Amphion One25A User manual

Reference manual
10/2023
One25A

32
beautifully honest
Contents
Introduction 4
Safety 6
Warranty and support 8
Instructions 10
Philosophy 12
Technical specications 14
Technologies and features 16
Controls and connections 20
Lights 22
Setup guide 24
Acoustic centre point 26
Sot mounting 27
Boundary control 28
Immersive 30

54
Introduction
Over a decade has passed since the introduction of Amphion’s studio monitor line.
Pushing the acoustic design and keeping the products electrically simple created
an intuitive and eective tool, which has been embraced by the world’s top sound
engineers. Going against the norm with the passive design was naturally bold and
risky, but we managed to get our ideas through. Amphion’s design focus is always
result - not technology - oriented. We have never opposed the basic principle of
active speakers. We simply felt we could achieve better resolution and naturalness
by applying passive design at the time.
Active approach has certain benets ie. matching the amps to drivers, overload/
overdrive protection and limiters, and the option of making really steep lters and
cut-o points. However, many active designs lose resolution due to their highly
complex signal paths. As we strongly believe in elegant and rened signal paths,
we are not against the use of DSP. But we feel strongly that unnecessary DSP and
AD/DA stages should always live outside of the speaker.
Welcome Presenting Amphion One25A ... a monitor true to Amphion’s core strengths of
advanced acoustic design, rened signal path, and high level resolution - enhanced
with the benets of active design without any of the downsides.
Anssi Hyvönen
Founder & Managing Director, Amphion Loudspeakers Ltd.

76
Safety
Safety warnings 1. Please read and follow these
instructions before using the product.
2. Do not use this apparatus near water.
3. Clean only with a dry cloth.
4. Do not block any ventilation openings.
5. Install in accordance with the
manufacturer’s instructions.
6. Do not install near any heat sources such
as sunlight, radiators, heat registers, or other apparatus (including ampliers) that produce heat.
7. The unit generates heat especially during prolonged operation at intensive levels. Please do not
cover or place objects on top.
8. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has
two blades with one wider than the other. A grounding-type plug has two blades and a third
grounding prong. The wide blade or the third prong are provided for your safety. If the provided
plug does not t into your outlet, consult an electrician for replacement of the obsolete outlet.
9. Protect the power cord from being walked on or pinched, particularly at plugs, convenience
receptacles, and the point where they exit from the apparatus.
10. Use only with the stand, bracket, or table which is sturdy and stable enough to support the units
substantial weight. Ensure the monitors do not tip/fall and cause injury or damage.
11. Any terminals marked with the preceding symbol are HAZARDOUS LIVE and any wiring
connected to these terminals must be installed by an INSTRUCTED PERSON or with ready-
made leads or cords.
12. Unplug this apparatus during lightning storms or when unused for long periods of time.
13. Refer all servicing to qualied service personnel. Servicing is required when the apparatus has
been damaged in any way, such as power-supply cord or plug is damaged, liquid has been
spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or
moisture, does not operate normally, or has been dropped.
14. These monitors can produce high sound pressure levels (SPL). Exposure to high volume has the
potential to cause hearing damage. Adjust the system’s volume level to remain within safe limits.
WARNING: TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK, DO NOT EXPOSE THIS
APPARATUS TO RAIN OR MOISTURE. DO NOT EXPOSE THIS EQUIPMENT TO DRIPPING OR
SPLASHING AND ENSURE THAT NO OBJECTS FILLED WITH LIQUIDS, SUCH AS VASES, ARE
PLACED ON THE EQUIPMENT. TO COMPLETELY DISCONNECT THIS EQUIPMENT FROM THE
AC MAINS, DISCONNECT THE POWER SUPPLY CORD PLUG FROM THE AC RECEPTACLE. THE
MAINS PLUG OF THE POWER SUPPLY CORD SHALL REMAIN READILY OPERABLE.

