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Test
Floorstanding loudspeakers
PMC OB1i

Price: 2583 GBP (2100 GBP netto)

Manufacturer:
PMC Limited | 43-45 Crawley Green Road
Luton | LU2 0AA | United Kingdom
tel.: +44 (0) 1582 405694 | fax: +44 (0) 870 4441045

e-mail: sales@promonitor.co.uk

WWW: PMC

Country of origin: United Kingdom

Text: Wojciech Pacuła
Photographs: PMC, Wojciech Pacuła
Translation: Krzysztof Kalinkowski

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PMC is a brand of the British company Professional Monitor Company Ltd.. This company manufactures speakers for recording studios and – although initially this was only a marginal activity – home loudspeakers. Founded in 1990 by Peter Thomas, a former employee of BBC and Adrian Loader, earlier – FWO Bauch. From their cooperation came first the bookshelf speaker BB5-A, active studio speaker, manufactured until today. It quickly found its admirers, like Maida Vale (BBC) from Metropolis Mastering and using it many discs from known artists were recorded, like Prince and Steve Wonder, and work also in Decca and Harmonia Mundi studios. PMC were also used in recordings and post production of many films, among others: Titanic, Mission Impossible, Iron Man 2, Jarhead, Die Another Day, Spiderman 3 and Pirates of the Caribbean. The company received an Emmy award for their input in recording arts.
Like every company, which wants to be successful and be different to other manufacturers, also PMC has its proprietary technology and uses it consistently win all their products – I am talking about ATL, Advanced Transmission Line. This is a special technology of loading the back side of the woofer by leading a long line, or tunnel, inside the cabinet, which length is calculated to match the used driver. A variant of the transmission line was also used earlier by the company Castle.

The tested loudspeakers OB1 are not the newest model, but in companies like PMC changes do not happen too often. This is a three-way loudspeaker, with a soft, made from a coated material, dome tweeter, dome midrange (in what it resembles another British specialist, the company ATC) and a woofer made from coated paper diaphragm. The latter is loaded with a long transmission line, with the exit in the front, at the bottom of the front baffle. The loudspeakers are coated with natural veneer, paired in such a way, that the left and right speaker are mirror images. Each loudspeaker is mounted by a individual person, who signs the well written manual accompanying the product – the tested pair was assembled by Phil. Thanks Phil – good job!

To date we tested::

SOUND

Discs used during the test:

  • Depeche Mode, Condemnation (Paris Mix), Mute, cd bong 23, EP CD.
  • Diorama, The Art Of Creating Confusing Spirits, Accession Records, EFA 23450-2, CD.
  • Donald Byrd, The Cat Walk, Blue Note/Audio Wave, AWMXR-0009, XRCD24.
  • George Michael, Faith, Special Edition, Epic/Sony Music, 7753020, 2 CD+DVD.
  • Porcupine Tree, Deadwing, Lava Records, 6793437, CD.
  • Suzanne Vega, Close-Up, Vol 1. Love Songs, Amanuensis Productions/Cooking Vinyl, COOKCD521, CD.
  • Wes Montgomery All-Stars, A good git-together, Lone Hill Jazz, LHJ10133, CD.
  • Wynton Kelly Trio& Wes Montgomery, Smokin’ At The Half Note, Verve, 2103476, Verve Master Edition, CD.

Japanese versions of the discs available on CD Japan.

When you sit down to listen to loudspeakers, which are different, than what you usually test, expectations are mixed with uncertainty, excitement and even slight anxiety. Because you do not really know what to expect. Even if you had contact with a company coming from the “pro” world. Being “pro” has two aspects, depending on whom are you asking. People from stage, from recording, mastering and post-production studios will tell that this is an asset, a guarantee of good sound. On the other hand if you ask somebody connected to the “reproduction” of the sound, and not with its “recording” – music lovers, audiophiles, etc – there is a big probability that they will frown and point towards bad recordings, connecting that automatically to the way sound is presented in high quality studio systems used for those recordings. Also with loudspeakers used for monitoring the recording sessions. And PMC, so also the OB1, have their heart on the other side of the studio window… That is why true wisdom is such usage of experience from the studio and stage to not lose the achievements of consumer audio. And this is why the listening session of those loudspeakers was so interesting.

