Pmc Twenty5 21i

PMC Twenty5 21i Bookshelf Speaker Review

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The British PMC Twenty5 i series is now in its first generation, with the Twenty series commemorating PMC’s founding anniversary, the Twenty5 series launching in 2016, and the Twenty5 i series launching in 2020. The Twenty5 21i, which was sent to the audition, is the smallest series of bookshelf speakers, allowing you to listen to the most appropriate music.

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Despite the fact that the Twenty5 21i has gone through a generation change, the Twenty5 21i’s appearance has remained relatively unchanged. However, when compared to the first generation, whether it’s a single splitter or transmission line speakers, everything is different, demonstrating that PMC continues to invest in R&D.

According to the PMC’s statement, the Twenty5 i series was created as a result of the new flagship speaker Fact Fenestria’s year-long research and development program, which resulted in new technological breakthroughs. As a result, the flagship speaker technology was extended to the Twenty5, and the Twenty5 i was born.

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The new Twenty5 i series, such as product maintenance, Twenty5 21i is the smallest size bookshelf speakers, it has a larger size brother Twenty5 22i, and then there are the speakers, respectively Twenty5 23i, Twenty5 24i, and Twenty5 26i, with the multi-channel system, there is a Twenty5 Ci, whether you intend to listen to two channels, or a group of multi-channel, Twenty5 i series is very suitable.

What, no mention of subwoofers? That’s right, the subwoofer hasn’t evolved to the Twenty5 i series. It’s still Twenty5 sub.


The Twenty and Twenty5 both have 27 mm SONOLEX silk soft dome tweeters, while the Twenty5 21i has a smaller 19 mm SONOLEX tweeter and has a 34 mm overhang. The most direct evidence of the Twenty5 21i’s devolution from Fact Fenestria Signature technology is this change. The tweeter on the Twenty5 21i is likely to be the same as on the Fact Signature, making the Twenty5 21i even more affordable.

Why is the tweeter mono-driver being replaced? This is related to the preset goals of the speaker design. PMC hopes to improve sound dispersion, so that listening to the sweet spot can be wider, so the high-end Fact tweeter has been decentralized, replaced by a smaller diaphragm diameter.

PMC wants the Twenty5 21i to sound good no matter where it’s placed. The listener doesn’t have to sit in the sweet spot position. It should sound good wherever you move around in the listening space.

In addition, the tweeter on the Twenty5 21i is protected by an ultra-hard fiberglass cover with tiny holes on the outside. When you look closely, you can see that the surface is distributed at regular angles, similar to a beehive.

The Twenty5 21i’s crossover point is set at 1.7 kHz, but based on the size of the crossover, it should still be a complex order crossover with a steep slope to achieve precise frequency splitting. The splitter is almost as big as the Twenty5 21i’s back panel, and it’s locked to the speaker’s metal back panel, with the speaker interface fixed directly to the splitter to achieve the shortest signal path design possible.

Twenty5 21i has a 1.7 kHz crossover point, which is lower than the previous generation Twenty 5.21. The previous two generations had a 1.8 kHz crossover point, which has now been lowered to 1.7 kHz.

Although the difference appears to be only 100 Hz, it allows the tweeter to be more burdened with high and midrange frequencies, while the bass and midrange do not need to fight the treble, allowing the workload of the two monoblocks to be maintained in their own.

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Then the Twenty5 21i speakers’ ATL Technology which is PMC’s core technology. ATL stands for “Advanced Transmission Line,” and the theory of the application is transmission line speakers. However, PMC emphasizes that its own transmission line speaker technology is more advanced and mature, so it’s called ATL.

In fact, there were many brands of speakers with different transmission line technology on the market in the 1980s, but as the market filtered out, only PMC supported the only show, with their own ATL nearly years in the audio jungle, which was not by chance, but by solid technical research and development. Because the theory of transmission line speakers, while excellent, is difficult to implement, and the production cost is higher than closed type speakers or bass-reflex speakers.

Because the wavelength of low frequency is relatively long, increasing the length of the transmission line effectively strengthens the low-frequency extension.

What is a transmission line speaker?

It is the design of the transmission line channel inside the speaker to increase the transmission distance of low frequency. So, as the transmission line distance increases, you can strengthen the low-frequency extension and sense of volume, then the speed can’t keep up.

If the low frequency is slow, then how does the music sound good? This is a technical problem, how to rely on the transmission line to strengthen the low-frequency extension and volume while also taking into account the speed.

This is a commercial secret for PMC even when I went to the PMC factory, I couldn’t find the answer. I know that PMC transmission line speakers use special shapes of acoustic cotton internally, but the thickness is not the same, and for each PMC speaker’s internal damping, the configuration is different.

Twenty5 21i ATL transmission line speakers, but also added Laminair design, that is, the air outlet below the front of the speaker, equipped with an aerodynamic design grille, its role is similar to that of a sports car’s rear wing or spoiler, can accelerate airflow conduction, resulting in faster and cleaner low-frequency response, but also less airflow noise.

PMC did not invent the Laminair low-frequency exit spoiler design. It was used in the first generation of the Twenty5, and the quality design is still used in the first generation of the Twenty5 21i.

