Audio T Verdict
The PMC twenty5i Active Upgrade Kit gives owners of compatible passive PMC twenty5 and twenty5i speakers a genuine alternative to replacing their complete loudspeaker system.
The original passive crossover and terminal panel are replaced by a model-specific analogue active crossover and two dedicated 100W amplifiers in each cabinet. One amplifier directly controls the tweeter, while the second powers the midrange and bass driver.
This removes the need for an external integrated or power amplifier and allows PMC to match the crossover and amplification directly to the speaker's existing drive units.
The conversion does change the rest of the system. Each speaker requires mains power and its own balanced XLR or unbalanced RCA signal cable. A suitable pre-amplifier, DAC/pre-amplifier or network streamer with safe volume-controlled analogue outputs is also required.
Although PMC describes installation as straightforward, Audio T recommends having the kit installed and configured by an authorised PMC retailer. This ensures the correct model setting is selected and the drivers, internal connections and cabinet finish are protected.
PMC twenty5i Active Upgrade Kit
The PMC twenty5i Active Upgrade Kit converts a compatible pair of passive two-way PMC twenty5 or twenty5i speakers into a fully active loudspeaker system.
It replaces the original rear terminal and passive-crossover panel with a new module containing:
- A model-specific analogue active crossover
- A dedicated 100W amplifier for the tweeter
- A dedicated 100W amplifier for the midrange and bass driver
- Balanced analogue XLR input
- Unbalanced analogue RCA input
- Selectable high and low input sensitivity
- Driver-filtering and protection circuitry
- A universal IEC mains connection
- A model-selector connection
The kit is designed to convert one stereo pair and therefore provides one active module for each speaker.
Compatible PMC Speakers
The upgrade is designed for the two-way models in the PMC twenty5 and twenty5i ranges.
Compatible models include:
- PMC twenty5.21
- PMC twenty5.21i
- PMC twenty5.22
- PMC twenty5.22i
- PMC twenty5.23
- PMC twenty5.23i
- PMC twenty5.24
- PMC twenty5.24i
Compatibility Must Be Confirmed Before Ordering
The upgrade does not fit every PMC speaker.
It is not designed for the three-way PMC twenty5.26 or twenty5.26i, twenty5 centre speakers, twenty-series speakers, Prodigy, prophecy, fact or other PMC ranges.
Contact Audio T with the exact model, serial numbers and photographs of the rear panels so compatibility can be confirmed before ordering.
What the Upgrade Changes
In passive form, a conventional external amplifier sends an amplified full-range signal through speaker cable to the crossover inside each cabinet.
The passive crossover then divides that amplified signal between the tweeter and the midrange and bass driver.
After conversion:
- A line-level analogue signal enters each speaker through XLR or RCA.
- The active crossover divides the signal before power amplification.
- The high-frequency signal is sent to a dedicated 100W amplifier.
- The midrange and bass signal is sent to a separate 100W amplifier.
- Each amplifier connects directly to the driver it controls.
The original external power amplifier and speaker-level cables are no longer required.
What the Upgrade Retains
The conversion retains the speaker's principal mechanical and acoustic components, including:
- The original cabinet
- The existing PMC Advanced Transmission Line
- The Laminair vent
- The original tweeter
- The original midrange and bass driver
- The original cabinet finish
- The original grille
- The original plinth or stand arrangement
The kit changes the crossover, amplification and input system rather than replacing the cabinet or drive units.
200W of Amplification per Speaker
Each upgrade module contains two dedicated amplifier channels:
- High-frequency amplifier: 100W RMS
- Midrange and bass amplifier: 100W RMS
A converted stereo pair therefore contains four 100W amplifier channels and 400W of total published amplifier output.
This should not be interpreted in exactly the same way as using a conventional 200W amplifier with a passive speaker.
Each amplifier handles only the frequency range required by its connected driver. The tweeter amplifier does not reproduce bass, while the midrange and bass amplifier does not reproduce the highest frequencies.
Class-D Amplification
The upgrade uses efficient Class-D power amplification developed around PMC's active loudspeaker experience.
Class-D technology allows the amplification to be incorporated into the rear of each speaker without requiring a large external amplifier chassis.
