Audio T Verdict
The PMC Active twenty5.21i combines the compact dimensions of PMC's smallest twenty5i standmount speaker with dedicated amplification and an active crossover engineered specifically for its drive units.
Each cabinet contains two 100W amplifiers. One powers the 140mm midrange and bass driver, while the other directly controls the 19mm soft-dome tweeter. This removes the need for a separate power amplifier and allows PMC to optimise the crossover, amplification and drivers as one complete system.
PMC's Advanced Transmission Line and Laminair vent help the compact cabinet deliver controlled and extended bass, while balanced XLR and unbalanced RCA inputs make the speakers compatible with a wide selection of suitable pre-amplifiers, DACs and network music players.
They are an excellent option for listeners who want the precision and control of a properly engineered active system without filling the room with separate power amplifiers. They do, however, require a source with volume-controlled analogue outputs and a mains connection for each speaker.
PMC Active twenty5.21i Standmount Speakers
The PMC Active twenty5.21i is a pair of compact, two-way active standmount speakers designed for high-quality music systems, professional-style listening setups and carefully configured home cinema installations.
Each speaker combines:
- A 140mm PMC g-weave midrange and bass driver
- A 19mm PMC and SEAS SONOMEX soft-dome tweeter
- A dedicated 100W amplifier for the midrange and bass driver
- A dedicated 100W amplifier for the tweeter
- A model-specific analogue active crossover
- PMC Advanced Transmission Line bass loading
- PMC Laminair aerodynamic vent technology
- Balanced XLR and unbalanced RCA inputs
- Two selectable input-sensitivity settings
- Dual-band driver-protection circuitry
The pair therefore provides four dedicated power-amplifier channels and a total published amplifier output of 400W across the complete stereo system.
A Volume-Controlled Source Is Required
The Active twenty5.21i does not contain a conventional volume control, source selector, network streamer or remote-controlled pre-amplifier.
Connect it to a suitable pre-amplifier, DAC/pre-amplifier, analogue-output streamer or another source with a properly controlled variable output.
Do not connect a fixed-level CD player, DAC or streamer directly unless the product manufacturer confirms that its output can be controlled safely.
What Does Active Mean?
In a conventional passive system, one external amplifier sends a full-range signal through speaker cable to a passive crossover inside each loudspeaker.
The crossover then divides that amplified signal between the speaker's drive units.
The PMC Active twenty5.21i takes a different approach:
- A line-level analogue signal enters each speaker through RCA or XLR.
- An active analogue crossover divides the signal at line level.
- The high-frequency signal is sent to its own 100W amplifier.
- The midrange and bass signal is sent to a separate 100W amplifier.
- Each amplifier connects directly to the drive unit it was designed to control.
This allows PMC to engineer the crossover frequency, crossover slopes, amplification, protection circuitry and drive-unit behaviour together.
200W of Amplification in Each Speaker
Each cabinet contains two dedicated 100W RMS amplifiers:
- High-frequency amplifier: 100W RMS
- Low-frequency amplifier: 100W RMS
This does not mean that each speaker behaves like a conventional passive speaker connected to a single 200W amplifier.
Each amplifier handles only the frequency range intended for its drive unit. The tweeter amplifier is not required to reproduce bass, and the midrange and bass amplifier is not required to reproduce the highest frequencies.
The direct connection between amplifier and driver also removes the passive crossover components that would otherwise sit between them.
Analogue Active Crossover
A precision analogue active crossover divides the incoming signal at approximately 1.65kHz.
PMC models the crossover specifically for each Active twenty5i speaker so that the drive units integrate correctly through the crossover region.
The crossover operates before the power-amplifier stages. This means each amplifier receives only the frequencies required by its connected drive unit.
PMC also incorporates filtering and dual-band limiting to protect the drive units without relying on a conventional passive protection network.
140mm g-weave Midrange and Bass Driver
The Active twenty5.21i uses PMC's 140mm long-throw g-weave cone driver in a cast-alloy chassis.
The driver handles bass and midrange information, including:
- Vocals
- Guitars and keyboards
- Acoustic instruments
- Drums and percussion
- Bass instruments
- Lower-frequency effects
The woven cone construction is designed to combine stiffness with low mass, helping the driver start and stop accurately as the musical signal changes.
Its long-throw design allows useful cone movement while maintaining the compact cabinet dimensions.
19mm SONOMEX Soft-Dome Tweeter
High frequencies are reproduced by a 19mm PMC and SEAS SONOMEX fabric soft-dome tweeter.
