This is my first post to Robert's forum. First I'd like to thank Robert for using my new amp to demo the Apollo's in his room at RMAF. On to current business...
I was reading Lynn's break-in ideas and the requests for break-in signals. Started playing around with the tone generator in Cooledit 2000. Cool edit can make some pretty strange sounding tones! You can choose the wave type, base frequency, how much to modulate it by and the modulation frequency. You can also add a start and stop frequency and sweep the whole mess.
I also discovered that my cats really don't like the sound of low frequency squarewaves played through the crappy little PC speakers on my desk. It's turned out to be a most usefull tool for removing my cat from the space between me and the monitor. Just click the preview button in Cooledit and watch the ears go back then the cats leave the room. Works very well even at at low volume.
I was thinking that a base frequency of 20 hz modulated by 5 hz with a modulation periode of 10 seconds would cover all the frequencies of interest quite nicely. This would give us a square wave sweep that ramps up and down every 10 seconds between 15Hz and 25Hz. If we made the modulation 10Hz so the fundimental ranged from 10 to 30 hz we would then cover all frequencies of the spectrum directly as the 3rd harmonic would come down to 30Hz and go up to 90Hz.
This test signal would cover the whole spectrum of frequencies while delivering a high G load to the driver. Recorded at a 96K sample rate we would have output up to 48Khz. This could be burned onto a DVD-V disk that any DVD player could play back. I'm not sure of the high frequency capabilities of most DVD players though...
If there are any takers I could burn a 96/24 DVD-V for the extended frequency version or put it on 44/16 CD for a more frequency limited version and send it to someone to try.
Gary