Can "Digital" damage my gear?


Faulty (or malicious) CD/CD-R or digital download can contain large levels of high frequencies outside of hearing range - for instance 20kHz. Such frequency at full power will overheat tweeter and most likely damage output Zobel network in my class D amplifier. Stereophile Test CD contains such tracks and warns against playing them at full loudness. My DAC will mute anything other than valid S/PDIF but will play any frequency at any level.

What do you think? Can bad or malicious recording from CD/CD-R or server damage my speakers or amp. Is there a way to prevent it?
128x128kijanki
Hi Kijanki -- yes, it's certainly conceivable that a malicious download containing high power signals at 20kHz or so could burn out a tweeter, without being audible (to many of us, anyway!).

If you have concern about a particular download or cd, a way to check it would be with a good audio editing program, that would allow you to examine the waveform, and/or that would provide amplitude and power statistics. Sound Forge 9, http://www.sonycreativesoftware.com/products/soundforgefamily.asp, a professional program costing about $300, can certainly do that, and in fact it would allow you to easily filter out the low frequency stuff in the file and examine the waveform and statistics just for the high frequencies that might be harmful to the tweeter.

Perhaps its consumer-grade counterpart, Sound Forge Audio Studio ($55) can provide those capabilities also, and perhaps some of the better free programs, such as Audacity, can. I have no particular knowledge of those programs, though.

Regards,
-- Al
Keep in mind that analog circuits can malfunction in ways that result in high volumes and/or high frequencies. Something as simple as a turntable phono cable that gets partially unplugged could blow a tweeter if the volume knob on the amp is turned up. Or, one of your neighbors could get into shortwave radio as a hobby with you finding out the hard way that your cable and equipment shielding is no longer adequate.

So, yes, there are some risks in the manner you describe with digital sources. That doesn't mean that you are risk-free if you have no digital. A bit of caution deals with most situations, however.
Mlsstl - I don't expect noise/EMI pickup of full amplitude but circuit malfunction is always possible. I don't have control over that. Digital "malfunction" appears to be in addition.

Al - I wouldn't know how to start. Inspecting huge files with Sound Forge seems to be time consuming and would have to be done for every digital file. It would be great if somebody can write piece of software that automatically detects malicious footprint (like antivirus).
I've got over 40,000 songs on my digital server. I have never come across a maliciously recorded digital song. I've had damaged CDs give me silence, clicks, pops and stutters but no blasts of noise.

Each person gets to worry about those things they choose to worry about, but it strikes me that you're concerned about item number 4,999 on the list of 5,000 things that can go wrong. The only way I might be concerned is if I were downloading music from "free" services or buying lots of pirated CDRs.

Lots of people have had blown tweeters over the years and I'd be fascinated to hear of one blown by a malicious digital recording.
Mlsstl -

"I've got over 40,000 songs on my digital server. I have never come across a maliciously recorded digital song."

That is very good to hear - thank you.

"I'd be fascinated to hear of one blown by a malicious digital recording."

- that's exactly what people said about computer viruses at the beginning. Computer virus won't physically damage your hard disk. In worst case you have to reformat and reinstall software (there was a virus overheating Pentium processors). Music virus can damage very expensive gear.

I know it is not likely but many people move to servers and in my opinion its only matter of time. It doesn't have to be pirated CDR or downloaded music - it's enough to play internet soundbite or video using main speakers.

Software engineer, I work with, says that Fourier analysis of such size files will take forever. He participates in SETI program and does analysis of small files on his computer. Ideal would be small crude scanner program that looks for high amplitudes above 2kHz.

I hope I'm just paranoid since I'm planning eventually to move to server (already use DAC) and get much better speakers.