PJB DOUBLE FOUR
OWNER’S MANUAL
Thank you for purchasing the PJB DOUBLE FOUR. A great deal of
dedication and passion went into designing and building this no
compromise, high performance compact-combo amplifier. It was
conceived to be a dedicated amplifier for the “connoisseur” bassist.
Reading this manual willenable you toget thebest performancefromitso that
you may enjoy many years of service.
READ THIS FIRST
· Before using the DOUBLE FOUR please read ALL the instructions.
· On receipt of product, check for any signs of physical damage arising from
shipping. If any damageis visible contact your dealer.
· Do not install this equipme nt in a confined or building-in space such as a
book case or similar unit, and remain a well ventilation co ndi tions at open
site. The ventilation should n ot be impeded by covering the ventilation
openings with items such as ne wspaper, table-cloths, curtains etc.
· WARNING: Only use attach ments/accessories specified or provided by the
manufacturer (such as th e exclu sive supply adapter etc).
· WARNING：Please refer the inform ation on exterior bottom enclosur e for
electrical and safety information before installin g or operating the apparatus.
· WARNING：To reduce the risk of fire or electric shock, do not expose this
apparatus to rain or m oisture. The apparatus shall not be exposed to
dripping or splashing and that objects filled with liquids, such as vases, shall
not be placed on apparatus.
· WARNING: The mains plug is used as disconnect device, the disconn ect
device shall remain readily operable.
· When not in use and during movement, please take ca re of the power cordset,
e.g. tie up the power cor dset with cable tie or something like that. It shall be
free from sharp edges and the like that can cause abrasion of the power
cordset. W hen put into u se a gain, please make sure the power cordset being
not damaged, If any damages found, please look for the service person to
replace the power cordset specified by the manufacturer or have the same
characteristics as the original one .
· Cor rect Disposal of this product. This mark ing indicates that this p ro duct
should not be d isposed with o ther household wastes thro ughout the EU. T o
prevent possible harm to the environment or human health from
uncontrolled w aste disposa l, recycl e it responsibly to promote the sustainab le
reuse o f material resources. To return your used device, please use the re turn
and collection systems or contact the retailer where the product was
purchased. They can take this product for environmental safe recycling.
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OVERVIEW OF THE DOUBLE FOUR
With the great success of the P JB Bass Cub, we had many requests to make a truly
affordable bass p ractice amp. There w ere two major obstacles: it had to be small and have
the great PJB sound. Using existing parts we could not achieve our goals so we started from
scratch with new driver design, acoustic loading and the latest digital amplifier technology.
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 K LIPPEL 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.
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