Plixir Power

Elite BDC Linear Power Supply

2 Amp (US$769 | S$802.50), 4 Amp (US$894 | S$909.50), 6 Amp (US$1,029 | S$1,059.30)

Plixir is a home-grown product that was conceptualized right here in Singapore. The brainchild of James Soh, it is claimed to be the world's first fully balanced power sound system. The product range consists of a balanced power conditioner, cabling, and a balanced DC power supply, which is the subject of this review.

James is no stranger to the local audiophile scene, starting in the audio modifications business in 2003. An engineer by training, he has worked in several leading electronics companies, focusing on audio-related products. He is also an accomplished tuba player, having represented Singapore in many overseas competitions. In 2013, he set up Sound Affairs Pte Ltd to concentrate on his audio business full-time, and the Plixir range of products was introduced a year later.

For the uninitiated, balanced power involves using a transformer to split the incoming mains AC power into two phases. Each phase is out of phase relative to the other. The local power supply is 230V, so this is split into +115V and – 115V. Your component sees 230V, which is the magnitude of difference between both phases and is none the wiser. 

The theoretical benefit is that the nasties in your power line are split by the transformer and are mirror images of one another. When combined at the destination, they should cancel out. The transformer also acts as a block to any DC that may be present in your mains and attenuates high-frequency noise, too (mains transformers are optimized to transfer 50 or 60Hz AC mains and are less efficient at transmitting high frequencies). The theory is simple enough, but implementation requires care in practice. For example, the windings have to be as symmetrical as possible, and the transformer's quality becomes paramount to avoid saturation.

UP CLOSE

The Elite BDC single output linear power supply is Plixir's flagship model and comes in three variants – the 2 amp (S$802.50), 4 amp (S$909.50) and 6 amp (S$1,059.30). The design has a special three-stage filter to provide the cleanest possible DC output. The first stage involves the use of a 200% rated balanced power transformer. This is then fed to the first pre-regulator stage, which is an open-loop design discrete transistor circuit. The second regulation stage operates on a closed-loop feedback system. Plixir calls this the brawn and brain method, with the pre-regulator doing the heavy lifting. The brainy second regulation stage is the final job to deliver the voltage to your component. 

This approach has several advantages. It greatly reduces the noise that reaches the final stage regulator. The workload and heat dissipation is distributed across both stages, which means reduced heat and greater reliability. Lastly, the noise produced from the component has less chance to pollute the AC mains as both regulator stages act as a barrier. I liken it to having a multi-stage water filtration system. A single filter will do the basic job, but you need multiple filtration stages if you are after the highest quality water. Some high-end audio manufacturers have also designed multi-stage regulation circuits for their power supplies, so they have clearly realized the benefits of this approach. Plixir claims that the resultant noise at the DC output is less than 1mV rms. Power supplies are available from 5V to 30V DC (non-user adjustable); the unit supplied for purposes of this review was a 12V DC, 6 amps model.

The shoebox-sized BDC measures 230x70x160mm and weighs 3.7kg, the bulk of which comes from the hefty English-made Noratel transformer. There is a mains switch on the side of the unit, and the DC cable is attached to the aircraft-style locking connector on the rear. The optional Statement DC cable was supplied with the review sample. I noticed that the unit runs quite warm, even when there is no load – so adequate ventilation is a must. I did not have any mechanical hum or buzzing issues, unlike some other power supplies I have tried in the past. 

The BDC was paired with two different components in my system. First was a Melco S100 network switch, the second a SoTM SMS-200 Ultra streamer. The Melco is part of my streaming setup for dedicated wireless control of my two music servers, a Melco N1Z/2EX-H50 NAS and an Intel NUC PC running Roon Optimized Core Kit. The SoTM was used in substitute of the Melco NAS running as a Roon endpoint, with all cabling remaining the same.

The stock switched-mode power supplies that came with both components were used for comparison purposes. Both the Melco and SoTM were well within the current limit of the review sample, with current draw at 1A and 2A, respectively.

THE LISTENING 

I've been around the block with power supplies. Most such products gave with one hand and took away with the other. For example, many linear power supplies that I have tried have added heft and weight to the tone, at the expense of top-end air and speed. 

Tonally neutral, the BDC did not tilt the balance of my system one way or the other. It gave the music a solid and sure-footed confidence with a tight, grippy and fast bassline. There was a clarity and focus throughout the frequency range that made the stock power supply muddy and vague in comparison. At first listen, the high frequencies seemed less obvious and energetic, but I realized this was due to a cleaner and tidier presentation. 

The Bassface Swing Trio's Oh, Lady Be Good is a dynamic recording with strong drive and impact from both the upright bass and drums. Also, the soft banter between the performers at the end of the track is a good test of a system's low-level resolution. The Elite BDC's control and speed helped to reproduce this track with the slam and tempo required. The plucking of the bass strings and the strike of the drum kit was deep, solid and tightly rendered. The banter was crystal-clear despite the low volume. In comparison, going back to plain vanilla put an undue emphasis on high frequencies, with the cymbal work sounding enthusiastic but splashy and uncontrolled. You could hear the strings of the bass, but it lacked the deep and tight articulation of the real thing. The drop in resolution also impaired the intelligibility of the banter. While you could hear the talking, the conversation was not clear enough to be made out.

Listening to Punch's Love Me showed off her powerful and emotive voice, which had a very expressive but slightly nasal character. The arrangement is simple enough, with the vocalist accompanied by instruments that come in throughout the song. The Plixir kept the mix in absolute control, with tight and precise placement of each instrument in the soundstage while the stock power supplies allowed them to wander about. It also made Punch sound overly nasal and robbed her voice of its emotive power. 

Jacintha is a well-known Singaporean actress and singer who has found success on the international scene. The opening of On Days like These starts off with a tuneful whistle. She has a rich and sensual voice that's inviting and easy to listen to for hours on end. Each draw of breath was obvious, while the whistling was pristinely clear. The stock power supply sounded airy and almost breathless but lacked the solid foundation and blurring detailed breathing delivered by the Plixir. Jacintha similarly sounded lighter and with less chest than usual.

Alice Sara Ott's Debussy: Réverie, L.68 has a beautiful dream-like atmosphere. The piano starts off with a gentle, flowing style but gets progressively firmer and more authoritative. The Elite BDC nailed this perfectly while the stock power supplies homogenized the changes in expression and mood, making the changes less obvious. The improvements were easily noticeable on the SoTM, and to a lesser but still significant degree, on the Melco S100. Some experimentation will be needed to find out which component benefits the most from an upgraded power supply.

The Plixir consistently provided added clarity to music while serving up a solid foundation in control and improved tonal density. This was done without any detrimental impact to dynamics or speed. The only drawback is cost and additional system complexity, especially if you factor in the rack space required and aftermarket power cords. 

THE VERDICT 

The Plixir Power Elite BDC is a quality power supply that provides an instant uplift to your system's capabilities without heavy-handed alteration of its tone. From a performance perspective, it manages to stand out from the crowd with distinction. Pricing is more than fair and well-worth the investment, in my view. 

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