The tweeter is ferrofluid cooled and uses a 34mm surround with a dispersion grille.
The design contributes to the speaker's published directivity of:
- 100 degrees horizontally
- 90 degrees vertically
This broad dispersion helps maintain a consistent tonal balance across a useful listening area rather than limiting the best result to one extremely narrow position.
PMC Advanced Transmission Line
The Active twenty5.21i uses PMC's Advanced Transmission Line, commonly shortened to ATL.
Energy from the rear of the midrange and bass driver enters a folded, acoustically damped internal line measuring approximately 1.72 metres.
The damping material is designed to absorb unwanted upper-frequency energy while allowing useful low-frequency output to reach the vent.
Compared with a conventional sealed or reflex enclosure, PMC uses ATL to pursue:
- Extended bass from a relatively small cabinet
- Controlled low-frequency decay
- Reduced unwanted midrange output from the vent
- Consistent bass performance at different listening levels
- Clearer integration between bass and midrange frequencies
Laminair Aerodynamic Vent
The transmission line terminates in PMC's Laminair vent at the front of the cabinet.
Laminair uses internal vanes shaped to promote smoother airflow as air leaves the transmission line.
Reducing turbulence at the vent is intended to minimise unwanted airflow noise and help the bass remain clean and controlled when the speakers are playing demanding material.
Published Frequency Response
PMC specifies a frequency response of 46Hz to 25kHz.
This is substantial extension for a cabinet measuring only 340mm high and 162mm wide, but the Active twenty5.21i should not be expected to reproduce the deepest sub-bass available from a larger floorstanding speaker or dedicated subwoofer.
The perceived bass performance in a room will also depend on:
- Speaker position
- Distance from walls
- Room dimensions
- Room construction
- Listening position
- Playback level
- The bass content of the recording
Balanced XLR Inputs
Each speaker provides a balanced analogue XLR input.
A balanced connection can be particularly useful when:
- The pre-amplifier provides balanced outputs
- Longer cable runs are required
- Signal cables must pass near mains equipment
- Improved rejection of common electrical interference is useful
- A professional-style connection is preferred
One XLR cable is required for the left speaker and another for the right speaker.
The system remains analogue at the speaker input. An XLR connector does not automatically mean that the signal is digital.
Unbalanced RCA Inputs
Each speaker also provides a conventional unbalanced RCA input.
This allows the Active twenty5.21i to connect to a wide range of domestic Hi-Fi components, including:
- Analogue pre-amplifiers
- DACs with variable RCA outputs
- Network streamers with volume-controlled outputs
- Suitable headphone amplifiers with pre-amplifier outputs
- AV processors with line-level pre-outputs
One RCA interconnect is required for each speaker.
Use either the balanced XLR inputs or unbalanced RCA inputs according to the source equipment and system requirements.
No Digital Inputs or Built-In Streaming
The Active twenty5.21i is not an all-in-one wireless speaker system.
It does not include:
- Wi-Fi
- Bluetooth
- Network music streaming
- AirPlay
- Spotify Connect
- HDMI ARC or eARC
- Optical digital input
- Coaxial digital input
- USB audio input
- A built-in digital-to-analogue converter
- A built-in phono stage
- A remote-controlled source selector
A digital source must therefore perform digital-to-analogue conversion before sending a controlled analogue signal to the speakers.
Active Does Not Mean Wireless
Both speakers require mains power and an analogue audio connection.
They do not communicate with each other wirelessly and they do not receive music directly from a phone, tablet or home network.
Two Mains Connections Are Required
Each speaker contains its own crossover and amplification module, so each cabinet requires a separate mains connection.
PMC specifies a universal operating range of 90V to 260V through an IEC C14 mains inlet.
Before installation, confirm that:
- A suitable socket is available near each speaker
- Mains cables can be routed safely
- Signal and mains cables are not placed under tension
- Cables do not create a trip hazard
- Ventilation around the rear electronics is not obstructed
Two Input-Sensitivity Settings
PMC publishes two input-sensitivity settings:
- Low setting: 1V RMS produces 96.5dB SPL at one metre
- High setting: 1V RMS produces 106.5dB SPL at one metre
The appropriate setting depends on the source component's output level, the room, the required listening volume and the usable range of the source's volume control.
Both speakers should be configured consistently unless the installation has been professionally measured and requires a deliberate difference.
Begin at a low volume and confirm the system's gain structure before increasing the level.
Input Impedance
PMC specifies an input impedance greater than 14 kohms.
The connected source or pre-amplifier should have a suitably low output impedance and be capable of driving the required cable length.
