![[-]](https://theultimatetone.com/images/collapse.png "[-]")
06-05-2023, 09:51 PM
Hi Champ81
Yes, delete it.
Regarding post-42:
If you are going to refer to any book, please give a page number or figure number.
Note that a superscript "2" following a quantity means that quantity is squared. A root-sign followed by a 2 is the square-root of 2 = 1.414.
It seems you are looking at the Dissipation Method for setting idle current (TUT2 pg.3-25). The equation quoted is to specifically set the idle heat to 50% of the tube rating. Frankly, it is of more practical use to simply calculate the maximum idle current and know that every value lower is going to extend tube life.
Pa / Va = Ik
25W / 442Va = 56ma
At higher Va, the maximum idle current would be lower, and at lower Va the current can be higher. This just follows Ohm's Law and the Power Equation, therefore:
THERE IS NO SPECIFIC IDLE CURRENT FOR EACH TUBE TYPE
There is no advantage to the sound or to the tube or anything else in the chassis in running the tube flat out. In fact it is mostly detriments. There is no magic idle percentage, 50%, 70%, etc, that all tubes work best at.
When testing an amp (fixed-biased) you will get a clean sine wave with 2mA or so of idle current. The tone may not be as warm as you want, but it does not take a lot to warm it up and beyond that point there is no benefit.
Yes, delete it.
Regarding post-42:
If you are going to refer to any book, please give a page number or figure number.
Note that a superscript "2" following a quantity means that quantity is squared. A root-sign followed by a 2 is the square-root of 2 = 1.414.
It seems you are looking at the Dissipation Method for setting idle current (TUT2 pg.3-25). The equation quoted is to specifically set the idle heat to 50% of the tube rating. Frankly, it is of more practical use to simply calculate the maximum idle current and know that every value lower is going to extend tube life.
Pa / Va = Ik
25W / 442Va = 56ma
At higher Va, the maximum idle current would be lower, and at lower Va the current can be higher. This just follows Ohm's Law and the Power Equation, therefore:
THERE IS NO SPECIFIC IDLE CURRENT FOR EACH TUBE TYPE
There is no advantage to the sound or to the tube or anything else in the chassis in running the tube flat out. In fact it is mostly detriments. There is no magic idle percentage, 50%, 70%, etc, that all tubes work best at.
When testing an amp (fixed-biased) you will get a clean sine wave with 2mA or so of idle current. The tone may not be as warm as you want, but it does not take a lot to warm it up and beyond that point there is no benefit.
