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?
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,, 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.

-- 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.
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.

Kijanki -- Although as you realize there is a learning curve and familiarization process involved in using an audio editing program, once you attained sufficient familiarization, doing what you describe would be trivially easy with Sound Forge (and possibly with the less expensive or free audio editing programs as well).

All you would have to do is to spend a few minutes setting up a preset in its equalizer function, that would sharply roll off everything below 2kHz, and then set up a preset in its "find" function to find everything above an amplitude that you specify.

Once you had those presets in place, you would copy the file you wanted to check to a separate folder, and open the copy with Sound Forge (that avoids the risk of accidentally modifying your original). Then all it would take would be a few clicks to call up the two presets, and voila! The processing time required by a reasonably powerful, fairly recent pc running Sound Forge would be a few seconds at most.

If you want to pursue this approach, I'd suggest starting with the free audio editing program Audacity (easily findable on the web). I haven't used it, but conceivably it might be able to provide similar functionality.

-- Al
Al - that sounds doable but now I started worrying about viruses. Main household computers will become servers for music. It is already happening. I'm afraid that eventually somebody will get an idea to write virus that will destroy tweeters or amps (as they wrote virus overheating Pentium processor). Separate computer not connected to internet might be better.
- that's exactly what people said about computer viruses at the beginning.
I've been involved with computers since the early 1980s. I don't ever recall such a statement by anyone. Viruses have always been a serious issue with networked computers from the beginning and that risk has grown with the internet putting more and more systems on open networks.

I've still not seen nor heard of any issue with recorded music in this fashion.

As for your concern over internet soundbites, perhaps that is a greater risk than ripped music but it also means it is far less convenient to scan prior to listening. If you're at a web site and cannot listen to a 10 or 20 second clip until after scanning you've lost a lot of ease of use and functionality.

If this is a concern, you could use a dedicated music server that doesn't do other computer duties. I do this and have no urge to use my main stereo for playing internet soundbites.

I gather this is just an issue of risk prioritization. But note that you were unable to give an example of a piece of stereo equipment - tweeter or otherwise - damaged by digital music and can only discuss it in terms of a theoretical exposure. Perhaps you are just more prescient than I, but at my house I think the bigger exposure is the dog chasing the cat and knocking something over.... ;-)
Mstll - I wouldn't ask the question if I could give an example. In class D amp it will destroy amp - just look at any Icepower datasheet.

Separate computer is good idea if you can afford it. Computer infected by virus might play destructive file without you knowing it. They did it to overheat Pentium and I suspect it will be done for audio. Chances are small but repair cost is high.

As for viruses being serious issue from the beginning (being treated seriously) - you must be kidding? People didn't want to use antivirus programs (initially free) and many don't use it still. Firewall was unheard of concept (until 1988) and not present in Windows 3.1/95/98. First IBMs went on sale around 1981 but first Norton anivirus, as well as firewall appeared around 1992 because of damages that viruses did and not before (remember Lehigh or Jerusalem viruses affecting .com files or Brain virus affecting boot sector?). Networks might be different story but it took big losses to make people believe. Whole networks went down because of viruses before people got serious about it. I think that people got serious in 1999 when Melissa virus created "epidemic".

As for viruses being serious issue from the beginning (being treated seriously) - you must be kidding?
Nope, I'm not. The fact that virus attempts have escalated over the years does not mean they did not exist before.

The first version of Windows (1983) was released about 10 years before the internet became open to the public. It took the commercialization of the internet to give the viruses, worms, trojans and all that a chance to go big time. The fact was Microsoft valued ease-of-use for non-technical consumers more than they valued security.

However, these malicious files work by targeting the operating system and programs. The vast majority of them have targeted Microsoft products. Music files don't do that. There is also the lack of a universal target. What corrupts an iTunes player won't work on a Windows Media Player. You've got a variety of software players plus an array of hardware players out there. Hackers can't get their jollies with one malicious file screwing with 90% of the users as they do with MS computers.

So you're pretty much left with putting a loud noise in a song. Would a commercial label do that? Unlikely; they wouldn't want the lawsuits. So we're kind of back to the risk of music from questionable sources, such as a listener using their megabucks stereo as speakers for listening to a low-bit-rate U-Tube video.

We're back to risk analysis and prioritization. I've had my share of situations with my stereo equipment over the past 35 some-odd years including blown tweeters, damaged styluses, and other things that required repair or maintenance. You are certainly free to worry about this problem to your heart's content, but it is not prominent on my radar screen.

There was an asteroid (2009 DD45) that just missed the earth the other day if you want something big to worry about. ;-)
I wouldn't worry about a CD. Loose interconnects are the typical reason for loud noises. That's why tweeters should have fuses. But, for some of you guys, your fuses cost more than a tweeter !
Eldartford - I have only one 0.5m XLR (locking) IC. My speaker cables have Cardas bar type (common knob) very secure connector on amp side while on speaker side I have very tight spade connection (I tend to overtight). No loose connection here.

