What causes the 2 lines?

[lbstyling]

Hello, I was just planning to time align the drivers in my speaker when I set the Wavelet analysis up..... This is a 2 way horn with a LR 12db/oct crossover set at 800hz. Its a 350hz horn speaker, so does this mean there is a reflection at 15m/s (15 feet or so?) that needs to be removed ?

 

[John Mulcahy]

Does look like a strong reflection, it should be visible in the impulse response.

 

[lbstyling]

Thanks John.

I am going to run several sweeps and tests to check I have not done anything too silly, before I start really digging into this in detail. (need the weather to pick up so I can run some tests outside!)

 

[jtalden]

No need to go outside. You can just move the mic to about 1 m from the speaker. The right REW window can then then be adjusted just before the first significant blip in the impulse response (maybe 4-5 ms). This is best done with the speaker on a stand away from walls, but I have had good luck using even a little less than 1 m distant from walls and floor. The window setting will exclude all room artifacts above about 500 Hz. The REW window control will indicate the lowest frequency that is meaningful. This won't work if you want to see the response lower than about 500 Hz.

Your chart reflection is so strong it almost suggests that the mic was positioned 1 m in front of one speaker for measurement and another speaker 12 ft away was also playing the test sound - very strange.

 

[NBPK402]

When we started to tune my floorstanders...I put a sheet of Roxul on each side of the speaker, 3 on the floor in front, and 1 sheet right behind the mic to try and cut all the reflections possible. This was with the mic 1 meter from the front surface of the speaker not the horn driver.