PMC twenty5.21i bookshelf speaker Review



Date: 2020-11-20


Article From《u-audio》

British PMC Twenty5 i series, count as the third generation! The first generation is the Twenty series to commemorate the 20th anniversary of the founding of PMC. The first revision launched in 2016, and then the Twenty5 i series debut in 2020. The Twenty5 21i sent to U-Audio for trial listening, is the smallest bookshelf speaker in the series. It is most suitable for near-field listening.

Fact Fenstria high-end technology

Although has undergone three generations of changes, the appearance of the Twenty5 21i has not changed much, but compared with the first generation, whether it is a single unit, a crossover or a transmission line speaker, all are different, showing that PMC continues to develop in R&D Invest. According to the original PMC data, the reason for the upgrade of the Twenty5 i series comes from the new flagship speaker Fact Fenestria . This five-year research and development project has brought new technological breakthroughs. Therefore, the flagship speaker technology has been led from Twenty5 to becomes Twenty5i.

The new Twenty5i series, the same six products, Twenty5 21i is the smallest bookshelf speaker, it has a larger brother Twenty5 22i, and then there are three floor speakers, respectively are Twenty5 23i, Twenty5 24i and Twenty5 26i, With the multi-channel system, there is also a Twenty5 Ci. Whether you plan to listen to two channels or a group of multi-channels, the Twenty5 i series is very suitable. Huh? Didn't mention the subwoofer? That's right, the subwoofer hasn't changed, it's still Twenty5.sub, and it didn't upgrade to Twenty5 i series.

"i" stands for Improved

The suffix "i" of the product series means "improved". In fact, there are not many changes in appearance. The changes are all internal. The biggest change is the tweeter. Both Twenty and Twenty5 use 27 mm SONOLEX silk soft Hemispheric tweeter, and the Twenty5 21i is replaced with a smaller 19 mm SONOLEX tweeter, and the overhang is increased to 34 mm. This change is the most direct evidence of the decentralization of Twenty5 21i and Fact Fenestria and Fact Signature technology, Fact Fenestria The tweeter of Twenty5 21i is 19.5 mm, with 36 mm wide overhangs, and the Fact Signature is 19 mm. The tweeter of Twenty5 21i is likely to be the same as Fact Signature. If it is true, it makes Twenty5 21i more valuable.

Why replace the tweeter? This is related to the preset goal of the speaker design. PMC hopes to increase the dispersion of the sound and make the sweet spot wider for listening. Therefore, the high-end Fact tweeter is lowered and replaced with a smaller diaphragm diameter, but New design with wider overhang. If improving sound diffusion and sounds more sweet like "acoustic terminology", then I can speak a little more vernacularly: PMC hopes that Twenty5 21i sounds nice no matter how it is placed, and you don't have to sit in the listening chair, and feel free to listen in the listening space. It sounds nice in anywhere in the room.

Improve high-frequency diffusivity

In addition, the Twenty5 21i's tweeter has a protective cover made of ultra-high hardness glass fiber material with small holes on it. It is not only a tweeter protective cover, but has a reinforced design to improve sound wave diffusion. Looking closer, the surface is distributed in a regular hexagonal shape, a bit like a honeycomb shape. This design is very common for BBC speakers decades ago. PMC's own high-end speakers are also used in several models, but the technical problem is the shape of the surface openings. How to achieve the effect of enhancing high-frequency diffusion, and the shape of the holes, The size is related to the density, and it needs to be tailor-made for the monomer. This is where the original Know-How is.

The 140 mm mid-woofer of Twenty5 21i is still a g-weave diaphragm with a concave dust cover design. It looks the same as the previous generation Twenty5. In the interview data of design engineer Toby Ridley, the bass unit is not mentioned. The only change is to replace the treble with a new unit, so it is likely to use the original Twenty5 mid-bass unit.

The crossover point is decreased by 100 Hz

Since the tweeter has been changed, the crossover has to be redesigned. The tradition of PMC is to prefer higher-order crossovers. However, the original specifications of Twenty5 21i only have the marked crossover point, which is set at 1.7 kHz. There is no indication of the number of partials, but from the perspective of the size of the crossover, it should be a complicated fourth-order partial, with a high slope to achieve accurate frequency division. How big is the crossover of Twenty5 21i? Almost as big as the back panel of the Twenty5 21i, this crossover is locked on the metal back panel of the speaker, and the speaker terminal is directly fixed to the crossover to achieve the shortest signal path design.