98
Warranty and support
Warranty
Handmade in Finland
Amphion Create products come with a two-year
warranty against defects in materials and our
workmanship. For warranty or out-of-warranty service,
in the rst instance please contact your original dealer
and provide a copy of the original sales receipt. If you
require additional assistance, please contact your local
sales representative or distributor. If you have diculty
making contact with either of the above, please contact
our headquarters. Please do not return or ship any
product to Amphion Loudspeakers Ltd. nor its resellers
without prior authorisation.
Amphion Loudspeakers Ltd. is awarded the right to use
the Association for Finnish Work’s Key Flag Symbol
mark of origin. This mark is granted to Finland-based
organizations that manufacture their products in Finland,
having a minimum domestic content of 50 percent.
Amphion Loudspeakers Ltd. was established in 1998. We design and build
loudspeakers that are characterised by honest and accurate sound reproduction.
All products are handmade in Finland (and the Amphion ampliers are assembled
in Finland) to ensure enduring listening quality.
www.amphion.
Social media
www.facebook.com/AmphionLoudspeakers
twitter.com/amphion_
www.youtube.com/user/AmphionLoudspeakers
www.instagram.com/amphion_loudspeakers
Company prole
Hear more
two years
warranty

1110
Unpacking
Connecting
Care
Maintenance
Instructions
Please contact your local Amphion dealer or sales representative for additional
guidance on cabinet, driver, or electronic maintenance. For more information, you
can also contact Amphion headquarters or our regional oces in Asia (Japan) and
North America (USA).
o
180
Handmade in Finland
Handmade in Finland
Handmade in Finland
0
dB
+1
+2
+4
-2
-4
+7
-1
-7

1312
Your ears are the most important tool in your studio. Providing them with detailed,
reliable information is the only way for making right, stress-free decisions. Pushing
the acoustic design allows our products to have a simple signal path, as well as
ensure transparency, resolution, and exceptional time and phase coherence. All
products use time-adjusted drivers and low crossovers. This leads into point-
source-like behavior and seamless driver integration. Rock solid “phantom” center,
life-like 3D imaging and a wide and deep sweet-spot are characteristic of all
Amphion products.
Amphion’s Uniformly Directive Dispersion (U/D/D) allows the speakers to work in a
predictable and acoustically-stable manner in all rooms. Amphion’s fth generation
waveguide ensures driver integration, eliminates cabinet diractions, and produces
a uniform and even response throughout a broad frequency band. The result is a
wide, even listening area, which provides predictable results in your current room
as well as your next. Use of sealed cabinet instead of a vent not only makes for a
more natural energy transfer and improved bass denition, but also enhances the
midrange clarity.
Hear it all
Truthful sound
Philosophy
Work smarter Achieving more in less time with minimum revisions, while keeping your clients
happy, is a must in today’s world. To achieve this, your monitoring must translate
well and guide you to focus on the essential information. Being able to totally trust
your monitors leads into substantial time savings and peace of mind - even when
working towards the tightest deadlines. World class translation and ability to make
fast intuitive decisions help achieve consistent results equally well for stereo and all
immersive formats.

1514
Technical specications
Frequency response 180.0100.0
dBSPL
90.0
80.0
70.0
60.0
50.0
20 100 1k 10k 20kHz
CLIO
Deg
108.0
36.0
-36.0
-108.0
-180.0
Operating principle
Tweeter
Mid
Bass
Crossover point
Amplier power
Power consumption (idle)
Power consumption (max)
Max SPL
Frequency response
Connections
Mains
Measurements (H x W x D)
Weight
Active, 3-way, sealed cabinet
25 mm / 1” titanium
15 cm / 5¼” aluminium
25 cm / 10” aluminium
100 Hz / 2000 Hz
Bass 700 W
Tweeter & Midrange 2 x 205W THD + N 0,002%
35W
350W
105 dB
22 - 55 000Hz (-3dB)
Balanced XLR Input
1x Female XLR, pin 2-hot
230 V / 50 Hz or 115 V / 60 Hz (Factory preset)
316 x 510 x 487 mm
41 kg / 91 lb

