PS Audio P300 Power Plant Page 3
The Power Plant has a feature that, as far as I know, is unique among equipment offered for audiophile use: variable AC frequency. This so-called Power Factor allows AC frequency to be varied from the normal 60Hz to a high of 120Hz. (The 50Hz setting is for countries where this is the normal AC frequency.) PS Audio claims that increasing the Power Factor makes the equipment's power supply more efficient, increasing the effective value of capacitors and decreasing the transformer's radiated magnetic field.
In my system, increasing the Power Factor produced a startling sonic improvement. Dynamics—already enhanced compared to the raw AC condition—were even more dramatic, to the extent that, after comparing the same CD track with the Power Factor at 60Hz and at 90Hz, one listener accused me of having turned up the volume. (I didn't—honest!)
There was a significant improvement in overall clarity, and voices sounded more rounded, less synthetic. My wife, a fan of the late John Denver, said that with the Power Factor at 90 his voice "sounded more like John." The most beneficial effect seemed to be at the setting of 90Hz or thereabouts, the 120Hz setting resulting in some thinning of the sound.
According to the manual, Power Factor settings of higher than 60Hz should not be used with turntables and tape decks that have AC-synchronous motors. My Linn LP12 has this type of motor, but its Lingo power supply isolates it from AC frequency, so this admonition doesn't apply. (The Lingo controls turntable speed by varying the frequency of its synthesized AC.) I used the Power Plant with the Linn at various Power Factor frequencies, and as you might expect, given the similarity between the Lingo and the Power Plant's approaches, I found the improvement over the sound of the turntable power supply plugged into the wall to be fairly minor; increasing the Power Factor setting seemed to make little or no difference.
As it happened, a couple of weeks before the Power Plant arrived, the Sonic Frontiers Processor Three digital processor I'd been using was returned to its manufacturer and my old PS Audio Ultralink Two processor (with HDCD update) was pressed into service. The Ultralink Two was considered a fine processor in its day (rated Class B in Stereophile's "Recommended Components" as recently as April 1997), but with my ears having been accustomed to the more refined sound available from the Processor 3, its sound seemed bright, edgy, and forward.
Plugging the Ultralink Two into the P300 Power Plant brought about a major transformation of the Ultralink's performance: smoother, less forward, altogether more listenable. My recollection is that the Processor 3 without the Power Plant still sounded better than the Ultralink Two with, but using the Power Plant considerably narrowed the sonic gap between these processors.
The performance of my system took a major leap forward when the Muse Two Ninety Six digital processor arrived on the scene. I must echo Shannon Dickson's enthusiastic endorsement (April 1999): This is indeed a great processor—even without use of the I2S link, and even just playing back ordinary CDs, let alone 24/96 DVD recordings.
The power supply of the Muse Two Ninety Six is much more elaborate than that of the Ultralink II, so you might think the Power Plant wouldn't be of much benefit. But it was. The difference in sound between the Two Ninety Six plugged directly into the AC wall receptacle and plugged into the Power Plant was not as dramatic as in the case of the Ultralink Two, but it was definitely there: enhanced dynamic contrasts, better sense of space, higher resolution. (By this time I had determined that the Power Plant performs best with the Power Factor set at 90Hz, so this was the setting used for all the comparisons.)
I also spent some time listening to the Rotel RCD-971 CD player, comparing its performance with and without the Power Plant. The RCD-971 offers superb performance for the price ($699), performance that reaches a higher level still with the Power Plant. Although the Muse/Lambda Two combo is clearly better (for $5000, it should be!), the RCD-971 powered by the Power Plant sounds astonishingly good.