RDH
Fractal Fanatic
Power tubesDoes "tube bias" refer to preamp of power amp tube bias? If I remember correctly there are parameters for each
Power tubesDoes "tube bias" refer to preamp of power amp tube bias? If I remember correctly there are parameters for each
Supply Sag is the most fundamental of the power supply controls. It controls the virtual resistance of the AC input. In a real tube amp the supply sags due to a combination of power transformer resistance and rectifier resistance. Increasing Supply Sag increases this resistance and vice-versa. The higher the resistance the more the supply sags and the more bouncy and spongey the amp will feel. I like to increase Supply Sag a bit and reduce gain. You can monitor the virtual supply on the hardware by selecting the Supply Sag parameter. The gain reduction meter will display the supply voltage in dB relative to idle.
So I can see the meter you describe, but I am a little puzzled as to whether what I am seeing is what you, Cliff, would expect. On none of the amps I tinker with does setting the sag higher have much of an effect on the meter; it seems to indicate around 0-.5db reduction as I play no matter how the sag is set. Is that right, or a bug?
That means your virtual power amp isn't working very hard (drawing much virtual current). What would you need to do to make the power amp work harder and thereby draw more current?
Plug the Axe into a variac?That means your virtual power amp isn't working very hard (drawing much virtual current). What would you need to do to make the power amp work harder and thereby draw more current?
Maybe, maybe not.boost your signal before the amp - that'll drive it harder?
In a real amp I'd expect that bumping the master up would do that. Or increasing the resistor value or choke value. But what I'm saying is that neither of those seems to affect the meter. I just double checked my Badger 30 patch and my Div13 patch. MV on 5 or 10, sag at 2 or 10, always the meter is going between 0 and -.5 db, occasionally -.6db.
Reload the firmware?
A prize to the person who can explain why "Class A" amps don't sag much.
A prize to the person who can explain why "Class A" amps don't sag much.
They have a constant, or close to it, average current. I believe this also makes them less efficient?A prize to the person who can explain why "Class A" amps don't sag much.
A true class A amplifier has no sag because the current draw at full power is the same as the current draw at idle. However, most class A amplifiers aren't biased exactly at the midpoint of the range, and will tend to clip asymmetrically, especially when going into grid clamp on the output tubes, so there will be an offset current component, but it will be much smaller than in a class AB output stage.