1716
Technologies and features
Internal view Waveguide
Sealed dual
cabinet
Isolated chambers
Acoustic
symmetry
Amphion’s Uniformly Directive Dispersion (U/D/D) allows the speakers to work in
a predictable and acoustically stable manner in all rooms. Amphion’s signature fth
generation waveguide ensures driver integration, eliminates cabinet diractions
and produces a uniform and even response through a broad frequency band. The
result is a wide, even listening area, which allows you to trust your monitors in your
current room as well as your next.
The internal bracing is designed both as a stiening support structure and as a
physical-energy dispersion lter. It utilizes the mass of the sub-driver, and how it is
connected to the bracing structure, to control the resonance of the whole enclosure
in a desirable way. The glue-joints of the enclosure are specically designed to
control various structural stinesses as well as enclosure edge vibration dispersion.
New midrange driver and tweeter are in an isolated sealed chamber which
minimizes the bass woofer’s negative eects like pressure changes, leading to high
midrange and treble resolution ensuring crystal clear transparency.
The channel between the two compartments ensures acoustic symmetry for
the midrange drivers, and acts as a transfer-insulator/lter by separating the two
chambers. The ecient surface damping qualities of the material between the
compartments acts as a vibrational and acoustical dampening lter for the whole
enclosure.
1
1
2
2
3
4
4 3

1918
Back
Technologies and features
Active speakers are typically complex with many sequential active stages - each
with countless electronic components. As a result, the sonic integrity tends to get
compromised. In DSP-based solutions, the situation is even worse: transparency,
depth, and detail is lost because of both conversion and processing. The beauty
of passive speaker crossovers lies in their simplicity, which helps to maintain a high
level of audio resolution. The One25A follows this design philosophy, but as an
active speaker, it is radically dierent. It could be described as a line-level passive
crossover, which is buered with ultra-clean FET buers. This gives us the best of
both worlds.
Instead of placing the ampliers and power supply inside the monitor, where they
are negatively aected by physical vibration and magnetic forces of drivers, all the
electronics are housed outside the cabinet. The rigid, well-isolated steel enclosure
can also be removed for sot mounting. Placing components in a well-cooled
enclosure ensures maximum ventilation and lowest possible operating temperature.
Amphion’s 8-step low frequency adjustment boundary control (+/-7dB). Please
refer to page 28 for more information.
Amphion’s overloadprotection circuitry. Pleaserefer topage 22formoreinformation.
Simple, rened
signal path
Removable Amp
Pack
Boundary control
Protection circuit
1
2
3
4
One25A
AUDIO INPUT LOW FREQUENCY CONTOUR AC MAINS POWER
1 24 3

2120
This is the XLR output for your mains. If you are using an unbalanced destination, it
is recommended to leave XLR pin 3 unconnected.
Amphion’s 8-step low frequency adjustment boundary control (+/-7dB). Please
refer to page 32 for more information.
IEC power connector. Selected between the 100-240V range by users region.
Please contact Amphion support if questions occur.
This is the power switch I = ON, O = OFF
Always turn power o before inserting or removing cables.
Input
Boundary Control
Power input
Power switch
PLEASE NOTE!
Controls and connections
Back
!
1
1
2
2
3
3
4
4

22 23
Lights
Standby / On mute
Wait for white light
Power on
Normal operation
Overload protection
Power ampliers overload protection is active (audio level and spectrum is limited
for monitor protection).
In order to keep the signal path as short and resolving as possible, the protection
circuitry is kept separate from the audio signal path and it remains inactive until
limiting is needed.
Instead of muting, cutting the signal, or skewing the frequency balance, the limiting
circuitry is designed to keep the workow undisturbed and the music playing.
Technically, it can be considered to be a soft, padded wall instead of a typical brutal
brick-wall approach. This gentle approach will help prevent damage to the speaker
drivers, but understands real-life situations where playback levels can get overly-
loud occasionally. To prevent damage to speaker drivers and human ears, it is
always advisable to turn the volume down when the red light is activated.
Blue
White
Red
Protection circuitry

2524
Setup guide
60°
Display Position
Studio-monitor
placement
Studio-monitor stencil
For both stereo and immersive installations, it is important to maintain symmetry.

