Qtx PHX300 User manual

PHX300
2 x 150W PA HEAD WITH DSP EFFECTS
Item ref: 178.738UK
User Manual

178.738UK User Manual
Caution: Please read this manual carefully before operating
Damage caused by misuse is not covered by the warranty
Introduction
Thank you for choosing the QTX PHX300 PA Head as part of your sound reinforcement system. This
mixer-amplifier is designed to offer high quality, dependable service for mobile and installed systems.
Please read this manual fully and follow the instructions to achieve the best results with your new
purchase and to avoid damage through misuse.
SAFETY SYMBOL AND MESSAGE CONVENTIONS
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
AVIS
RISQUE DE CHOC ELECTRIQUE NE PAS
OUVRIR
This symbol indicates that dangerous voltage constituting a risk of electric shock is present
within this unit
This symbol indicates that there are important operating and maintenance instructions in
the literature accompanying this unit.
Warning
To prevent the risk of fire or electric shock, do not expose any components to rain or moisture.
If liquids are spilled on the casing, stop using immediately, allow unit to dry out and have checked by
qualified personnel before further use. Avoid impact, extreme pressure or heavy vibration to the case
No user serviceable parts inside –Do not open the case –refer all servicing to qualified service
personnel.
Note: This unit must be earthed
Safety
Check for correct mains voltage and condition of IEC lead before connecting to power outlet
Speaker leads should be of good quality and have cores which are capable of full power output
Do not allow any foreign objects to enter the case or through the ventilation grilles
Placement
Keep out of direct sunlight and away from heat sources
Keep away from damp or dusty environments
Ensure adequate air-flow and do not cover cooling vents at the front and rear of the amplifier
Ensure adequate access to controls and connections
Cleaning
Use a soft cloth with a neutral detergent to clean the casing as required
Use a vacuum cleaner to clear ventilation grilles of any dust or debris build-ups
Do not use strong solvents for cleaning the unit

178.738UK User Manual
Input Channel
1. Channel output level (volume)
2. Pan control (left/right)
3. DSP Effects level
4. High frequency EQ control
5. Low frequency EQ control
6. Channel Gain level
7. Peak level LED indicator
8. High impedance input (e.g. Line / instrument) - unbalanced 6.3mm jack
9. Low impedance input (e.g. Microphone) - balanced XLRF
Master Section
10. USB player control & display
11. DSP effects (FX) section
12. FX send level
13. 2-track input level
14. FX return 6.3mm jack
15. FX out (send) 6.3mm jack
16. USB device input
17. REC output connectors (L+R RCA)
18. 2-track input connectors (L+R RCA)
19. Power and level meter LEDs
20. Graphic EQ frequency sliders
21. Main Left and Right output level
22. FX return level
23. Phones output level
24. Phones output - stereo 6.3mm jack
25. Phantom power switch (+48V)
26. Line out 6.3mm jack

178.738UK User Manual
Rear Panel
27. Cooling fan
28. Power on/off switch
29. IEC mains inlet and fuse holder
30. Right channel SPK + jack outputs
31. Left channel SPK + jack outputs
Setting Up
Connect speakers via the outputs on the rear panel (30, 31) using good quality speaker leads with
6.3mm jack or SPK connectors and twin core cable, recommended no smaller than 2 x 0.5mm² CSA.
When connecting speakers to the outputs, ensure that the combined load on either channel is no
lower than 4 Ohms (4Ω). To make sure of this, check the manufacturer’s information.
If connecting more than one speaker, observe the following calculation method.
Most PA and sound reinforcement speakers are 8Ω, so we consider that 1/8 + 1/8 = 1/4
Therefore, when connecting 2 x 8Ω speakers to a channel on the PHX series PA head, the resulting
total load is 4Ω.
When 2 speakers are connected to a single output, each speaker will receive half of the rated output
of that channel.
With the power switch (28) in the Off position, connect the IEC inlet (29) to the mains using the
power lead provided.
Connect a microphone via one of the balanced XLR inputs (9) or a line input to an unbalanced jack
connector (8) for each channel to be used.

178.738UK User Manual
Wiring for balanced mic and unbalanced line inputs are shown below.
Operation
To check an input, ensure that Pan and Low / High EQ controls (2, 4, 5) are set to the vertical
(12 o’clock) position and the Level, FX and Gain controls (1, 3, 6) are turned fully down.
Turn the Master volume controls (21) down and set all Graphic EQ sliders (20) to halfway position.
Some microphones and DI boxes require phantom power to operate (check manufacturer’s spec.)
A Phantom power switch (25) provides +48V to all XLR inputs with an indicator to show when active.
Switch the mains power on (28) and check the microphone or line level input whilst increasing the
Gain control (6) until the red Peak LED (7) lights when the loudest sound is produced at the input.
Back the Gain down control down until the Peak LED lights only momentarily on the loudest sounds.
The channel gain is now set to match the input source.
Turn up the Master volume controls up part way and gradually increase the Channel output level (1)
for the microphone or line input source whilst checking the output through the connected speakers.
Alternatively, a USB pen drive with compressed audio tracks stored can be connected to the USB
Audio Player (10) for checking playback. More details are shown in the “USB player” section below.
Once the sound has been checked through the speakers, increase the Master volume to the required
level, ensuring that the LED level meter (19) doesn’t continually reach into the red (+7dB).
The red +7dB level meter LED should only ever light briefly on the loudest peaks of the sound (e.g.
bass drum beat) and if it lights for anything longer than momentarily, the Channel or Master levels
must be reduced until it stops lighting.
Adjust the channel output level controls (1) to balance the mix and if required, adjust the tone of any
channel by boosting or cutting the Low and High controls (4, 5) –the vertical position is neutral.
Further tone adjustment for the overall mix is available via the master Graphic Equalizer (20).
This section is home to 2 sets of 7 sliders which range from 63Hz to 16kHz centre frequencies.
Halfway up the slider is neutral, top position is 12dB boost and bottom is 12dB cut of that frequency.

