Averaging Listening Positions when doing multi-channel equalization. (1 Viewer)

[Wayne A. Pflughaupt]

brucek, thanks for the link.

Regards,
Wayne A. Pflughaupt

 

[Larry Chanin]

Hi Bruce:

quote:
--------------------------------------------------------------------------------
Second, I'd like to sincerely apologize to everyone for putting you through what may have been an intellectual wild goose chase
--------------------------------------------------------------------------------
No problem Larry. This is a learning process that I'm sure others can benefit from. A lot of the information that we've covered here is theoretical background that I suspect many have never known or thought about.
I don't expect we'll abandon you because of a bad cable....
brucek

I really do appreciate the support.
Larry

 

[Larry Chanin]

Well, here we go again.

Hi Mark:
Here's some, hopefully accurate, new measurements with the additional measurement that you requested. That new measurement, with the theater's doors open and the utility room closed, is the best of the four combinations.
Improvement of Frequency Response by Opened Doors.
I don't know what's going on, but I guess opening the doors is preventing out of phase reflections from cancelling the direct sound?
This huge above 200Hz dip is what I alluded to a couple of posting prior. It's waaay too large to be handled by an equalizer.:frowning:
Larry

 

[Larry Chanin]

Hi All:
With regard to the best listening position, here's a comparison of the three main listening positions with all the doors closed.
Frequency Responses at Three Listening Positions
Listening position#4 is the best. Position #2 and #3 are about the same. But the > 200Hz dip for position #4 still seems too big to attack with an equalizer.
Larry

 

[Pete Mazz]

Something MUST be wrong with those measurements. A 50 dB difference in SPLs from 100 Hz to 1KHz has to be wrong. Are you positive the sub/s were off?

Pete

 

[Greg Monfort]

I assume that when you listen to music or dialogue that it sounds OK so this implies an issue in the measurement chain.

GM

 

[brucek]

Larry,

There is no way a single main speaker is measuring 100dB SPL from 60Hz to 100Hz and then under 60dB SPL from 600Hz to 15KHz. The Radio Shack meter will only measure down to 50dB, yet your graph shows a blue and green line between 40dBSPL and 50dBSPL.

Something is very wrong....

brucek

 

[Larry Chanin]

Thanks Guys:

Larry,
There is no way a single main speaker is measuring 100dB SPL from 60Hz to 100Hz and then under 60dB SPL from 600Hz to 15KHz. The Radio Shack meter will only measure down to 50dB, yet your graph shows a blue and green line between 40dBSPL and 50dBSPL.
Something is very wrong....
brucek

My Radio Shack meter's battery is showing that its in the good range, but I think I'll change it and see if anything happens.
Well, I guess this is both good news and bad :frowning: news. The good news, apparently is nothing real in my room could be this bad so maybe I'll eventually be able to use an equalizer after all. The bad news is that I've purchased some software that I don't know how to get to work right.
As much as I don't want to do this, it looks like I'm going to have to do some independent measurements. Tonight I'll see if I can dig up that program that generates test signals and plots graphs. Otherwise I guess I'm in for a lot of manual charting. :frowning:
Although this is a bit embarrassing, I'm actually relieved by your responses.
Thanks again for the patience.
Larry

 

[Larry Chanin]

Hi Bruce:
This is probably a long shot, but I was wondering whether the big dip between the low and mid frequency response I got might be due to the low range Radio Shack meter correction values I used?
Here's the documentation of the source of our Radio Shack correction values:
Radio Shack SPL meter compensation chart.
Michael Sims, the author of the correction values, in documenting his correction procedure, says:

(easily available from various CDs), with the mic pointed at the speaker.

The ETF5 software uses Maximum Length Sequences (MLS)test signals. MLS test signal are a type of white noise. So I'm wondering whether this might account for the strange results since the Acoustisoft Radio Shack correction values, presumably designed for MLS signals, begin at 400Hz?
Although this might be an explanation, it doesn't seem to agree with your experiences with the demo software in which your ETF5 results seemed to agree with your hand charted measurements.
Any thoughts?
Larry

 

[Greg Monfort]

>The ETF5 software uses Maximum Length Sequences (MLS)test signals. MLS test signal are a type of white noise.
====
Hmm, WRT pink noise, white noise rises at 3dB/octave. Pink noise through an RTA yields a flat FR response since acoustic energy decreases with increasing frequency. FWIW, pink noise is made by passing white noise through a multi-stage R-C shelving network, and from 20-20kHz its energy falls 30.1dB.

