PJB COMPACT PLUS User manual

COMPACT PLUS BG-450
OWNER’S MANUAL

Thank you for purchasing the PJB COMPACT PLUS. A great deal of dedication and passion
went into designing and building this high-performance compact-combo amplifier,
without compromising on any aspect. It was specifically created to cater to the needs of
discerning bassists. By reading and following this manual, you will be able to achieve the
best performance from the amplifier and ensure its longevity.
READ THIS FIRST
Before using the COMPACT PLUS, please read all the instructions carefully.
Upon receiving the product, inspect it for any signs of physical damage caused
during shipping. If you notice any damage, contact your retailer immediately.
Ensure that the amplifier is not installed in a confined or built-in space such as a
bookcase. The amp should remain in an open site with good ventilation, and the
ventilation openings should never be obstructed by items such as newspaper,
tablecloths, or curtains.
Warning: Use only attachments/accessories specified or provided by the
manufacturer to avoid any potential hazards.
Warning: To avoid the risk of fire or electric shock, keep the amplifier away from
rain or moisture. The amp should not be exposed to dripping or splashing
liquids, and no objects filled with liquids should be placed on top of the amp.
When the amplifier is not in use or during transportation, take care of the power
cord by tying it up with a cable tie. The power cord should be free from sharp
edges that may cause abrasion. Before using it again, check that the power cord
is not damaged. If any damages are found, replace it with a cord specified by the
manufacturer or with the same specifications as the original one.
 Correct disposal of this product: This marking indicates that this product should
not be disposed of with other household waste throughout the EU. To prevent harm
to the environment and human health from uncontrolled waste disposal, recycle it
responsibly to promote sustainable reuse of material resources. To return your
used device, use the return and collection systems or contact the retailer where
you purchased the product for environmentally safe recycling.
 Warning: The apparatus with CLASS I construction must be connected to a
MAINS socket outlet with a protective earthing connection to ensure safety.
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OVERVIEW OF THE COMPACT PLUS
Experience uncompromised and powerful performance with our latest model,
which is based on the legendary PJB Suitcase amplifier. Our engineers have taken
the iconic design and elevated it to new heights with a smaller physical size,
greater acoustic output, less weight, and improved frequency response. Don't be
fooled by its compact size; this amp packs a punch that cuts through the air like a
hot knife through butter. With solid and powerful low-end response typically
associated with much larger combos, it delivers an incredible sound that will leave
you wanting more. Plus, it shares the same size as our popular Compact-4
enclosure, making it an ideal choice for any musician looking for a portable and
versatile solution.
The PJB Suitcase Compact bass combo features a single channel preamp with a
more extensive 5-band EQ. Finding "your sound" is simple with this EQ , as it offers
incredible control and transparency, allowing you to hear the true character of
your own playing and instrument.
At the heart of this amp is a formidable ultra-high-energy power supply that feeds
an efficient class D power amplifier, utilizing nearly 95% of the energy to drive the
four internal PJB Piranha speakers. The Compact Plus outputs a healthy 300 watts
RMS onto its own speakers, and when paired with a Compact-4 cabinet, it becomes
500 watts.
Understanding power in a bass amplifier.
When amplifying a bass guitar, the relationship between power and loudness is
crucial to understand. However, a higher-powered amplifier doesn't always mean a
louder amplifier, as there are other factors involved such as speaker efficiency and
amplifier frequency response. Nevertheless, the BG-450 amplifier is undoubtedly
louder than the BG-400 for several reasons.
Firstly, the BG-450 features a higher peak power output, enabling it to handle the
dynamic range of the bass guitar signal and deliver a clean and powerful sound.
Secondly, the BG-450 has a higher continuous power output, providing the necessary
headroom to ensure the sound remains clear and undistorted even at high volumes.
Additionally, the BG-450 boasts an advanced design with improved components and
circuitry that enhances overall performance. The power supply is specifically designed
to deliver more current to the amplifier, providing a stable and reliable power source
even under heavy loads. This design allows the BG-450 to drive speakers more
effectively, resulting in a louder and more dynamic sound.
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When choosing an amplifier for a bass guitar, it is vital to consider not only its
continuous power output but also its peak power output and ability to handle the
dynamic range of the instrument's signal. A high peak output amplifier can provide
the necessary headroom and dynamic range to ensure that the bass guitar's sound is
clear, powerful, and dynamic.