2726
The acoustic center point of Amphion One25A is located between the drivers
(under the waveguide, on top of the woofer), which allows them to be used both
vertically and horizontally. Line the acoustic centre point to your ear-level for optimal
performance. Depending on your listening distance and room size, the tweeter can
be placed both inward and outward. With shorter distances you can increase the
size of the soundstage by placing it outward, while with longer distances it can be
placed inward.
Between the drivers Removable amp
Acoustic centre point Sot mounting
Due to our sealed design the One25A is well suited for sot mounting. The amplier
pack can be detached and separated from the speaker and a rack mountable
Amp Pack version is available. Please contact your local Amphion partner or
headquarters for additional guidance.

2928
Boundary control
2010
10
5
dBu
0
-5
-10
-15
550 100 200 500 1k 2k 5k 20k10kHz
CLIO
One25A’s boundary control system allows ne tuning the bass response in eight
steps i.e. +/- 1dB, 2dB, 4dB, and 7dB (measured at 20Hz).
Placing speakers close to boundaries such as walls tends to cause bass build-
up, which can be compensated easily with a turn of a dial, which is located next
to the XLR input. Please note that boundary control allows both decreasing and
increasing the bass level to ne tune the response to dierent rooms, wall density,
placement and personal preference. Note that the oor is also considered a
boundary, which means that the mounting height of the speaker will aect the
response at the lowest frequencies.
The adjustment is a smooth shelf-type curve mostly operating at frequencies below
150 Hz. Even if results sound sonically ne, use caution when applying correction
as large amounts of boost will use more amplier power and result in longer driver
excursion. Note that the speaker is designed to work in most rooms of various size
without any need for adjustment.
8-steps Boundary control

3130
Immersive
Immersive environments set new demands for monitoring. Precise imaging,
dened depth information, and immaculate phase behaviour are a must when
placing objects on the 3D-grid. As the number of channels grow, even the smallest
shortcomings in monitoring lead to a lack of cohesion. Amphion’s unique acoustic
design ensures an exquisite, three-dimensional, reference quality soundscape
that’s needed to achieve industry leading results.
Our professional studio monitors can be mixed and matched completely seamlessly,
as their acoustic design, tonal characteristics, and dispersion are precise and
uniform. All Amphions utilize proprietary waveguides, sealed enclosures, tweeters
with similar crossovers, and drivers with tight production tolerance - which lead
to a seamless sound-eld and contribute to sonic conformity and consistency in
all settings. Our advanced acoustic design minimizes electrical clutter and allows
harnessing the full power of the latest signal processing devices, as well as room
correction or other types of advanced software. Due to their phase coherence
and pinpoint imaging, Amphion monitors translate particularly well to any playback
devices, as they allow you to correctly reproduce information in all planes - including
width, height, and depth.
For surround or immersive formats, we recommend that all speakers are aimed
directly at the listening position, to ensure consistent balance and focus across the
whole sound eld. Please refer to page 28.
LCR
ONE25A
This is an example, many
different configurations can
be created.
Bass Extension shown in
sideview.
LFE
FLEXBASE25
SURROUND
ALL MODELS
OVERHEAD
ONE12, ONE15, ONE18
Seamless and uniform

AE/RMKR/INEN/1023
Amphion Loudspeakers Ltd.
Telkkistentie 2
70460 Kuopio
Finland
[phone]
info@amphion.
amphion.