Has anyone here measured a TD15M? (I have them)

[pos]

If you look at the FR with the marker set at the start of that wiggle you will actually see at which frequencies this breakup is resonating, and also the effect of any crossover you might want to try and measure.

[dumptruck]

I'm not at my measurement set up right now, but I will do that later today and post it. Presumably, I'll get the same thing shown in the links above.

[dumptruck]

Okay, here comes some data. This post: impulse, with frequency responses at various gate times. The key on the freq. response plots also corresponds to the circles on the impulse response. The peak before each gate time is one that makes a significant difference. I only included new gates and responses for the peaks that make a significant difference in response. Time zero referenced on the response plots is the start of the impulse, not the time zero shown on the impulse. The next post will show time windows after the start of the impulse, as requested.

Between gates 1 and 2 in the impulse is the blip that is not a consistent feature. It is something with my cabinets that I should be able to fix.

[dumptruck]

Here are two responses from time windows restricted to the area of interest. Sorry I had to change the magnitude scale from above. All gates are uniform here and above, btw - no hanning taper. The pink one (I think) is the real subject here, while the blue one includes the cabinet-related thing I should be able to figure out on my own.

I hope you can interpret how this refers to the previous post - it is hard to make this easy to follow!

[dumptruck]

Anybody? I'm going to see what more I can figure out tonight or tomorrow night. Any tips/ideas appreciated.

[tuxedocivic]

It looks like reflections are getting in once the gate moves past about 2.5ms, as the question about the 2.45ms issue would suggest?? Are you sure you're reflection free more than 1m in all directions? The red response looks useful...

[dumptruck]

Originally Posted by tuxedocivic

It looks like reflections are getting in once the gate moves past about 2.5ms, as the question about the 2.45ms issue would suggest?? Are you sure you're reflection free more than 1m in all directions?

I'm not sure I understand what you're saying - you realize the 2.45ms cannot be any normal reflection, right? If you're saying there's too much other stuff going on to examine the 2.45ms issue, I may need to use a measurement without the 1.7-2.0ms reflection instead of just trying to start the gate after it. I'll give that a try next.

[keto]

Hey, I don't know if this is exactly what you're looking for, but here is a shot taken at 9" in a 2 cu ft box and driven by a SET amp, with and without filtering.

[dumptruck]

Thanks, but not really. I need measurements from farther away, and without smoothing.

[dumptruck]

Thanks for updating Keto. If you can give me enough details I can try to replicate that. Looks similar to what I'd get with averaged periodic noise, I think.

I'm not having much luck with eliminating the other anomaly above so far. I removed the back of the cabinet, put fiberglass all over the place, and wrapped cork around baffle edges (because that has an effect on the DE250 being tested in the same enclosure). No noticeable change in the impulse, and nothing but fractions of a decibel here and there in the freq. response. So, I figured maybe I'll go back to the other woofer in free air, but that immediately seemed silly - too many other issues to deal with. Not sure what I'll try next. Maybe this is all the same issue as the 2.45ms thing.