Quantum 2.00 Tips Part 1

I played around with a few of these parameters last night. I have never liked the two rock model but switched cabs, changed sag and a few more tweaks and just couldn't put the guitar down.

This is awesome info Cliff! and the sag param is absolutely wonderful now.
 
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?
 
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?
 
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?

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?
 
The Sag-O-Meter on the Badger 30 seems less responsive to Master and Sag values, but it does respond. On the other hand, the Euro Blue or a Plexi or...
 
boost your signal before the amp - that'll drive it harder?
Maybe, maybe not.

If the preamp is already clipping hard, increasing the amp's input signal won't drive the power amp any 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?

Your firmware is fine. If the power supply isn't sagging much then it is what it is. Some amps just don't sag much, especially cathode biased amps (aka "Class A").
 
Keep in mind there are a couple of meters on that page. You see the B+ meter when you have Supply Sag highlighted on the front panel and you see the gain reduction meter when the other parms are highlighted.
 
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.
 
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.

Found the same:
http://www.aikenamps.com/index.php/what-is-sag
;)
 
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