[Mark Korda]

Hi, I just read the latest Stereophile. John Atkinson reviewed the Sony SS-NA2ES loudspeaker. I like him because he's honest. He told the fact that during a test called the sweep,that he destroyed the tweeter when he left the DAC's volume control all the way up without knowing it. Sony replaced a new set of speakers for the review. My question is what is a sweep,I know it's a oscilloscope thing, but I'm trying to recap an old Heathkit 5W amp, that has a circuit called the (tweeter saver),ala 1956,as old as me. I was wondering why a 10,000 dollar pair of speakers could be done in by a volume control setting 56 years later? One of the amps used was the infamous Lamm which is low powered, but I'm not sure about the Classe and MBL mono blocks. Any one got a clue,Monk, Columbo, I'm all ears.......Mark Korda

[WireNut]

I was wondering why a 10,000 dollar pair of speakers could be done in by a volume control setting 56 years later?

Here's a voice coil from a Seas Excel tweeters after a long and loud listening session. To much volume = to much heat to the voice coil. 

I have a stereophile test CD that has a volume warning right before it runs a high frequency sweep.

[Pete Schumacher]

Hi, I just read the latest Stereophile. John Atkinson reviewed the Sony SS-NA2ES loudspeaker. I like him because he's honest. He told the fact that during a test called the sweep,that he destroyed the tweeter when he left the DAC's volume control all the way up without knowing it. Sony replaced a new set of speakers for the review. My question is what is a sweep,I know it's a oscilloscope thing, but I'm trying to recap an old Heathkit 5W amp, that has a circuit called the (tweeter saver),ala 1956,as old as me. I was wondering why a 10,000 dollar pair of speakers could be done in by a volume control setting 56 years later? One of the amps used was the infamous Lamm which is low powered, but I'm not sure about the Classe and MBL mono blocks. Any one got a clue,Monk, Columbo, I'm all ears.......Mark Korda

A sweep is a gradual change of frequency, usually from low to high, at a fixed amplitude.  Speakers are designed with music in mind, which generally has an energy distribution weighted to the low frequencies.  A 100W amp will produce about 20W RMS pink noise without clipping horribly.  The distribution of of that power will be more than 70% below 2500Hz.  The smallest amount will be in the top octaves covered by a tweeter.

Running a sweep at full power into a small voice coil will do what is in wirenut's picture.  There's just not enough thermal mass in that tiny coil to withstand the power level of a big amp at full swing.

Most dome tweeters really can't do more than about 50W, and only for short duration.

[Mark Korda]

Hi Wirenut and Pete, thanks for your answers. I did look up sweep test in a book called How to test almost anything electronic by Delton Horn but your answers and picture were much more easier to understand. Thanks again.......Mark Korda