GM

 

[brucek]

Larry,

Here's the documentation of the source of our Radio Shack correction values:

I sure hope you didn't use the values listed in that thread? Those are the correction values to use when you use the RS meter standalone - not with ETF.

When you enter the values into ETF5, you must enter the negative of the value. If you did not do this, your readings will be wayyyyyyyyyyyyyy off.

Here is the RS.cal file to enter into ETF for 20Hz to 20Khz.

Copy and paste these values into a file called rs.cal..
The value at 20Hz for example says that at 20Hz the meter is 7.5dB low and that ETF must compensate....

**********************************

20.000 -7.500 0.000
25.000 -5.000 0.000
31.500 -3.000 0.000
40.000 -2.500 0.000
50.000 -1.500 0.000
63.000 -1.500 0.000
80.000 -1.500 0.000
100.000 -2.000 0.000
125.000 -0.500 0.000
160.000 0.500 0.000
200.000 0.500 0.000
250.000 -0.500 0.000
315.000 0.500 0.000
400.000 0.000 0.000
500.000 0.500 0.000
515,625 0,000 0,000
539,063 0,015 0,181
562,500 0,029 0,364
585,938 0,041 0,544
609,375 0,052 0,739
632,813 0,063 0,949
656,250 0,076 1,187
679,688 0,091 1,444
703,125 0,111 1,711
726,563 0,135 1,978
750,000 0,162 2,237
773,438 0,191 2,488
796,875 0,222 2,729
820,313 0,255 2,962
843,750 0,288 3,187
867,188 0,322 3,408
890,625 0,357 3,625
914,063 0,392 3,839
937,500 0,428 4,051
960,938 0,465 4,265
984,375 0,503 4,474
1007,813 0,541 4,682
1031,250 0,580 4,888
1054,688 0,619 5,088
1078,125 0,660 5,293
1101,563 0,700 5,492
1125,000 0,741 5,687
1148,438 0,781 5,880
1171,875 0,818 6,069
1195,313 0,857 6,259
1218,750 0,893 6,451
1242,188 0,931 6,646
1265,625 0,968 6,841
1289,063 1,008 7,039
1312,500 1,049 7,236
1335,938 1,091 7,433
1359,375 1,134 7,633
1382,813 1,179 7,830
1406,250 1,224 8,031
1429,688 1,272 8,221
1453,125 1,322 8,409
1476,563 1,376 8,581
1500,000 1,433 8,724
1523,438 1,491 8,832
1546,875 1,547 8,900
1570,313 1,599 8,938
1593,750 1,648 8,947
1617,188 1,693 8,938
1640,625 1,733 8,920
1664,063 1,770 8,906
1687,500 1,804 8,900
1710,938 1,837 8,902
1734,375 1,868 8,910
1757,813 1,900 8,920
1781,250 1,931 8,935
1804,688 1,961 8,947
1828,125 1,990 8,952
1851,563 2,020 8,959
1875,000 2,049 8,964
1898,438 2,076 8,963
1921,875 2,102 8,967
1945,313 2,128 8,969
1968,750 2,152 8,976
1992,188 2,177 8,987
2015,625 2,203 8,996
2039,063 2,227 9,005
2062,500 2,250 9,012
2085,938 2,275 9,017
2109,375 2,301 9,020
2132,813 2,327 9,017
2156,250 2,351 9,012
2179,688 2,374 9,004
2203,125 2,395 8,999
2226,563 2,415 8,991
2250,000 2,435 8,987
2273,438 2,453 8,985
2296,875 2,471 8,978
2320,313 2,489 8,973
2343,750 2,505 8,962
2367,188 2,519 8,962
2390,625 2,532 8,963
2414,063 2,543 8,980
2437,500 2,555 9,013
2460,938 2,568 9,070
2484,375 2,586 9,136
2507,813 2,608 9,198
2531,250 2,633 9,246
2554,688 2,659 9,280
2578,125 2,683 9,299
2601,563 2,706 9,307
2625,000 2,728 9,305
2648,438 2,749 9,295
2671,875 2,770 9,280
2695,313 2,788 9,261
2718,750 2,806 9,238
2742,188 2,820 9,217
