McGary Audio

Essential Sound

Tuesday, July 31, 2012

Home Recording Review!
PMC AML2 Powered Speaker:
Glorious Sound In a Small Package!

powered speaker

Price: $10,499
Likes: accuracy, clean bass
Dislikes: only XLR inputs
Info: PMC AML2

by John Gatski

  When the PMC AML1 was launched in the 1999, it was a revelation for a small powered monitor. The high-end, made-in-Great Britain speaker sported a unique transmission line design that could output high levels of deep bass with a small driver and deliver audiophile-quality midrange and treble, thanks to its quality onboard amp and tweeter.
  The upgraded AML2, still only 15-inches tall, builds on the AML1’s performance by adding more EQ flexibility, an all-new, improved amp power supply and a redesigned cabinet — offering even more accuracy and output level. It may be the best powered small monitor available today. But it ain’t cheap, retailing for $10,499!

  The AML2 features a 1.25-inch soft dome tweeter, designed and manufactured by PMC, with a high-frequency focusing lens, and a 6.5-inch honey comb designed Nomex carbon fiber bass driver. The patented Advanced Transmission-line (ATL) bass system allows the small driver/cabinet to cleanly put out bass to below 40 Hz with out significant roll-off or distortion. The effective length of the transmission line cavity is more than five feet!. The ATL places the bass driver near one end of a small “tunnel” that is damped with acoustic material to filter out upper bass sounds, but allowing the lower bass to pass through. The equalized air pressure of the ATL also helps to control low bass distortion, enabling the AML2 to provide impressive clean bass at higher levels.
  The crossover is also key to the AML2’s sonic signature, centered at 1.4 kHz instead of the typical 2 kHz-3 kHz that is typical for most active or passive two-ways, allowing a more natural midrange that is not edgy, exaggerated or peaky.
  The AML2’s performance is enhanced by the onboard amplification that includes 100 watts RMS for the bass driver and 80 watts for the tweeter. This Bryston-designed, Class A/B bipolar output amplifier delivers the dBs with a smooth, precise audio character — with plenty of juice to make these puppies play loud.
  The AML2 is equipped with top-mounted controls including EQ and level, and on/off cleverly hidden under a hinged panel. The adjustable crossover and adjustable EQ allow for custom tailoring of the AML2 to fit the room with high- and low-frequency cuts and boost to compensate for room interaction, boundary placement etc.

One characteristic you immediately notice with the AML2’s is how smooth the treble is. Having auditioned numerous powered speakers that project an edgy, ragged upper-mid/low treble, the AML2s deliver a natural, uncolored, and importantly, no harshness as you crank up the volume.

  The adjustable crossover augments the primary crossover with a -3 dB roil-off at bass frequencies of 90 Hz, 50, Hz or 30 Hz. The low-frequency tilt offers further bass tailoring with boost or cut (-3 dB, +1.5 dB or +3.0 dB) centered at 500 Hz. The high frequency tilt allows high-frequency EQ of -5 dB, -2.5 dB or +2.5 dB from 1.6 kHz to 20 kHz.
  All the onboard controls can be bypassed. I found the EQ perfectly suited for tweaking the speakers for placement of minor room correction. Most of the time though, I left them in their flat position except when placing them near my console right against the wall, which I would enable the -3 dB mode in the LF tilt.
  In keeping with its pro recording-focused features, the AML2 has only balanced XLR speaker connections; no RCA or TRS connectors are used. The power cord slot and on/off switch are on the back.
  Specs include a 33 Hz to 20 kHz frequency response (no tolerance given), 111 dB maximum SPL. Crossover frequency is 1.4 kHz. The analog amp delivers 100 watts (woofer) and 80 watts of the tweeter at .09 percent distortion. Slew rate is 60V/uS
  Cabinet-wise the AML2 is made from composite material that make it very inert and audibly impervious to cabinet resonance and sonic coloration. Each speaker measures 15.75 inches tall, 7.87 inches wide and 14 inches deep. They are a 35 pounds each. Not too heavy to move around for variations in usage, especially if you are setting up several in a 5.1 or 7.1 system
  The cabinet has mounting inserts so it can be secured to PMC’s custom-104 pipe stands or anchored to the ceiling or walls with special mounts. Its size makes it especially versatile.

The setup
  I located the PMC AML2’s next to my Trident (now ORAM) 16-T analog console, and also set them in the middle of my room to see how they performed without boundary reinforcement. Sources included analog tape, DSD and high-res PCM from my recorder workhorse, the TASCAM DVRA-1000HD, and a Macbook Pro recording setup. I even played some audiophile LPs through it via a Pass Labs XP-25 discrete phono preamp — just to get a sense of its versatility.
  Most of the audition time was spent with the PMC’s in proximity to the console on Apollo monitor stands at at ear level and eight inches from the wall.

