SWR Black Beauty Instrucciones De Funcionamiento página 17

EXTENSION SPEAKER OUTPUT SECTION
This section of the manual will deal with the proper connection of extension speaker cabinets to the power amplifier in the Black
Beauty. We recommend that you read this section carefully, as power amplifiers, impedance and speaker cabinets are all crucial in
determining how best to operate your new Black Beauty with an extension speaker cabinet.
SPEAKER OUTPUTS - Connect the internal speakers or external speaker(s), 4 Ω minimum total load, at these jacks. WARNING:
Disconnect internal speakers before connecting any external speaker(s).
HOW IMPEDANCE AFFECTS POWER RATINGS
People often have questions about impedance. What is it? The root of the word "impedance" is the verb "impede," which means to
block or resist. That's what impedance is—resistance to power.
Power amps do not have a pre-determined impedance. They deliver power at whatever impedance the speaker cabinet tells it to.
That's why you hear the term "slave amp"—amplifiers only do what they're told. So if someone tells you that they have a "4 ohm power
amp," their terminology and understanding of the concept is way off the mark.
Unlike power amps, every speaker cabinet has a pre-determined impedance rating measured in "ohms." In most cases this rating is
either 4 or 8 ohms (though there may still be some old 2 ohm creakers out there). The higher the impedance of the speaker cabinet,
the more resistance to power it will offer. The lower the resistance of the speaker cabinet, the less resistance to power it will offer. In
other words, HIGHER IMPEDANCE MEANS LESS POWER CAN ENTER THE SPEAKER CABINET. LOWER IMPEDANCE MEANS MORE
POWER CAN ENTER THE SPEAKER CABINET.
You may be thinking that you've found the solution to the universe—just use speaker cabinets with really low impedances and you can
get skull-crushing power out of your amplifier, right? Wrong. There's a catch. Power amps have limits as to how low an impedance
they can drive safely. This is what's known as an amplifier's "Minimum Impedance Rating." If you try and operate a power amp below
its minimum impedance rating, it will give you lots and lots of power for about five minutes...and then overheat, short out and fail com-
pletely. In other words, THE LOWER THE OPERATING IMPEDANCE OF THE AMPLIFIER, THE HOTTER IT WILL GET.
EXTENSION SPEAKER OUTPUT JACKS
One Speakon Jack and one 1/4" phone jack (both wired in parallel) are provided for connection of an extension speaker to the Black
Beauty. Whenever possible, use of the Speakon jack is recommended. Speakon jacks and connectors offer the best possible connec-
tion and are far superior to banana or 1/4" phone jacks in that they not only lock in place (preventing accidental disconnection), but
also offer a greater and more stable connection surface. This solid connection provides a more effective transfer of power to your
speaker.
Only SPEAKER CABLE of 18 gauge or heavier (the heavier the cable, the lower the gauge) should be used to connect an extension
speaker to your Black Beauty. Do not use shielded instrument cable in this application, as this can result in intermittent power loss,
cause your amp to oscillate and damage itself and/or your speakers, and render the cable useless for any purpose.
SPEAKER FUSE
The speaker fuse is provided to protect your speakers in the unlikely event of a power amp failure or to protect your power amplifier
from incorrect speaker impedances or hookups. Size and rating of the fuse is 3AG, 10 amp, fast-blo. Do not defeat the purpose of
this feature by using a higher rated fuse as it can damage your amplifier and void your warranty.
The fuse can open as a result of a fault in the speaker cable, the speakers themselves, or the power amp being sent well into clip-
ping. With this in mind, it is wise to carry extra fuses at all times.
BLACK BEAUTY • 17