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When EQ-ing a Khorn w. notch filter - which mic perspective is dominate with what one hears ?

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Posted on September 19, 2016 at 21:00:34
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 my room is cluttered to the max, a couple of little Karlson in front of the Khorn - but don't think that matters much with a Khorn. (the Karlson have their apertures blocked)

at around 8 feet back and ~ midhorn height, response looks pretty good considering 1/24 octave resolution.

laying the mic on the floor at ~8 feet back, there's a peak around 136Hz

Poking a mic into the basshorn's mouth shows a maximum at the same ~136Hz point.

Are the floor plane and near-mouth perspectives the ones to follow for adjustments via passive notch/active EQ?

I have some 8mH chokes which might make a notch filter- I'm not sure how to juggle R and C. I see Klipsch had an AK4 network which assume worked with a K33 type in Khorn and that filter used 6mH, 130uF and 3R IIRC

1/6 octave

1/24 octave


Karlson Evangelist

 

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- which mic perspective = what we hear? is the boom and indistinct bass my room walls or the Khorn Peak ?, posted on September 20, 2016 at 18:26:02
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 look at my graphs and give an opinion on why my Khorn sound so boomy and indistinct in the bass. North Reading Engineering suggests a notch filter for the basshorn. I may rig one up out of whatever values are laying around and see what happens.
Karlson Evangelist

 

RE: - which mic perspective = what we hear? is the boom and indistinct bass my room walls or the Khorn Peak ?, posted on September 21, 2016 at 13:37:11
tomservo
Manufacturer

Posts: 8209
Joined: July 4, 2002
 Hi Freddyi

Hey if you can take an impedance curve for your woofer, i give your a hand with something that should work first try.
Tom
Hey i am a southerner now, live in Georgia

 

RE: - which mic perspective = what we hear? is the boom and indistinct bass my room walls or the Khorn Peak ?, posted on September 21, 2016 at 15:57:25
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 hey Tom - wish I had mobility

(ugh - my 14 year old measuring pc is failing to load xp)

anyhow - below are two series notch filter schemes for the Klipschorn - one by North Reading Engineering, the other used in Klipsch's AK4 network. I wonder why they seem to be tuned differently? Did Khorn change woofer parameters from nominal K33E at some later point?

North Reading used 12.9mH, 3.8R (not including coil resistance) and 156uF

Klipsch AK4 used 6mH, 3R (not including coil resistance) and 130uF

Series Notch Filter Calculator http://lautsprechershop.de/index_hifi_en.htm?http://lautsprechershop.de/tools/t_ps_schwingkreis_en.htm

