Associated Equipment:
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Digital Front End
Amplification
Loudspeakers
Cabling
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The Multiple Personalities Of Perpetual Technologies' P-1A / P-3A Digital Processors

Marshall Nack

2 March 2001

Preface

This is my first foray into high-end digital. Even though I'm a happily dedicated vinylphile, I know I've been missing the last 20 years' worth of recordings. The thought occasionally crossed my mind that something good might have happened in classical music after the left turn the genre took in the second half of the twentieth century. Especially in my (current) principal area of interest, the Baroque, I know that there are some fantastic new players on the scene. I wanted to get my feet wet with a respected but affordable rig and gradually move up later on. The PT gear fits the bill.

Cosmetics

The two units are small enough to fit side by side on a component shelf. They're each about the size of a quality paperback and weigh four pounds apiece. They look like high-tech PC computer accessories. Fit and finish is adequate but not in the same league as, for example, Krell gear. Likewise, the AC wires are decidedly mid-fi. I set the two pieces up in the vertical position with their supplied aluminum brackets on my PolyCrystal rack.

Since one purpose of this review is to gauge the impact of the Monolithic Power Supply upgrade, I used the PT gear without any AC conditioning until the Monolithic arrived. I connected the digital front end to the Ensemble Mega PowerPoint AC power strip and that went straight into the wall.

I acquired a SONY DVP S7000 for the purposes of this review. The SONY made a stir a couple of years ago as a CD transport and commands respect in that regard.

Getting Started A Small Problem

After about a week of burn-in, I sat down and ran through the setting options and, believe me, there are many! When I switched the P-1A to CD Resolution Enhancement I detected a constant high frequency whistle, even with the volume at zero. The noise was just loud enough to be audible from the sweet spot. Because of this, I switched the P-1A to Bypass, circumventing Resolution Enhancement for the time being, until some help could arrive from PT.

Clement Perry came by one day and suggested that substituting an Acoustic Zen MC2 Silver coax digital cable for the I2S cable would improve the sound. The I2S cable, which comes with the units, is PT's preferred digital link. I followed Perry's suggestion and, sure enough, the Zen did sound better, with improvements immediately noticeable in treble extension, spatial definition, and soundstage openness. I left both cables connected so I could easily compare them. But with Resolution Enhancement that noise was still there.

The problem's solution came purely by accident. One day, thinking I might tidy up the unsightly wire mess, I removed the I2S cable. That was it! With the I2S out, the whistle was gone! I contacted Mark Schifter, who diagnosed the problem over the telephone as a ground loop. The grounding configuration of the I2S cable is different from that of the coax. When the I2S is used, roughly 50% of systems need to be grounded; the rest need the ground lifted. At his suggestion, I put a 2-prong cheater AC adapter onto the power cord for the P-1A. Then I connected the I2S cable, switched to Resolution Enhancement, and no noise! Now I could explore the gear's capabilities.

I was still worried that, even without the I2S cable, I might have a system problem causing the ground loop. Nothing to worry about, according to Mark. Simply lift the ground when using the I2S; otherwise leave the system AC alone. The ground loop with the I2S does not mean there's a systemic problem.

Initial Impressions

I wired up the PT gear with all Acoustic Zen cabling, including two lengths of the MC2 Silver coax digital, the Silver Reference analog and the Krakatoa power cord. With the P-1A in its Bypass mode, the sound was smooth, with no glare whatsoever so smooth that it sounded as if I was using a top-notch AC conditioner. In Resolution Enhancement mode it was even smoother, too much in fact. There was no question that Resolution Enhancement was smoothing edges and blunting transients, with a concomitant loss of information. It was also rolling off the treble. The sound was homogenized. The Bypass mode had more edge, more powerful transients, less smoothing effect. Note: I tried the PT gear in another system without any AC conditioning and found the same results.

Then I tried using the P-3A by itself as a DAC. This sounded good not as smooth and relaxed as with the P-1A in place, but on the other hand, without objectionable digital artifacts. In fact, the PT gear never sounded objectionably digital in any of the setup variations I tried.

The Two Faces of Pt Meet The Other Face

Still waiting for the Monolithic P3 to arrive, I decided to see what would happen using my full AC conditioning package on the PT. I employed an extravagant combination of the Accuphase PS-500 sine wave shaper in series with the Legend Audio Live Performance. All components are then connected to the Legend. WOW! I was stunned a night-and-day difference! Then I installed a Kimber Kable Illuminati Orchid digital interconnect. KABOOM! The Illuminati and the AC conditioning made all the difference in the world.

The improvement was vast. The objectionable smoothness was gone. The Resolution Enhancement mode presented a wealth of detail. The sound grew bigger, more vivid, more impressive. Tonal balance, timbre, and overtone information were spot-on. The bottom had more fullness and extension. The mids were fleshed out and the treble quite extended, without glare or harshness. There was no grain to speak of. Violins sounded more like themselves. (I find this impossible to describe; they simply sounded more real.) The PT's presentation had now transformed. It was a close second to my analog source.

In a face-off of Waltz for Debby by the Bill Evans Trio between an Original Jazz Classics CD (OJCCD-210-2) and a Riverside LP reissue (RLP 9399), the winner was too close to call. The CD's bass response went lower and was tighter, with better articulation and definition. Then there's that wonderful ability to handle crescendos without breakup, cleanly and distortion free, with effortless dynamic expansion beyond that of my analog rig. On a larger percentage of recordings the soundstage exhibited terrific width, depth, and image separation. The presentation was larger and more vivid. I was reminded of the intense saturation of Technicolor movies. Yet compared with analog, the CD's bass lacked the treble overtone component, and therefore sounded dull and artificial. Most recordings seemed too closely miked too up-front for my taste, perhaps the result of cable effects. At the same time the overall sound erred slightly on the soft and relaxed side, with transients remaining a little dull. Nevertheless, the experience went way beyond my expectations. Analog was getting a run for its money. We were in a place where a change of power cord could make or break a comparison.

