Friday, February 13, 2015

Sounds Affairs Plixir Balanced DC Power Supply and Balanced AC Power Conditioner


Sound Affairs is a relatively new name in the local hi-fi scene, although it's principal, Mr. James Soh is a name familiar to many local audiophiles, especially for his previous work under the banner of Effective Audio Mod. 

Sound Affairs marks his move into a full-time retail business, with both sales and distribution of a complete range of hi-fi equipment, while continuing with modification work.

Sound Affairs offers a number of unique made-to-order products, including a DC power supply, and balanced AC power conditioner, which are the subject of this review.

I took the opportunity to ask James some questions about his approach to design in coming up with these products.

Design and Philosophy

James explained that that the Plixir Balanced DC Power Supply takes a unique approach. The custom wound transformer provides a balanced AC voltage supply (read on further for benefits of balanced AC power). Only two diodes are used for rectification instead of four. James believes that this is beneficial as all diodes create noise and distortion, so the less diodes used, the better. This topology, however requires the transformer to be double in power rating, increasing size and cost. The voltage regulation is done in two stages. The first regulation stage eliminates most of the voltage ripple, leaving an easier job for the second stage to handle. This also allows the heat to be distributed across both regulators, lowering temperature conditions. As a result, you get lower thermal noise and drift, better reliability etc. James mentioned that many single stage DC power supplies boast high attenuation of ripple at lower current, but as load current increases, the ripple increases as well. Only a two stage (or more) design can effectively solve this issue to ensure a low noise power supply to the load at high current.

Other design features include high speed, fast recovery diodes, and used of snubbers across these diodes.

Coming to AC power conditioning, I asked James on his views on balanced AC power versus other methods, e.g. noise filtering using capacitors, chokes or power regeneration. He drew parallels between the use of his balanced transformer to the output transformer of a tube amplifier. A tube amplifier output transformer couples the high impedance of the power tubes to present a low output impedance on the amplifier's output. Similarly, his  balanced transformer is designed to couple the high impedance of the power line to present a low output impedance source of AC power. He mentioned that balanced power is commonly used in professional audio to resolve ground loop and noise issues. The transformer used in his Balanced AC Power Conditioner is also lossy at high frequencies, while being efficient at the 50 Hz mains frequency used locally. This helps to filter out high frequency pollution on the mains line.

In comparison, James felt that mains filtration using capacitors is a hit-and-miss affair, as there is guesswork involved in the effective range of the filters. Further, the choice of capacitor influences the tone of the system. As for inductors, his view was that these limit current and adversely affect impedance by adding resistance, and distort the AC wave form.

James acknowledged that power regeneration has many benefits but had reservations on the transient speed and dynamics. The AC/DC/AC conversion was to him an unnecessarily complicated approach. The "speed" of DC supply was also a question mark, as the chemical conversion to electricity (whether through the discharge of capacitors, or drawing from a battery supply) may not be quick enough to cope with fast fluctuations in current demand. Long term reliability is also impacted by heat and the complexity of the design.

Plixir Balanced DC Power Supply

The Plixir Balanced DC Power Supply is a compact power supply housed in a simple but smartly finished aluminum box. The rear panel contains the IEC inlet, a fuse holder, the power switch, and a socket for the detachable DC lead. The supplied lead is of high quality and comes with a locking collar.

In operation, it runs cool to the touch even when left on permanently. 

I purchased a 15 V DC model to power my Auralic Aries. Prior to that, I was using another well regarded linear power supply, which sounded better than the stock switched mode power supply,  but too dark and lacking in air for my taste. 

The Plixir was noticeably superior in all aspects, sounding more open, faster, while retaining a solid bass foundation and quiet background. Unlike most upgrades that involve some kind of trade-off, this was an all round improvement and easy to recommend. 

Plixir Balanced AC Power Conditioner

Plixir BAC 800

I was provided two different models for purpose of this review, a BAC 150 and BAC 800 (the model number denotes the rating of the conditioner in watts). 

