C-level executives' objections to Sarbanes-Oxley regulations ring hollow
It's been interesting to read the virulent responses to the Sarbanes-Oxley Act (see April 11, page 6, and April 4, page 33). You'll notice the complaints are coming mostly from CEOs, CFOs and other top executives.
Did any of these C-level managers complain about the onerous provisions of ISO 9000? Of course not. That's because the onus of ISO certification could easily be transferred to engineers and low-level management. All executive management had to do was proudly display the ISO certification plaques in their offices and tell their customers and the media how committed they were to doing a quality job.
But now comes something that requires the exertion of an ISO-like effort on the part of top-level executives. They have to certify that their financial statements have at least some basis in reality. They have to document their business processes. In other words, they have to show what they're doing to earn their high salaries, options and bonuses.
Makes you want to cry for them, doesn't it?
John Forster, Engineer, San Francisco
'Fawning' interview sparks a wish for Altman-B-Gone
I could not believe the fawning treatment you gave Mitch Altman in your interview in the March 28 issue (page 1). I think that your reporting [on Altman's TV-B-Gone] without raising obvious ethical objections was irresponsible, and your bringing up blocking cell phones was reprehensible. And this from a publication I've read and enjoyed for well over 20 years.
The next time you're annoyed by a TV in a public place, as I have been on occasion, try a simple, low-tech solution. Move to another area. Ask an employee if they can turn it down. Ignore it. If it's in a restaurant or bar, stop patronizing the establishment. Try to imagine that the entire world is not set up to avoid offending your delicate sensibilities 24/7.
Here are some questions I would have liked you to ask Altman:
What gives you the right to turn off a TV in a public place? (The answer here is "Nothing.")
Did anybody you talked to say this was a really bad idea? Why didn't you listen to them?
Did you ever stop to think about bad outcomes? How about one Yankees fan in a Boston sports bar? One person who doesn't want a TV on when a major news story is unfolding, as on 9/11?
The article just flat out stank. One can only hope that Altman will get sued out of existence and go back to doing something useful, like designing RAID controllers.
Al Zachary, Hardware Engineer, Cisco Systems Inc., San Jose, Calif.
Not even engineers are immune to the hard sell
George Woodward's letter about car audio amplifiers (see March 14, page 30) is an excellent example of how even engineers, who should know better, fall prey to marketing hype specifically, in this case, the notion that a 70-volt/microsecond slew rate is of value, or even likely to exist, in a 50-watt audio amplifier.
First, using the quoted numbers of 50 W and 4 ohms, here is how the required slew rate can be calculated: The voltage to produce 50 W is about 14 Vrms or 40 Vp-p. The highest audio frequency, a 20,000-Hz sine wave, has a period of 50 µs.
The steep portion of the sine wave from one peak to another occupies perhaps one-third of the period, or 17 µs. So we have 40 V in 17 µs, or a required slew rate of only 2.35 V/µs. It's always good practice to provide some headroom over the requirements, so perhaps a slew rate of 5 V/µs is worthwhile but 70 is clearly overkill.
Second, there is a huge disconnect between the quoted full-power bandwidth of 20,000 Hz and the "slew rate" of 70 V/µs.
The power bandwidth of an amplifier is usually smaller than the small-signal bandwidth and is in fact determined by the slew rate. Again, using the above numbers, 3(40/70) equals a period of 1.7 µs, or a frequency of 580 kHz. This means a true slew rate of 70 V/µs in a 50-W, 4- amplifier would produce a whopping power bandwidth of 580 kHz, not 20 kHz!
I suspect that the '70s Sanyo amp may have had a small-signal bandwidth of several hundred kHz (possible in a solid-state amp not encumbered with an output transformer, but not a good idea if the vehicle is driven near AM broadcast transmitters); thus, someone measured the rise time with a small signal and erroneously called it the slew rate.
Mark Spellman, Principal Engineer, Harman/Becker, Automotive Systems, Farmington Hills, Mich.