What is Super Scaling?
• Super Scaling is a technique that allows the power output of
a small amplifier to be boosted to a higher level to drive a speaker.
Doesn't a regular power amplifier do this?
• No. Conventional power amplifiers monitor the input voltage only and
scale this voltage to drive a load to a higher power level. The final
load is fully isolated from the signal source.
What about a Guytron amp? It has a small amp driving a large amp.
• The large amp in the Guytron is like any other conventional power
amplifier: it monitors the voltage across the load for the small amp,
then boosts the voltage only. This produces an increased output, but
the characteristics of the large amp dominate the final tone and interaction
with the speaker.
So how does a Super Scaling amp monitor input power?
• Super Scalers are essentially just the final power stage of a power
amplifier, where a driver stage would provide some amount of drive
power to achieve output power. The difference is that the driver stage
is missing, so this drive power must be obtained from an external
source.
How does this retain the sound of the driving amp?
• In a Super Scaling amp, no output power can be produced unless input
power is provided. The two quantities are intimately related. As you
drive the Super Scaler harder, the speaker is driven harder. The speaker's
back-EMF tries to buck the signal from the Super Scaler, which then
bucks back at the source. The driving amplifier can then 'feel' the
speaker and interacts with it.
The Super Scaler is still a big amp, so doesn't it provide better damping
to the speaker than the small driving amp would?
• The Super Scaler is transparent. Its inherent damping is low –
in the same range as a typical tube amp or less. However, the driving
amp is able to 'see' and 'feel' the speaker through the Super Scaler,
so that the sound is the same as if the small amp itself was driving
the speaker directly, but to the new, higher power level.
How much boost does a Super Scaler provide?
• The boost for a typical tube Super Scaler is 4-100, with most in the
4-20 range. Nested Super Scalers can provide further boosts up to
1,000 times. The boost for a solid-state Super Scaler is anywhere
from 4-1,000.
Can the boosts be varied?
• Not easily. Solid-state circuit are more easily adapted to variable
boost ratios, but the circuits become much more complex. Nested tube
Super Scalers can be made variable more readily than simpler tube
Super Scalers.
Won't a solid-state Super Scaler change the sound of a tube amp driving
it?
• Not if it is properly designed. Our solid-state Super Scalers
use special mosfets with characteristics approximating tube performance,
but then the circuit is optimized for drive by a tube amp. Solid-state
Super Scalers can be made with multiple selectable boost ratios for
different performance situations, while still retaining tone.
What is a Nested Super Scaler?
• This is a unit with two or more cascaded Super Scaling circuits for
very high boost ratios. A half-watt input might produce 700W of output,
but with the tone of the half-watt source amplifier.
What is tube life like in a Super Scaler?
• The simplest Super Scalers use conventional receiving-type power tubes
in pure class-B circuits. Tube life is longer than in a conventional
amplifier even though the internal voltages are somewhat higher.
Do I need matched tubes in a Super Scaler? Can I mix tubes like I can
in London Power's Power Scaling amps?
• Matched tubes are not required in the simplest Super Scalers, but
they should be the same type. The circuit itself assures 'matched'
performance by taking advantage of some of the tube characteristics
that cannot be fully utilized in conventional amplifiers.
In Super Scalers using filamentary triodes such as the 811A, SV572-160 or
572B, the tubes should be similar, and there is a benefit if matched pairs
are installed.
Can I drive a Super Scaling amp with a Power Scaling amp and still have
power amplifier distortion at any level?
• Yes. The Super Scaler will shift all the power levels up by six times
typically, for a simple tube Super Scaler. Most players find this
to be an ideal situation because they can use the same "quiet" home
settings on their Power Scaling amp when they are on stage or playing
with a full band.
Using a Super Scaler with a Power Scaling amp gives a modular system where
you can bring along only as much power as you need.
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SUPER
SCALING Q & A