2765,625 2,833 9,198
2789,063 2,845 9,182
2812,500 2,856 9,167
2835,938 2,867 9,154
2859,375 2,877 9,145
2882,813 2,888 9,132
2906,250 2,899 9,124
2929,688 2,908 9,113
2953,125 2,917 9,099
2976,563 2,925 9,083
3000,000 2,932 9,068
3023,438 2,936 9,053
3046,875 2,939 9,043
3070,313 2,939 9,036
3093,750 2,940 9,034
3117,188 2,940 9,040
3140,625 2,940 9,054
3164,063 2,938 9,082
3187,500 2,935 9,122
3210,938 2,932 9,173
3234,375 2,929 9,248
3257,813 2,926 9,333
3281,250 2,926 9,432
3304,688 2,928 9,535
3328,125 2,931 9,637
3351,563 2,936 9,743
3375,000 2,941 9,846
3398,438 2,947 9,948
3421,875 2,953 10,045
3445,313 2,958 10,146
3468,750 2,962 10,243
3492,188 2,968 10,345
3515,625 2,975 10,449
3539,063 2,982 10,557
3562,500 2,990 10,671
3585,938 2,998 10,789
3609,375 3,006 10,916
3632,813 3,015 11,053
3656,250 3,025 11,199
3679,688 3,039 11,354
3703,125 3,055 11,520
3726,563 3,074 11,682
3750,000 3,095 11,837
3773,438 3,118 11,983
3796,875 3,142 12,112
3820,313 3,167 12,230
3843,750 3,192 12,331
3867,188 3,217 12,422
3890,625 3,243 12,502
3914,063 3,270 12,578
3937,500 3,297 12,648
3960,938 3,325 12,710
3984,375 3,352 12,766
4007,813 3,379 12,815
4031,250 3,406 12,855
4054,688 3,433 12,890
4078,125 3,461 12,912
4101,563 3,488 12,930
4125,000 3,514 12,938
4148,438 3,540 12,939
4171,875 3,565 12,929
4195,313 3,591 12,915
4218,750 3,616 12,892
4242,188 3,640 12,863
4265,625 3,664 12,828
4289,063 3,686 12,780
4312,500 3,706 12,725
4335,938 3,724 12,661
4359,375 3,740 12,599
4382,813 3,753 12,535
4406,250 3,764 12,483
4429,688 3,772 12,440
4453,125 3,781 12,409
4476,563 3,788 12,392
4500,000 3,795 12,383
4523,438 3,804 12,391
4546,875 3,812 12,404
4570,313 3,820 12,427
4593,750 3,829 12,456
4617,188 3,838 12,492
4640,625 3,849 12,533
4664,063 3,860 12,585
4687,500 3,872 12,651
4710,938 3,885 12,729
4734,375 3,901 12,822
4757,813 3,919 12,924
4781,250 3,938 13,032
4804,688 3,961 13,143
4828,125 3,986 13,258
4851,563 4,013 13,369
4875,000 4,043 13,476
4898,438 4,076 13,576
4921,875 4,112 13,664
4945,313 4,150 13,741
4968,750 4,190 13,803
4992,188 4,230 13,850
5015,625 4,269 13,883
5039,063 4,309 13,900
5062,500 4,350 13,906
5085,938 4,391 13,904
5109,375 4,432 13,895
5132,813 4,471 13,885
5156,250 4,510 13,873
5179,688 4,550 13,870
5203,125 4,592 13,879
5226,563 4,638 13,894
5250,000 4,687 13,913
5273,438 4,742 13,923
5296,875 4,802 13,913
5320,313 4,866 13,871
5343,750 4,933 13,790
5367,188 5,002 13,667
5390,625 5,071 13,501
5414,063 5,141 13,288
5437,500 5,211 13,035
5460,938 5,280 12,732
5484,375 5,347 12,388
5507,813 5,413 11,997
5531,250 5,472 11,564
5554,688 5,525 11,091
5578,125 5,570 10,586
5601,563 5,606 10,061
5625,000 5,635 9,528
5648,438 5,655 8,999
5671,875 5,670 8,481
5695,313 5,680 7,985
5718,750 5,684 7,507
5742,188 5,686 7,050
5765,625 5,685 6,613
5789,063 5,681 6,190
5812,500 5,675 5,783
5835,938 5,666 5,395
5859,375 5,653 5,024
5882,813 5,638 4,674
5906,250 5,622 4,345
5929,688 5,607 4,037