Twenty5 21i sets the crossover point of 1.7 kHz, which is lower than the previous generation Twenty 5.21. The previous two generations were both 1.8 kHz, and now it is lowered a bit and reduced to 1.7 kHz. It seems that there is only a 100 Hz difference, but it can make the tweeter more burden on the mid and high frequencies. The mid-bass can reduce the workload, and make two units is maintained in their most comfortable state.

ATL advanced transmission line speakers are PMC core tech

Time to talk about Twenty5 21i speakers again. ATL transmission line speakers are the core technology of PMC. ATL is the abbreviation of "Advanced Transmission Line". The applied theory is transmission line speakers, but PMC emphasizes its own transmission line. The speaker technology is more advanced and mature, so it is called ATL, PMC all speakers, large and small, all adopt ATL transmission line speaker design.

In fact, in the 1980s, there were many speaker brands advertised as transmission line speakers on the market, but they were not matched by the market's screening and elimination. Only the PMC was the only one who used its own ATL for nearly 30 years. This is not luck, but rely on solid technical research and development, although the theory of transmission line speakers is very good, but it is difficult to make, and the production cost is higher than that of closed cabinet speakers or bass reflex speakers. If a certain number of speakers are not sold, the company is very difficult to maintain long-term operation, so there are only PMC with all current series of speakers are designed with transmission line speakers. Other brands may see one or two transmission line speakers, but they are not the core technology. Only PMC focuses on the same design theory. For nearly thirty years, the transmission line speakers have been made perfect.

Measuring instrument with repeated listen

what is the speaker transmission line? It is to design the transmission line channel inside the speaker to increase the low frequency transmission distance, because the low frequency wavelength is relatively long, increasing the length of the transmission line can effectively strengthen the low frequency extension. Well, here the problem. The increase in the transmission line distance can strengthen the low frequency extension and sense of volume, but can the speed keep up? If the low frequency is slow, it sounds muddy, how can the music be good? This is a technical problem. It is necessary to rely on the transmission line to strengthen the low-frequency extension and sense of volume, but also to take into account the speed, what should be done?

Sorry, this is a secret. Even I went to the original PMC factory three times and couldn't find the answer. I know that PMC's transmission line speakers use special-shaped sound-absorbing cotton inside, and the thickness is different, but the internal damping and configuration of each PMC speaker are all different. As for the design, PMC only tells me to use the instrument to test and listen and compare repeatedly. I want to ask if there are any special formulas or formulas for PMC. The answer is no. All depends on measurement and audition. Therefore, the development time of each speaker is difficult to quantify. Sometimes it is fast and sometimes slow. Although this kind of instrument assists and listening is time-consuming, but it is still impossible to replace the human ear with measure the instrument.

Continues the Laminair airflow conduction design
Twenty5 21i also adds the Laminair design, which is the air outlet under the front of the horn, and is equipped with a grille with aero-hydrodynamic design. Its function is like a sports car's tail or spoiler. The flow plate can accelerate the conduction of air flow, making the low frequency response faster, cleaner, and less air flow noise.

Laminair's low-frequency exit spoiler design is not a pioneering work for PMC. The second-generation Twenty5 has already been used. By the third-generation Twenty5 21i, the high-quality design will of course continue to be used.

The standard equilateral triangle placement

In the U-Audio audition Twenty5 21i, I used the near-field listening setting, that is the speaker spacing is about 2 meters away from me and the left and right channel speakers is also about 2 meters, using a standard equilateral triangle placement and adjust the toe-in angle. It is about looking from the listening position. Only the front of the Twenty5 21i can be seen, but the side of the speaker cannot be seen, which is an ideal equilateral triangle placement.

Take the commonly used Linear Acoustic LAV-60 MKII, a integrated amplifier with 100 watts of output power, and push the Twenty5 21i with an efficiency of 86.5 dB. It is generally easy and the price is reasonable, but the editorial department just came to the delicate equipment, Audia Flight Strumento No1 MKII pre-amp and Papworth M200 power amp. Although I know this is a million-level equipment, I can't help but want to try the limits of Twenty5 21i, so I connected it.