The BG-450's peak power output is significant because it allows for short bursts of
power when needed, resulting in a more dynamic and louder sound, even if the
average power output is lower. This is due to the Class D amplifier design, which uses
a switching circuit to rapidly turn the power transistors on and off, creating an
amplified signal. This design allows for greater efficiency, resulting in less heat
dissipation and a smaller amplifier size, while also enabling the amplifier to output
higher peak power for short durations. For example, the BG-450 amplifier may have a
continuous RMS power output of 300 watts into 8 Ohms, but it can deliver transient
peak power output of over 500 watts (or 800 watts into 4 Ohms) for short bursts to
improve loudness and dynamic range.
In conclusion, while power is not the only factor that determines the loudness of an
amplifier, the BG-450's higher peak and continuous power output, as well as its
advanced design, make it undoubtedly louder and more capable of handling the
dynamic range of a bass guitar signal than the BG-400. Whether performing live or
recording in the studio, the BG-450 is an excellent choice for anyone seeking a
powerful and dynamic bass guitar sound.
The Suitcase Compact bass combo is a prime example that the trend of amps moving
towards "smaller and better" has already arrived.
FEATURES
A switchable input for active (high-output) and passive (high pickup
impedance) basses with mute function.
 Auxiliary input for other audio sources with volume control.
 Dedicated 5-Band EQ for total tonal control of instrument.
 A Balanced Line Output with ground lift.
 Line In.
 Line Out.
 EXT-Speaker Out.
 Sophisticated protection circuitry.
 Power output 300W at 8 Ohms/500W at 4 Ohms (MAX).
 Ultra-low noise pre-amplifier circuit.
 IEC universal AC input 100-240 volts AC. (Operates on all world voltages)
3

TOP PANEL OVERVIEW
TOP PANEL DESCRIPTION
1. INPUT JACK
This is a high impedance input and is designed for all passive and active
instruments.
2. CLIP LIGHT
When the amplifier output is clipping, the LED will light up in red. When the
amplifier is muted, the LED will light up in green.
3. INPUT SWITCH
MUTE: mute the input stage, when switch on, the clip LED will light up in green.
ACTIVE: lower sensitivity input setting for guitars with onboard electronics.
PASSIVE: higher sensitivity, high impedance input for passive guitars.
4. INPUT LEVEL CONTROL
Factors of different instruments, playing styles, and players all can affect the
signal level. Adjust this control accordingly, so that the signal overload clip light
does not light up. This optimizes the best signal to noise ratio between the amp
and instrument, and will give you the full extent of the amplifiers tone and power.
5. FX SEND SOCKET
Connect the FX Send to auxiliary FX unit input.
6. FX RETURN SOCKET
Connect the FX Return to auxiliary FX unit output.
7. MIX CONTROL
8. AUX INPUT
Stereo input for Drum machine or I-pad/ digital audio player.
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9. HEADPHONE SOCKET
This jack accepts 3.5mm stereo headphone jacks.
When a headphone is connected to the jack, the speakers will be muted.
10. LOW BASS EQ CONTROL
This will adjust the fundamental tones of E and A strings on 4 string basses and B, E & A
on 5 string basses.
11. HIGH BASS EQ CONTROL
This will adjust the fundamental tones of D and G-strings on 4 & 5 string basses.
12. LOW MID EQ CONTROL
13. HIGH MID EQ CONTROL
14. TREBLE EQ CONTROL
15. AUX INPUT VOLUME CONTROL
Control the level of backing/rhythm track.
16. MASTER VOLUME CONTROL
This is the master volume control, which determines how much power is sent to
the speakers and the line out socket at the back of the amp. When setting up your
tone or plugging in your instrument, it is recommended to start this control at a
low level. Output from different instruments' pickups can vary greatly, and
likewise, players may play softly or with great force.
17. POWER LED INDICATOR
When power is switched, on the LED light will turn bright green.
NOTE: When power is on, the indicator will light up. If no signal comes in after 30
minutes, the standby function will activate, and the power indicator LED will light
up in red. When a signal comes in from INPUT or AUX socket, the amplifier will
restart in about 2 seconds.
This standby function is regulated by the European Union's (EU) Ecodesign Directive,
which sets minimum energy efficiency standards for a wide range of products, including
all consumer electronics. Under the directive, manufacturers are required to ensure that
their products consume no more than 0.5 watts of power in standby mode, and must
also provide an automatic shut-off feature after a set period of time. These regulations
have been implemented across the EU and apply to all electronic devices, The aim of
these regulations is to reduce energy consumption and promote energy efficiency in
consumer electronics, which can have a significant impact on reducing greenhouse gas
emissions and addressing climate change.
