sine waves and studio monitors

[hakanai]

so the short version of the story is i was working on a mix and heard some high frequency noise. i had worked on the tracks before and knew that it wasn't the recording. so i pulled up logic's test tone ocillator and ran through the 20 to 20 sweep once or twice. i heard the noise when it go over 16k-ish so i used the sine wave generator to go through that last range more slowly. i got some crackling at 17k and when i hit 20k i stopped for maybe 10-20 seconds MAX. i looked up and there was smoke coming from one of my tweeters! I shut everything down instantly and called the tech support/warranty department. after 40 minutes of talking i was basically told that sine waves are dangerous for studio monitors, especially tweeters, and basically this is commonly accepted information.

now in those 40 minutes i was explaining how in my experience test tones (sine waves) are all but a ubiquitous calibration and diagnostic tool. I've always understood the dangers of low frequency signals but have never heard of high frequency issues. i also understand that too much level is too much level, but considering I was sending the signal out of my DA to one stem on my OTB summing unit with no make up gain set yet and it's passive attenuator never passing 2/3 of it's maximum, then to my active monitors with there own amps set to -17db, too much level is all but impossible!

so basically:

A. am i an idiot who has completely missed out on something and blew his speakers?
B. did i get bullshitted by a warranty department?
C. i guess, just what do you make of this?


i've already accepted that A is going to be a part of the answer no matter what

[hakanai]

oh and i realize that that isn't much of a "short" version, sorry

[hakanai]

maybe this should be moved to "geekslutz" ?

[Ethan Winer]

Originally Posted by hakanai

am i an idiot who has completely missed out on something and blew his speakers?

Not an idiot, but you learned an expensive lesson.

Bass drivers can take more sustained level because that's what they're designed for. Bass players sustain low notes, and that's equivalent to a sine wave for five seconds or whatever. But tweeters are smaller, and overheat more readily, and music rarely contains a single frequency or more than a quarter second if that.

--Ethan

[chrisj]

Yeah, sine waves are very high RMS compared to typical music signals in the high frequencies.

You've seen active monitors that are like, 80W lows and 10W highs? If you start a sine at 20 hz and go to 20K at a quarter of the top volume for bass, that's 20W lows... and 20W highs. *foom*

If you did it with a pink noise curve so it was steadily losing volume as it went, you might be more OK, but I'm not familiar with any tone generators that do that...

[tINY]

Yep, tweeters blow pretty easy.

Continuous sine wave above about 1.5k should be used with caution. Don't play it loud....




-tINY

[timbreman]

Originally Posted by hakanai

so the short version of the story is i was working on a mix and heard some high frequency noise. i had worked on the tracks before and knew that it wasn't the recording. so i pulled up logic's test tone ocillator and ran through the 20 to 20 sweep once or twice. i heard the noise when it go over 16k-ish so i used the sine wave generator to go through that last range more slowly. i got some crackling at 17k and when i hit 20k i stopped for maybe 10-20 seconds MAX. i looked up and there was smoke coming from one of my tweeters! I shut everything down instantly and called the tech support/warranty department. after 40 minutes of talking i was basically told that sine waves are dangerous for studio monitors, especially tweeters, and basically this is commonly accepted information.

now in those 40 minutes i was explaining how in my experience test tones (sine waves) are all but a ubiquitous calibration and diagnostic tool. I've always understood the dangers of low frequency signals but have never heard of high frequency issues. i also understand that too much level is too much level, but considering I was sending the signal out of my DA to one stem on my OTB summing unit with no make up gain set yet and it's passive attenuator never passing 2/3 of it's maximum, then to my active monitors with there own amps set to -17db, too much level is all but impossible!

so basically:

A. am i an idiot who has completely missed out on something and blew his speakers?
B. did i get bullshitted by a warranty department?
C. i guess, just what do you make of this?


i've already accepted that A is going to be a part of the answer no matter what

Dude that is a seriously harsh lesson to learn. Yes I know this is an old thread but I am still surprised at this. At very least those who arent familiar with such things learned from your expensive mistake. Didnt the monitors you were using have some kind of overload protection?? Would something like that even apply in this scenario??

[andimara]

And, where's the limit? I mean, 'cause as he said for me the 20 to 20 sine sweep it's a great tool for hearing my speakers in a room I don't know. I've never had problems and I set it to do the whole round in 1 min. Also, for doing impulse response is a great tool. So, when am I pushing it too hard?