Perpetual Technologies P-1A D/D & P-3A D/A processors Followup

Robert Deutsch wrote a Followup on the ModWright P-3A modification in October 2001 (Vol.24 No.10):

Perpetual Technologies' P-3A digital processor offers astonishingly good performance, surpassing some highly regarded products that cost significantly more than its $799 price. (See my review in the January 2001 issue.) However, the fact that the P-3A is built to sell at a relatively modest price means that component quality cannot be the best. With this sort of product, the question that occurs to audiophiles who are into DIY (Do It Yourself) is whether the sound of the unit could be improved by substituting better parts.

ModWright's Dan Wright, by training a mechanical engineer, is an audiophile of the DIY persuasion, and he set about the task of improving the P-3A's sound simply by substituting parts of the highest quality in its analog stage and power supply. His efforts were so successful that he began to offer the P-3A modification service, and pretty soon the word on the Internet was that if you wanted to improve the sound of your P-3A and you already had the Monolithic Sound P3 upgraded power supply, the ModWright's mod was the way to go. The final measure of his success was when Perpetual Technologies itself endorsed Wright's mod, acknowledging it as a worthwhile upgrade and extending their factory warranty to apply to modified units.

The modifications in what is now called the P-3A Signature are quite conservative, in that they involve only parts substitutions, with no changes in circuitry or component values (footnote 1). The mods are in six areas:
• power-supply rectifier diodes replaced with ultrafast soft-recovery diodes (Harris FREDs), lowering switching noise
• surface-mount digital input resistor replaced with a 1% metal-film Caddock resistor
• analog filter-stage capacitors upgraded
• four Burr-Brown OPA-134 op-amps ($1.50 each) replaced with Burr-Brown OPA-627s ($14 each)
• coupling capacitors upgraded
• analog signal-path resistors upgraded to Caddock and Vishay 1% metal-film types

The Signature mod is available for $300 plus return shipping and insurance; alternatively, you can buy a P-3A Signature from Wright for $1099. As I wanted to do a direct comparison, I asked him to send me a P-3A Signature to compare with the stock unit I had on hand.

Substituting the P-3A Signature for the stock unit, the first thing I noticed was a drop in background noise, which resulted in music emerging from the background with greater clarity. The treble became more open, detailed, and airy, with no added edge or hardness. There was also an enhancement of dynamics. On its own, without direct comparison with the Signature, the P-3A actually sounds very good, but once I heard the Signature I had trouble going back to the stock unit. These differences were apparent when the P-3A was used by itself or in combination with the Perpetual Technologies P-1A digital upsampler/interpolator (my preferred configuration), but were more apparent when using just the P-3A.

In either case, Dan Wright's Signature mod is well worth the extra $300. It represents outstanding value, whether considered from the parts/labor cost or the sonic improvements gained. Highly recommended.—Robert Deutsch

Footnote 1: Dan Wright has now made available another level of modification, this involving a minor circuit change and an upgrade of the digital coupling capacitors. This mod adds $100 to the $300 cost of the Signature mod. Wright is also working on mods for Sony SACD players, and can be reached at (971) 207-0912.—Robert Deutsch

Perpetual Technologies
368 S. McCasling Blvd. #189
Louisville, CO 80027
(303) 543-7200