my Khorn's woofer impedance as a graph

TEXT


Freq Impedance Phase
1.029 3.664 2.082
1.059 3.664 2.082
1.091 3.664 2.082
1.122 3.664 2.082
1.155 3.664 2.082
1.189 3.664 2.082
1.224 3.664 2.082
1.260 3.664 2.082
1.297 3.664 2.082
1.335 3.653 3.557
1.374 3.653 3.557
1.414 3.653 3.557
1.456 3.653 3.557
1.498 3.653 3.557
1.542 3.653 3.557
1.587 3.653 3.557
1.634 3.653 3.557
1.682 3.653 3.557
1.731 3.653 3.557
1.782 3.653 3.557
1.834 3.653 3.557
1.888 3.653 3.557
1.943 3.653 3.557
2.000 3.674 4.272
2.059 3.674 4.272
2.119 3.674 4.272
2.181 3.674 4.272
2.245 3.674 4.272
2.311 3.674 4.272
2.378 3.674 4.272
2.448 3.674 4.272
2.520 3.674 4.272
2.594 3.674 4.272
2.670 3.730 5.005
2.748 3.730 5.005
2.828 3.730 5.005
2.911 3.730 5.005
2.997 3.730 5.005
3.084 3.730 5.005
3.175 3.730 5.005
3.268 3.730 5.005
3.364 3.753 5.659
3.462 3.753 5.659
3.564 3.753 5.659
3.668 3.753 5.659
3.775 3.753 5.659
3.886 3.753 5.659
4.000 3.771 6.316
4.117 3.771 6.316
4.238 3.771 6.316
4.362 3.771 6.316
4.490 3.771 6.316
4.621 3.771 6.316
4.757 3.797 7.076
4.896 3.797 7.076
5.040 3.797 7.076
5.187 3.797 7.076
5.339 3.808 7.774
5.496 3.808 7.774
5.657 3.808 7.774
5.823 3.808 7.774
5.993 3.821 8.509
6.169 3.821 8.509
6.350 3.821 8.509
6.536 3.821 8.509
6.727 3.824 9.230
6.924 3.824 9.230
7.127 3.824 9.230
7.336 3.844 10.028
7.551 3.844 10.028
7.772 3.844 10.028
8.000 3.865 10.859
8.234 3.865 10.859
8.476 3.865 10.859
8.724 3.884 11.740
8.980 3.884 11.740
9.243 3.884 11.740
9.514 3.900 12.591
9.792 3.900 12.591
10.079 3.915 13.347
10.375 3.915 13.347
10.679 3.938 14.133
10.992 3.938 14.133
11.314 3.966 14.974
11.645 3.966 14.974
11.986 4.003 15.904
12.338 4.003 15.904
12.699 4.032 16.826
13.071 4.032 16.826
13.454 4.061 17.736
13.849 4.061 17.736
14.254 4.093 18.644
14.672 4.119 19.628
15.102 4.119 19.628
15.545 4.160 20.551
16.000 4.209 21.498
16.469 4.209 21.498
16.951 4.287 22.433
17.448 4.342 23.554
17.959 4.389 24.705
18.486 4.389 24.705
19.027 4.432 25.776
19.585 4.546 27.409
20.159 4.593 27.986
20.749 4.686 29.171
21.357 4.785 30.378
21.983 4.897 31.567
22.627 5.019 32.838
23.290 5.158 34.098
23.973 5.321 35.376
24.675 5.509 36.695
25.398 5.725 37.961
26.143 5.965 39.108
26.909 6.240 40.162
27.697 6.552 41.168
28.509 6.929 42.129
29.344 7.611 43.465
30.204 8.470 44.531
31.089 9.250 44.881
32.000 10.896 44.108
32.938 13.014 41.395
33.903 15.683 34.924
34.896 18.324 24.599
35.919 19.808 9.781
36.971 19.719 -6.412
38.055 17.507 -21.604
39.170 14.052 -32.590
40.317 12.188 -35.693
41.499 10.328 -37.601
42.715 8.464 -37.794
43.967 7.243 -36.151
45.255 6.388 -33.846
46.581 5.767 -30.693
47.946 5.323 -27.651
49.351 5.027 -24.667