PMC AML2's Onboard Controls
  All connections made to the PMC were linked via Alpha-Core solid-silver XLR cables. I also thought that the $10,000-per-pair AML2s deserved a nice power cord, so they were plugged in to the AC via ESP Music Cord Pro cords, which were plugged into an ESP reference power strip. The ESPs are very resistant to any AC line noise and hash.
   Through the PMC's, I played various kinds of music I have recorded, including acoustic guitar, jazz guitars, percussion, and organ tunes, courtesy my Nord Electro 3’s Hammond B3 mode. I also pumped a lot of 24-bit pre-recorded music through the AML2s from SACDs, DVD-As and high-res downloads from ITrax and HD Tracks music download services.
  The PMC manual mentions at least a 20-hour break-in period for the AML2’s, but since my pair was a well-used company demo tandem, I immediately began compiling my listening impressions.

The audition
  One characteristic you immediately notice with the AML2’s is how smooth the treble is. Having auditioned numerous powered speakers that project an edgy, ragged upper-mid/low treble, the AML2s deliver a natural, uncolored, and importantly, no harshness as you crank up the volume. The combination of a low-crossover frequency, the use of an excellent Class A/B amp section and PMC’s carefully selected tweeter contribute to upper-end detail that is dead on. From violins to piccolos, energetic pop percussion, and the metallic decay of jazz drum cymbals, the top-end was never strained.
  And we must not forget that this pin-point accuracy enhances the layering that takes place in its two channel presentation. The PMC’s have great front-to-back depth and left-to-right/right-to-left audible width. You can clearly pick out subtle audible detail in the mix — without the sound becoming buried or blurred. Quite impressive.
  The cabinet design and construction also is key to its clean midrange sound — with no unwanted resonances or unflattering color to the sound. A well recorded SACD from Tom Jung’s 1990s string of DSD jazz recordings revealed exquisite piano tones with precise transients and rounded overtones, just like a well-recorded Steinway D should sound.
  A 24/96 Martin D35 acoustic guitar PCM recording that I did with a pair of Audix SCX-25 microphones and a True P2 discrete mic preamp sounded extraordinarily open through the AML2s — with the crisp strums and string detail that is nicely separated. These speakers have not once ounce of treble coloration.
  The bass side of the AML2’s performances is equally as impressive — especially for a small speaker. With the adjustable crossover and EQ controls bypassed, bass drums, electric and acoustic bass recording were showcased with an amply loud, but tight, fast bass. No artificially puffed up midbass here. With test tones and a RTA measurement, the AML2 bass response easily was flat to 42 Hz in my studio — at eight inches from the back wall. 
  The speakers could play all this low bass well into the 95 dB plus range without sounding strained, though my room is not so big as to overwhelm the little guys when cranked up. In a bigger room, say a cinema mixing suite, you may want to help out the lowest bass octave with a supplemental subwoofer. But with most small to modest rooms, the AML2s are just fine.
  I also placed the AML2s in the middle of one of my demo spaces to see how it performed as a midfield speaker. Out to 12 feet or so, it filled the room nicely again with convincing bass and the uncolored treble character that you hear close up. I did not find the bass lacking — even without the close boundary reinforcement of my console setup. It is quite a testament to PMC’s choice of drivers and the ATL cabinet.
  As for ergonomics, I love the top-mounted control panel for the EQ and crossover. It is cleverly hidden under a sliding panel. I also like the little PMC logo light. PMC ships each speaker with a nicely done manual, which is full of technical info and tons of setup recommendations.

 The bass side of AML2’s performances is equally as impressive — especially for a small speaker. With the adjustable crossover and EQ controls bypassed, bass drums, electric and acoustic bass recording were showcased with an amply loud, but tight, fast bass.

  My only criticism with the PMC’s is a mere quibble; the speakers don’t have an unbalanced input option. Although most pros will use it balanced, home studio users — and those who may opt to signal the speakers with high-end audiophile gear — often have more spare RCA outputs than XLRs. Alas, XLRs are all there is on the AML2. I have sampled many powered monitors and a good number do have balanced and unbalanced inputs.
  Lets talk about the price of these speakers. European- and USA-manufactured studio, as well as audiophile, speakers are not for the faint of wallet. You are not going get this kind of performance from a powered speakers at say $1,200. The PMCs are indeed more expensive than the plethora of Chinese-manufactured powered speakers you see at online pro dealers. But in my opinion, the extra clean high-end and the amazing bass extension from such a small speakers is worth the money — if you are after the utmost in quality from a small speaker. And these speakers are built like audiophile speakers. No cost-cutting omissions here. They are an investment at $10,000 grand but should reward you with years of excellent sound.

