Roar Quad 15, User Manual

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6. P
OWER
A
TTENUATOR
The built-in Power Attenuator lets you control the desired listening level while retaining a natural “speaker cabinet”
response. A total of 12 steps let you go all the way down to bedroom level with as much power amp overdrive as you
prefer. The selector switch can be turned 360 degrees, enabling direct switching from “Full power” to “Mute”.
Power attenuator
Rotary switch - position
Power to speaker Internal load
Full power 15 W to speaker cabinet Disconnected
-3 -3 dB power to speaker Connected
-6 -6 dB power to speaker Connected
-9 -9 dB power to speaker Connected
-12 to -36 - 12 dB to – 36 dB power to speaker Connected
Mute Speaker disconnected Connected
The power attenuator is based on an internal speaker emulator load made with high quality components (inductors, resistors and
capacitors). The 12 step rotary switch on the front panel distributes the power between the speaker and the internal load in a way, so
that the 6V6 power tubes are operated at their optimal point at all times. In this way, a natural sounding power tube overdrive is
achieved, even at very low sound levels, and with a fully dynamic bass response. (Many power attenuators are made with resistors
only, which does NOT sound like a speaker cabinet.) A reactive load with a resonance frequency around 100 Hz (typically) is essential
for an authentic sounding power attenuator.
Please notice that there might be an audible difference between the Power attenuator settings at “Full power” versus the lower power
settings due to the different damping characteristics of speaker cabinets; especially in the bass frequencies. Speakers with low Q-
values have a tendency to deliver less and tighter bass and vice versa. Also, a speaker driver will “break up” or add “speaker distortion”
as you turn it up, which will not be “simulated” at lower settings. However, the power attenuator is a unique way to control speaker
distortion, when you're in the studio.
GAIN:
Overdrive/distortion
VOLUME:
Power amp Overdrive
POWER ATTENUATOR:
Power to speaker