PSB AM5 Active Speakers

An Alpha on Steroids

It’s no secret that I’ve been an avid user of PSB speakers for decades. I started using them nearly 30 years ago as my recording studios’ monitors. I remember I had 12 pairs of PSB speakers at one point. To my ears, they sound uncoloured and I always get satisfactory mixes as a result. Since then, I keep my ears on the ground following their every step. I majorly follow their budget speakers as I believe it is more difficult to design good quality budget speakers over amazing quality price-no-object speakers.

The latest iteration of their budget Alpha line is the AM5, the active-speaker version of their Alpha P5 passive offering.

Each Alpha AM5 enclosure measures 11.4″ H x 6.75″ W x 9.5″ D – the exact identical dimensions as the Alpha P5. The primary, left speaker, which houses the Hypex-based 50 W pc class-D amp that powers both channels, weighs 11.3 pounds. The secondary, right speaker weighs 10.2 pounds – another identical weight as each speaker of a pair of Alpha P5s. Going back to the built-in amplifier, it is essentially PSB shoved a NAD D3020 into the speakers as they sound, to my ear, identical in nature.

The AM5 has a cabinet of 0.5″ – thick MDF wrapped in textured vinyl in matte black, a 1″ – thick front baffle, and comes with a magnetically attached metal grille. While it’s vinyl in nature, the finish quality is nowhere as pedestrian as the name vinyl suggests. Too bad that matte black or white are the only options available on the AM5 as opposed to the Walnut finish offered on the P5. Talking to the PSB founder and chief designer Paul Barton over the phone, he confirmed that the grille is acoustically transparent.

The driver components and passive crossover of the Alpha P5 and Alpha AM5 are the same: a 5.25″ polypropylene midrange-woofer with rubber surround and steel basket, crossed over at 2.5 kHz to a 0.75″ ferrofluid-damped aluminum-dome tweeter with neodymium magnet. As he’s done in other speaker models, Barton places the tweeter below the midrange-woofer. As he explained to me, with the speaker’s Linkwitz-Riley 24 dB / octave crossover network, this arrangement ensures that the outputs of the two drivers remain in phase in the crossover region whether the listener is sitting or standing. The AM5’s specified frequency response is the same as the P5’s: 55 Hz – 20 kHz, ± 3 dB.

Because of its inability to go lower than 55 Hz, PSB completes these powered speakers’ features with a subwoofer out. When the subwoofer output is enabled using the Sub button on the remote, the powered Alphas implement a low-pass filter for the sub and a high-pass filter for the main speakers, both centered on 80 Hz. This way, the speakers are only producing sound down to 80 Hz enabling them to produce an even cleaner sound with even less distortion.

As if that’s not enough, these AM5s employ a high-precision phono stage made by NAD. During my listening, I was impressed by the quietness of this phono stage. It’s the quietest built-in phono input in all the powered speakers I’ve ever tested and I have tested at least a dozen of them in the last 2-3 years alone. Through the phono input, with the volume set to about 2/3 of the way but nothing playing, I could hear only very faint hiss with my ear from about half a foot away from the tweeters in my extremely low noise-floor and acoustically treated review room. From my regular 8 ft of listening distance, I can’t hear anything. Bear in mind, also, that 2/3 of the volume is REALLY loud. During all my tests, I only played at about half volume level. Therefore for all intents and purposes, there is virtually no noise from the phono pre-amp.

Another feature that impresses the production studio side of me is the utilization of Waves Audio Ltd., an extremely well known brand of DSP plugins for professional digital audio workstations.

One of these algorithms, MaxxBass, is always running except when the subwoofer output is selected. From the literature, it is said that MaxxBass analyzes bass content below a crossover frequency set by the designer (38 Hz in the case of the AM5), and creates a series of harmonics based on that content. MaxxBass applies a high-pass filter to remove bass below the crossover frequency, then adds the harmonic series, exploiting a known psychoacoustic phenomenon in which listeners perceive missing fundamental bass frequencies based on harmonics of those frequencies.

It’s a psychoacoustics trick that works well as I have personally experienced and used this method many times, many years ago as a music production tool. It works so well, in fact, I didn’t use subwoofer for any of my listening tests.

Waves claims that MaxxBass can extend the perceived LF response from a speaker by as much as 1.5 octaves. Waves claim that MaxxBass preserves the dynamics and the perceived loudness of the original bass apparent fundamentals. Had I not told that MaxxBass is used, I wouldn’t know from simply hearing the music as it is done that seamlessly. All I knew was that I was hearing bass that sounded surprisingly low for so small a pair of speakers.

That’s why the first impression I had was of a much more solid low-end presence than any bookshelf speakers including the already terrific PSB Alpha P5 with their 5 1/4-inch high efficiency woofers setup.

While the low-end frequency response stood out, the mid-range and treble were also excellent. The soundstage was also an upgrade compared to a pair of P5 running on my Marantz M500 monoblocks. I ran through a wide range range of records, CDs and digital tracks streamed through my Bluesound Vault 2i, with bands ranging from The Beatles, Pink Floyd to Judas Priest and a slew of Telarc and DMP reference recordings. The listening experience was thoroughly enjoyable no matter what genre or input source I tried.

So what do I think? I always liked PSB speakers for the sound quality. Having a great performance to price ratio is even better. Moreso, with the AM5. PSB have managed to put the P5, NAD D3020 sounding Hypex amp and NAD phono pre-amp into a pair of speakers for pricing at much less than $1,000 CA. What’s not to like?