It's amazing amplifier combination

I was really shocked when I heard it. I didn't expect Twenty5 21i can be so amazing! I only take "Tears In Heaven" from Eric Clapton's "Unpluged" album. The LAV 60 MKII can deliver a full guitar sound and the sound field positioning is described clearly and beautifully, showing that Twenty5 21i is a good speaker, but Replaced with Strumento No 1 MKII and M200, the speakers completely disappeared in the listening space. The 3D stereo image of the stage space is clearly presented behind the speakers. The strength of each guitar playing, the progress of the bass, and the foil of the harmony group, Many details make the live concert recording more lifelike and vivid.

I know that no one will use one million front and rear grades to push hundreds of thousands of Twenty5 21i, but this shows how good Twenty5 21i is. The higher the level of amplifier to push, Twenty5 21i can give you more direct and rich music details.

Not only good, is great

after not rational to match with around one million grade level, let me higher evaluation of Twenty5 21i, originally I just think it is a good speaker, but coupled with extremely high-quality front-end equipment, Twenty5 21i Turns into a pair of excellent bookshelf speakers with excellent music detail reproduction ability, mid-low frequency is stable enough, and can faithfully present the dynamic changes of music, the tone is going to be neutral and clean and balanced, but the mid-frequency band maintains an appropriate warm tone and rich musical texture.

Listening to "Tears In Heaven", Twenty5 21i clearly shows the appearance of the stage. With near-field listening settings, the speakers naturally disappear into the space. Eric Clapton's intro is on the right, and the second guitar is inserted on the left. The intro is more rich , Eric Clapton gently sang "Would you know my name, if I saw you in heaven......" Twenty5 21i vividly presents the vicissitudes of the song. This is Eric Clapton's song to commemorate the early death of his beloved son. The father doesn't know if he recognizes each other when he meets his son in heaven, but what's more difficult is that he thinks he won't go to heaven, so he has to go strong. Twenty5 21i sings the emotions in the song sincerely, I listened rapturously, until the applause sounded, did he come back to his senses, and listened to the applause, "Lonely Stranger" continued the concert improvisationally with beautiful blues phrases.

The detailed expression of the guitarist is clearly presented

The same is the guitar, Twenty5 21i can clearly show the details and atmosphere of different recordings, such as Carol Kidd and Nigel Clark's "Tell Me Once Again", listen to the classic jazz standard "Stormy Weather", the opening nylon string guitar, pound The string strength is more fleshy, not as bright and crisp as Eric Clapton, the tone is warmer, the more varied jazz chords, plus many unexpected harmony, and Carol Kidd's singing complement each other.

Since it is a studio work, the recording background of "Stormy Weather" sounds much cleaner than "Unpluged". Carol Kidd’s singing and Nigel Clark’s guitar are both drawn closer together. Compared with the clean recording background, Twenty5 21i presents The vivid vocals and guitar shape, the details of pure teeth and the sliding sound of the guitar are natural and clear, which enhances the realism of listening.

Demarcative of the piano sound

The guitar and vocals are so great, how about piano? Take out Nobuyuki Tsujii’s "Carnegie Hall Preliminary Performance". This is the first live recording of a young blind Japanese pianist on stage at Carnegie Hall. The first movement of the first track of "Beethoven: The Tempest" is The first note he played in Carnegie Hall, the recording deliberately only started in the third second, but the commotion of the concert scene has been faithfully conveyed from twenty5.21i, before the first arpeggio entered, the faint chair friction sound and slight coughing in the auditorium. twenty5.21i clearly showed the broadness of the live recording. The piano was condensed in the center of the stage, and then into the stormy and frantic notes. The pianist is fully in the zone, showing the strong dynamic contrast of the storm, the keys sometimes burst fiercely, sometimes tender, and twenty5.21i clearly shows the strength of the pianist’s fingertips.