PJB is a company concerned about our planet’s health, so we have implemented this
feature on models sold in and outside Europe. Other first world countries will be
adapting similar laws in the near future.
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BACK PANEL OVERVIEW
BACK PANEL DESCRIPTION
18. XLR-DIRECT OUTPUT SOCKET
This is an ultra-low impedance (200Ω) balanced line output intended for use with
recording or PA mixing consoles. Unlike the volume control, the level of this output
is not adjustable. However, the level of the DI output will vary depending on the
level of your instrument.
19.BALANCED LINE PRE/POST EQ
By toggling this switch, you can activate or deactivate the EQ on the balanced line.
This allows you to decide whether you want to use the tone settings on your amplifier
for live performances or recordings, or if you prefer to apply external EQ adjustments
on the mixing console that the signal is being sent to.
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20. BALANCED LINE OUT GROUND LIFT SWITCH
Sometimes AC hum is induced into a sound system when both the PA and bass amp
are connected to different ground potentials, which is known as a ground loop. This
switch can disconnect the amp's grounding from the PA or recording system to
eliminate this hum. It allows the grounding of the balanced out socket to be
disconnected, which is useful if you are experiencing hum caused by grounding loop
problems.
21. LINE IN
This input allows for a high signal output from a source, such as the preamp out from
another amplifier or a mixer output, so that the BG-450 can function as a slave unit. It
bypasses the internal preamp.
22. LINE OUT
Can be used for driving a second amplifier or powered monitor speaker.
23.EXTENSION SPEAKER OUT
The output is designed for driving an additional 8 Ohms speaker, such as the PJB
Compact-4. Using a speaker with an impedance lower than 8 Ohms will cause the amp
to overheat and shut down. To connect the speaker, use a "Speakon" connector
instead of a conventional jack. This is necessary because the amplifier's output is
strong and capable of delivering higher currents than jack sockets can handle. This
socket can also power the PJB EAR-BOX (See notes in this manual under operating and
positioning.)
24. POWER ON/OFF SWITCH
This switch controls the main power supply for the amplifier, allowing you to turn it on
or off as needed. Upon turning on the power, there will be a 2-second delay to protect
the speaker. To ensure the longevity of the amplifier and prevent any potential
damage, avoid leaving it plugged into a power source for extended periods when not
in use. It is recommended to unplug the amplifier or turn off the power switch when
not in use.
25.AC INPUT SOCKET
This accepts grounder IEC cables. This amp can work on any AC voltage from 100-
250volts.
7

OPERATION & POSITIONING
Before plugging in your instrument, turn the volume down and switch the input
on the COMPACT PLUS to mute.
CAUTION: To prevent loudspeaker failure, it is essential to avoid extreme overload
on the amplifier. Although the COMPACT PLUS is designed to deliver optimal bass
performance, it is important to ensure that the amplifier is not pushed beyond its
limits. If you hear any distortion from the speakers, immediately turn down the
master volume control until the distortion disappears. Please note that the
amplifier is rated for a power output of 300W at 8 Ohms or 500W at 4 Ohms,
without audible distortion. While the amplifier can handle even more power on
transient inputs, exceeding this limit may cause distorted sound waves from over-
driven amplifiers. Amplifier clipping, which is caused by overloading the amplifier,
is one of the most common causes of loudspeaker failure. Please note that any
damage resulting from misusing the amplifier by overloading it is not covered by
the warranty.
The amplifier has a power output of 300W at 8 Ohms / 500W at 4 Ohms with no
audible distortion. However, please note that the amplifier is not limited to 300W
at 8 Ohms / 500W at 4 Ohms, and the power with distortion could be double the
wattage. Overdriven amplifiers producing distorted sound waves are the primary
cause of loudspeaker failures, which are considered misuse and are not covered
under the warranty. It is imperative to use the amplifier with care and avoid
pushing it beyond its limits to ensure maximum performance and longevity of the
equipment.
Positioning the COMPACT PLUS for Best Sound
Often, your bass instrument will sound different in various venues due to the acoustics
of the space, which can influence the low-frequency waves emitted by your speaker.
Bass waves are larger, and room dimensions can heavily impact them when sound
waves are reflected by walls, causing them to either add together or cancel each other
out. As a result, some fundamental notes (the ones you feel more than hear) may ring
out louder than others, while some may not be audible at all.
