PMC twenty5 sub User manual

No.
Hand built by
user guide

Please take a few moments to register your warranty at www.pmc-speakers.
com (click on ‘register a product’) or complete the warranty card at the
back of this booklet. This records the purchase of your subwoofer and provides
you, the customer an opportunity to make suggestions and provide feedback
directly to PMC.
For product support, accessories or servicing advice, please contact
a PMC authorised dealer – See www.pmc-speakers.com.
IMPORTANT – Register your warranty
HOLME COURT, BIGGLESWADE, SG18 9ST, UK
T [phone] F [phone]
[email protected]
www.pmc-speakers.com
© 2016 PMC. All rights reserved.
Ref No: 782
PMC Stock Code: 15089

At PMC, we believe that music is what really matters; it’s what moves us and
gives us the passion for what we do. The company was founded because there
wasn’t a loudspeaker that was transparent enough to convey all of music’s
expressive power – and we knew we could remedy this.
One of our core beliefs has always been that the same loudspeaker can be
through post-production and mastering, right to the listener at home. Discerning
listeners all over the world agree. Our designs are involved in every link of the
music-making chain, from the recording studio to listening at home, which
means we know exactly how to present music as transparently as possible,
just as the artist intended. This knowledge, combined with our love for music,
drives us to create products that you listen through rather than to. We want
you to share the thrill of the original recording because there is nothing like the
emotional impact of true musical communication.
Loudspeakers are where science meets art; we understand the science so that
you can connect with the art.
Peter Thomas, Owner &
Oliver Thomas, Head of Design

Congratulations – You have joined the elite
earned an unrivalled reputation for
loudspeakers. Simply put, our speakers
provide a reference for the world’s
They are found at every stage of the
creative process, from conception
to recording and broadcast and, of
course, in the home.
Our client list reads like a who’s who
of the sonically aware, with Elbow,
Stevie Wonder, Coldplay, Brian May,
Universal, EMI, Sony, Pinewood Studios,
Dreamworks, Deutsche Grammophon
and the BBC among the makers
of movies and music who use our
products.
Our loudspeakers were also used in
the production of , ,
James Bond’s and ,
,
, and during broadcasts
of the Beijing and London Olympics.

Contents
General usage guidelines
Introduction
Advanced Transmission Line ( )
System description
Unpacking and care
Installing the resonance absorbing plinth bars
Connections
Positioning and alignment
Operational controls
User EQ options
Integration - Initial setup settings
Running in
Service
The series
Our meticulous attention to detail
Inspection checklist
Warranty on-line
Help us improve - Your comments

Read these instructions and keep them in a safe place for future reference.
Heed all electrical safety warnings, including any on the subwoofer itself.
Do not use the subwoofer near water.
should only be cleaned with a dry, lint-free, cloth. Do not use solvents, abrasives, waxes
Floor spikes are sharp and should be treated with great care during installation and use.
Do not install near any heat sources such as radiators, ovens, other equipment that
Unplug this product from both source and power during electrical storms or when unused
for extended periods of time.
Packing material can pose danger to the young and vulnerable.
Ensure these items are kept or disposed of safely.
High volume audio signals, however short their duration, have the potential to cause
hearing damage. Use care when setting the system volume level to ensure playback
sound pressure levels remain within safe comfortable limits.
Do not attempt to service the equipment. There are no user serviceable parts inside.
Please refer all servicing to PMC authorised personnel.
Servicing is required when the apparatus is damaged, exposed to moisture,
or exhibits a distinct or sudden change of operation or audio performance.
PMC has made efforts to provide accurate installation information and good quality
indirect or consequential - arising out of use or inability to use this product safely and
properly.
Thesubwoofer contains very powerful magnets and therefore may have
a detrimental effect if left in close proximity to magnetically sensitive items such as;
and videotapes.
General usage guidelines

Thank you for choosing the PMC active subwoofer. This guide provides installation and
operating instructions.
series speakers to gain
extra bass extension and headroom, or they can be used to reproduce a low frequency effects
illustrated in this guide.
The electronics built into the subwoofer cabinet include an ultra-low distortion Class-D power
routed via the . Balanced stereo analogue and AES3 digital inputs are accepted to
feed the subwoofer system, and these input signals are also passed through to the analogue and
digital outputs for connection with other devices. The outputs can be unprocessed or high-pass
The input source, analogue input sensitivity, gain trim, and overall volume are all adjustable, as are
a single parametric equaliser is provided to assist with in-room alignment. The analogue and digital
available with the unique (Advanced Transmission Line) bass loading principle, ,
technology
uses contemporary materials to provide optimised absorption of unwanted low-midrange energy
The two long-throw bass drivers employed in the subwoofer are a bespoke
PMC design delivering an unparalleled transient response. The cabinet has a small
footprint, making it more convenient and easier to place than typical cube-shaped designs.
Introduction