I want to emphasize that dynamic contrast is not the loudness , but the contrast between the loudest and the smallest. The piano expresses the strength and weakness of the music, using the volume of the keys. The pianist must control the strength of the fingertips to show the different. When we replay the recording on the speaker, if the speaker has excellent dynamics, it can let us hear the various changes of the pianist at the fingertips. If the speaker is loud and weak, it is The dynamic contrast is not enough, the music will sound boring, but listening to "The Tempest" on twenty5.21i, it is real presence and vivid.

Before the first movement of "The Tempest" enters the ending, there is a note that seems to be a monologue. At this time, the pianist cleverly uses the sustain pedal, the notes are floating in the air, the music is hesitating to speak, and then enters the firm phrase, ready to meet In the final ending, the piano sound is firm and clear. With the breathing sound of Tsujii Nobuyuki playing, twenty5.21i seems to bring us back to the concert on November 10, 2011.

 The violinist’s playing style is clearly identified

Able to presence and expressive, use twenty5.21i to compare different playing styles, and immediately hear the differences between musicians. Like Perlman’s violin, the tone is always warm and dense. Listening to "Perlman’s Movie Fringe" is the most representative. The theme song "Tango" of the movie "Scent of a Woman" is Adapted from Piezola’s works, Perlman’s violin is rarely passionate, but after a slightly emotional prelude, it enters the dense tango theme. Perlman’s dense and sweet violin tone exudes oily and smooth luster at high frequencies. , The ending rhyme is decorated to be round and mellow, twenty5.21i is also a leisurely and contented appearance, the middle and high frequency spreads soft and romantic appearance of tango.

Switch to Lakatos’s “Lakotos” album and listen to “Brahms Hungarian Dance”. This gypsy violinist’s playing style is distinctive and has a strong Hungarian style. He played Brahms’s songs when he was young. It is full of heat, strong tension, the opening of the adagio is rich and thick, the two-string ending phrase resonates the end rhyme, the mood is strong, a large part of the solo ups and downs ends with overtones, and enters the allegro movement, piano, violin, In addition to the double bass, he also joined the Yangqin ensemble, adding the exotic flavor of Hungarian dance music. Twenty5.21i sings Lakatos, it is completely different from Perlman's taste, more power, the dulcimer sound of the substrate is intertwined with the violin, and the taste is also different from the traditional classical music orchestration, and twenty5. 21i presents different musical interpretation emotions in a real appearance.

Volume close to the concert site

It’s time to expand the compilation to listen to the "Mozart Piano Concerto No. 20 K. 466" by Abbado and Agrich. I listened to the 2013 Lucerne Festival, not the two Studio version of the collaboration when they were young. The rare minor Mozart piano concerto, Abbado laid out a slightly tense theme lightly, contrasting the strength of the uplifting, Twenty5.21i presents a beautiful orchestra configuration, the violin is on the left, and the theme is quietly performed. The cello and the double bass are placed to the right. The wood pipe blows a long note from the depths of the sound field, and then the theme is up and down. After the timpani is added, the tension is more intense. The timpani drum of twenty5.21i is clear and bounces vigorously. , Intensified the tension of the rhythm.

Afterwards, Agrich’s piano joined, with transparent and crystal clear notes, and a little bit sentimental in minor phrases. twenty5.21i portrays the force of the keys very beautifully. At the beginning of the piano coming in, the orchestra stops, only the piano monologue. Each note is beautifully condensed in the air, with moderate strength. At this time, the subtle clothes rubbing behind the orchestra, and the tiny chair moving sounds, truly reproduce the sense of space in the recording. After the orchestra joins, the piano gradually strengthens its strength and rises. At the high point, after entering the second theme, the phrase of the orchestra and the piano dialogue, Aglisi returned to medium strength and used a gentle expression to talk to the orchestra.

When I listened to the first movement of K. 466, I tried my best to listen at the volume "close to the concert site". twenty5.21i is very powerful. Even the smallest bookshelf speaker in the twenty5 series is not afraid of being forced by loud volume. The ground opens up the wide sound field, the piano notes rise and fall, strong and weak, the pianist’s expression is quite vivid, and the dialogue with the orchestra has a dramatic effect. However, at this time, the limit of twenty5.21i is also heard, that is the timpani. Although the drum beat is very clear, the low frequency is clean and fast, but the bottom part of the timpani shape is less full. If you are concerned about this lack, add a super bass to make up for a little texture, and the timpani will become very full.


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