To enhance your comprehension of the fundamental bass frequencies' location, here is
an overview of the estimated frequencies and corresponding acoustic wavelengths of
open strings:
F# string 24Hz 46 feet: (Sometimes used on 7 or more strings)
B string 31Hz 36 feet: (lowest string on 5-string bass)
E string 41Hz 27 feet: (lowest string on 4- string bass)
A string 55Hz 20 feet
D string 73Hz 15 feet
G string 98Hz 11 feet
C string 130Hz 9 feet
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The frequencies of the open strings provide an idea of which notes might be
causing excessive resonance or reduced volume compared to others. For instance,
if you place your speakers five feet away from a wall, you might notice that the
open A string sounds weak. This could be due to the reflected sound from the wall
traveling the exact same distance as the direct sound from the speaker, resulting in
cancellation of that frequency. Essentially, the reflected sound waves and the
direct sound waves meet each other at the same point, which results in a decrease
in the perceived volume of that particular frequency. To overcome this, you can try
different solutions, such as moving the speaker or instrument to another location,
or using sound-absorbing materials to minimize reflections. Experimenting with
different positions until you find the optimal spot where the bass response is
balanced and even is the best course of action.
The position of the COMPACT PLUS can have an impact on its ability to produce
low-frequency sounds. To achieve the best possible sound quality, it is
recommended that you place the COMPACT PLUS on the floor. If you place the
speaker on objects that are not on the floor, it can result in a weaker bass sound
and a lack of impact in the lower frequencies.
In contrast, if you place the COMPACT PLUS with its back near a wall, it can help to
reinforce the lower notes, creating a more robust and powerful bass sound.
Similarly, placing the speaker in a room corner can further enhance the low notes,
providing an even more powerful and impactful bass experience. Therefore, the
position of the speaker is crucial to obtaining the best possible sound quality from
the COMPACT PLUS. This reinforcement effect is due to the waveguide property of
the corner, which channels the sound waves in a specific direction. The corner
directs the bass frequencies towards the center of the room, where they can
accumulate and create a more powerful and impactful bass sound.
Bass frequencies are omnidirectional, meaning that they radiate equally in all
directions from the source. This is because the longer wavelengths of bass
frequencies can diffract around objects and fill a room more easily. In contrast,
mid-range and high frequencies tend to be directional and beam like headlights on
a car. This is because the shorter wavelengths of these frequencies are less able to
diffract around objects and are more easily absorbed or reflected by surfaces.

When you stand in front of your bass guitar amplifier, it can affect the sound for
other people listening in the room. This is because your body can absorb and
reflect sound waves, which means that the sound waves from your amplifier will be
partially absorbed or reflected by you. As a result, the sound can be quieter and
less clear for people standing farther away from you, especially in the mid-range
and high frequencies.
Furthermore, you may hear a different sound than the other listeners in the room
because you're hearing a more direct sound, while they're hearing a combination
of direct and reflected sound waves. This can make it hard for you to really hear
your playing due to room acoustics and the position of you and your amp.
Fortunately, there's a solution to this problem: the EAR-BOX (EB-200) by PJB. This is
a small loudspeaker that can be mounted on a straight microphone stand and
positioned close to you at ear level. The EarBox fills in the critical mids and highs
that you may be missing when you're not in the axis of the front of your amplifier.
It's directly connected to the speaker out or link from your extension speaker, and
won't affect the amplifier load. This greatly enhances your listening experience
and also eliminates any sonic latency if you're a distance from your amplifier.
Information can about the EAR-BOX can be found on our website.
www.pjbworld.com/cms/index.php/product-eb-200/
It's important to note that sound travels at approximately 1 foot per millisecond,
so if you're standing 15 feet from your amp, you're hearing the sound 15
milliseconds later. This can affect how you play, just like the latency effect that
keyboard players can experience with MIDI.
To avoid these issues, it's best to position your amplifier so that it's not obstructed
by your body or other objects, and to ensure that the sound is distributed evenly
throughout the room by adjusting the positioning of the speaker and using
equalization to balance the sound.
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TRANSPORTING AND STORING THE COMPACT PLUS
When transporting the amplifier in a vehicle, it is recommended that you use an
external case, or a heavy-duty cover to prevent it from damage.
Storage
Keep in a dry location, preferably at room temperature.
Do not store in temperatures below -20 Degrees C or above 40 Degrees C.
Do not allow it to get wet. If this occurs, never turn it on in this condition.
