interpreting readings

**08-25-08, 05:09 PM**

So far, I have successfully taken readings and applied the BFD to fix the low frequencies in my room. What about higher end frequencies? I've attached a picture of what the full range reading looks like, and after about 750hz, things get a little crazy. What causes this? Is it not possible to read high frequencies without a better mic? The measurements were taken with an ECM8000 (calibration file loaded).

Thanks!

**brucek** · **08-25-08, 06:16 PM**

Quote:

after about 750hz, things get a little crazy. What causes this? Is it not possible to read high frequencies without a better mic?

The measurement is fine. The rather rough signal is know as comb filtering, caused by reflections. It's expected, and so as to reveal the underlying trend of the signal you should turn on ~1/3 smoothing feature (from the left panel). Only use smoothing when looking at full range signals such as yours. If you are looking at a sub signal from 15Hz-200Hz, do not use smoothing, as any filters you create will not match the modal resonances they are designed to eliminate.

brucek

**08-26-08, 04:38 PM**

OK, that makes much more sense with the smoothing feature applied! I've attached another image of it. As you can see there is a nasty dip at about 3K. If I EQ that out with the BFD, it's going to sound pretty harsh. It's kind of strange, because I have 10 panels in this room (made from 80 pcf rock board), and it sounds pretty dead in here. Would adding/re-positioning the panels be a smarter move, or will EQ'ing the 3K dip suffice?

Neil

**brucek** · **08-26-08, 06:14 PM**

Quote:

or will EQ'ing the 3K dip suffice?

EQ'ing should be limited to subwoofer frequencies....

The 3KHz problem is a bit high for treatments.

Positioning is your best bet to smooth a 3KHz dip.....

brucek

**Wayne A. Pflughaupt** · **08-26-08, 08:55 PM**

Is that graph with both mains, or only one? If both, let’s see what a single one looks like.

Regards,
Wayne

**08-31-08, 11:14 AM**

That is with both mains. What difference will only one main make? Either way, I'll give it a try to see what happens.

**brucek** · **08-31-08, 12:22 PM**

Quote:

What difference will only one main make?

Quite a bit of difference.

A single main will show room effects from its position. The other main will do the same given its position. Two mains show effects from the room (given both their positions) and also cancellation effects occuring between the two spekaers (since the REW signal is mono).

brucek

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