Benefits of the integrated arrangement include:
- Direct amplifier-to-driver connection
- Amplification selected by the speaker manufacturer
- No passive crossover between amplifier and driver
- Short internal signal paths
- Reduced system-box count
- No external power amplifier
Pure Analogue Active Crossover
The incoming signal remains within an analogue crossover and amplification path.
The upgrade does not rely on a built-in digital-to-analogue converter or digital signal-processing input stage.
The crossover divides the incoming line-level signal before it reaches the two power amplifiers, allowing each amplifier to work only across the frequency range intended for its connected driver.
PMC's active loudspeaker documentation describes a fourth-order, 24dB-per-octave analogue crossover arrangement.
Model-Specific Crossover Settings
The same upgrade platform is used across several differently sized PMC speakers, but the crossover configuration is not identical for every model.
Each compatible speaker has its own model-specific setting to account for differences including:
- Drive-unit size
- Tweeter generation
- Crossover frequency
- Cabinet dimensions
- Transmission-line length
- Acoustic sensitivity
- Low-frequency extension
A supplied model-selector jumper is fitted to the position corresponding with the speaker being converted.
The Correct Model Setting Is Essential
The selector must match the exact speaker model.
An incorrect setting may apply the wrong crossover and gain configuration to the drivers. Both modules must be checked before the system is powered.
This is one reason Audio T recommends authorised retailer installation.
No Universal Speaker Frequency Response
The upgrade module does not have one universal loudspeaker frequency response or crossover frequency.
The final response depends on the cabinet, drive units and model-specific crossover setting of the speaker being converted.
For example, the compact twenty5.21-based models have different acoustic characteristics from the larger twenty5.24 floorstanding designs.
The upgrade kit's specification should therefore concentrate on its amplification, inputs, impedance, mains requirements and compatibility rather than presenting the figures of one speaker model as though they apply to every conversion.
Driver Control and Active Operation
Removing the passive crossover from the amplified signal path allows each internal amplifier to connect directly to its corresponding driver.
PMC identifies several potential advantages from this arrangement:
- Greater control over driver movement
- Improved damping of unwanted resonances
- Faster transient response
- Reduced colouration
- Improved low-level resolution
- Greater dynamic consistency
- More precise integration between the drive units
The scale of the difference will depend on the original amplifier, source equipment, room, speaker model and installation.
Balanced XLR Inputs
Each module provides one balanced analogue XLR input.
A balanced connection may be particularly useful when:
- The pre-amplifier or streamer provides balanced outputs
- Long signal-cable runs are required
- The cables pass near mains equipment
- Improved rejection of common electrical interference is useful
- A secure professional-style connection is preferred
One XLR interconnect is required for the left speaker and another for the right speaker.
The XLR input carries an analogue signal. It is not an AES or other digital connection.
Unbalanced RCA Inputs
Each module also provides one conventional unbalanced RCA input.
This makes the converted speakers compatible with a wide selection of domestic 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 analogue pre-outputs
One RCA interconnect is required for each speaker.
Use either RCA or XLR according to the available outputs and installation requirements.
Do Not Connect Speaker-Level Outputs
The RCA and XLR connections are line-level inputs.
Do not connect them to the speaker terminals of an integrated amplifier, receiver or power amplifier.
The converted speakers must be driven from suitable variable pre-amplifier outputs.
A Pre-Amplifier or Volume-Controlled Streamer Is Required
The active modules provide crossover and power amplification but do not provide a conventional source selector or user volume control.
A suitable partnering component must provide:
- Left and right analogue outputs
- Safe and predictable volume control
- Enough volume-control resolution for everyday listening
- An output level compatible with the selected sensitivity setting
- RCA or balanced XLR connections
Suitable equipment may include:
- A dedicated analogue pre-amplifier
- A DAC with an integrated pre-amplifier
- A network streamer with variable analogue outputs
- A suitable CD player with a genuine variable output
- An AV processor with line-level pre-outputs
Take Care with Fixed-Level Sources
Most conventional CD players, DACs and streamers provide a fixed line-level output unless configured otherwise.
Connecting a fixed-level source directly could send an extremely high playback level to the speakers.
Confirm that the source provides proper volume control before making the connection.
