IB 10Hz video imageshack group URL test

[chrisbee]

Still messing about with videos of my IB: ;D

The screen size on Imageshack was useless so I have deleted that post.

Here's a big screen video using Picasa albums.

picasaweb.google.com/Chrisbydk

Click on the link above then on the picture and be patient for a while until the video starts showing. If not try clicking on the next picture.

Same details as before. 10seconds of 10Hz ~+/-5mm excursion for 90dB @ 8 feet using REW and a Galaxy 140 SPL meter set to C-weighting.

The cone appears to be moving much more slowly than 10Hz. This may be a result of the technique I have used: A Sony still camera using video capture. Cone excursion seems much more than reality too.

My drivers have an Xmax of +/-16mm but a steady reading above 100dB[C) @ 10Hz on my Galaxy SPL meter is rather uncomfortable.
So I made do with 90dB for the purposes of this video expeiment.

I used the sinwave generator in REW for this test.

[ThomasW]

Funny....

Was the entire house vibrating?

Next thing we know you'll be hanging out at the car audio websites where they post videos of woofer "porn"..... ;D

[chrisbee]

Hi Thomas

I'm not brave enough to push the excursion more than a few millimeters at 10Hz! The pressure is awful.

I was just playing around with REW and thought I'd try capturing a video with my still camera.

I think the compression is far too heavy to get decent picture quality.

Has anyone tried uploading an image file from a proper digital video camera? Is the picture quality just as bad on these free video online hosting services as it is from my still camera?

[inm8]

I think its the frames per second, rather then the compression which is making it the cone appear to move in and out slower then it actually does. At 10Hz I'm betting you would need a high speed camera to capture the cones movement properly. What we're seeing is probably a sample of many cone in and out cycles, since your camera would only be quick enough to capture a certain portion of each one.

Nice vid btw, lucky the IB I'm building is ceiling mounted or much of my time may have went into similar shenanigans ;D

[chrisbee]

That's the problem with having an easily accessible IB. ;D

I'm a bit worried about my SPL measurements at 10Hz though.

If I'm reading 100dB @ 10Hz on my Galaxy 140 SPL meter then that is a true 111dB!

I'm not sure that is allowed in the Cult rules!

In truth, it's probably a bit of harmonic distortion added in for good measure.

Do you think I need more drivers?