are differing opinions on if matched tubes actually sound better. I'm torn on this one but in general, I think it is best if you can match them. They work together better that way. They still sound good if they are not matched exactly. I don't think Fender ever bothered to match tubes at the factory. They just popped them in.
Link to Weber Bias Calculator: www.tedweber.co...
Link to most Fender amp circuit schematics: www.thevintages...
7 сен 2024