No Built-In Streaming or Digital Inputs
The upgrade kit does not turn the speakers into a wireless all-in-one 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 digital-to-analogue converter
- A phono stage
- A remote control
These facilities can be added through the selected source or pre-amplifier.
Using a Network Streamer
A network streamer with volume-controlled analogue outputs can provide a particularly compact system.
Depending on the chosen model, a streamer can add:
- App-controlled music streaming
- Compatible subscription services
- Internet radio
- AirPlay
- Bluetooth
- Digital source inputs
- Television connectivity
- Remote volume control
The Bluesound NODE ICON is one possible partner because it provides both variable balanced XLR and unbalanced RCA outputs.
A suitably configured Linn Selekt DSM Classic Hub can provide a modular higher-performance streaming pre-amplifier with the appropriate output cartridge and DAC modules.
Connecting a Turntable
A turntable cartridge cannot connect directly to the active modules.
A complete vinyl system requires:
- A turntable
- A compatible cartridge
- A suitable moving-magnet or moving-coil phono stage
- A volume-controlled pre-amplifier
- Analogue cables to both speakers
The phono stage and volume control may be built into the same suitable component, but both functions must be provided before the signal reaches the speakers.
Connecting a Television
The modules do not provide HDMI, optical or coaxial digital inputs.
Television audio requires an intermediary component such as:
- A streamer with HDMI eARC and variable analogue outputs
- A DAC/pre-amplifier with an optical input
- An AV processor with analogue pre-outputs
- A television with suitable variable analogue outputs
The system must provide secure volume control and should not be capable of unexpectedly switching to a fixed full-level output.
Home Cinema Integration
Converted PMC speakers can be used in a multichannel installation when the AV processor provides a suitable analogue pre-output for each channel.
The processor should provide:
- Master volume control
- Individual channel-level adjustment
- Speaker-distance and delay adjustment
- Suitable bass management
- Room calibration where required
Each converted speaker requires its own mains socket and analogue signal cable.
Adding a Subwoofer
The active modules do not include a subwoofer output or user-adjustable bass management.
A subwoofer can be added when the connected pre-amplifier, network streamer or AV processor provides a suitable variable subwoofer output.
The controlling component should ideally provide adjustment for:
- Subwoofer level
- Crossover frequency
- Phase or polarity
- Time alignment
- High-pass filtering where available
High and Low Sensitivity Settings
A sensitivity switch allows the overall gain of the active electronics to be matched more appropriately to the source component.
The two settings are intended to accommodate differences in source-output voltage and system requirements.
The correct setting depends on:
- The exact PMC speaker model
- The source component's maximum output voltage
- The usable range of its volume control
- The room size
- The listening distance
- The required playback level
Both speakers should normally use the same setting.
Begin with the source volume turned down and establish the complete system gain before increasing the playback level.
Greater Than 14-Kilohm Input Impedance
PMC specifies an active-module input impedance greater than 14 kilohms.
The partnering source or pre-amplifier should provide a suitably low output impedance and be capable of driving the chosen cable length.
Audio T can check compatibility where the source manufacturer's output specification is unclear.
Two Mains Connections Are Required
Each speaker receives its own active module and therefore requires a separate mains connection.
The module uses an IEC C14 inlet and supports a wide mains-voltage range.
Before conversion, confirm that:
- A suitable earthed mains socket is available near each speaker
- Mains leads can be routed safely
- Signal cables are not placed under tension
- Cables do not create a trip hazard
- There is free airflow behind each speaker
- The rear controls and connections remain accessible
Both Modules Must Be Earthed
The converted speakers must be connected to properly earthed mains sockets using suitable earthed mains leads.
Do not use unearthed adapters or remove the protective-earth connection.
Status and Protection Indicator
The active electronics include a rear status indicator.
The indicator can communicate operating and protection conditions:
- Green: Normal powered operation
- Flashing red: Driver protection is operating and the input level should be reduced
- Continuous red or blue: A fault may be present and the authorised retailer should be contacted
Repeated protection activation indicates that the system is being driven too hard or requires investigation.
Installation Process
PMC designed the kit so that the rear panel can be replaced without changing the cabinet or drive units.
