Analog



The phono cartridge is the dingus at the end of the tonearm on a turntable--including the diamond stylus that rides in the grooves of the LP, and magnets and wire coils that convert vibrations into voltage changes. The most careful attention to detail is required in everyaspect of cartridge manufacture, to enable it to accurately resolve the infinitesimal vibrations associated with low-level detail in sound recordings. I have been absolutely delighted with the Lyra Helikon phono cartridge. Its sound is very natural, and it produces only a tiny fraction of the tracking distortion produced by other very good cartridges like the Grado Sonata and Sumiko Blue Point Special that I had used previously.

The voltages produced by phono cartridges are smaller than any others in the signal path of audio equipment, and so a high-quality tonearm cable is needed to minimize signal degradation on the way to the preamplifier. I use an Audioquest LeoPard tonearm cable.

The tonearm is the counterweighted tube that the phono cartridge is attached to. A high-quality tonearm is needed to enable the stylus to rest comfortably in the groove as the LP spins on the platter, even when the record is not entirely flat. The slightest tendency to stray out of the groove reduces the fidelity with which the stylus responds to variations in the groove wall. The tonearm must also not resonate in sympathy with particular frequencies of vibrations produced by the phono cartridge riding in the grooves, or distortions will be produced. I use a Linn Ittok tonearm, which was state-of-the-art when it was made over 20 years ago, but could stand to be upgraded if I had an extra few thousand dollars.

The turntable contains the physical mechanism that enables the LP to rotate, including the motor and platter; as well as the electronics that ensure that rotation is maintained at a constant speed regardless of the counterforces resulting from the drag of the cartridge in the grooves. I use a Linn LP12 turntable with a Linn Lingo power supply, which synthesizes a pure AC signal to drive the motor at a constant speed even when there is noise and variation in the AC power coming from the wall socket.

The phono stage and preamplifier process the voltages coming from the phono cartridge, to produce an output signal that can be read by the A/D converter. High-quality electronics and design are needed to minimize any alterations to the input signal that might degrade the sound. I use a PS Audio PCA-2 preamplifier with inboard phono stage and outboard power supply. The PCA-2 has recently been superceded by a new line of PS Audio amplifiers using a revolutionary gain cell technology that you can read about on their website. Still, I have been very happy with the sound of the PCA-2.

The A/D converter turns a fluctuating analog voltage signal into a bit stream that represents the instantaneous voltages in that signal at regular time intervals. CD-quality digitization samples the analog signal 44,100 times per second and uses 16 bits of data to quantify each sample. For audio purposes, this is only enough to produce a decent approximation of the signal, which is why the newer DVD audio technology samples at 96,000 times per second and uses 24 bits of data to quantify each sample. To faithfully reproduce the signal, an A/D converter must have an accurate clock to time the samples at regular intervals (measured in tens of microseconds), and it must measure the voltage accurately at each time point. I use an M-Audio Audiophile USB A/D converter, which is by no means the best available, but produces remarkably good results at a very reasonable price. It is capable of 24-bit quantization, but I use only 16 bits for the Avant Garde Project to make the files compatible with CD players.

The interconnect cable between the preamplifier and A/D converter is important for the same reason a high-quality tonearm cable is important, but without quite the same stringencies as the voltages involved are higher. I use Kimber PBJ interconnects, which are by no means the best available, but like the Audiophile USB provide excellent results for the money.

Audio electronics use AC power to process voltage signals that drive speakers to produce sound vibrations. The electronic processing that occurs is only as good as the AC power that makes up the raw material. Noisy, variable AC power will produce corresponding distortions of the voltage signal. To minimize this, I use a PS Audio P300 Power Plant, which uses AC power from the wall to synthesize pure 117V, 60Hz AC power that drives the PCA-2 power supply, the Lingo power supply, and the A/D converter. The Power Plant is in turn plugged into a PS Audio Ultimate Outlet, which eliminates much of the noise in the AC power that feeds it. To deliver AC power to the PCA-2 power supply and P300, I use PS Audio xStream Power Cords.

Keeping both LPs and stylus clean prevents any microscopic films or grit from interfering with the reading of the grooves. Even a seemingly pristine LP may sound a bit fuzzy before cleaning, while cleaning exposes the finer details in the sound. Before transcribing any LPs for the Avant Garde Project, I clean them using two different cleaning solutions and a Record Doctor II cleaning machine, which vacuums the cleaning fluid out of the grooves, thus enabling the LP to be played right away. I use Record Research Lab LP stylus cleaner after every few sides of play. Occasionally, I deep-clean the stylus using a Signet SK305 ultrasonic stylus cleaner.

Electronic devices become very slightly magnetized over time by the changing electrical fields that pass through them. For most devices, the magnetization is far too little to affect performance. But sound reproduction can be affected even by slight changes in the propagation of voltages through the circuitry. Moving coil cartridges like the Lyra Helikon are particularly susceptible to magnetization of the coil by the magnets that surround them. Periodically, I demagnetize my phono cartridge and electronics using the Cardas Sweep Record, which reproduces a sine wave signal that ascends gradually from low frequencies to above 20,000 Hz.

To minimize sinusoidal depleneration throughout my house, I have installed a Rockwell Automation turbo-encabulator in line with the power feed coming in from the street.

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