Two things distinguish those loudspeakers from within other constructions – a dome midrange driver and a transmission line loading the woofer. And that this is something completely different than 99% of the competition you can here after just a few minutes of listening to any disc.
I started the session with Faith George Michael, in a special edition, a new re-master. This is the first solo disc by George Michael, also the first one recorded completely digitally (Chris Heard writes interestingly about that in his column Vinyl Frontier in the newest edition of “Hi-Fi News& Record Reviews”, April 2011, Vol 56, No.04, p. 65). Those were still the early days of that way of recording, what can also be heard here, but it was still far away from the so called “loudness war”, the tendency to compress everything that moves. Many times the results were really good, like on the discs Brothers in Arms Dire Straits or Offramp Pat Metheny Group – discs from the 80. (1982 and 1985 - respectively), recorded digitally, being the first kind of such registration in the career of those artists. Faith is a rather late recording, from 1987, but a certain dryness, lack of worked out harmonics of the midrange, etc, are still visible on that disc.
Just with the PMC the new version of Faith sounded great, within its limitations, but really great. Like I said, you can get really convinced about their character quickly. With this disc we could immediately determine, that the loudspeakers sound, as if they would have no dynamic limits and as if there was no compression. The latter is especially striking, because most commercial loudspeakers compress sound. Usually we perceive it quite positively, because then you can emphasize some things with timbre, for example, but when we hear loudspeakers like the tested PMC, then we would know, that this is an error, that we do need dynamics for full presentation of music.
I quoted Faith on purpose – please have a listen to the sequence opening the discs, with the organ becoming slowly louder and louder, and we will hear not really a volume increase, although it is the base for the effect, but “growing”, a similar thing, yet coming together with the increase of the virtual source size. The organ does not just become better audible, but becomes bigger. And this makes a big impression. Differentiation of dynamics is brilliant, regardless the kind of music we are listening to. This was splendidly shown by the disc Deadwing Porcupine Tree, where I had kind of “keeping” the mood, and in some places letting loose the emotions, the same thing happened with a formally much simpler, but requiring the same care in handling the “climate” album The Art Of Creating Confusing Spirits Diorama. Both discs were involving with things happening there, they attracted attention; I was waiting to hear what happens next, although I know them by heart to the last note.

To a large extent the splendid, fantastic dynamics – its shading, the ability to show the halfshadows, and not only a simple beat – is a result of using both solutions I already mentioned earlier – a midrange dome driver and a transmission line. I am not sure with which element I should start – because those two are tied together, and together they are making the added value. But to make my writing more clear, I will take a look at both items separately.
The bottom octave is very, very low reaching and colorful. It is not monotonous, although a transmission line is often accused of that. On the lowest bottom the timbre of the bass elements is not as well differentiated as from the best closed cabinet loudspeakers, but most loudspeakers, including bass-reflex ones, do not reach so low, what makes the lowest bass seem a bit monotone. Here the shading of the dynamics of bass attacks, bass drum and synthesizers is very truthful and thorough. Listening to the mentioned disc Faith was really a big surprise, because it was with the PMC that it could be heard, that it was very well mastered in terms of the low frequencies. But not only that – also Diorama and discs like A Good Git Together Montgomery brothers (recordings from 1958-1959) sounded more seriously, the sound had a larger volume than with much bigger speakers. The instruments and voices from the first plane were big and shown solidly. N o vibration of their edges, coming from phase inconsistencies, from bad matching of the left and right speaker.

An incredible impression! On the other hand the midrange dome driver gives splendid resolution and fantastically opened sound, regardless of the angle we place the loudspeakers on. In my room they sounded best oriented directly at my ears, but usually we cross their axes in front or behind us. With normal loudspeakers this means, that some of the upper midrange is withdrawn – cone drivers have a tendency to narrow down their emission – the higher the frequency, the narrower the emission radius gets. This makes them very directional at cross-over point. Here we do not have that problem - the dome has a much wider angle of radiation, regardless of the angle we are listening at. It gets even better – the character of its radiation is identical to the dome tweeter. Together they create a duo, that is heard like one speaker.
The timbre of the frequency range reproduced by them is very open, very detailed, but never harsh. It has a nice, well shaped front, resulting in a slightly delicate sound, slightly noble, in the sense, that it is well thought through.
The vocals sound incredible. They are not boosted, not enlarged by stronger lower midrange (I will get back to that in a moment) but due to exceptional resolution, splendid coherence they seem big, full and strong. And they are brilliantly differentiated. Closer-further away, stronger-softer – everything is shown immediately.

To some extent the tested loudspeakers behave like studio monitor speakers. They are not bright or sharp, they just show things exactly as they are. Although not all recordings are ideal, with those loudspeakers we can hear what I learned after years of listening with the best systems – if the audio gear is of high class, then each disc having any message to convey, can sound in a way, that will tie us to the speakers. We hear the flaws of the recording, but we have the tendency to re-qualify some of them from “flaw” to “characteristic” or “choice”. I think this is closer, to what the musicians and sound engineers wanted to achieve.
And now I return to the midrange. It may seem a bit dominating, especially in the upper range. This is not so, except from a hill around 200Hz those are very tonally balanced loudspeakers. But because we get a lot information from the midrange, and not all of it is sensible (this is a problem of the recordings), the subjective gravity point is shifted upwards.
Maybe a similar mechanism makes the upper bass and lower midrange region, around 200Hz, become seemingly stronger. This was nicely shown by the disc Close-Up, Vol 1. Love Songs Suzanne Vega, where the lower part of the acoustic guitar was stronger than it should be – a guitar does not sound so strong in the lower end. Unless… Unless it is amplified with an amplifier. It was audible as if the microphone would be placed very close to the sound hole. And one more thing was clear – that the vocals and the guitar were recorded separately. They were not heard as a coherent whole, because the loudspeakers showed clearly, that the guitar was slightly muted and the vocals made louder – it was bigger, closer to us and in a completely different plane than the guitar.

