Phil Jones Bass Double Four BG-75 Black

The DOUBLE FOUR is a single channel bass amplifier that has an auxiliary
input for ipad/ipod, mp3 or drum machine. It features 3 band EQ that is
perfectly tailored for bass guitar, headphone out jack and a line out
for recording. It is ideal for all kinds of basses and can handle the
open B string on a 5 string bass with ease.

The Enclosure
It
is well known that big speakers are capable of reproducing true bass
fundamental frequencies but as you decrease the physical size of a
speaker, the bass response will fall away. Same reason why Violins are
small and Double Basses are big!
So how do you get huge bass sound
from a small speaker cabinet? Well with our know how of using smaller
drivers to get the ultimate bass sound, we applied our vast experience
to an even smaller driver just 4 inches across. It is built with Swiss
watch precision; it has to be to cope with the extreme signals coming in
from an amplified bass guitar. Using our extensive R&D facility
which includes the largest anechoic chamber in the bass guitar amplifier
industry and the KLIPPEL transducer measurement system (it uses
lasers!), we were able to develop the perfect 4 inch loudspeaker. We
analyzed the neodymium magnetic system, the cone behavior at all
frequencies in 3D representation, cone suspension, frame etc. until we
had achieved a transducer beyond what anyone would have ever though
possible. Then we looked at the acoustic loading using the acoustic
simulation software and calculated exactly the full power cone
displacement at every frequency.
We designed a custom Rectangular
Auxiliary Low Frequency Radiator (RALFR®). That is a pneumatically
coupled radiator loaded to the rear of the two 4 inch speakers that
operates at the lowest bass frequencies only. It augments the output of
the loudspeakers at frequencies from 30 to 150 Hz. It also reduces the
cone excursion of the speakers allowing greater power handling.
The
proprietary PJB NeoPower 4-inch speakers are full frequency range to the
highest audio frequencies. Not only does this give greater clarity and
transparency to your instrument but also gives a high fidelity sound to
any backing track fed into the auxiliary input.
Each speaker is fed
with its own Pulse Width Modulation PWM amplifier. PWM amplifiers are
extremely efficient compared to more traditional analog solid state
amplifiers converting more electrical energy to power the speakers
instead of getting hot. Heat in electrical circuits is the enemy to
reliability and since the amp is running at lower working temperature,
the DOUBLE FOUR will give years of service long after other amps have
faded away. By using dual amplifiers one to each speaker, the bass
control is greatly improved since the damping factor is doubled. Damping
factor is the amplifiers ability to put on the “brakes” stopping the
speaker cone from overshoot and tightening up the bass sound, so the
sound is punchy, tight but never muddy or bloomy out of control bass.

The
cabinet may be as small as a shoe box but it is built to the same
standards of all PJB cabinets, heavily braced internally and damped with
acoustic damping materials to prevent cabinet coloration that can kill
the true sound of your instrument. What you hear from the DOUBLE FOUR is
the closest you can get to how your instrument actually sounds.

The
DOUBLE FOUR may just be a practice amp but it does not mean that it has
to sound like a practice amp. The sound is huge for its size and you
may find it hard to believe that all the sound from your bass is just
coming out of such a tiny jewel.