5953,125 5,595 3,750
5976,563 5,584 3,484
6000,000 5,574 3,229
6023,438 5,565 2,986
6046,875 5,557 2,748
6070,313 5,552 2,508
6093,750 5,548 2,264
6117,188 5,544 2,005
6140,625 5,540 1,731
6164,063 5,536 1,443
6187,500 5,530 1,145
6210,938 5,521 0,846
6234,375 5,509 0,551
6257,813 5,496 0,265
6281,250 5,480 -0,010
6304,688 5,464 -0,274
6328,125 5,448 -0,526
6351,563 5,430 -0,767
6375,000 5,412 -0,999
6398,438 5,393 -1,222
6421,875 5,375 -1,437
6445,313 5,359 -1,643
6468,750 5,344 -1,845
6492,188 5,332 -2,041
6515,625 5,322 -2,237
6539,063 5,316 -2,442
6562,500 5,310 -2,658
6585,938 5,306 -2,895
6609,375 5,302 -3,151
6632,813 5,296 -3,429
6656,250 5,287 -3,724
6679,688 5,276 -4,032
6703,125 5,262 -4,349
6726,563 5,246 -4,667
6750,000 5,228 -4,986
6773,438 5,209 -5,304
6796,875 5,190 -5,620
6820,313 5,171 -5,937
6843,750 5,152 -6,257
6867,188 5,130 -6,583
6890,625 5,105 -6,919
6914,063 5,077 -7,264
6937,500 5,048 -7,617
6960,938 5,018 -7,980
6984,375 4,985 -8,350
7007,813 4,950 -8,725
7031,250 4,910 -9,102
7054,688 4,867 -9,478
7078,125 4,820 -9,848
7101,563 4,769 -10,206
7125,000 4,713 -10,548
7148,438 4,652 -10,870
7171,875 4,589 -11,169
7195,313 4,523 -11,442
7218,750 4,454 -11,689
7242,188 4,384 -11,906
7265,625 4,313 -12,093
7289,063 4,241 -12,249
7312,500 4,168 -12,371
7335,938 4,097 -12,459
7359,375 4,026 -12,513
7382,813 3,958 -12,537
7406,250 3,892 -12,530
7429,688 3,830 -12,501
7453,125 3,772 -12,453
7476,563 3,718 -12,393
7500,000 3,668 -12,324
7523,438 3,620 -12,246
7546,875 3,575 -12,166
7570,313 3,533 -12,081
7593,750 3,495 -11,994
7617,188 3,460 -11,907
7640,625 3,428 -11,825
7664,063 3,400 -11,753
7687,500 3,374 -11,696
7710,938 3,351 -11,656
7734,375 3,329 -11,637
7757,813 3,307 -11,637
7781,250 3,283 -11,656
7804,688 3,260 -11,689
7828,125 3,234 -11,731
7851,563 3,207 -11,776
7875,000 3,178 -11,819
7898,438 3,146 -11,854
7921,875 3,113 -11,875
7945,313 3,080 -11,881
7968,750 3,047 -11,872
7992,188 3,016 -11,847
8015,625 2,988 -11,812
8039,063 2,964 -11,771
8062,500 2,943 -11,732
8085,938 2,927 -11,699
8109,375 2,914 -11,679
8132,813 2,905 -11,679
8156,250 2,897 -11,701
8179,688 2,891 -11,750
8203,125 2,885 -11,826
8226,563 2,878 -11,933
8250,000 2,870 -12,070
8273,438 2,860 -12,238
8296,875 2,848 -12,434
8320,313 2,830 -12,654
8343,750 2,808 -12,896
8367,188 2,780 -13,146
8390,625 2,746 -13,399
8414,063 2,706 -13,645
8437,500 2,661 -13,875
8460,938 2,611 -14,087
8484,375 2,557 -14,275
8507,813 2,500 -14,438
8531,250 2,442 -14,573
8554,688 2,381 -14,678
8578,125 2,319 -14,750
8601,563 2,256 -14,787
8625,000 2,192 -14,787
8648,438 2,129 -14,751
8671,875 2,068 -14,680
8695,313 2,012 -14,579
8718,750 1,959 -14,452
8742,188 1,912 -14,310
8765,625 1,871 -14,156
8789,063 1,834 -13,998
8812,500 1,803 -13,841
8835,938 1,775 -13,691
8859,375 1,751 -13,550
8882,813 1,730 -13,423
8906,250 1,712 -13,312
8929,688 1,697 -13,219
8953,125 1,683 -13,144
8976,563 1,670 -13,088
9000,000 1,658 -13,054