TM
Advanced Transmission Line
The source of PMC’s legendary natural and wholly
realistic sound is the Advanced Transmission Line
( ) bass-loading technology.
is an ingenious design which uses energy
generated by the bass unit in a much more
based on ported or sealed boxes.
In loudspeakers, the highly braced cabinet
is lined with a multitude of custom-designed
acoustic materials that absorb all but the very
lowest frequencies. These are guided to exit from
a vent on the front-panel, extending the low-
frequency response and creating the impression
of a far larger speaker with an extra, ultra-high
quality bass unit.
improves more than just the bass response:
because the low end is clean and clear it doesn’t
mask the rest of the music. Vocals in particular,
are beautifully projected and ultra-vivid.
bass extension does not change with volume
level – so even when listening quietly the bass
This cross-sectional view of the
loudspeaker shows the cabinet
arrangement and the unique vents

With the launch of the series, loudspeaker audio performance has been taken to the
next level with the addition of the aerodynamic vent.
The design involves air moving under pressure at high speeds, and PMC’s Head of Design,
Oliver Thomas was able to apply aerodynamic principles transferred from his previous industry,
Formula 1 to the concept.
The result is the unique aerodynamic vent which creates an even smoother, laminar
This innovative solution
reduces turbulence and
drag at the vent,
reducing resistance,
eliminating air noise, and
provides bass with supreme
timing and the ultimate
dynamic range.

System description
The active subwoofer has a powerful
of 96kHz.
The two balanced analogue inputs are
conditioned by an adjustable low-noise gain
stage prior to A-D conversion to optimise the
signal-to-noise ratio. The converter is a very
high quality delta-sigma device, producing
a 24-bit, 96kHz output. The left and right
channels are summed to drive the subwoofer
speakers, but passed on as separate signals
to the analogue outputs.
The AES3 digital input accepts sample rates
up to 192kHz, and is sample rate converted
to 96kHz automatically. Either channel, or a
sum of both, can be selected to drive the
subwoofer, and both are passed on to the
digital output.
The DSP engine provides the system volume
equalisation, and phase alignment for the
management options for the analogue and
digital outputs. It also provides non-invasive
excursion limiting to protect the drivers.
The DSP system generates three sets of outputs.
In addition to the digital output, there are
two separate D-A converters. One converter
provides the analogue outputs, while the
connected to the loudspeaker(s).
The analogue and digital outputs are always
available and can be formatted to provide
which can be used for satellite speakers or other
follow the system volume control setting.

The PMC active subwoofer is packed in a heavy-duty protective carton. Please retain the
carton to ensure that the loudspeaker can be transported safely if the need arises in the future. If you
dispose of the packaging please do so in an environmentally responsible and safe way.
In normal usage PMC speakers should provide many years of trouble-free operation, but in the unlikely
event that you suspect damage or failure has occurred do not attempt to repair the unit yourself.
There are no user-serviceable parts inside. Contact your dealer for advice and a service return
address.
Clean the cabinets with a dry and lint-free cloth, and avoid the use of solvents as they may damage
Unpacking and care
1x
2x plinth bars
1x Grille
4x Cork isolators
4x Spike pucks
4x M8 spikes
4x M8 countersunk bolts
1x AC mains power cable
2x RCA - XLR phono adapter
1x Cleaning cloth
1x User Guide
!

Installing the resonance absorbing
plinth bars
Resonance damping plinth bars and spikes enhance the performance and
stability of the . The bars attach to the base of each speaker
using 4 x M8 countersunk bolts. The series spikes can be used on
Carefully invert the subwoofer so that its base is uppermost. Take care not
to damage the top of the cabinet when it is upside-down, the use of a
soft cloth or square of carpet is suggested.
Locate the large M8 bolts and tighten them using the allen key
.
Do not over tighten. Over tightening will reduce the effect of the
resonance absorbing material
The spikes are sharp and should be treated with great care and may
You have the option of using the spike pucks for use on more sensitive
Re-invert the loudspeaker so that the spikes and plinth are at the bottom.
Once in position, level the loudspeaker by adjusting each spike in turn.