178.738UK User Manual
An auxiliary 2-track input is provided on L+R RCA connectors (18) for a line level playback source.
The level of 2-track to the outputs is controlled by the 2-track level rotary control (13)
For recording, there is a REC output on L+R RCA connectors (17) delivering line level stereo output.
A mono line output is also provided via a 6.3mm jack (26) for monitoring and further amplification.
For monitoring with headphones, there is a stereo 6.3mm Phones jack output (24)
The headphone output level is governed by the Phones level control (23)
DSP effects
The PHX300 has a 16 program DSP effects (FX) section for vocal or instrument digital effects (11).
Use the UP/DOWN keys to step through the 16 internal programs and ENTER to select.
The effects section is fed from each channel via its FX rotary control (3) and the combined input level
is governed by the master FX level control (12) to avoid overdriving the DSP circuit.
If the internal DSP is not required, this signal can be fed out of the PHX300 via the FX out jack (15)
This can be used as a separate auxiliary output, governed by the FX level control or as a separate
mix and back into the PHX300 via the FX return jack (14) forming a send/return loop.
A list of the internal effect programs in the PHX300 is shown below.
Program
Effect
1
Flanger
2
Hall 1
3
Room 2
4
Hall 2
5
Hall 3
6
Plate 1
7
Phaser
8
Gated Reverb
9
Chorus 1
10
Chorus 2
11
Hall 4
12
Large Hall
13
Delay 1
14
Delay 2
15
Hall 5
16
Reverse Reverb

178.738UK User Manual
USB player
The PHX300 PA head has a built-in audio player which can playback compressed digital audio files
stored on a USB memory device.
32. Play/pause status
33. Repeat status
34. Folder and track number
35. EQ mode
36. USB device status
37. Track time elapsed & remaining
38. Track name
39. Playback active display
40. Stop key
41. Play/pause key
42. Next/volume+ key
43. Previous/volume- key
44. EQ/repeat key
To begin using the USB/SD audio player, insert a USB pen drive with standard compressed audio files
stored on it into the USB type A connector on the front panel (16). Maximum capacity 32GB
Press Play/Pause key (41) to alternately pause or play the current selected track.
Pressing the Stop (40) key will stop playback and return to the start of the track.
To navigate through tracks stored on the USB device, press the Next or Prev keys (42, 43).
Pressing and holding these buttons adjusts the output volume up or down.
The EQ/Rpt key (44) steps through preset EQ profiles for playback, indicated on the LCD display.
Holding this key down toggles the repeat play modes, also indicated on the LCD display.

178.738UK User Manual
Specifications
Power supply
230Vac, 50Hz (IEC)
Fuse
T5AL
Power rms @ 4 Ohms
2 x 150W
Power rms @ 8 Ohms
2 x 100W
Channel inputs
Balanced XLRF or unbalanced 6.3mm jack
Channel controls
Level, Pan, Aux, High, Low, Gain
Music source
Onboard USB audio player
Music control
Stop, Play/Pause, Previous, Next, Repeat
Effects
16 preset program DSP
Auxillary output
Effects send (6.3mm jack), REC out (RCA)
Auxiliary input
Effects return (6.3mm jack), 2TK in (RCA)
EQ master bands
63, 150, 400, 1k, 2.5k, 6.3k, 16kHz (stereo)
Master controls
Aux return, Main L, Main R
Phantom power
Globally switchable +48V (XLR inputs)
Phones output
Stereo 6.3mm jack (with level control)
Line output
Stereo 6.3mm jack
Speaker outputs
L+R SPK or 6.3mm jack
Dimensions
450 x 270 x 265mm
Weight
9.4kg
Troubleshooting
Power LED is not lit
Check power is switched on at the mains and at the rear panel
Check IEC fuse –if blowing fuses, refer to qualified service personnel
Power LED is on but no other LEDs
and no output
Check input signals and condition of connection leads
Check channel gain and EQ controls are not turned fully down
Check Master and channel level controls are not fully down
Power and level meter LEDs are
lighting but no speaker output
Check output connections to speakers
Check that speakers are in good working order
No playback from USB media
Check that files are standard compressed audio format
Check the volume setting within the audio player
Output is very loud or distorted
Check level of input signal is not too high
Reduce channel level and EQ settings
Ensure Hi-Z line level input(s) not connected via XLR
Check AUX level control and reduce if necessary
Output is working but at very low
level
Check input audio source level is not too low
Ensure low impedance line or mic signal is not connected via jack
Increase channel level control and EQ settings if turned down
Feedback with microphones
Face microphone away from speakers and monitors
Reduce channel level control and/or EQ level(s)
Disposal: The “Crossed Wheelie Bin” symbol on the product means that the product is classed as Electrical or
Electronic equipment and should not be disposed with other household or commercial waste at the end of its useful life.
The goods must be disposed of according to your local council guidelines.
Errors and omissions excepted.
Copyright © 2015. AVSL Group Ltd.