![what is bias guitar amp what is bias guitar amp](https://images.reverb.com/image/upload/s--08dW7hjq--/t_card-square/v1600037880/llug3ac1e4xr79tetecm.jpg)
Let’s see how not to get cheesed off with us ! Then you can come another set from this website ?, but later be cheesed off as the new set lasted 5 months and you will think I sell rubbish 6L6’s. Above 30 watts, you will cause them to start glowing dull red ( “red plating”) and they will be cooked to death. Most manufacturers state the maximum power the valve can dissipate is 30 watts. The same process is true for E元4‘s, KT66, KT77, KT88, but the numbers will be different according to the maximum power the valve can handle In this example, I will use the figures for the popular 6L6GC as found in Mesa Boogie, Peavey, Fender etc etc etc. Also this affects the amount of power they use. This is to allow the valve to operate in the straight part of the amplification characteristic so that they produce a nice clean sound. A bit like a car engine needs a certain amount of fuel to run when the car is just sitting. Output valves need to have a certain amount of current flowing through them even when sitting doing nothing. This is a challenge as my wife tells me that I can make a cheese sandwich sound complicated ! I am attempting to write this so as the musicians can understand and so the idea is that I make it hopefully simple to understand.
![what is bias guitar amp what is bias guitar amp](https://i.ytimg.com/vi/j__if38cm2o/maxresdefault.jpg)
There is talk of setting the bias “cool” or “hot” and the effects on output valve life. This is also related to the matching of the valves. Tape up any openings in the pot case, the pot can then be placed in a vise, held at the shaft tip and cut down with 1/8" of the shaft protruding.Ī needle file or fine metal cutting blade can be used to cut a slot in the shaft for screwdriver adjustment.There is a lot of discussion on the black magic of setting the bias on the output valves in your amp. The advantage with dual biasing.U don't necessarily need a set of matched tubes and as the tubes age, you can always keep them in the audible sweet spot zone.įWIW.if your bias control is prone to being bumped, I have an easy fix which I have used when the correct pots are not available. between tube draw.Īs Dan suggests, don't sweat the numbers too much, in the end, it's all about how it sounds. I use separate bias controls.(one for each side of the o/p transformer) on the amps that I build and the audible 'sweet spot' tweak is very noticable.Įven with a set of fresh 'matched' tubes, measurements can show a spread of 0 to as much as 5 m.a. After the tweak, check you bias reading again with the amp at idle /no guitar ,to be sure you are not exceeding the high side of current draw.
![what is bias guitar amp what is bias guitar amp](https://i.pinimg.com/originals/e0/72/8a/e0728accc9d6388660cf4769a9ce2b78.jpg)
and u get them into that 35-45 range, I would suggest a fine tweak by ear.With the amp warmed up, running and tone/volume controls set to mid points, plug your guitar in, let a low note sustain and do a fine clockwise/counter clockwise adjust on your bias control, you should hear a sweet spot where the bottom end opens up.
#What is bias guitar amp how to
Once you have contacted Chris on how to monitor your current draw on the o/p tubes with your multi-meter. So, how many test points do you have to measure off of. Too much current and the tubes would have a short life, too little current and distortion rises. However if it's common to both tubes, 60ma would be pretty cold. In your case, from the schematic, 60ma per tube would be right near the maximum but still safe. The bias setting is determined by the tube in question, and its maximum plate power dissipation based on the voltage on the tube. Also, did he give you one test point (common to both tubes) or two test points (each tube).
#What is bias guitar amp install
The question is, did Chris install 1 ohm at both tubes or each tube. Chris probably installed 1 ohm cathode resistors to measure off of, so the math is basically whatever you read in millivolts, it's the same as milliamps. Then, a little thing called Ohms Law is used to calculate the current. While it can be measured directly in milliamps, typically it is measured in millivolts taken across a 1 ohm or 10 ohm resistor. Bias set the amount of current flowing through the tube at idle (no guitar playing).