Sound Performance

For the sound performance test for the Twenty5 21i in the audio-visual room, I use near-field listening settings, that is, a speaker distance of about 2 meters, and a distance of about 2 meters with the left and right channel speakers, with the standard orthogonal placement of near-field listening.

Take the widely used Linear Acoustic LAV-60 MKII amplifier to push, 100 watts of output power integrated amplifier, push up the efficiency to 86.5 dB Twenty5 21i.

I was surprised to hear it, but I didn’t expect the Twenty5 21i to be so good! As an example, take Eric Clapton’s “Tears In Heaven”. The LAV 60 MKII can reproduce a full guitar tone and accurately depict soundstage positioning, demonstrating the Twenty5 21i’s capabilities as a good speaker.

Many details to make the live concert recording more realistic and subtle include the speaker disappearing completely in the listening space, the 3D stereo sound of the stage space being clearly presented behind the speaker, the force of each guitar playing changing in the march of the bass, and the harmonic group accompaniment, and many others.

I understand that no one would use expensive pre and power amplifier stages to push the Twenty5 21i, but it does demonstrate how good it is. The more powerful the amplifiers used to drive the Twenty5 21i, the more direct and infinitely rich the musical details it provides.

I have a higher evaluation of the Twenty5 21i, I initially only thought it was a good speaker, but with the extremely high-quality amplifier equipment, Twenty5 21i becomes a very good bookshelf speaker, with excellent musical detail regeneration ability, low and mid-range stable enough

It can faithfully present the dynamic changes in the music, the tone towards neutral clean, and balanced, However, hear the rich texture of the music in the midrange band to maintain an appropriate warm tone.

Twenty5 21i clearly shows the appearance of the stage when listening to “Tears In Heaven” using near-field listening settings, the speaker naturally disappears into the space. Eric Clapton’s intro is on the right, the first guitar inserted on the left, and the intro is richer.

Eric Clapton wrote this song in memory of his beloved son, who died young. The father wasn’t sure if he’d recognize his son in heaven, but it was even more difficult because he didn’t think he’d make it, so he had to be strong and continue on his own. It wasn’t until the applause began that I regained my composure and followed the applause.

If guitar and vocals are so good, how about piano? The first note he played at Carnegie Hall was on track 1 of “Beethoven: The Tempest” and the recording deliberately started at the first second, but the commotion of the concert was already faithfully conveyed from the Twenty5 21i.

Before the first arpeggio entered. Twenty5 21i cl clearly presents the expansiveness of the live recording, the piano coalescing in the center of the stage, then entering the stormy frenzy of notes, the pianist fully in the situation, showing the strong dynamic contrasts of the storm, the keys sometimes violently exploding, sometimes gently.

I want to emphasize that the dynamic contrast is between the loudest and smallest sounds. The piano in the performance of music is strong and weak, using the keys of the loud and small sound, the pianist to control the force of the fingertips, to show the difference between the loud and small sound changes.

If the speaker has excellent dynamics, we can hear the pianist in the performance of music strong and weak, If the speakers are loud and noisy but soft and weak, the music will sound monotonous. However, listen to “The Tempest” on the Twenty5 21i, which is both fax and evocative.

Comparing different playing styles with the Twenty5 21i and hearing the difference in the musicians immediately demonstrates the Twenty5 21i’s ability to be both facsimile and evocative. Perlman’s violin, for example, always has a warm and moist tone, with warm and dense tones.

The high frequencies have an oily sheen to them, and the end rhymes are rounded. The Twenty5 21i also sings in a leisurely and relaxed manner, with a soft yellowish sheen on the mid and high frequencies, giving the tango a romantic appearance.

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This violinist has a distinct playing style with a strong Hungarian influence, and his renditions of Brahms’ youthful compositions are fiery and powerful. The Twenty5 21i sings Lakatosch, which is very different from Perlman’s taste and has a more wide atmosphere, which is not typical of classical orchestration. The Twenty5 21i offers a unique musical interpretation of emotions, as well as a realistic appearance.

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Twenty5 21i is a beautiful configuration for orchestra, with violins on the left, whispering the theme, cellos and double basses on the right, with an uneasy atmosphere. Woodwinds blow long notes from deep in the soundstage, followed by a strong turn of the theme. With the timpani joining in, the tense Twenty5 21i’s timpani is clear and bouncy, adding to the rhythmic tension.

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Even though it is the smallest bookshelf speaker in the Twenty5 series, the Twenty5 21i is very impressive. It is not afraid of being pushed to high volumes and still maintains a wide sound field in a calm and relaxed manner.

At this point, however, the Twenty5 21i’s limitations become apparent, and that is the timpani. Although the drums are clear and the low end is clean and fast, the lowermost section of the timpani shape is not as thin, so if this is a concern. If adding a subwoofer to compensate for the volume loss, the timpani will become very full.


I’d like to point out that the Twenty5 21i is an excellent bookshelf speaker that meets or exceeds my expectations. The perfect matching with the amplifier equipment, the better the performance of Twenty5 21i, implying that Twenty5 21i is inherently good enough.

PMC Twenty5 21i bookshelf speaker has a good power tolerance, good in the rich and natural music details in the upper and middle range, revealing the vivid face of music.

I recommend that you put Twenty5 21i on your priority list and listen to it if you are looking for quality bookshelf speakers.

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