50.797 4.794 -21.698
52.285 4.629 -18.927
53.817 4.512 -15.243
55.394 4.444 -12.550
57.018 4.430 -10.949
58.688 4.413 -7.972
60.408 4.399 -5.372
62.178 4.380 -2.545
64.000 4.375 -0.414
65.875 4.428 1.764
67.806 4.480 3.599
69.792 4.524 5.380
71.838 4.573 7.623
73.943 4.713 10.157
76.109 4.959 11.989
78.339 5.256 12.517
80.635 5.450 12.345
82.998 5.650 12.083
85.430 5.877 11.645
87.933 6.101 10.204
90.510 6.246 7.784
93.162 6.271 5.369
95.892 6.184 3.233
98.701 6.045 1.933
101.594 5.848 1.511
104.571 5.691 2.209
107.635 5.661 3.207
110.789 5.697 3.453
114.035 5.678 3.159
117.377 5.615 3.395
120.816 5.594 3.868
124.356 5.600 4.201
128.000 5.585 4.063
131.751 5.511 4.553
135.611 5.558 6.048
139.585 5.748 6.673
143.675 5.996 4.300
147.885 5.808 1.136
152.219 5.406 1.233
156.679 5.183 5.316
161.270 5.456 7.529
165.995 5.725 6.440
170.860 5.786 3.552
175.866 5.538 0.748
181.019 5.198 0.323
186.324 4.878 1.916
191.783 4.680 5.175
197.403 4.625 8.239
203.187 4.643 10.846
209.141 4.727 13.402
215.269 4.858 15.122
221.577 4.953 16.199
228.070 5.045 17.475
234.753 5.200 18.719
241.632 5.374 19.056
248.712 5.500 18.867
256.000 5.588 18.755
263.501 5.654 18.713
271.223 5.743 19.053
279.170 5.932 18.309
287.350 5.928 15.802
295.770 5.649 14.584
304.437 5.381 16.899
313.358 5.414 19.754
322.540 5.507 21.031
331.991 5.542 22.166
341.719 5.606 24.030
351.732 5.810 26.064
362.039 6.168 26.994
372.647 6.599 25.290
383.567 6.653 20.929
394.806 6.263 18.799
406.375 5.876 20.946
418.282 5.876 24.013
430.539 6.025 25.729
443.155 6.159 26.406
456.140 6.246 26.953
469.506 6.353 27.384
483.264 6.454 27.378
497.424 6.448 27.113
512.000 6.382 27.828
527.003 6.380 29.437
542.445 6.492 31.058
558.340 6.679 32.080
574.701 6.852 32.091
591.541 6.899 31.999
608.874 6.899 32.692
626.715 6.978 33.994
645.080 7.135 35.112
663.982 7.338 35.676
683.438 7.477 35.982
703.464 7.595 36.479
724.077 7.866 37.569
745.294 8.166 36.255
767.133 8.141 35.100
789.612 7.937 35.703
812.749 8.039 37.942
836.565 8.304 39.146
861.078 8.585 39.697
886.309 8.900 40.020
912.280 9.284 39.588
939.012 9.623 37.750
966.527 9.567 35.291
994.849 9.257 34.502
1024.000 9.040 35.964
1054.005 9.045 37.696
1084.890 9.189 39.244
1116.680 9.412 40.529
1149.401 9.658 41.404
1183.081 9.938 42.280
1217.748 10.365 43.148
1253.431 11.048 42.871
1290.159 11.528 39.434
1327.964 11.272 36.375
1366.876 10.709 36.513
1406.929 10.696 38.550
1448.155 10.842 38.929
1490.589 10.874 39.493
1534.266 10.987 40.395
1579.224 11.176 40.928
1625.499 11.270 41.126
1673.129 11.365 41.905
1722.156 11.533 42.658
1772.619 11.727 43.290
1824.561 11.936 43.839
1878.024 12.154 44.312
1933.055 12.371 44.726