9023,438 1,647 -13,041
9046,875 1,635 -13,051
9070,313 1,624 -13,082
9093,750 1,610 -13,136
9117,188 1,594 -13,208
9140,625 1,575 -13,301
9164,063 1,552 -13,402
9187,500 1,525 -13,501
9210,938 1,493 -13,584
9234,375 1,459 -13,641
9257,813 1,424 -13,666
9281,250 1,391 -13,661
9304,688 1,361 -13,636
9328,125 1,335 -13,598
9351,563 1,312 -13,555
9375,000 1,294 -13,518
9398,438 1,280 -13,492
9421,875 1,270 -13,481
9445,313 1,262 -13,489
9468,750 1,255 -13,518
9492,188 1,248 -13,568
9515,625 1,241 -13,640
9539,063 1,233 -13,732
9562,500 1,225 -13,841
9585,938 1,215 -13,965
9609,375 1,203 -14,101
9632,813 1,188 -14,245
9656,250 1,171 -14,395
9679,688 1,152 -14,546
9703,125 1,131 -14,698
9726,563 1,109 -14,851
9750,000 1,088 -15,008
9773,438 1,066 -15,168
9796,875 1,043 -15,335
9820,313 1,018 -15,510
9843,750 0,989 -15,692
9867,188 0,958 -15,877
9890,625 0,922 -16,059
9914,063 0,883 -16,234
9937,500 0,841 -16,390
9960,938 0,796 -16,520
9984,375 0,748 -16,619
10007,810 0,700 -16,684
10031,250 0,653 -16,714
10054,690 0,608 -16,712
10078,130 0,567 -16,684
10101,560 0,530 -16,639
10125,000 0,499 -16,593
10148,440 0,472 -16,560
10171,880 0,449 -16,552
10195,310 0,427 -16,576
10218,750 0,405 -16,628
10242,190 0,382 -16,706
10265,630 0,359 -16,801
10289,060 0,333 -16,910
10312,500 0,305 -17,028
10335,940 0,275 -17,154
10359,380 0,243 -17,281
10382,810 0,208 -17,411
10406,250 0,173 -17,540
10429,690 0,136 -17,670
10453,130 0,099 -17,798
10476,560 0,061 -17,926
10500,000 0,023 -18,060
10523,440 -0,015 -18,194
10546,880 -0,055 -18,333
10570,310 -0,095 -18,478
10593,750 -0,137 -18,629
10617,190 -0,180 -18,784
10640,630 -0,225 -18,942
10664,060 -0,273 -19,098
10687,500 -0,323 -19,252
10710,940 -0,376 -19,397
10734,380 -0,429 -19,529
10757,810 -0,482 -19,643
10781,250 -0,535 -19,741
10804,690 -0,586 -19,826
10828,130 -0,635 -19,905
10851,560 -0,684 -19,977
10875,000 -0,731 -20,056
10898,440 -0,777 -20,146
10921,880 -0,823 -20,253
10945,310 -0,867 -20,375
10968,750 -0,914 -20,511
10992,190 -0,961 -20,662
11015,630 -1,012 -20,817
11039,060 -1,066 -20,976
11062,500 -1,123 -21,133
11085,940 -1,183 -21,280
11109,380 -1,246 -21,413
11132,810 -1,312 -21,532
11156,250 -1,380 -21,635
11179,690 -1,449 -21,719
11203,130 -1,520 -21,790
11226,560 -1,592 -21,844
11250,000 -1,664 -21,887
11273,440 -1,737 -21,919
11296,880 -1,810 -21,945
11320,310 -1,883 -21,962
11343,750 -1,957 -21,974
11367,190 -2,034 -21,980
11390,630 -2,113 -21,977
11414,060 -2,194 -21,958
11437,500 -2,278 -21,920
11460,940 -2,362 -21,855
11484,380 -2,448 -21,758
11507,810 -2,533 -21,630
11531,250 -2,616 -21,462
11554,690 -2,696 -21,261
11578,130 -2,773 -21,031
11601,560 -2,845 -20,780
11625,000 -2,911 -20,517
11648,440 -2,971 -20,251
11671,880 -3,026 -19,986
11695,310 -3,076 -19,738
11718,750 -3,122 -19,504
11742,190 -3,164 -19,295
11765,630 -3,203 -19,111
11789,060 -3,238 -18,957
11812,500 -3,272 -18,832
11835,940 -3,305 -18,741
11859,380 -3,337 -18,678
11882,810 -3,370 -18,648