Audio T can confirm compatibility where the source manufacturer's output specification is unclear.
Suitable Sources and Pre-Amplifiers
A suitable partnering component must provide:
- Left and right analogue outputs
- Safe and predictable volume control
- An output level compatible with the PMC sensitivity settings
- RCA or balanced XLR connections
- Enough volume-control resolution for comfortable everyday use
Potential system partners include:
- A dedicated analogue pre-amplifier
- A network streamer with variable analogue outputs
- A DAC with an integrated pre-amplifier
- A turntable pre-amplifier with volume control
- A home cinema processor with calibrated pre-outputs
Bluesound NODE ICON System
The Bluesound NODE ICON Reference Music Streamer is one possible partner.
Its volume-controlled balanced XLR and unbalanced RCA outputs allow it to act as a network streamer, DAC and pre-amplifier for compatible active speakers.
A system built around the NODE ICON and PMC Active twenty5.21i can provide:
- App-controlled music streaming
- AirPlay 2
- Bluetooth
- Digital and analogue source connections
- Headphone listening
- Volume-controlled XLR or RCA output
- A compact two-component stereo system
Output level, cable type and the PMC input-sensitivity setting should be established during setup.
Linn Selekt DSM System
A suitably configured Linn Selekt DSM Classic Hub can provide a higher-performance modular source and pre-amplifier.
Selekt DSM requires the appropriate stereo line-output cartridge and DAC module to provide conventional analogue outputs for the PMCs.
Depending on configuration, it can add:
- High-resolution network streaming
- Analogue and digital source inputs
- Moving-magnet and moving-coil phono inputs
- HDMI television connectivity
- Space Optimisation
- Balanced XLR or unbalanced RCA line outputs
Audio T will specify the required Selekt DSM output and DAC configuration before ordering.
Connecting a Turntable
A turntable cannot normally connect directly to the Active twenty5.21i.
A complete vinyl system requires:
- A turntable
- A cartridge
- A compatible phono stage
- A volume-controlled pre-amplifier
- Analogue cables to both speakers
The phono stage may be built into the turntable, pre-amplifier or source component, but the system must still provide safe volume control before the signal reaches the active speakers.
Do Not Connect a Cartridge Directly
A turntable cartridge produces a very small, equalised signal that requires phono amplification and RIAA correction.
Connecting it directly to the PMC's line-level input will not provide a usable result.
Connecting a Television
The speakers do not contain HDMI ARC, optical or coaxial digital inputs.
Television sound therefore requires a suitable intermediary component, such as:
- A streamer with HDMI eARC and variable analogue output
- A DAC/pre-amplifier with an optical input
- An AV processor with analogue pre-outputs
- A television with genuinely variable analogue line outputs
Confirm that the television system provides proper volume control and that switching sources cannot unexpectedly send a full-level signal to the speakers.
Home Cinema and Immersive Audio
PMC identifies the compact Active twenty5.21i as a potential effects speaker within an immersive audio installation.
For this type of system, the AV processor must provide:
- A separate line-level pre-output for each speaker channel
- Reliable channel-level calibration
- Distance and delay adjustment
- Suitable bass management
- A master volume control
Each PMC still requires its own mains socket and analogue signal cable.
Professional design and calibration are strongly recommended for a multichannel active installation.
Adding a Subwoofer
The speakers do not contain a dedicated subwoofer output or user-adjustable bass-management system.
A subwoofer can be added when the connected pre-amplifier, streamer or processor provides suitable bass management or a variable subwoofer output.
The system controller should ideally provide control over:
- Subwoofer level
- Crossover frequency
- Phase or polarity
- Time alignment
- Whether the PMCs remain full range or are high-pass filtered
Audio T can advise on suitable source components and subwoofer integration.
Standmount or Bookshelf Placement
PMC describes the Active twenty5.21i as suitable for stand or shelf placement.
A dedicated stand normally provides greater freedom to position the speakers correctly and place the tweeters close to seated ear height.
A suitable support should:
- Be strong and stable
- Support the 6.15kg cabinet safely
- Provide an appropriately sized top plate
- Allow safe routing of mains and signal cables
- Position both speakers at an equal height
- Avoid blocking the front Laminair vent
Browse speaker stands and brackets at Audio T or ask your local store about an appropriate stand and filling material.
Speaker Positioning
Begin with the speakers:
- Placed at equal height
- Positioned the same distance from the listening seat
- Separated enough to create a clear stereo image
- A similar distance from the rear and side walls
- Angled towards the listener if required
- Supported on stable furniture or stands
The front transmission-line vent provides useful placement flexibility, but wall distance and room boundaries will still influence bass performance.
