NHT 1259 question

[Dylan Ginsburg]

I have a sub I built with the NHT 1259 driver. This was my first
attempt at a DIY audio project and I'm very pleased with the result.
But I'm wondering what sound the driver makes when overdriven. At very
high volumes I get this squeaky friction type sound. It's sort of like
the fingernails on chalkboard sound though not as high pitch or
piercing. My guess is that the driver is being driven past it's
desired excursion limits and I'm it's rubbing against the metal
framework. But I'm not sure if this is what it is and I was hoping I
could hear from others who've used this driver. Thanks.

-Dylan

[Daniel J. Marshall]

Try looking for small air leaks, that may be making a whistle sound.
Driving the speaker beyond it s linear excursion limits usually results
in frequency doubling. If you have an audio oscillator, any air leaks
should be easily tracked down.
]
Dan Marshall