The principal stages are:
- Disconnect the complete system from the mains.
- Remove the original passive terminal and crossover panel.
- Disconnect the original internal multipin driver connection.
- Select the correct model setting on the active module.
- Connect the active module to the speaker's internal multipin plug.
- Fit and secure the new rear module.
- Repeat the process for the second speaker.
- Check that both model settings match.
- Connect one RCA or XLR signal cable to each speaker.
- Connect each speaker to a suitable earthed mains socket.
- Set both sensitivity switches appropriately.
- Begin with the source volume at minimum.
PMC states that each module can be fitted in approximately five minutes by someone following its installation instructions.
Audio T nevertheless recommends retailer installation, particularly where the owner is not confident handling speaker cabinets, internal connectors and mains-powered equipment.
Why Choose Audio T Installation?
Audio T can:
- Confirm speaker compatibility
- Inspect the existing speakers before conversion
- Protect the cabinet finish during installation
- Select the correct model jumper position
- Check the internal multipin connection
- Install both modules securely
- Check the rear controls and status indicators
- Confirm the source provides safe variable outputs
- Configure the input-sensitivity settings
- Compare RCA and balanced XLR connections
- Check cable lengths and mains access
- Demonstrate safe everyday operation
Active Upgrade or New Active Speakers?
Choose the Upgrade Kit When
- You already own compatible PMC twenty5 or twenty5i speakers
- The cabinets and drive units remain in good condition
- You want to retain the existing finish
- You no longer need a separate power amplifier
- A suitable pre-amplifier or streamer is available
- Mains power can be provided near both speakers
Consider New Active Speakers When
- You do not already own a compatible pair
- Your existing speakers require substantial repair
- You want a different speaker size or finish
- You are moving from an older model to the current twenty5i range
- You want a complete factory-built active speaker package
- You intend to trade in the existing passive speakers
Explore the PMC Active twenty5.21i and PMC Active twenty5.22i to compare PMC's factory-built active models.
Key Features
- Active conversion kit for one stereo pair
- Compatible with selected PMC twenty5 speakers
- Compatible with selected PMC twenty5i speakers
- Compatible with 21 and 21i
- Compatible with 22 and 22i
- Compatible with 23 and 23i
- Compatible with 24 and 24i
- Not compatible with twenty5.26 or twenty5.26i
- Two active rear modules
- Two amplifier channels per speaker
- 100W tweeter amplifier per speaker
- 100W midrange and bass amplifier per speaker
- 200W total amplification per speaker
- 400W total published amplification per pair
- Class-D power amplification
- Pure analogue active crossover
- Model-specific crossover settings
- Model-selector jumper configuration
- Direct amplifier-to-driver connection
- Driver filtering and protection
- High and low sensitivity settings
- Greater than 14-kilohm input impedance
- Balanced analogue XLR input per speaker
- Unbalanced analogue RCA input per speaker
- IEC C14 mains connection per speaker
- Wide mains-voltage compatibility
- Rear operating-status indicator
- No external power amplifier required
- No passive speaker cable from an amplifier
- Volume-controlled source required
- Separate mains connection required for each speaker
- No built-in network streamer
- No built-in DAC
- No Bluetooth or Wi-Fi
- No digital inputs
- PMC retailer installation available
Frequently Asked Questions
What does the PMC Active Upgrade Kit do?
It replaces the passive crossover and terminal panel in compatible PMC twenty5 and twenty5i speakers with an active crossover, two amplifiers, analogue inputs and mains connection.
Is the kit supplied for one speaker or a pair?
It is designed to convert one stereo pair, with one active module installed in each speaker.
Which PMC speakers are compatible?
The two-way twenty5 and twenty5i 21, 22, 23 and 24 models are supported.
Does it fit the twenty5.26 or twenty5.26i?
No. The 26 models are three-way designs and are not compatible with this two-way upgrade.
Does it fit the PMC twenty5 centre speaker?
No. Centre-channel models are not included in PMC's compatibility list.
Does it fit the older PMC twenty range?
No. The upgrade is specified for the later twenty5 and twenty5i ranges.
Does the kit replace the drivers?
No. The existing tweeter and midrange and bass driver are retained.
Does it replace the cabinet or ATL?
