Review: PWX power supply for Black Cube

This review is a preliminary review and evaluation of the PWX power supply that is optional for the Lehmann Audio Black Cube phono preamp. I have spent the last several evenings using the PWX, and wanted to share some initial reactions.

The PWX power supply replaces the standard remote power supply for the Black Cube, and can be retrofitted to all Black Cube models. The unit is 9”x4”x1.75”, and the sturdy metal housing is identical in construction to the Cube’s. One end of the PWX has an IEC connection for the electrical power, and a 4-pin Neutrik connector that links the PWX to the Cube. (If you are interested in seeing a picture of the PWX, look at the ad from HyEnd Audio on page 105 of the June-July issue of TAS.)

The PWX has a much beefier power supply than the stock original. The advertising for the PWX claims a ten-fold increase in voltage over the original power supply unit. The claim seems fully substantiated when one looks inside the housing, which contains a donut-sized (cake donut, not raised), German-made 35 VA toroidal transformer, and two 4500 mFd filter capacitors. The PCB, parts, and assembly reflect the usual high German quality standards. All wiring is heavy-duty, with excellent soldering.

The PWX is available from HyEnd Audio (www.hyendaudio.com), the importer, for $245, or $275 if you send your Black Cube to them and have them do the replacement procedure. If you decide to do the work yourself, you must be able to solder the 4-pin Neutrik connector onto the end of the umbilical cord from the Cube. This is not difficult for hobbyists who are good with a soldering iron, but others may prefer to have HyEnd Audio do the soldering. (Contact HyEnd and talk to the owner, Leo Massi. Leo’s a good guy who shipped the PWX to me on my word that I’d mail him a personal check. Trust is such a rare commodity today.)

So, how does the PWX unit “sound” with the Black Cube? To assess the PWX’s contribution to improved sound quality, I listened to a cross-section of music: chamber and orchestral music (LP’s by Reference Recordings); jazz combos and bands (e.g., M&K’s D-to-D LP “For Duke”); blues; folk (the MoFi 200 gram Anadisk pressing of Joan Baez’s “Diamonds and Rust”); and some rock (Creedence; The Doors; Beach Boys; The Eagles; etc).

The advertising for the PWX claims “an incredible improvement that adds dynamics, pace, rhythm, speed, focus, and holography”. Based on my initial listening experiences, the claims may be a bit hyperbolic, but I can attest to a detectable improvement in the sound from my LP’s. The most notable improvement, as one might expect from an enlarged power supply, was in the dynamics, speed, and transients. Bass was tighter and had more “oomph”, and transients such as plucked guitar strings were quicker and had more immediacy. I also had the sense that vocalists were more “in the room”, and there also the feeling of enhanced acoustic space – this may be partially because the background seemed “blacker” and quieter, which allowed vocalists to stand out more.

When conducting critical listening to a new component, one must be careful not to be biased by claims of improved performance. I can say, however, that I heard good, although not dramatic, improvements in the audio quality from my LP’s. The type and level of improvement that I heard are nuances, and it takes an already good audio system to take advantage of this. I think this $250 upgrade is a good investment for people who own Black Cubes, AND who have good sound systems. Anyone who is planning to buy a Black Cube should consider investing the extra money and get the PWX power supply rather than the stock version