The warmth and character of output tube break-up is an essential part of the Class A “sound” and the Black
Pearl 30® provides for this with its adjustable power levels, which enhance the amps performance for both
lower power bedroom/studio use and higher output stage applications.
4 Tube/2 Tube Switch –
Turns off the 2 outer power tubes, thus lowering the output level to ½ power
(15 watts or 8 watts depending upon the position of the Pentode/Triode switch) allowing for more power tube
distortion at lower output levels. It is not necessary to turn the amp off to use this switch.
Pentode/Triode Switch
– This switch easily and safely reduces the output power of the amp from 30 watts
to 15 watts (or 15 watts to 8 watts when using in the 2 tube position). Changing the parameters by which the
power tubes function (Pentode or Triode) the amplifier takes on an entirely new set of tonal characteristics. In
the Pentode mode the amp responds with its “spanky” rich clean tone and classic overdriven sustain. In the
Triode mode the BP30 produces a fuller tone with a more dynamic response and increased power tube break-
up with a darker complexity. It is not necessary to turn the amp off to use this switch.
PENTODE/TRIODE BACKGROUND INFORMATION –
The native mode for virtually all power tubes in
guitar amplification is the power pentode. In conventional pentode connected power amplifiers, the screen grid
connects to the screen supply via screen resistors and the screen potential varies (somewhat) with the audio
signal thus increasing the efficiency of the amplifying process and maintaining more controlled linear high
frequency response. There is a sonic difference that is added by these additional control elements though, and
some may prefer alternate modes of operation.
Power triodes do have a mellowness and warmth that is a desirable character for some players. A true power
triode has only an anode, cathode and one control grid. Without suppressor grids there is a lack of control of
the electron stream, which can cause electrons to stray from the intended path and collide with unintentional
targets. This wastes energy and efficiency but provides a unique tonal character that some players seek.
Fortunately, several methods exist that allow us to operate a pentode power tube in triode mode by fixing
the screen grid more solidly to the plate supply (with the Triode/Pentode switch), effectively eliminating the
screen’s “useful” effect from the circuit. This design effectively makes the circuit (including the tube itself)
behave as a power triode. The high frequency character, output impedance changes, and the circuit’s
efficiency is decreased just as one would expect from a power triode output circuit, causing the mellower/
darker complexity of the amp in the triode mode. This is a personal choice that is available to you on the Black
Pearl 30® and provides you the flexibility for further experimentation in tone.
IMPEDANCE SELECTOR SWITCH –
This 3 position switch is designed to easily select the appropriate
output transformer impedance tap for the desired cabinet load used. It is important to know the impedance of
the guitar cabinet or cabinets being used with your amp. It is critical for amplifier performance, tube life and
output transformer protection to select the correct impedance for your chosen guitar cabinet.
CABINET IMPEDANCE –
The Black Pearl 30®
is offered in 3 combo configurations. The BP30-112 is an 8
ohm cabinet impedance and the BP30-212 is a 16 ohm cabinet impedance. The BP30-310 cabinet impedance
is slightly lower than 8 ohms. It will accept a 16 ohm extension cab. These models ship from the factory with
the Impedance Selector switch set to the correct location for the speaker configuration.
SPEAKER JACKS –
These parallel speaker jacks are provided for connecting the guitar cabinet of choice.
Always confirm that the speaker impedance matches the impedance selected on the back of the amp.
WARNINGS:
• NEVER UNPLUG THE SPEAKER CABLE FROM THE GUITAR CABINET WHEN THE AMP IS ON!
• DO NOT OPERATE THIS AMP WITHOUT A SPEAKER LOAD PLUGGED INTO ONE OF THE SPEAKER
JACKS. THE BP30 DOES OFFER SOME PROTECTION AGAINST DAMAGE BUT IT IS NEVER A GOOD
IDEA TO OPERATE ANY TUBE AMP WITHOUT A SPEAKER LOAD ATTACHED.