Summing up, I would like to return to that, with what I started. Those are loudspeakers with many assets of studio monitor speakers, they have characteristics rarely discussed in the audiophile world. They are not ideal, because except for the slightly upped bass (and you will like it, I guarantee!) and slightly too softly drawn further planes they are also characterized with a subjective shift of the tonal balance towards the upper midrange. Anyway they have that one characteristic, that places them in special light: they are incredibly communicative and everything in them is so tuned, that we want to listen to them, that we are sitting down with curiosity with each disc – new and old ones alike. A certain problem could be the choice of the amplifier. It is clear, that those loudspeakers will sound as I described with an amplifier having clean timbre, but also with a very well controlled bass. And it cannot be brightened. The problem is, that most powerful amplifiers have a not enough saturated, often bright sound. So you have to choose your electronics carefully, giving it a lot of thought.

DESCRIPTION

OB1i is a part of the i series, which also includes the stand mount models DB1i and TB2i, floor standing FB1i and EB1i and the central speaker CB6i and a subwoofer TLE1. OB1i is a second model from the top. This is a three-way loudspeaker with a soft dome tweeter, made from a coated material, with a diaphragm diameter of 27mm, bought from the Norwegian SEAS. Its symbol 27TFFC-PMC suggests that this is a special version of the driver, manufactured only for PMC. This driver is called Sonolex and is cooled with ferrofluid. It has a plastic front, but PMC places a metal cover on it, which is there to make it stiffer. It has cut holes to improve the dispersion of the sound.
The midrange is handled by a big, dome midrange driver, D 7608/920010 from Scan-Speak. Its diaphragm is also made from fabric and coated to minimize the internal resonances. The front of the speaker is made from plastic and profiled to create a short tube. Its Neodymium magnet has a shape of a very big, flat slice. The speaker is closed in a plastic, rigid chamber and damped with sponges. I could not unscrew the woofer – probably it was glued in place, to make the chamber behind it completely tight. It has a diaphragm from coated paper with a diameter of 170mm and a cast spider. It is loaded with a long transmission line, with the outlet in the front baffle, at the bottom, and closed with a sponge.

The cabinet is made from MDF – it is very rigid, because it is enforced with a 3.3m long transmission line, so there are two extra vertical and horizontal cross-bars. The inside is not damped, there is only sponge glued to the cabinet sides. The loudspeakers are covered with natural veneer, handpicked, so that the loudspeakers are mirror images. Despite the transmission line inside, the loudspeakers are sleek and not so deep. But because those are quite high – the tweeter is almost exactly in the middle of the ribbon speaker from the Ascendo System ZF3 SE – they have plinths bolted on the bottom, what allows the spikes to be placed wider. The plinths are made from black varnished MDF. Interestingly they have holes cut in the middle like openwork. Maybe the manufacturers wanted to minimize their mass, so that they would not accumulate the energy of the sounds coming from the transmission line?
The cross-over – a very big one – is mounted on a PCB and bolted to a large, removable part of the back plate. The cross-over points are on 380Hz and 3.8kHz, with a filter 24dB/oct; those are Linkwitz-Riley filters. It seems, that the plate is made from MDF, on which a thick plate from acryl was glued, and the PCB was bolted to that one using long, plastic washers. On the PCB we’ll find good polypropylene capacitors of the PB-MKP FC type from the company SRC (6 pieces). However all coils are of the core type. The signal is transferred with cords with PMC logo on them, connected with tags to the drivers. It would be worth to solder them. Interesting is the fact, that we have three pairs of wire terminals. Those are Chinese, of mediocre quality, although they are gold plated. And the shitty plates (jumpers)… But I wanted to tell you – PMC is a professional company and opts for separate driving of each speaker. This is why we can even use tri-amping with the OB1i. This is also possible with a company recommended option – Bryston amplifiers called Powerpac TM120.

Technical data (according to manufacturer):
Frequency response: 28Hz – 25kHz
Efficiency: 87dB (1m/1W)
Nominal impedance: 6Ω
Cross-over frequencies: 380Hz, 3.8 kHz | 24 dB/oct.
Dimensions (HxWxD): 1025 x 200 x 325mm
Weight: 21.5 kg

Manufacturer:
PMC Limited
43-45 Crawley Green Road
Luton
LU2 0AA
United Kingdom

tel.: +44 (0) 1582 405694 | fax: +44 (0) 870 4441045

e-mail: sales@promonitor.co.uk

URL: www.pmc-speakers.com

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