Introduction

I met Dusty Vawter, the designer of the VDA-1 DAC and VAC-1 high current power supply, during a visit to Las Vegas' Consumer Electronics Show, around 1993. At the time he was working for Audio Alchemy. Dusty's interest in audio began at age 14 when he started to build speakers and speaker cabinets. Shortly thereafter, he went to work at a car stereo shop as a technician, repairing car stereos. He was hired by Audio Alchemy to manage the service department. While working at Audio Alchemy, he acquired some techniques of audio design working with Peter Madnick. After leaving Audio Alchemy in November of 1996, he established Channel Islands Audio, supporting and modifying Audio Alchemy products. At the same time, he worked with Monolithic Sound as an independent contractor co-designing preamps, power amps, phono stages and power supplies with Greg Schug. His recent efforts include a passive preamp, DAC, power supply, phono stage and 50 watt mono block IC amps. His solid state product line is reasonably priced. Starting at USD$249 for the preamp, the amplifiers are the most expensive component at USD$899 per pair.

The DAC, the VDA-1 (USD$349), is capable of processing up to 24 bits at 96 KHZ with locking frequencies at 44.1, 48, 88.2 and 96 KHZ. It was designed with a simple signal path, about 6 inches from input to output, consistent with the designer's philosophy of minimal coloration -- a window on the music. Its output impedance is 100 ohms. The input receiver is a Burr Brown DIR 1701, a low jitter receiver--<50 ps. The signal is then passed to a Burr Brown PCM 1716 DAC and then to a class A biased dual op amp at the analog stage, a Burr Brown 2134. The DAC has as its standard power supply a 14 volt AC wall transformer. An upgrade, the VAC-1, a high current power supply is available at $159. The VAC-1 features a transformer with 2.5 times the current capability of the stock transformer, an IEC socket, some AC filtering, selectable voltage -- 115 or 230 volts and ferrite beads on the output, i.e., input to the DAC. Essentially, this upgrade is a higher current, higher grade, low impedance, and quieter version of the stock unit.

The Sound

The following performance attributes were noted using the VAC-1:

1) Cable sensitivity, with one exception, described below

2) Grain free sound

3) Realistic depth and layering

4) Resolution without being analytical

5) Tonality slightly lean of neutral

The DAC has a low output impedance. When combined with a low input impedance pre amp, the effect of high capacitance analog interconnect cable is greatly reduced. Although a tube preamp was used, a comparison between a one meter and 6 meter pair of Alpha Core TQ2 cable revealed a barely noticeable difference. In other cases, the sound of the stereo system changed as the interconnect and digital cables varied. A somewhat lean tonal balance was occasionally present. However, this tendency was not always objectionable and could be offset by prudent selection of interconnect and digital cable. In contrast, there are components whose sonic personality is so pervasive that the coloration is noticeable regardless of what cable is used.

The DAC's ability to resolve detail and present foreground/background information in a credible manner can be experienced when auditioning the JVC-XRCD version of Offenbach's Gaite Parisienne. After 50 seconds of track one have elapsed, a triangle and wood block can be heard. Both instruments are clearly delineated. The sense of space separating them is obvious. One need not be an expert listener to perceive this phenomenon. The recording creates the illusion that one instrument is located a row or two behind the other and the DAC gets out of the way allowing the listener to observe what the recording has depicted. On several occasions, I was aware of a slight over emphasis of the upper midrange and lower treble, in part because of the presence of ribbon tweeters operating at 5 KHZ and above. They were used to compensate for the Quad's attenuated treble response. Using my tubed CD player as the digital source reduced the incidence of brightness.

This DAC could 'frequency challenge' some stereo systems, especially those having peaks within the above mentioned regions. Although this effect may be alleviated by judicious cable selection, I would suggest that some solid state systems and this DAC may not be synergistic.

Several CDs were used to test the tonality of the DAC. The first was a NAXOS recording of Wilhelm van Wassenaer's Concerti Armonici. These concerti grossi feature strings, harpsichord and organ. At times the sound of the strings was somewhat steely. The second recording was the FIM hybrid SACD Jazz at the Pawn Shop. Listening to track one, disk two, Lady be Good, one observes a cymbal in the background. A slight change in sound was detected, creating a less-than brass-like decay -- a small departure from timbral accuracy. Finally, the third CD, Bob James/Earl Klugh Two of a Kind features Earl Klugh playing acoustic guitar. Here again the guitar strings took on a slightly steely quality. Although the essential nature of the composition of the guitar strings, nylon, was still recognizable, the pitch seemed somewhat elevated.

Unless one is overly critical and analytical, the aforementioned instances of 'sharpness' of pitch need not interfere with the enjoyment of the music. The severity of the 'problem' will depend upon the stereo system, i.e., the nature and degree of its coloration, and the source(s). In my own system of tube electronics, I was able to significantly reduce the effect of brightness by experimenting with cable and line cords.

The preceding remarks apply to the interface of the DAC with the high current power supply.

With the standard 14 volt transformer in place there was a noticeable 'softening' of the sound. Extremes were attenuated, bass was less controlled, and there was a slight veiling and loss of resolution. In contrast, with the VAC-1, the 'sound' was more open, more focused and more resolved.

The two power supplies were compared using 3 CDs. Consider the JVC-XRCD recording of Gaite Parisienne. Drum thwacks were more controlled, the pitch of the triangle was slightly higher, the snare drum was more defined and there was greater perceived separation between the triangle and woodblock when the VAC-1 was used instead of the stock unit. The Telarc recording of Baroque Favorites, featuring the Jacques Loussier Trio was the second CD in the group. With the 14 volt transformer, the acoustic bass sounded somewhat vague and unfocused. The cymbal was slightly obscured and not precisely separated from the snare drum, whereas with the high current power supply, the bass was more articulated and the instruments were more defined and separated from each other. Finally, the FIM version of Jazz at the Pawnshop, disk 2, track one served as the third and last CD in the group. With the 14 volt AC transformer, the cymbal was lower in pitch, the acoustic bass was less extended and the ring of the telephone was less distinct, relative to the VAC-1, which provided more detail and frequency extension.

While there exists a qualitative difference between the two power supplies, the magnitude of that difference and the cost/benefit of each can only be ascertained from an audition in one's own stereo system.

In summary, The VAC-1 is probably a more accurate device than the stock power supply. The advantage of one over the other may depend upon the quality of the recording. One might prefer the VAC-1 with better recordings and the stock unit with poorer quality recordings.

Conclusion

The VDA-1 DAC and VAC-1 power supply (upgrade) (USD$508, retail) may be a cost effective way to achieve a highly resolved, grain free and dimensional presentation. However, there is a possibility that one may experience some extra energy in the upper midrange and lower treble. Associated equipment (see below) can either be a palliative or exacerbate this tendency. In addition, one's preference for or against a 'crisp' sound will also determine whether such a condition is a 'vice' or a 'virtue'