A number of build options are offered, including upgraded AC outlets, UPOCC internal wiring and Bybee Quantum Purifiers. The units I tested were stock models, which were supplied with high quality Meikosha outlets from Japan.

Similar to the DC power supply, both units ran cool (neither were loaded beyond 50 % of their maximum rating throughout my period of review).

A number of combinations were tried in both of my setups.

1. BAC 150 with source equipment in my main listening room

I tried the BAC 150 first with an Audio-Gd NFB-10ES2 headamp / DAC and also my Cary CD-500, which are in my main listetning room. The power quality there is the highest and most of the audio equipment do not share power lines with noisy household appliances and the like.

Bass quality improved with a nice increase in heft and slam. There was also a noticeable reduction in the noise floor, and the enhancement of detail. The midrange took on a smoother and more laidback feel. I felt that this came at the expense of a darker tonality and a slight reduction of "air".

I did not try my amplifiers with the BAC 800 as their current draw exceed the unit's rating.

2. BAC 800 with Antelope Zodiac Platinum and Job 225

My bedroom setup is less fortunate. It sits on the same line with a whole range of things, including a Plasma TV set, a cable set top box, alarm clock and a computer. 

First, I tried the much bigger BAC 800, with both my source and amplifier plugged into the conditioner. 

Interestingly, I did not notice any mellowness, or reduction in "air" here. I would think that most people would be suitably impressed with this combination. 

Bass was tighter, more extended, and dynamic. You could really feel the added extension, drive and energy of bass lines.

Soundstaging also improved in depth, while there was improvement in detail, separation and refinement. This was most noticeable on heavy mixes, where the additional coherence and detail retrieval allowed you to follow the separate instrument lines clearly. 

3. BAC 800 with Antelope Zodiac Platinum

I also tried hooking up just my source to the BAC 800, with the Job 225 plugged directly into the wall.

The reason I tried this was to see whether the conditioner was restricting current to the power amplifier. This did not seem to be the case here.I actually thought that this sounded worse compared to having both my source and the Job 225 plugged into the BAC 800.

4. BAC 150 with Antelope Zodiac Platinum, and BAC 800 with Job 225

James had in fact suggested that I try out using two separate conditioners,and had supplied me with two sets for this purpose. 

While the system tonality was similar to just using the BAC 800 alone, there was significant improvement in soundstaging, high frequency extension, low level resolution, and a modest improvement in all the other audiophile niceties observed earlier.

I happened to be listening to a live recording, and you could really feel the acoustic space of the venue, and the reverb from the vocalist and accompanying instruments. 

In fact, I would rate the step-up in improvement moving from one to two balanced power supplies to be on par with the improvement going from stock to a single balanced power supply. I had no reservations using this combination and it was nice to be able to have your cake and eat it too !


I was very pleased with the performance of both products. The DC Power Supply makes an excellent alternative to the multitude of other power supplies out on the market, and the ability to work with someone locally to provide custom options is a boon.

While the benefits of the Balanced AC Power Conditioner is more dependent on the quality of your mains power supply, I was suitably impressed with the BAC 800, and even more impressed using the BAC 800 in combination with the BAC 150.

The Plixir line impressed me with it's good build quality, reasonable pricing and outstanding performance. Highly recommended.

I would like to thank James Soh of Sound Affairs Pte Ltd for his time in answering my questions and for supplying the review units.

Specifications and Price

Plixir Balanced DC Power Supply

Specifications and dimensions vary with voltage and maximum current.
Price - S$ 449 upwards

Plixir BAC 150 Balanced AC Power Conditioner 

150 watts
Two outlets
Weight - 4 kg
Dimensions - 220 mm x 50 mm x 225 mm
Price - S$ 450

Plixir BAC 800 Balanced AC Power Conditioner

800 watts
Four outlets
Weight - 9 kg
Dimensions - 144 mm x 155 mm x 250 mm

Price - S$ 1,190

Sound Affairs Pte Ltd
100 Beach Road, Shaw Tower
Singapore 189702

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