No. The existing cabinet, transmission line and Laminair vent are retained.
How much amplification is included?
Each speaker receives one 100W amplifier for the tweeter and one 100W amplifier for the midrange and bass driver.
How many amplifier channels are included for the pair?
Four 100W amplifier channels.
Do I still need an integrated amplifier?
No. A conventional integrated or power amplifier is no longer required.
Do I need a pre-amplifier?
Yes. You need a pre-amplifier, DAC/pre-amplifier, streamer or another source with safe variable analogue outputs.
Can a fixed-output CD player be connected directly?
No. It requires a suitable volume-controlled pre-amplifier between the CD player and speakers.
Can I use the speaker outputs from my existing amplifier?
No. The modules accept line-level RCA or XLR signals, not amplified speaker-level signals.
Which inputs are included?
Each module provides one balanced analogue XLR input and one unbalanced analogue RCA input.
Are the XLR inputs digital?
No. They are balanced analogue inputs.
Does the kit include optical or coaxial inputs?
No.
Does it include a DAC?
No. Digital-to-analogue conversion must be performed by the source or pre-amplifier.
Does it include Wi-Fi or Bluetooth?
No.
Does it include network streaming?
No. A separate streamer is required.
Does each speaker need a signal cable?
Yes. One left-channel and one right-channel RCA or XLR cable are required.
Does each speaker require mains power?
Yes. Each active module requires a suitable earthed mains connection.
Do the speakers connect to each other?
No conventional speaker cable is required between them. Each speaker receives its own line-level signal and mains power.
What is the input impedance?
PMC specifies an input impedance greater than 14 kilohms.
Why is there a model-selector jumper?
The upgrade uses different crossover and gain settings for the compatible speaker models. The jumper selects the correct configuration.
Can the wrong model setting damage the speakers?
An incorrect setting can apply unsuitable crossover or gain behaviour, so the configuration must be checked before the modules are powered.
Is the crossover digital?
No. PMC uses a model-specific analogue active crossover.
Can I connect a turntable?
Yes, but a suitable phono stage and volume-controlled pre-amplifier are required.
Can the converted speakers work with a television?
Yes, through a suitable streamer, DAC/pre-amplifier or AV processor providing controlled analogue outputs.
Can a subwoofer be connected?
Yes, when the source, pre-amplifier or processor provides a suitable variable subwoofer output.
Can the converted speakers be used in home cinema?
Yes, where the AV processor provides suitable line-level pre-outputs, master volume control and channel calibration.
How long does installation take?
PMC states that each module can be installed in approximately five minutes by someone following the instructions.
Can I install the kit myself?
PMC designed it for straightforward installation, but Audio T recommends authorised retailer fitting to protect the speakers and ensure the correct model configuration.
What does a flashing red indicator mean?
The protection system is operating. Reduce the source volume immediately.
What does a continuous red or blue indicator mean?
It may indicate a fault. Switch the system off and contact an authorised PMC retailer.
Does the kit have one universal frequency response?
No. Frequency response depends on the speaker model, cabinet, drivers and selected crossover configuration.
What warranty applies?
PMC's published warranty table currently lists home-audio active designs with two years of standard cover or five years when registered. The treatment of a retrofit kit fitted to an existing speaker should be confirmed with Audio T and PMC when purchased.
Related PMC Products and Audio T Guides
Why Buy From Audio T?
- PMC speaker compatibility checks
- Serial-number and model verification
- PMC Active Upgrade demonstrations
- Passive and active system comparisons
- Authorised upgrade-kit installation
- Correct model-selector configuration
- Internal connection and operation checks
- Streamer and pre-amplifier matching
- Source-output compatibility checks
- Balanced XLR and RCA comparisons
- System-gain and sensitivity setup
- Mains and signal-cable planning
- Turntable and phono-stage integration
- Television and home cinema planning
- Subwoofer integration
- Home demonstrations where available
- Part exchange on suitable existing amplifiers
- PMC warranty and registration guidance
- Ongoing system and after-sales support
Contact your local Audio T store with your exact PMC speaker model and serial numbers to confirm compatibility, arrange installation or discuss suitable streamers, pre-amplifiers, cables and system configuration.