Equalization
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Each Monolith has external strapping which makes bi-amping (and bypassing of the internal crossover components) relatively simple. I used an M&K 100Hz passive crossover to feed the BEL for the high end and the Eagle at the bottom. There ws some improvement in quality across the board, but not as much of an improvement through the lower midrange and upper bass as I had hoped for. The low end remained rather ill-defined and still had what I felt to be entirely too much high end, but biamping produced the best sound up to that point in my testing.
Sidebar 1: The Full-Range Electrostatic: Pros & Cons
The main inherent advantage of the fullrange electrostatic speaker system is that it allows a single diaphragm to embody the conflicting attributes needed for optimal performance at both extremes of the audio range. Its thin-membrane diaphragm can be made exceedingly light, for superb transient response and extended HF response, yet it can be about as large in area as desired, for extended LF response. And since that diaphragm is driven uniformly over its entire surface, instead of from a relatively small voice-coil, it circumvents…
Sidebar 2: Specifications
Description: Two-way electrostatic/dynamic loudspeaker. Drive-units: curved electrostatic panel, 12" cone woofer. Crossover frequency: 100Hz. Frequency range: 28Hz–22kHz. Nominal impedance: 8 ohms. Sensitivity: 90dB/W/m.
Dimensions: 74" H by 27" W by 12" D. Weight: 160 lbs per speaker.
Price: $4850/pair (1985); no longer available (2005).
Manufacturer: MartinLogan, 2101 Delaware Street, Lawrence, KS 66046. Tel: (785) 749-0133. Fax: (785) 749-5320. Web: www.martinlogan.com.
Time to 'fess up: How many of you actually read the "Measurements" sections of Stereophile's equipment reports and understand what's being measured, and why? I suspect that many readers skip over the technical assessment of the reviewed product and make a dash for the "Conclusion."
This is unfortunate, as there is lots of useful information under the "Measurements" heading that has real-world implications for the purchaser of that component. However, without an understanding of measurements and the significance of the results, the graphs and measurement text can become a confusing mess…
The standard CD-player output voltage is 2V RMS, with units varying between 1.74V on the low side (the Audio Research DAC1) and a whopping 7.2V on the high side (the Theta DS Pro Basic). Most CD players and processors put out between 2.2V and 3.5V. Note that this value is the highest RMS output voltage possible from the player—there's no digital signal greater in amplitude than 0dBFS (see the "Decibels" sidebar).
Bottom line: High-output processors are not an ideal match for high-gain preamps. On the other hand, a high output level is a bonus when used with a passive level control…
Squarewaves (by JA)
A processor's reproduction of a 1kHz, full-scale squarewave can be either boring or exciting. Because the CD system is limited to a maximum bandwidth of half the sampling rate—22kHz—it can't actually reproduce squarewaves. A squarewave can be shown by Fourier analysis to comprise a series of odd-order harmonics regularly dropping in amplitude with increasing frequency. For perfect reproduction of a 1kHz squarewave, therefore, we would need to be able to reproduce the 1kHz, 3kHz, 5kHz, 7kHz, etc., components, all the way to infinitely high frequency. However, as the CD…
A processor's reproduction of a 1kHz, full-scale squarewave can be either boring or exciting. Because the CD system is limited to a maximum bandwidth of half the sampling rate—22kHz—it can't actually reproduce squarewaves. A squarewave can be shown by Fourier analysis to comprise a series of odd-order harmonics regularly dropping in amplitude with increasing frequency. For perfect reproduction of a 1kHz squarewave, therefore, we would need to be able to reproduce the 1kHz, 3kHz, 5kHz, 7kHz, etc., components, all the way to infinitely high frequency. However, as the CD…
Frequency response
Because the errors are much smaller, frequency response doesn't usually reveal clues about a processor's overall tonal balance, as it often does with loudspeakers. We include it anyway, in case anything unusual is going on in the unit under test. Most processors are down a few tenths of a decibel at 20kHz.
Because the errors are much smaller, frequency response doesn't usually reveal clues about a processor's overall tonal balance, as it often does with loudspeakers. We include it anyway, in case anything unusual is going on in the unit under test. Most processors are down a few tenths of a decibel at 20kHz.
More revealing, however, is a CD player's or processor's de-emphasis error. Some CDs have had the treble boosted (emphasized) during recording, and carry a flag in the datastream that tells the CD player to switch-in its de-emphasis circuit to restore flat…
The same type of spectral analysis, but with the processor driven by "digital silence" (all zeros), is also performed and plotted to 200kHz. This test can reveal the presence of spurious junk in or above the audioband, and of such DAC artifacts as self-generated tones (seen as a peak in the trace). Ideally, the trace should be a smooth line, with no peaks at the power-line frequencies and no audioband spikes. The effects of noise-shaping in 1-bit-type converters can also be seen in this measurement as a steep upward slope to the trace. Noise shaping is a resolution-enhancement technique that…
Low-level resolution
Related to linearity performance is how well a DAC can reproduce a very low-level signal. One way to examine a DAC's behavior on small signals is to capture its analog output waveform when reproducing a -90dB, undithered 1kHz sinewave. This test signal produces three quantization steps: 0, +1, and -1. The three levels should be of equal amplitude, and the signal should be symmetrical around the center horizontal division. Fig.8 shows the ideal waveshape (assuming an infinite bandwidth); a nearly perfect reproduction of this signal is shown in fig.9, which overlays…
Related to linearity performance is how well a DAC can reproduce a very low-level signal. One way to examine a DAC's behavior on small signals is to capture its analog output waveform when reproducing a -90dB, undithered 1kHz sinewave. This test signal produces three quantization steps: 0, +1, and -1. The three levels should be of equal amplitude, and the signal should be symmetrical around the center horizontal division. Fig.8 shows the ideal waveshape (assuming an infinite bandwidth); a nearly perfect reproduction of this signal is shown in fig.9, which overlays…
In a perfect processor, the five traces would overlap, indicating that there was no change in the noise level or spectral content as a function of signal level. All processors, however, exhibit some deviation between the traces. The tighter the traces, the better. Any time one trace crosses another, the noise floor's spectral balance has shifted. The amount of this shift can be calculated by looking at the deviation between traces, using the horizontal division scale on the graph's far left-hand side. Examples of good and bad noise-modulation performances are shown in figs.11 and 12,…