The verdict
  Although the $10,000 price tag may make you gasp, the ability to deliver clean sub-40 Hz bass and nearly perfect top end also will make you gasp at the PMC AML2’s sonic performance. It truly is an amazing small monitor that can meet the sonic needs of most home studio recordists and commercial engineers. Save your money and buy a pair of these speakers. They are that good. Since they are British, I also think it is appropriate that I “bestow” our Everything Audio Network Stellar Sound Award on the AML2s.

PMC USA President Maurice Patist
On The New AML2 Active Loudspeaker

Editor's Note: Maurice Patist is president of British speaker manufacturer PMC USA. Originally a live engineer, he ended up working in the studio environment, where he was blown away by the PMC sound. This spawned the start of his PMC career, which has blossomed over the past decade, and seen him hop across the Atlantic several times, boosting the profile of both the pro-audio and hi-fi sides of the business.

EAN: What are the key improvements of the AML2 over the AML1?
MP: Despite being very happy for 10 years with the results of the AML1, we still found ways to improve; revised cabinet structure, new amplifier mounting mechanism, changes in the design of the amplifier and the components that were used, revised ATL™ with additional damping for even less distortion, different cosmetics but still very recognizable as a PMC speaker!

EAN: What are the design elements of the AML Series that allow them to relay audio, especially when playing 24-bit PCM or DSD, that is about as accurate as I have ever heard from a professional speaker.
MP: It really comes down to the interaction of all the individual parts (driver-, cabinet-, amp- and ATL™ design) that allows the speaker to give the least amount of distortion (which normally colors the sound) at any volume level and still being able to present the full frequency response. It doesn’t add or take away anything from the music, which makes it the ultimate tool to make the right mixing or mastering decisions, or to just truly enjoy the quality of recordings while playing back music.

EAN: Your ATL (advanced transmission line) design is key to getting full range out of a small speaker. How is your system different from other ported, bass reflex or passive radiator bass-augmentation schemes?
MP: PMC’s innovative approach places the bass driver near one end of a long tunnel (the Advanced Transmission Line). This tunnel is heavily damped with acoustic material specified carefully to absorb the upper bass and higher frequencies radiating from the rear of the bass driver. The lowest frequencies are allowed to pass down the line and emerge from the large vent in the same polarity as the driver’s frontal radiation, the vent acting essentially as a second bass driver.
  Another important benefit of this approach is that the air pressure inside the cabinet, loading the bass driver, is maintained. This helps to control the driver over a wide frequency range and significantly reduces LF distortion. Consequently, the upper bass and midrange detail is not masked by harmonic distortion and the result is PMC’s characteristically transparent midrange, fast, attacking bass and outstanding clarity.
  A further advantage is greater bass extension and loudness than a ported or sealed design of a similar size, even if similar drivers were used. Moreover, the very consistent bass driver loading brings the welcome benefit that the frequency response remains consistent regardless of listening level, and analytical auditioning can be conducted without the need for high replay volumes to achieve optimal bass response – a unique and very valuable characteristic.

EAN: If an end user wants more bass below 35 Hz (cinema effects in a surround setup perhaps), which PMC subwoofer do you recommend?
MP: There are two models that are being used in 5.1 systems. In smaller rooms the PMC TLE1 active subwoofer with 2 x 6” bass drivers and again a Bryston designed amplifier is recommended. There were the room is bigger and more output is required, we would recommend our SB100, (single 10” bass driver)  again powered with a Bryston designed amplifier.

EAN: Who designs your amplifiers? Why do you stick with Class A/B rather than go with digital designs?
MP: As a lot of people know, we have enjoyed a long (almost 20 years now) technical partnership with Canadian manufacturer Bryston. Over the years we have been able to use their designs and voice them towards the PMC speakers, with these results. On our bigger active models like the flagship system BB5-XBD-A (see picture), we use again Bryston designed PMC active amplifiers, getting the best results possible. We find that in many active speaker designs, it is usually the amp design that limits the performance. We did not want any limitations on the performance of our active speakers. In regards to the digital designs, we found that despite the improvements in their designs, until recently they have not been able to match the quality of the analogue designs we have used. We expect to see better digital designs in the very near future that would come very close. The issue here is pretty much the same as with analogue designs, you just cannot cut corners to get the best possible results!

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