Moving the speakers closer to a wall may increase perceived bass weight. Moving them farther into the room may improve low-frequency definition and stereo depth.
Small adjustments should be made while listening to familiar recordings before the final position is chosen.
Active twenty5.21i or Active twenty5.22i?
Choose the Active twenty5.21i When
- The room is small or medium sized
- Compact cabinet dimensions are important
- A 140mm bass and midrange driver is appropriate
- 46Hz bass extension suits the system
- The speakers will be used at shorter listening distances
- A discreet standmount installation is preferred
Consider the Active twenty5.22i When
- The room is larger
- Greater low-frequency extension is required
- A larger 170mm driver is preferred
- Higher sound-pressure capability is useful
- The larger cabinet and dedicated stand can be accommodated
- 39Hz published bass extension better suits the system
Explore the PMC Active twenty5.22i Standmount Speakers to compare the larger model.
Active or Passive twenty5.21i?
Choose the Active Version When
- A separate power amplifier is not required
- PMC-matched amplification is preferred
- A pre-amplifier or variable-output streamer is available
- Balanced XLR connectivity is useful
- A simpler amplification system is wanted
- Each speaker can be connected to mains power
Choose the Passive Version When
- An existing integrated or power amplifier will be retained
- Amplifier choice is part of the system-building process
- Speaker-level cabling is easier to install
- Mains sockets are not available near both speakers
- A conventional passive home cinema installation is preferred
- Future amplifier changes are important
Active Upgrade for Existing Owners
Owners of compatible two-way PMC twenty5 and twenty5i passive speakers may be able to convert them to active operation using the PMC Active twenty5i Upgrade Kit.
The upgrade replaces the passive rear connection and crossover panel with a module containing:
- Balanced XLR and unbalanced RCA inputs
- A model-specific active crossover
- Two 100W amplifiers per speaker
- Driver-protection circuitry
- A selector configuration for the compatible speaker model
Audio T can confirm speaker compatibility and arrange installation.
Diamond Black, Oak and Walnut Finishes
Audio T currently lists the Active twenty5.21i in:
All three options provide the same drivers, amplification, crossover, inputs and published performance.
Key Features
- Compact active standmount speakers
- Supplied as a stereo pair
- Two-way active design
- Four amplifier channels per stereo pair
- 200W total amplification per cabinet
- 400W total published amplification per pair
- 100W RMS tweeter amplifier per speaker
- 100W RMS bass and midrange amplifier per speaker
- Analogue active crossover
- Model-specific crossover design
- 1.65kHz crossover frequency
- Dual-band driver protection
- PMC Advanced Transmission Line
- 1.72m effective ATL length
- PMC Laminair vent
- 140mm g-weave long-throw driver
- Cast-alloy bass-driver chassis
- 19mm SONOMEX fabric soft-dome tweeter
- Ferrofluid-cooled tweeter
- 34mm tweeter surround
- Tweeter dispersion grille
- 46Hz to 25kHz frequency response
- 100-degree horizontal directivity
- 90-degree vertical directivity
- Balanced analogue XLR input
- Unbalanced analogue RCA input
- Low input-sensitivity setting
- High input-sensitivity setting
- Greater than 14-kohm input impedance
- 90V to 260V universal mains operation
- Separate mains connection for each speaker
- No external power amplifier required
- No passive speaker cable required from an amplifier
- Compatible with suitable variable-output streamers
- Compatible with suitable analogue pre-amplifiers
- Compatible with suitable DAC/pre-amplifiers
- Suitable for small-to-medium rooms
- Suitable for stand placement
- Suitable for stable shelf placement
- Potential immersive-audio effects speaker
- Diamond Black finish available
- Oak finish available
- Walnut finish available
- 340mm cabinet height
- 162mm cabinet width
- 269mm depth including connectors
- Approximately 6.15kg per speaker
- Five-year registered PMC warranty
Frequently Asked Questions
Are the PMC Active twenty5.21i speakers supplied as a pair?
Yes. The product is supplied as a stereo pair.
Do they contain built-in amplifiers?
Yes. Each speaker contains one 100W amplifier for the tweeter and another 100W amplifier for the midrange and bass driver.
How much amplification is built into the pair?
The complete pair contains four 100W amplifier channels, giving a total published output of 400W across the stereo system.
Do I need a separate power amplifier?
No. The power amplification is built into the speakers.
Do I still need a pre-amplifier?
