TUTORIAL:
AMPLIFIER ‘ADVANCED’ PAGE PT. 3
IN THE BELLY OF THE BEAST
I know everyone wants to hear about the new 5.0 parameters now. Having
spent many hours last week working with the new Dynamics and Bias settings I
can tell you these controls are subtle “icing on the cake” for an already well-designed
patch. You can make noticeable changes to string attack, and ‘feel’ with them. However, there
are more important and basic parameters to first master. So, I will do a Dynamic’s Page
tutorial shortly, but we are going to learn to ‘walk before we run’, and finish the Advanced Page
discussion. In our last tutorial we got thru reviewing the Power Amp Bias control,
and what it does sonically. The following settings down the Advanced Page menu
are some of the most critical for your amp model’s sound:
DAMPING – In an amplifier circuit, negative feedback refers to the "feeding back" of a small amount
of signal from a later part of the circuit to an earlier part, usually from a tap on the output
transformer back to the phase inverter. The applied negative feedback improves amp performance
in a number of ways, but what concerns us is the damping factor it produces. Because the feedback
decreases output impedance, it causes the amp to react less to the speakers. This is ‘damping’.
Our Damping control ranges from 0.00 to 10.0. Sonically, the closer you set
the value to 0.00 the more ‘old school/vintage’ and smooth the string feel will be.
Amp volume will seem to drop. As you turn up towards 10.0 the response becomes
much louder, tighter, and punchier. More reminiscent of modern hi gain amps.
This is one of the most powerful controls on the Advanced page for determining
amp “feel”. If you were trying to create a small, old Fender amp, you’d want
your settings around 2-3. For a modern gain monster, 7-10. Some vintage amp
models also, will sound very realistic with higher Damp settings, like Twin (Double
Verb) and Hiwatt (Hipower) models.
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!
B+ TIME CONSTANT – “B+” refers to one of the high voltage ‘taps’ or outputs
of the main power transformer. This parameter controls the nature of its
interaction with the amp’s rectifier (to which this ‘tap’ is attached in real amps).
The range of our control goes from 1ms to 100ms. Setting the value towards
1.00ms will increase the ‘vintage’ feel, giving your string attack more sweetness
and bounce. Closer to 100ms will make attack more aggressive, tighter, and
slightly louder.
TRIODE 1 & 2 PLATE FREQUENCY – These are a couple of my favorite controls
on the Advanced page. I use it to dial out sharpness in string attack to make the
amp models in my patches sound smooth and sweet. Their range goes from
400-40000Hz, which is huge. Generally, they are preset to the top of their
range (some amp models are preset to lower values), but I usually drop
them down below 10000Hz. On some of my Tweed-style patches clear
down around 2200Hz! If you are going for a sweet, sing-y lead tone,
these controls are the fastest way to get it. Try playing with these, and
setting them by ear in your next patch. You’ll be surprised how exactly
you can dial in your desired ‘smoothness/cut’ with these controls.
Back next week with more Advanced page mysteries. If Cliff keeps evolving
the amp models, and adding parameters, like he has been, we may never be
done reviewing this page!