Scaling the Heights

When I did AB comparisons of the Duke Ellington Blues In Orbit on Mobile Fidelity CD (UDCD757) to the Classic Records 45 RPM re-issue LP (CS8241-45) of the same recording, the differences between the two mediums were more apparent, and swung further in favor of the analog. Had I listened only to the CD, it would have been completely satisfying, but by comparison with the 45 RPM LP, the CD was reduced to a two-dimensional facsimile. One must keep in mind that normal listening involves average quality LPs and CDs, and that the 45 RPM recording is well above average. I'm not the kind of audiophile who plays the same 30 perfect LPs over and over.

Additional Recordings Used for This Review

Classical
The defunct FI magazine Deutsche Grammophon sampler
The Originals, (DG 457 098-2):

Corelli Concerti Grossi Op. 6 numbers 7 12, Philharmonia Baroque Orchestra, led by Nicholas McGegan, Harmonia Mundi (HMU 907015), Peter McGrath engineer. This performance rates five stars, while the sound gets about four stars. I did notice a constancy or "sameness" to the decay that sounded artificial. Indeed, this is a studio recording and any reverb that's present, I bet, is a post-production addition. The Acoustic Zen cables accentuated this decay, while the Legend lessened it.

Jazz
The FI magazine Analogue Productions sampler, especially track 14, the Bill Evans Trio doing "My Foolish Heart".

Portraits in Ivory and Brass CD, Mapleshade (02032)

Tweaks and Fine Tuning

I used a Shakti Stone over the SONY transport, with PolyCrystal Ref ISO 3 Footers under it. The Audience Power Chord on the P-1A (prior to getting the Monolithic P3) sounded good. It added body and fullness. Later, I tried a new Legend power cord and enjoyed its analog-like warmth. The Legend cord has a quality that I would describe as "coherency." The frequency spectrum is presented in equal proportion and arrives time-aligned at the listening position.

Kimber Kable's Illuminati Orchid digital interconnect sounded superb. A Harmonic Tech Silver balanced cable saw play time, and the Legend Digital Reference interconnect replaced a length of Acoustic Zen MC2. The Legend cable has less treble bloom than either the Kimber or HT, but was more coherent and analog-like, just like the Legend power cord. Top picks for the digital cable would be a toss-up between the Illuminati and the Legend cables.

Perpetual Technologies' Setup Recommendations

Jon Lane of PT recommends these two scenarios, depending on the digital cable used to connect the P-1A to the P-3A:

  1. For I2S connection: set the P-1A to 24/96. Use the I2S cable and engage I2S Direct mode in the P-3A. This will eliminate redundant upsampling in the P-3A input receiver.

  2. For other cable types: defeat the upsampling in the P-1A and let it happen in the P-3A. Use these switch settings on the P-1A: Select Resolution Enhancement, 44.1 sample rate, and 24-bit output. The P-3A will see a 24-bit, 44.1 sample rate, and will upsample to 96k. Since this is just prior to D/A conversion, it will theoretically have less jitter, and should sound better. Scenario # 2 worked best for my cable arrangement, and I used it for the bulk of my listening.

Additional Tech Points

Resolution Enhancement constructs the 24-bit words. The P-1A does this by interpolation, converting 16 bit words to 24-bit words using preprogrammed algorithms. Bypassing Resolution Enhancement, the P-3A will use 16-bit words to convert to analog.

Each input cable type has to have the sample rate selected individually. If you programmed 96 when using a coax cable, you will have to re-program if you switch to AES/EBU. Go through the settings once for each cable type. The unit as shipped is set for I2S usage.

Don't connect more than one input to the P-3A at a time. Avoid connecting both the I2S and a different cable type in order to do A-B testing, because this has the potential to cause ground loops.

Conclusion

The P-1A/P-3A combo has multiple personalities. When used without the Monolithic P3 or the benefit of decent AC power line conditioning, I think you can do better elsewhere. However, when external power conditioning is employed, another, the units reveal another, more exciting personality. It is only in tandem with excellent AC conditioning that the PT combo can scale the sonic heights. I was shocked at how close the sound was to my analog rig, which retails for about five times the price. I had always assumed that analog would remain unassailable. You can gauge how good the fully accessorized PT combo is if I tell you that I've actually started to buy CDs now. I have not auditioned the competition, but I would think you'd be hard pressed to find a better value in this product class.

POSTSCRIPT: Arrival of the Monolithic P3

The stock power supplies are made to a price point. Hence, the optional Monolithic Power Supply represents an obvious upgrade. It has a female IEC connector to accept an external AC power cord, and 12 VAC and 9 VAC output jacks for connection to the P-1A and P-3A, respectively. However, the supplied voltage-carrying wires appear to be the same mid-fi quality as the ones supplied with the stock wall-wart power supplies. The good news is that the Monolithic P3 Power Supply is indeed an improvement. Connected into the Ensemble AC distributor, it presented a layered soundstage, pure and clean. I could have stopped at this point and been happy. Using the P3, it was only by comparison that some degree of smoothing was apparent without AC conditioning, yet further refinements appeared all areas when I added the Legend Live Performance. In my view, using the Monolithic P3 in conjunction with my other AC conditioners puts the PT into a rarified realm.

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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