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Our hero found that the original store wasn't big enough to suit him. He needed six showrooms at least. The smaller, less intimidating systems would be situated near the front door---Rotel, Nakamichi, Luxman, Paradigm; in the middle, a McIntosh room; across the hall, Celestion, Superphon, B&K, Well-Tempered. Each room would be more exotic than the last. One could move from McIntosh to ARC to Rowland to Krell to FM Acoustics. Venturing deeper into the store would take one to higher and more rarefied levels of experience and expense, a retailing ploy akin to that used by adult boutiques…
He sometimes ranted shamelessly for 20 or 30 minutes, often in full view of customers, while his employees stood around staring at the floor. Creditors called to inquire about late payments. Krebs would placate them with promises he probably never intended to keep, then march into the service shop to express his rage. A technician might be elbow-deep in surgery on a large power amp, only to be jolted by the spectacle of a flailing maniac in the middle of the floor. "You guys are a bunch of incompetents! Morons! I'm going to clean house and rid myself of all of you!" This sort of thing became…
It was a wild roller-coaster ride. When a salesman made an especially lucrative deal, or a final payment came in from a big custom installation, Krebs would dance for joy, like the day James "Domino" Jefferson, star forward for the Xanadu Meteors, came in and paid cash for a home-theater system. Krebs was certain that all of Domino's teammates would follow suit. He made partial payments to all parties threatening legal action. He paid some of his back rent. He got chummy with his employees, forgetting for a moment their "incompetence and working-class values." He even offered to take them to…
Letters in response appeared in Vol.14 No.10, October 1991
A critical look at July
Editor:
"Pavane Pour un Dealer Défunt" was clearly the high point of the July issue. What an amazing piece of "fiction." The story could apply to practically any business, not just audio. I have seen several "high-tech" companies follow a similar path, almost to the letter.
---Fred E. DavisHamden, CT
Xanadu revisited
Editor:
Yes, Barry Willis's piece "Pavane Pour Un Dealer Défunt" in the July issue was an entertaining read. Fiction? An imaginative account of the results of…
No High End in Xanadu?
Editor:
I live in Xanadu, and Barry Willis was almost right on the money about his "mythical" high-end stereo emporium. Even in its first incarnation that establishment had two types of customers: Those who bought at no other place and those who wouldn't buy dogfood from them. The word is arrogance. Xanadu is a nouveau riche city that, to a great extent, has been affected by Circuit City---I can get it cheaper somewhere else. In the present economic situation even Xanadu is suffering---something the economic pundits of the area haven't seen in the previous…
Editor:
I live in Xanadu, and Barry Willis was almost right on the money about his "mythical" high-end stereo emporium. Even in its first incarnation that establishment had two types of customers: Those who bought at no other place and those who wouldn't buy dogfood from them. The word is arrogance. Xanadu is a nouveau riche city that, to a great extent, has been affected by Circuit City---I can get it cheaper somewhere else. In the present economic situation even Xanadu is suffering---something the economic pundits of the area haven't seen in the previous…
High-quality digital audio systems require that all digital interfaces in the signal path exhibit signal transparency. The widely adopted AES/EBU and S/PDIF interfaces have been criticized for a lack of signal transparency; here we (footnote 1) address possible problems with such interfaces and present methods for improving the interface standard.
In a correctly functioning (uniformly quantized and sampled) digital audio system, the only observable signal impairments should be attributable to band-limitation and an additive noise residue. Thus, although digital audio's subjective sound…
We now proceed to model a bandwidth-limited link by filtering the subframe signal with a first-order (RC) low-pass filter, and determine what degree of filtering will result in bit errors. Using the first-order filter model is a gross simplification of the time-domain behavior of a real link—accurate analysis requires the use of transmission-line theory at the high frequencies involved—but it's a good starting point for investigation.
Consider the top section of fig.5, which shows a simulation of the subframe signal carrying an audio word value of 255 and filtered using a time constant of…
In order to reduce the jitter sampling rate to a useful value, we take advantage of the following argument: In a practical interface receiver circuit the PLL will usually employ a loop filter with a break frequency of <20kHz. If we assume that the audio sampling rate is much greater than the PLL loop frequency, then the zero-crossing time to jitter-mapping operation can be performed by computing a running average of the zero-crossing times across two subframes. Thus, the jitter value associated with a pair of adjacent subframes can be written:
Equation 8:
where M is…
Comparison of Measured Results with Simulations: Using the techniques discussed above, we will now compare the results of simulations with measured results from the experimental interface receiver of fig.4. This circuit allows the instantaneous frequency of the recovered clock to be measured by monitoring the control voltage on the varicap diode. In order to recover the jitter signal on the clock, we must convert the instantaneous frequency signal to a timing error. Consider a frequency deviation Δf in a recovered clock of nominal frequency fo; over a time period dt, the timing error tj can…
Interface Noise: Besides increasing the (low) possibility of amplitude errors, interface noise can also be the cause of timing jitter in a band-limited interface. Consider a link with a time constant of RC, where, at the zero-crossing points, the rate of change of the received interface signal will be equal to Vd/RC (where Vd is the transmitter driving voltage). Thus, peak interface noise of vn results in a jitter noise of peak amplitude given by:
Equation 15:
Hence, a peak interface noise 20dB below the driving voltage and a time constant of 100ns will result in 10ns…