11906,250 -3,403 -18,644
11929,690 -3,439 -18,667
11953,130 -3,475 -18,712
11976,560 -3,514 -18,773
12000,000 -3,555 -18,849
12023,440 -3,598 -18,933
12046,880 -3,645 -19,025
12070,310 -3,693 -19,126
12093,750 -3,744 -19,225
12117,190 -3,796 -19,321
12140,630 -3,850 -19,415
12164,060 -3,906 -19,502
12187,500 -3,963 -19,584
12210,940 -4,021 -19,644
12234,380 -4,081 -19,694
12257,810 -4,141 -19,730
12281,250 -4,199 -19,739
12304,690 -4,257 -19,737
12328,130 -4,311 -19,725
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14601,560 -10,156 6,445
14625,000 -10,147 6,982
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14718,750 -10,094 8,732
14742,190 -10,072 9,078
14765,630 -10,051 9,384
14789,060 -10,027 9,615
14812,500 -10,002 9,801
14835,940 -9,982 9,923
14859,380 -9,963 9,983
14882,810 -9,951 10,019
14906,250 -9,946 10,008
14929,690 -9,944 9,980
14953,130 -9,950 9,972
14976,560 -9,959 9,945
15000,000 -9,967 9,971
15023,440 -9,980 10,020
15046,880 -9,989 10,071
15070,310 -9,995 10,169
15093,750 -10,000 10,248
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15140,630 -9,981 10,432
15164,060 -9,965 10,507
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15304,690 -9,764 10,266
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15375,000 -9,631 9,621
15398,440 -9,587 9,315
15421,880 -9,546 8,935
15445,310 -9,509 8,512
15468,750 -9,482 8,063
15492,190 -9,465 7,550
15515,630 -9,453 7,037
15539,060 -9,456 6,522
15562,500 -9,465 6,002
15585,940 -9,481 5,516
15609,380 -9,505 5,073
15632,810 -9,532 4,651
15656,250 -9,566 4,286
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15726,560 -9,675 3,307
15750,000 -9,716 3,011
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15796,880 -9,789 2,443
15820,310 -9,826 2,162
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15867,190 -9,908 1,611
15890,630 -9,956 1,333
15914,060 -10,007 1,083
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15960,940 -10,122 0,626
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16242,190 -11,202 -0,750
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16359,380 -11,733 2,688
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16429,690 -11,829 5,411
16453,130 -11,828 6,380
16476,560 -11,821 7,299
16500,000 -11,799 8,195
16523,440 -11,770 9,101
16546,880 -11,734 9,955
16570,310 -11,686 10,818
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16617,190 -11,577 12,488
16640,630 -11,510 13,296
16664,060 -11,440 14,086
16687,500 -11,362 14,822
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16734,380 -11,205 16,294
16757,810 -11,119 16,974
16781,250 -11,036 17,703
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16828,130 -10,851 19,047
16851,560 -10,751 19,751
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16945,310 -10,281 22,030
16968,750 -10,154 22,550
16992,190 -10,032 22,982
17015,630 -9,903 23,382
17039,060 -9,778 23,758
17062,500 -9,652 24,046
17085,940 -9,519 24,337
