trancegodz
Power User
Should SAG be set to zero when using a real tube power amp like the Mesa Boogie 50/50 and a couple of real cabs, or should it just be turned down, and if so by how much?
Turning it to zero seems to make everything sound better with the above setup, but I am wondering if it still needs to be on but just lowered a lot?
Below is everything I could find about SAG:
Setting SAG (see below) to zero will disable Power Amp simulation, at which point the MASTER becomes a simple level control with 40 dB of range.
MAINS IMPEDANCE (SAG) — This controls power amp dynamics. Higher settings simulate higher power supply impedance, and thus greater tube plate voltage “droop,” for a more compressed feel. This control interacts with the Master and will have little effect if the power amp is not being pushed. As the power amp is pushed and draws more virtual current from its virtual power supply, the Sag control will have more effect.
* IMPORTANT: Turning this control fully counterclockwise defeats power amp simulation for an individual AMP block so you can use it as a PREAMP into an external tube power amp without globally disabling power amp simulation.
Turning SAG to zero disables power amp simulation for the preset. The SAG control has no effect at all when Power amp simulation is switched off in the Global menu.
MAINS IMPEDANCE (SAG) – In a tube amplifier there are physical components of the amp which impede the flow of power in the instance of large transient signal spikes (like slamming a hard power chord). Principally, the transformers, filter capacitors, and rectifier (if it’s a vacuum tube). The power supply voltage falls off in the spike, producing a momentary ‘squish’ in the signal, known as “Sag”. Solid state amps do not produce this effect, only Class AB tube amps (there is no sag in true class A amps as full output power is always present). Sag is what makes old tube amps sound/feel cool. That dynamic reactance to your playing. Our control goes from 0.01 to 10.0 (a 0.00 setting turns the power amp emulation completely off, leaving you with just the preamp portion of the simulation). The closer to 0.01, the tighter and more solid-state like the attack will be (essential for extreme hi gain settings). The closer to 10.0, the looser the feel and string attack. I personally love sag (being an old guy), and wish we had an even greater range with this control. Try dialing more Sag into your next patch!
Early valve amplifiers usually used unregulated power supplies. This was due to the high cost associated with high-quality high-voltage power supplies. The typical anode supply was simply a rectifier, an inductor and a filter capacitor. When the valve amplifier was operated at high volume, the power supply voltage would dip, reducing power output and causing signal attenuation and compression. This dipping effect is known as "sag", and is sought after by some electric guitarists.[10] Sag only occurs in Class AB amplifiers. This is because, technically, sag results from more current being drawn from the power supply, causing a greater voltage drop over the rectifier valve. In a Class A amplifier, current draw is constant, so sag does not occur.
As this effect is more pronounced with higher input signals, the harder "attack" of a note will be compressed more heavily than the lower-voltage "decay", making the latter seem louder and thereby improving sustain. Additionally, because the level of compression is affected by input volume, the player can control it via their playing intensity: playing harder results in more compression or "sag". In contrast, modern amplifiers often use high-quality, well-regulated power supplies. In theory, these keep the supply voltage constant, but in reality there is still some small variation, largely due to resistive losses in the cabling from the power supply to the gain stage.
Turning it to zero seems to make everything sound better with the above setup, but I am wondering if it still needs to be on but just lowered a lot?
Below is everything I could find about SAG:
Setting SAG (see below) to zero will disable Power Amp simulation, at which point the MASTER becomes a simple level control with 40 dB of range.
MAINS IMPEDANCE (SAG) — This controls power amp dynamics. Higher settings simulate higher power supply impedance, and thus greater tube plate voltage “droop,” for a more compressed feel. This control interacts with the Master and will have little effect if the power amp is not being pushed. As the power amp is pushed and draws more virtual current from its virtual power supply, the Sag control will have more effect.
* IMPORTANT: Turning this control fully counterclockwise defeats power amp simulation for an individual AMP block so you can use it as a PREAMP into an external tube power amp without globally disabling power amp simulation.
Turning SAG to zero disables power amp simulation for the preset. The SAG control has no effect at all when Power amp simulation is switched off in the Global menu.
MAINS IMPEDANCE (SAG) – In a tube amplifier there are physical components of the amp which impede the flow of power in the instance of large transient signal spikes (like slamming a hard power chord). Principally, the transformers, filter capacitors, and rectifier (if it’s a vacuum tube). The power supply voltage falls off in the spike, producing a momentary ‘squish’ in the signal, known as “Sag”. Solid state amps do not produce this effect, only Class AB tube amps (there is no sag in true class A amps as full output power is always present). Sag is what makes old tube amps sound/feel cool. That dynamic reactance to your playing. Our control goes from 0.01 to 10.0 (a 0.00 setting turns the power amp emulation completely off, leaving you with just the preamp portion of the simulation). The closer to 0.01, the tighter and more solid-state like the attack will be (essential for extreme hi gain settings). The closer to 10.0, the looser the feel and string attack. I personally love sag (being an old guy), and wish we had an even greater range with this control. Try dialing more Sag into your next patch!
Early valve amplifiers usually used unregulated power supplies. This was due to the high cost associated with high-quality high-voltage power supplies. The typical anode supply was simply a rectifier, an inductor and a filter capacitor. When the valve amplifier was operated at high volume, the power supply voltage would dip, reducing power output and causing signal attenuation and compression. This dipping effect is known as "sag", and is sought after by some electric guitarists.[10] Sag only occurs in Class AB amplifiers. This is because, technically, sag results from more current being drawn from the power supply, causing a greater voltage drop over the rectifier valve. In a Class A amplifier, current draw is constant, so sag does not occur.
As this effect is more pronounced with higher input signals, the harder "attack" of a note will be compressed more heavily than the lower-voltage "decay", making the latter seem louder and thereby improving sustain. Additionally, because the level of compression is affected by input volume, the player can control it via their playing intensity: playing harder results in more compression or "sag". In contrast, modern amplifiers often use high-quality, well-regulated power supplies. In theory, these keep the supply voltage constant, but in reality there is still some small variation, largely due to resistive losses in the cabling from the power supply to the gain stage.
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