North Reading's notch filter impedance

AK-4 notch filter impedance

my right Khorn's response

North Reading Engineering's response without and with fitler

Karlson Evangelist

 

RE: When EQ-ing a Khorn w. notch filter - which mic perspective is dominate with what one hears ?, posted on September 21, 2016 at 17:36:28
weltersys
Industry Professional

Posts: 685
Location: FL
Joined: September 28, 2004
 "at around 8 feet back and ~ midhorn height, response looks pretty good considering 1/24 octave resolution."

Fred,

A flat, omnidirectional microphone placed at your ear's listening position is fairly representative of what your ears are "hearing", but not what may "sound good" to your ears. The response you posted shows 40 Hz with less SPL than 1000 Hz, and a rapid drop below 40 Hz.

In general most recording engineers and audiophilanthropic types prefer a fairly "flat" response from as low as the speaker can produce without "crapping out" at the desired listening SPL to around 1kHz, then everybody differs by a dB here or there as to what the roll off above should be, opinions often depending on the loudspeaker's directivity "Q", and the room's HF absorption (measured in Sabins, IIRC).

The 136 Hz peak is not present at around 8 feet back and ~ midhorn height, if that is where your ears are at, try EQ for there, take two asprin, call me in the morning.

Art

 

RE: When EQ-ing a Khorn w. notch filter - which mic perspective is dominate with what one hears ?, posted on September 21, 2016 at 18:49:01
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 (need more than that for my old age problems - hahaha) why did North Reading decide to make a notch filter? their graph was close to my floor plane graph. Why did Klipsch incorporate a notch filter on their later K-horns?

BEST
ps- love your Dad's little Ks
Karlson Evangelist

 

RE: When EQ-ing a Khorn w. notch filter - which mic perspective is dominate with what one hears ?, posted on September 22, 2016 at 08:12:39
weltersys
Industry Professional

Posts: 685
Location: FL
Joined: September 28, 2004
 "why did North Reading decide to make a notch filter? their graph was close to my floor plane graph. Why did Klipsch incorporate a notch filter on their later K-horns?"

I would assume the filters were employed because the products you mentioned had narrow band peaks that require reduction both in free space and typical rooms.

From your descriptions, your room is not so very "typical" ;^), apply filters as required for it, and as you like for your hearing.

Have fun,

Art

 

RE: When EQ-ing a Khorn w. notch filter - which mic perspective is dominate with what one hears ?, posted on September 23, 2016 at 21:13:30
Inmate51
 You should acquire a copy of two books (and likely a couple of others):

"Master Handbook Of Acoustics" - F. Alton Everest
"Why You Hear What You Hear" - Dr. Eric Heller

These will help. You'll learn a lot.

:)

 

RE: When EQ-ing a Khorn w. notch filter - which mic perspective is dominate with what one hears ?, posted on September 23, 2016 at 22:53:35
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 thanks for the references, but being "old" I need to sell some of my classic books and audio components. With flexy/resonant walls, K-horn's response per AES October 2000, room modes, i just want clear bass from the damn thing (if possible from a folded horn with small mouth mated to a small mouth midhorn in a poorly constructed house) - I'll try North Reading's notch filter and just unwound a 20mH coil to ~12.9mH/0.6 ohm dcr.

I think Klipsch's AK4 notch filter is tuned closer to the AES response than North Reading. That said, John Warren presents favorable data on that website.

maybe some corner traps would help

AES graph



North Reading before and after their ~13mH/156uF/4.5R (total resistance of coil and series R)


Karlson Evangelist

 

F'whoop! , posted on September 27, 2016 at 04:23:15
Timbo in Oz
Audiophile

Posts: 23221
Location: Canberra - in the ACT - SE Australia
Joined: January 30, 2002
 The sound of some ideas passing you by?


Warmest

Tim Bailey

Skeptical Measurer & Audio Scrounger


 

RE: - which mic perspective = what we hear? is the boom and indistinct bass my room walls or the Khorn Peak ?, posted on September 29, 2016 at 11:36:36
tomservo
Manufacturer

Posts: 8209
Joined: July 4, 2002
 Hi Freddyi
Sorry for the delay.
What you want is a series tank or notch filter.

Using your magnitude and impedance and eye balling your peak at around 10dB over flat, what you should try is a 3mhy choke, in parallel with 500mfd np and also in parallel 6 ohms.

That is in series with your woofer.
This should flatten your response nicely.
Have fun, best
Tom

 

RE: - which mic perspective = what we hear? is the boom and indistinct bass my room walls or the Khorn Peak ?, posted on September 29, 2016 at 14:56:54
freddyi
Audiophile

Posts: 3852
Joined: December 6, 2001
 thanks - - I'm wondering why the use of a "series" filter in the first place? - I'll add some wire to a 2mH - order an electrolytic.

I think its hopeless due to wall resonance - its modern 2x6 16"OC, vinyl siding for outside wall, room wall = 3/4" flooring plywood topped with 3/4" sheetrock. When I thump the wall with my hand, it rings with a nasty "booommmmmmm" for a long time. Maybe PWK's false corners would help?? - but they take enough wood to build a whole new system.

Do K-horns ring in a room with rigid walls? I remember them somewhat better in my old house which had oak 2x4 and plaster over lathe.


BEST,
Freddy
Karlson Evangelist

 

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