17109,380 -9,397 24,542
17132,810 -9,264 24,627
17156,250 -9,133 24,649
17179,690 -9,015 24,534
17203,130 -8,910 24,253
17226,560 -8,817 23,951
17250,000 -8,757 23,592
17273,440 -8,702 23,196
17296,880 -8,667 22,892
17320,310 -8,650 22,578
17343,750 -8,633 22,295
17367,190 -8,636 22,081
17390,630 -8,639 21,775
17414,060 -8,641 21,568
17437,500 -8,653 21,338
17460,940 -8,663 21,122
17484,380 -8,681 20,955
17507,810 -8,703 20,727
17531,250 -8,716 20,550
17554,690 -8,738 20,409
17578,130 -8,756 20,241
17601,560 -8,770 20,120
17625,000 -8,782 20,017
17648,440 -8,793 19,881
17671,880 -8,790 19,757
17695,310 -8,791 19,580
17718,750 -8,776 19,347
17742,190 -8,765 19,127
17765,630 -8,762 18,828
17789,060 -8,756 18,462
17812,500 -8,755 18,139
17835,940 -8,760 17,762
17859,380 -8,765 17,409
17882,810 -8,773 17,069
17906,250 -8,782 16,712
17929,690 -8,788 16,390
17953,130 -8,793 16,034
17976,560 -8,791 15,712
18000,000 -8,791 15,381
18023,440 -8,790 15,003
18046,880 -8,782 14,619
18070,310 -8,782 14,224
18093,750 -8,781 13,772
18117,190 -8,781 13,359
18140,630 -8,792 12,935
18164,060 -8,803 12,508
18187,500 -8,817 12,102
18210,940 -8,836 11,728
18234,380 -8,860 11,360
18257,810 -8,887 10,990
18281,250 -8,914 10,632
18304,690 -8,945 10,293
18328,130 -8,986 9,976
18351,560 -9,029 9,618
18375,000 -9,077 9,333
18398,440 -9,135 9,034
18421,880 -9,195 8,765
18445,310 -9,264 8,577
18468,750 -9,341 8,383
18492,190 -9,417 8,264
18515,630 -9,501 8,208
18539,060 -9,587 8,172
18562,500 -9,669 8,190
18585,940 -9,750 8,254
18609,380 -9,828 8,346
18632,810 -9,901 8,491
18656,250 -9,981 8,620
18679,690 -10,048 8,709
18703,130 -10,116 8,825
18726,560 -10,187 8,900
18750,000 -10,255 8,942
18773,440 -10,329 8,992
18796,880 -10,404 9,002
18820,310 -10,482 9,031
18843,750 -10,564 9,054
18867,190 -10,647 9,089
18890,630 -10,730 9,150
18914,060 -10,815 9,228
18937,500 -10,897 9,311
18960,940 -10,974 9,418
18984,380 -11,049 9,519
19007,810 -11,114 9,610
19031,250 -11,176 9,724
19054,690 -11,237 9,774
19078,130 -11,286 9,804
19101,560 -11,336 9,848
19125,000 -11,386 9,826
19148,440 -11,429 9,810
19171,880 -11,476 9,763
19195,310 -11,514 9,692
19218,750 -11,549 9,623
19242,190 -11,581 9,561
19265,630 -11,606 9,453
19289,060 -11,628 9,391
19312,500 -11,651 9,264
19335,940 -11,669 9,102
19359,380 -11,681 8,921
19382,810 -11,697 8,698
19406,250 -11,708 8,455
19429,690 -11,728 8,189
19453,130 -11,746 7,845
19476,560 -11,763 7,514
19500,000 -11,789 7,183
19523,440 -11,820 6,806
19546,880 -11,854 6,440
19570,310 -11,889 6,085
19593,750 -11,922 5,741
19617,190 -11,955 5,439
19640,630 -11,986 5,144
19664,060 -12,015 4,873
19687,500 -12,040 4,626
19710,940 -12,064 4,382
19734,380 -12,084 4,147
19757,810 -12,101 3,910
19781,250 -12,115 3,679
19804,690 -12,127 3,446
19828,130 -12,139 3,215
19851,560 -12,150 2,966
19875,000 -12,158 2,731
19898,440 -12,169 2,491
19921,880 -12,175 2,263
19945,310 -12,188 2,059
19968,750 -12,201 1,822
19992,190 -12,212 1,606

