Basically just as the title states. I've had a couple drivers now (mostly Daytons and Tang Bands) that I'll break in for a couple hours in free air. I don't send silly wattage to them and generally only run at around 1/2 of their xmax, so excursion isn't the deal. I'm just wondering why I start to get some mechanical noises on most all of them around 1/2 xmax in free air. Interestingly, when I stuff them in the box they're going to live in, the noises vanish up until they're either overpowered, or hit excursion limits. I'm not really worried about it, but I am curious what causes the noise in free air. Thoughts?
Thing to remember is that free-air operation gives you a 6dB/octave acoustic highpass filter. Any little bit of HF that the driver produces is given huge advantage over the low end when it comes to hearing it.
When loaded into an enclosure, the low end is restored and might be 40dB above the HF noises. ie, the HF noises will be virtually inaudible.
PS - add in wind noise from the motor structure, tinsel leads slapping the cone etc etc. When mounted cone-out, those noises remain inside the box, more-or-less.
Chris
When loaded into an enclosure, the low end is restored and might be 40dB above the HF noises. ie, the HF noises will be virtually inaudible.
PS - add in wind noise from the motor structure, tinsel leads slapping the cone etc etc. When mounted cone-out, those noises remain inside the box, more-or-less.
Chris
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