REW & RS Digital Meter - strange results in the high freqs

[cyberbri]

I was wondering how accurate or inaccurate the newer digital RS meters are in the higher frequencies. I know they are pretty close in the bass region.

But I ask because this is the result I got with REW from my Ascend 340SE center channel (I had the receiver in DPL II Movie) + sub, with the meter on a tripod in the LP aiming diagonally up, as well as aimed forward.

Aimed diagonally up:


Aimed straight forward:


In my room I do have absorber panels on the left/right sides, and I have a large 3~4" thick floor cushion that I put on top of the large square coffee table.

Any idea why the frequency response looks like this in the highs?

[Sonnie]

I would use 1/3 or 1/6 octave smoothing... it's almost impossible to read a response graph full resolution in the high frequency range.

[cyberbri]

BTW, here are graphs that show very close to what I have right now.

I have bass traps (2x GIK Acoustics 244 panels in each front corner, with a 224 panel at each 1st ref point), along with a BFD, of course, eqing my HSU VTF-3 MK2. Speakers are Ascend 340SE (3 across front).

The graphs show interaction between the sub and the 2 mains, with crossover on sub disabled, set to 80Hz in receiver, and sub running with 180-deg phase in Max Extension mode (1 port plugged).

Here's my filters, probably over-done a bit by I'm anal about getting flat response.

Freq BW Adjustment
24Hz 8 -3
30 10 -4
48.5 3 -5
40 6 -7
44.5 6 -12
53.25 3 +6
72.35 10 -16
83 6 -5
51 2 +4
89 2 +6
37.88 3 +3
100 4 -7


After I did these graphs, I eased up on the cut at 73.25 (was -19) amd at 30Hz (was -6), as well as easing up on the cut by 1dB or so around 100 (was -8 or -9). I also backed off the boosts at 53.25 and 89 (both were +7). Those were the filters when the graph was taken, and the above list was what I currently have - slightly different than how the graphs now look.

The first graph should be the standard dimensions used here - 15Hz to 200hz, 45hz to 105Hz high. For the second one I widened it a bit to see the response to 10Hz rather than 15Hz.

[cyberbri]

Sonnie wrote:

I would use 1/3 or 1/6 octave smoothing... it's almost impossible to read a response graph full resolution in the high frequency range.

Still, that's a 7dB or rise around 5K, and then it falls 30dB starting at 10KHz. Is that C-weighting, or just something with my sound card/setup?



I also just read this:
http://www.avsforum.com/avs-vb/showt...&&#post9542081

So I guess I need to do different tests that focus on just the high range. Another thing is, REW often (always?) tells me the signal coming from the SPL meter is clipped. I guess I'll just run some different tests.

And on another thread on another forum, someone said that RS meters aren't good with treble frequencies. Is there a .cal file that can be used for measuring up through 20K~?

[Sonnie]

Yeah... I think the RS meter is pretty useless above about 8KHz or so.

[brucek]

And on another thread on another forum, someone said that RS meters aren't good with treble frequencies.

That's correct. Don't use an RS meter for full range. You need to purchase a better microphone for that job.

brucek

[cyberbri]

brucek wrote:

That's correct. Don't use an RS meter for full range. You need to purchase a better microphone for that job.

brucek

That's good to know. I guess... So I won't bother with full-range measurements then. Don't feel like buying a better mic right now.

[Sonnie]

The Behringer ECM8000 is pretty good... 50 bucks and you'll need a phantom powered mic amp... generally around 50 bucks.

[cyberbri]

I moved my speakers tonight, experimented with REW some more, etc. I redid my BFD filters, on a different filter grouping, and instead of having a bunch of cuts, I only used a few filters and lowered the gain on the sub.


Here's my results, current filters:
Freq BW Cut/Gain
74Hz 6 -13
45Hz 8 -7
66Hz 2 -4
54Hz 8 +4
37Hz 4 +4
53Hz 3 +2


Attached graphs are:
10-20KHz, 1/3 octave smoothing
15-200Hz, sub+ speakers, no BFD
15-200Hz, sub+ speakers, Current/above filters
10-400Hz, sub+ speakers, Current/above filters, 1/12 octave smoothing