Fast fuse (straight wire) wouldn't affect audio but would protect my tweeters. Amp is different story.
My feeling is, and my (extensive) computer experience has been, that if you use a good anti-virus program, have a good firewall in place, keep your Windows patches up to date, and don't visit or download from questionable sites, viruses are not a significant worry.

In the last 10 years or so, during which the several computers in my house have received extensive use, most of it on the internet, I think there have only been two instances of virus infections that were not blocked at the moment of potential introduction. In both cases they were due to Windows or Internet Explorer vulnerabilities for which patches had not yet been released. They were detected within another day or two by the anti-virus program, when updated definitions were released, and no harm was done.

FWIW, I use the NOD32 anti-virus program. I use a SonicWall hardware firewall, which costs $450 but provides business-class protection for my entire LAN, with no performance impact on the computers. I also use Firefox 3 for web browsing, which is both better and safer than IE (as well as being much better than earlier versions of Firefox).

I set Windows to notify me when updates are available, rather than automatically downloading and installing them. I then use Microsoft Update to update manually. I believe that setting for automatic download and silent updating sometimes results in the process being delayed, for days or weeks. I know that was the case when XP Service Pack 3 was released.

I also regularly (perhaps once a month) use an imaging program to create an image of my entire "c" partition (in addition to doing backups of data files daily), so that if an infection were to occur I could simply reformat, restore the image, restore the data backups, and be back in business in less than an hour.

I consider all of these things to be basic to any serious use of a computer. But my observation has been that probably 95% of all computer users don't follow these or similar practices, which is why virus-writers, cybercriminals, botnets, etc., have proliferated.

-- Al
Bad digital will probably hurt your ears first before causing any damage to your equipment. Don't worry about it, just relax and enjoy the music.
Sidssp - 25kHz at full blast will take tweeter fast (minutes) as well as my amp and I won't even hear that - sometimes it is the case when amp's output stage goes to high frequency oscillation (instability). That was main reason, other than clipping, for tweeter fuses that Eldartford mentioned.

Al - Remember what is at stake: my amp and the tweeters.

I do Windows at work (I refuse to put-up with Windows stupidity and clumsiness for free). Windows still have a lot of dangerous services enabled by default like Telenet or Remote Registry Access.

I enjoy my 1 year old MacMini but still remember years of being confused and scorned by Windows. Never again (for free).

Antivirus might be useless with new unknown virus. Mac does it much better than Windows executing applications in "sandboxes" etc. The only viruses I know for Mac are Windows applications' viruses.
Actually, the last high frequency oscillation problem I had involved a Conrad Johnson PV-10A tube preamp several years ago. A power supply cap went bad and it had a high frequency oscillation that I couldn't hear but fortunately my 24 year old son could. (It was up close to 20 KHz.)

Another option to consider for your operating system is Linux. I use that for my music server (Fedora Core 8). There are very few viruses for Linux and none that install at the "user" level. (You have to be "root" or "superuser" mode for a root-kit to install and proper Linux protocol dictates that you do not do day-to-day computing in that mode.)

Oh well, off to hear the Dublin Philharmonic tonight in a live concert. Remember to enjoy your music!
I have had some BIG pops on an LP, that I would worry more about then anything digital ?
"I have had some BIG pops on an LP, that I would worry more about then anything digital ?"

Can they damage amplifier?
Can LP clicks & pops damage a system?

Very unlikely, but theoretically possible if the volume control were high. Over the years there has been a few times that a damaged record has sent me diving to turn the volume control down.

Once a record is in your collection and you know how it has been treated this would be an exceptionally rare event. But the first time you play a record, especially a used one, it wouldn't hurt to exercise a bit of caution.
Mlsstl - I asked because I checked data sheet for Icepower 200ASC used in my Rowland 102 and it shows that full power blast of 20kHz will damage amp (Zobel network) in 20ms and 20W oscillation will do the same in about 1s. This would imply I wouldn't even have time to react (and is inaudible).
I wouldn't worry about damage to your amp from LP clicks and pops. Over the past 10 years I've converted my LP collection to digital using Adobe Audition. It allows you to zoom in on clicks and pops and most are not more than a thousandth of a second long, even when they are loud.

Your bigger worry would be HF oscillation in the circuit due to other factors, such as the faulty preamp I noted above, but you'd need a worse case than the one I had.

Back to your original issue, there are lots of things that can cause damage to your equipment. The particular concern you had is frankly one of the more remote scenarios. If you suffer equipment damage, you're far more likely to get from one of the old fashioned and time tested methods. ;-)
Mlsstl - I'm probably paranoid but digital offers new way of destroying speakers and even amp in addition to good old ones. It just seems strange to me that one can have amp and speakers destroyed by just playing defective song.

Class D amps have output filter (Zobel network) designed to withstand full power at 20kHz for only 20ms. Normal music carry very little energy at high frequencies but modified digital file can. I suspect it might be only problem of class D amps since inductor, often in series with the output, in traditional class A or AB is more robust.

Avoiding internet downloads from questionable sides is definitely advisable. It is a little bit like virus except virus doesn't destroy expensive hardware (and virus can detected).
Highly unlikely. Listening only to vinyl might be one step in the right direction. Correct: the gurus of internet sabotage via hacking are always at work.