***************************************

brucek

 

[Larry Chanin]

Hi Bruce:
Thanks for the response.

I sure hope you didn't use the values listed in that thread? Those are the correction values to use when you use the RS meter standalone - not with ETF.

No, I used the file that you attached.
Just to check my long shot, I reran a test with the original Acoustisoft correction file without the new low frequency values. Still bad results.
As I mentioned in my previous posting what concerned me was that Mr. Sim's original corrections were developed from pink noise test signals, not MLS test signals. If you'll notice the new low frequency values that we've added to the Acoustisoft correction file were taken from Mr. Sim's correction file. Mr. Sim has 17 correction values from 500Hz to 20,000Hz. If his low frequency values are good to use with MLS test signals, then we would expect to see the adjustments somewhat matching the Acoustisoft values for those 17 frequencies. However, if you compare them with the closest frequency values on the Acoustisoft file, you'll notice that there is no correlation between the adjustment values. This would suggest to me the lower frequency values that we obtained from Mr. Sim's correction file do not apply to MLS test signals.
Regardless, as it turns out eliminating these new low frequency values still doesn't correct the problem of the usually dip from low frequencies to mid range.:frowning:
Larry

 

[Larry Chanin]

Hi Greg:

Thanks for the response.

The ETF5 software uses Maximum Length Sequences (MLS)test signals. MLS test signal are a type of white noise.
====
Hmm, WRT pink noise, white noise rises at 3dB/octave. Pink noise through an RTA yields a flat FR response since acoustic energy decreases with increasing frequency. FWIW, pink noise is made by passing white noise through a multi-stage R-C shelving network, and from 20-20kHz its energy falls 30.1dB.

GM

Yeah, I was hoping that something like that was going on in the low frequency range corrections to explain this huge dB drop. Unfortunately, I have to assume that the original correction file provide by Acoustisoft, which has 832 values in the ~500Hz to 20,000Hz range, was designed for MLS signals. The only part of the correction curve that I was using that might not have been derived from MLS test signals was the new low frequency portion,(20Hz-400Hz) which so far still doesn't account for the huge dB drop.

Doug Plumb, the author of ETF5, and I have exchanged some emails this evening. I've got my fingers and toes crossed that he'll be able to figure out what's going on.

Larry

 

[Pete Mazz]

Could you try a measurement without using a cal file for the RS meter?

Pete

 

[Wayne A. Pflughaupt]

brucek,
Yikes! How many months did it take you to put that together?
Regards,
Wayne A. Pflughaupt

 

[Larry Chanin]

Hi Pete:

Could you try a measurement without using a cal file for the RS meter?

Pete[

I'll give it a try this evening.

Larry

 

[Larry Chanin]

Hi Wayne:

brucek,

Yikes! How many months did it take you to put that together?

Regards,
Wayne A. Pflughaupt

I assume you're referring to the "calibration" file in Bruce's message.

To clarify so everyone understands my previous concerns about the correction file:

The 832 correction values from 516.625Hz to 19,992.19Hz on the file that Bruce attached were provided by Acoustisoft, and presumably they were derived using MLS test signals.

The first 15 records of Bruce's correction file were developed by Michael Sims using pink noise test signals so their use with ETF5 (which is designed to use MLS test signals) comes into question.

Regardless, the use of these 15 correction values do not explain the 55dB drop in response because when I delete them from the correction file I continue to obtain unrealistic results.

Larry

 

[brucek]

Larry,

The first 15 records of Bruce's correction file were developed by Michael Sims using pink noise test signals so their use with ETF5 (which is designed to use MLS test signals) comes into question

Yeah, the rather lengthy file I provided is simply the concatonation of the ETF5 RS meter calibration numbers provided by Acoustisoft and the inverse of the accepted 1/3 octave correction constants.
Certainly it's obvious that the cal chart works to correct the ETF response, but whether the constants used are effective for MLS signals could be in question as you mentioned. To prove the cal chart is compensating you simply need to add it in when you do the two cable loopback setup and you'll see your corrected soundcard response follows the inverse of the cal chart.
My quess is that the correction constants from 20Hz to 500Hz are indeed close for MLS signals. I say this because when I was experimenting with ETF about a half a year ago I got very similar response returns from both ETF and my tried and true tones CD method.
My advice at this point would be to get a simple tone generator in your PC (see page 1 of this thread) and do some very simple tone tests using the RS meter from your listening position and applying the standard RS correction factors. This will quickly reveal whether ETF is in question here...
brucek

 

[Larry Chanin]

Hi Bruce:

This will quickly reveal whether ETF is in question here...

There's no question that we're not looking at a real room response result. With a 55dB drop in level I shouldn't be hearing anything, but of course I do. Doug Plumb indicates that something is definitely wrong with my set-up, the problem is that so far he doesn't know what it is. I sincerely hope he's right and its something I've done rather than the program.
Larry

 

[Larry Chanin]

Hi All:
At Doug Plumb's suggestion I reran the measurements direct to the amplifier without going through the processor. There's a significant difference. As shown below:
Comparison of Frequency Response Curves through Processor vs. Direct to Amplifier
These measurements were made using Acoustisoft's correction file for the Radio Shack meter.
So...I feel a little better in that the measurements are starting to resemble more of the real world, but I'm concerned :frowning: because I don't understand why sending the test signal through the processor would cause such weird results.
I set the main speaker to large and the subwoofer to off for these measurements, so I would have thought that the processor would not have influenced the response.
Pete:
I did try a measurement through the processor without the correction file, but I still got that huge dip in the response.
Larry