Yes. A suitable pre-amplifier, variable-output DAC or streamer is required for volume control and source selection.
Can I connect a fixed-output CD player directly?
No. A fixed-output source requires a suitable pre-amplifier or another safe method of controlling volume.
Do the speakers have a volume control?
No conventional user volume control is provided. Volume must be controlled by the connected source or pre-amplifier.
Do they have a remote control?
No. Remote operation depends on the connected source or pre-amplifier.
Do they include a network streamer?
No.
Do they have Bluetooth or Wi-Fi?
No.
Do they support AirPlay or Spotify Connect?
Not by themselves. These features can be added through a compatible network streamer.
Do they have HDMI ARC?
No. Television sound requires a suitable streamer, DAC/pre-amplifier or AV processor.
Do they have optical or coaxial digital inputs?
No. The speaker inputs are analogue.
Do they contain a DAC?
No. Digital-to-analogue conversion must be performed by the connected source or pre-amplifier.
Which analogue inputs are included?
Each speaker provides one balanced XLR input and one unbalanced RCA input.
Do I need two audio cables?
Yes. One left-channel cable connects to the left speaker and one right-channel cable connects to the right speaker.
Do the speakers connect to each other?
Each speaker receives its own line-level audio signal and mains power. No conventional speaker cable is run from one cabinet to the other.
Does each speaker need mains power?
Yes. Two suitable mains sockets are required.
What is the mains operating range?
PMC specifies 90V to 260V through an IEC C14 connection.
What is the crossover frequency?
Approximately 1.65kHz.
Is the crossover digital or analogue?
PMC uses a model-specific analogue active crossover.
What is ATL?
ATL stands for Advanced Transmission Line. It uses a long, damped internal acoustic line to manage energy from the rear of the bass driver and support controlled low-frequency output.
What is Laminair?
Laminair is PMC's aerodynamic transmission-line vent, designed to promote smoother airflow at the line exit.
What is the ATL length?
Approximately 1.72 metres.
What size is the bass and midrange driver?
Each speaker uses one 140mm long-throw g-weave cone driver.
What size is the tweeter?
Each speaker uses a 19mm SONOMEX fabric soft-dome tweeter.
What is the frequency response?
PMC specifies 46Hz to 25kHz.
What are the sensitivity settings?
At one metre, a 1V RMS input produces 96.5dB on the low setting or 106.5dB on the high setting.
Which sensitivity setting should I use?
It depends on the source output, room and required volume range. Audio T can configure the speakers and source together.
Can they connect to a turntable?
Yes, but a suitable phono stage and volume-controlled pre-amplifier are required.
Can they be used with a television?
Yes, through a suitable HDMI, optical or digital source component that provides controlled analogue outputs.
Can a subwoofer be added?
Yes, when the connected source or pre-amplifier provides a suitable subwoofer output or bass-management system.
Can they be used in a home cinema system?
Yes, where the AV processor provides the necessary line-level pre-outputs, master volume control and channel calibration.
Can they be placed on a bookshelf?
Yes, provided the shelf is strong, stable and allows safe cable routing and suitable speaker positioning.
Are dedicated stands preferable?
Suitable stands normally provide greater placement flexibility and make it easier to position the tweeters near seated ear height.
What are the dimensions?
Approximately 340 x 162 x 269mm per speaker, excluding the additional 9mm grille allowance.
How much does each speaker weigh?
PMC's current product page specifies approximately 6.15kg per speaker.
Which finishes are available from Audio T?
Diamond Black, Oak and Walnut.
Is the warranty 20 years?
No. PMC's current UK warranty table gives home-audio active designs two years as standard or five years when registered with PMC within 10 days of purchase.
Related PMC Products and Audio T Guides
Why Buy From Audio T?
- PMC Active twenty5.21i demonstrations
- Active and passive speaker comparisons
- PMC Active twenty5.21i and 22i comparisons
- Streamer and pre-amplifier matching
- Balanced XLR and RCA connection comparisons
- Source-output compatibility checks
- System gain and sensitivity setup
- Turntable and phono-stage integration
- Television and HDMI system planning
- Home cinema pre-output configuration
- Subwoofer integration
- Speaker-stand matching
- Speaker and listening-position guidance
- Mains and signal-cable planning
- PMC Active Upgrade installation
- Home demonstrations where available
- Part exchange on suitable existing equipment
- PMC product-registration guidance
- Ongoing system and after-sales support
Contact your local Audio T store to arrange a demonstration or discuss source components, pre-amplifiers, stands, cables, room placement and system setup for the PMC Active twenty5.21i.