Persephone is the version of the Reference Tube DAC built on the Philips TDA1541, the 16-bit stereo chip most associated with non-oversampling converters. Dmitriy Gubchenko voices it as fast and articulate.
The Philips TDA1541
Philips introduced the TDA1541 in the mid-1980s as the 16-bit stereo successor to the 14-bit TDA1540 of its first CD players; the TDA1541A followed later in the decade. It is a multibit converter: each sample is resolved in one step from binary-weighted current sources, one per bit. To keep those currents accurate the chip uses dynamic element matching, which continuously swaps the most significant current sources so that their small errors average out.
One chip carries both channels, and like every chip of the five it delivers a current rather than a voltage. Converting that current to a voltage and driving the cable is the job of the output stage.
Grades and old stock
Selected grades of the TDA1541A, marked S1 and S2 and known as the single-crown and double-crown parts, were sorted for better linearity. The chip has long been out of production, so every TDA1541 in a converter today is old stock. Remarked chips circulate, and each part is checked before it is fitted.
Why non-oversampling
In Persephone the TDA1541 converts each 16-bit / 44.1 kHz sample as it arrives over coaxial S/PDIF, with no digital interpolation filter and no upsampling. The impulse response shows no pre-ringing, and the path from data to output stays short.
The cost is known: a gentle treble roll-off of about 3 dB at 20 kHz, and image frequencies above 22.05 kHz that the output stage has to pass cleanly. The stock output stage is solid-state; a tube stage on 6Zh4, EF14, EL8, AL4 or ML6 with a 5Ts4M rectifier is optional. Our guide to NOS multibit DACs sets out the trade-off in full.
Persephone among the five
Listeners commonly describe the TDA1541 as fluid and full-toned, with strong dynamics, and Persephone is the fast, articulate voice of the five. Calliope on the earlier TDA1540 is natural and organic; Artemis on the Burr-Brown PCM63 is large-scale and weighty. All five versions share the same chassis, input, output options and price, and each unit ships with its own measurement report.