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Parts Connection Assemblage DAC-1 D/A converter kit

"Dinner's fried chicken, honey."

"And I hay-ulped!"

Gap-toothed and demented-looking, the Shake'n'Bake urchin comes to mind every time I regard the Assemblage DAC-1—which I built. Like that insanely happy child-actor, my true participation was rather limited: the DAC-1 comes with a fully assembled circuit board, requiring only that the AC filter, three LEDs, three RCA jacks, and the feet be attached. Oh yeah, you also have to screw the top down and plug it in. Which brings us to a couple of key questions: Why a kit? and Why so basic a kit?

Kits may seem exotic to…

Parts Connection Assemblage DAC-1 D/A converter kit Page 2

While I definitely consider the DAC-1 to be a fine D/A, it's not going to siphon off a lot of sales from its $1000-and-up competitors. Truthfully, it emphasizes midband warmth and has a few tonal irregularities: it "whitens" high-amplitude pitches, causing the coloration to wander. I wasn't particularly bothered by this, since so much of the information that I value passed through comprehensibly and coherently. In its strengths, it offers competition to all comers; but I must also say that such units as the McCormack, MicroMega, and Arcam DACs all added unwavering focus, more uniform tonal…

Parts Connection Assemblage DAC-1 D/A converter kit Hearing Aids

Sidebar 1: Hearing Aids

Metaphor 5 loudspeakers, the Valve Amplification Company's PA 80/80 power amp, and the McCormack Micro Line Drive or Audio Alchemy's DLC preamps were used for all evaluations. I compared the DAC-1 to Krell's Reference 64, McCormack's DAC, Micromega's DAC, Arcam's Black Box 50, and Audio Alchemy's DAC in the Box (DITB) and DDE v1.1 D/A converters, as well as to the internal DACs in the Audio Research CD-1, Arcam Alpha One, NAD 504, and MicroMega Stage 2—using the transport sections of those units to make the comparisons.

A McCormack Digital Drive supported…

Parts Connection Assemblage DAC-1 D/A converter kit Measurements

Sidebar 2: Measurements

The Assemblage DAC-1's maximum output level was 1.96V—just under the CD standard of 2V. Output impedance was a low 77 ohms at any audio frequency, and I wasn't able to measure any DC offset at the analog output jacks. The DAC-1 doesn't invert absolute polarity, and had no trouble locking to 32kHz and 48kHz datastreams.

Fig.1 shows the DAC-1's frequency response and de-emphasis error. The response is down 0.35dB at 20kHz—a slightly greater rolloff than the 0.25dB specified in the data sheet. The de-emphasis error was negligible, and about as good as you can…

Parts Connection Assemblage DAC-1 D/A converter kit Specifications

Sidebar 3: Specifications

Description: Digital/analog converter kit. Digital inputs: coaxial on RCA jack, optical on TosLink jack. Analog output: one stereo unbalanced output on RCA jacks. Maximum output voltage: 1.969V. Frequency response: DC–20kHz, +0dB, –0.25dB. S/N ratio: 105dB unweighted. Crosstalk: <100dB, 20Hz–20kHz. THD+noise: <0.01%.
Dimensions: 9.5" W by 2" H by 7" D. Weight: 4.5 lbs.
Serial numbers of units reviewed: 9437L0011, 94390064.
Price: $449 (1995); no longer available (2009). Approximate number of dealers: factory-direct only. Warranty: 2 years parts and…

Cut and Thrust: RIAA LP Equalization

Until the Recording Industry Association of America hit the headlines in recent years with its antipiracy campaign, the initials RIAA meant one thing to seasoned audiophiles: the vinyl-disc equalization characteristic introduced in the 1950s to standardize what had previously been an anarchy of different EQs. Three decades later, as CD gained ascendance, a large proportion of audiophiles still knew what RIAA equalization was, and a good number of them had some idea or better of what the RIAA EQ curve looked like, and why it was applied.

But that was a generation ago. In the interim…

Cut and Thrust: RIAA LP Equalization Page 2

In the summer 1978 issue of Stereo, technical editor Edward J. Foster wrote of the IEC revision: "What point is there in paying literally thousands of dollars for a stereo system capable of response to below 40Hz and then blowing it all on a sloppy subsonic filter?...The record-warp problem will not be solved by changes in equalization. It will be solved by changes in manufacturing technique and in improved quality control. Flat records can be made; it just takes a bit longer and costs a bit more." While in the "News and Views" section of High Fidelity, under the title "Phono Equalization:…

Cut and Thrust: RIAA LP Equalization Page 3

This is only the first of a host of objections that can be raised against incorporating the "Neumann correction" in RIAA replay circuits. A second, already raised in these pages by John Atkinson (footnote 12), is that ultrasonic frequencies from record clicks will be less effectively suppressed. But the most telling criticism of the "Neumann correction," as described, is that its core assumption is wrong. The claim of a 3.18µs pole being added to the record EQ of Neumann cutters is inaccurate. Moreover, a detailed investigation of record cutting and replay shows the entire situation to be…

Cut and Thrust: RIAA LP Equalization The Neumann 4th pole (sic)

Sidebar: The Neumann 4th pole (sic)

Using the phrase "4th pole" to describe the addition of a further time constant to curtail the RIAA record EQ at ultrasonic frequencies is a misnomer. Talk of poles takes us into what will be unfamiliar territory for many Stereophile readers, so a brief—and necessarily simplified—explanation is given here.

Filter circuits are described by a mathematical equation called a transfer function, which in general form is a ratio of two polynomials (ie, power series) in a variable denoted s (s=jw, where w is angular frequency (2PIf) and j is the square…

Threshold T2 preamplifier

Threshold is one of the longest-surviving high-end audio companies. Founded in the 1970s by Nelson Pass and René Besne, it was acquired by a large, publicly traded corporation in 1988. This had both positive and negative results in that Threshold was then able to expand its activities, adding the cost-effective Forté line of products, but energies were drained away from cutting-edge design. Besne left the company in 1991, while Pass resigned in 1992 to pursue other interests. (These blossomed into the Pass Aleph 0 amplifier reviewed by DO in March '95, Vol.18 No.3.)

Threshold's…