We recommend that you do not keep the COMPACT PLUS amplifier
permanently connected to a power source as a safety precaution, particularly
during thunderstorms. While it is not a common occurrence, during severe
weather conditions, there is a risk that the electrical grid may experience high
voltage spikes due to lightning strikes, which can cause damage to the
amplifier.
Therefore, when setting up a sound system, it's important to consider the
directional properties of different frequency ranges. Placing a bass loudspeaker in
a corner or against a wall can help reinforce the bass frequencies by taking
advantage of their omnidirectional nature. In contrast, mid-range and high
frequency loudspeakers may need to be aimed or angled towards the listener to
ensure optimal sound quality. Unfortunately, low frequencies are always
challenging to control for bass players when room acoustics are present. The
wavelengths of the notes being played often correspond to the room dimensions,
causing the reflected sound from the walls to interfere with the sound from the
speaker as the listener moves further away from it.
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SPECIFICATIONS
Amplifier
Type: Class A pre-amplifier. Class D power amplifier with digital switch-mode power
supply.
Power output: 300W at 8 Ohms / 500W at 4 Ohms (MAX transient peak output
400 watts into 8 Ohms / 800 watts into 4 Ohms).
Signal to Noise Ratio
≥85 dB(A) (EQ off, Volume on Full.)
Impedance
Passive Input: >2MΩ/22pF
Active Input: >100KΩ/22pF
Line Input: >75KΩ
Pre Amp Line Out: < 2KΩ
Bal. Out: <200Ω
Levels
Passive Input: 10mV-1.5V
Active Input: 20mV-4.5V
Pre-Amp Line Out: 1.2V
Balanced Line Out: Typical 500mV
Protection Circuits
1. AC line filter.
2. Loudspeaker Short-Circuit Protection.
Speaker
Computer Optimized Vented Enclosure: Increased bass output with reduced cone
excursion.
Speaker Frequency Response: 35Hz–15KHz
Speaker Compliment: 4 x 5 inch proprietary PJB, extended-range drivers
Speaker Sensitivity: 93dB/W/M
Internal Speaker Impedance: 8 Ohms
Dimensions (WxHxD): 14.2x14.3x13.2 inch (361x362x336 mm)
Weight: 14.1kg (31 lbs).
Included Parts
Detachable IEC 6 ft AC Power Cord
Protective slip-on cover

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SERVICE/WARRANTY INFORMATION
The COMPACT PLUS is covered by a 2-year limited warranty for parts and labor, which is
valid only if the product is purchased from an authorized PJB dealer. The buyer must
complete and return the enclosed warranty card within 15 days of purchase, or register
online at www.pjbworld.com, to activate the warranty. This warranty covers any
defects in materials or workmanship that occur during normal use. PJB will repair or
replace any defective unit, free of charge for both labor and parts, during the warranty
period. However, the buyer must use the unit strictly in accordance with the
instructions provided in this manual and the amplifier manual to ensure warranty
coverage.
This warranty is non-transferable and is only provided to the original owner. Damage or
defects caused by the following conditions are not covered under this warranty:
Improper handling, neglect, or failure to operate the unit in compliance with the
instructions provided in the user manual.
Connection or operation in any way that does not comply with the technical or
safety regulations applicable in the country where the product is used.
Speakers are not covered for damages caused by incorrect connection or when
powered beyond the limits described in the user manual. Manufacturing defects
are usually detected during early usage.
Repairs or modifications carried out by anyone other than an authorized PJB service
agent.
Damages or defects caused by forces of nature or any other condition that is beyond
the control of PJB.
IMPORTANT:
In all warranty issues, the retailer you purchased the product from should be your
first point of contact, even if you bought the product from an online source.
When a local distributor is available, customers who prefer to purchase online from
another country may be required to pay shipping charges to the retailer to obtain
service.
Warranty policies may differ in countries outside the USA. Please check with local
distributors for warranty information in your region. Registering first with your local
distributor, if available, will provide you with better and quicker service when
needed.
Further questions, please contact your local distributors or PJB by email
[e-mail].
PHIL JONES BASS
American Acoustic Development LLC
8509 Mid County Industrial Dr St Louis,
MO 63114 USA
Tel: [phone] (855-BASS-510)
www.pjbworld.com
[e-mail]
For services outside the USA please contact our distributor in your country.
Information can be found on our website.

American Acoustic Development LLC
8509 Mid County Industrial Dr, St Louis,
MO 63114 USA
WWW.PJBWORLD.COM
Printed in China