Edward J M
Senior HTF Member
- Joined
- Sep 22, 2002
- Messages
- 2,031
Hello Everyone:
I figured it was time to verify the in room frequency response of my SVS 20-39PC+.
I burned a CD using a 1/12 octave frequency generator downloaded off the Shiva Sonotube webpage. Each tone is 10 seconds long, and the sweep ran from 10 Hz to 71 Hz.
I am using a factory certified professional-grade Bruel & Kjaer Model 2205 SPL meter which I just calibrated. This SPL meter is accurate down into the subsonic range, and does not need a "Rat Shack" type correction factor for bass tones. Meter settings are C-Weighted, Slow.
I mounted the B&K on a tripod at the listening position, about 11 feet from the sub, pointed toward the front of the room, and tilted about 40 degrees up toward the ceiling.
I set the master volume on my receiver to give me about an 80 dB average volume. I am not using any type of equalizer or feedback destroyer. This is the real deal in my HT room at the couch.
For the purposes of the test, I set the SS filter to 12 Hz, just to see how low this thing can really go.
I ran Test #1 with all three vent ports open, and Test #2 with two vent ports open and one vent port plugged with the factory supplied foam port plug.
I plotted all of this in an Excel spreadsheet which looks really neat, but I can't attach it here, so here are the test numbers. The first column is the frequency, the second column is Test 1, and the third column is Test 2.
Test 1 All Ports Open:
As can be seen from Test 1, the sub holds a nice flat +/- 4 dB from 70 Hz down to about 30 Hz, and then begins a gentle rise, cresting at +10 dB at 24 Hz, and then dropping back down to -3 dB at around 16 Hz. It hangs in there suprisingly well checking in at -5 dB at a staggering 11 Hz.
Test 2 Two Ports Open, One Port Plugged:
As can be seen from Test 2, the sub holds +/- 4 dB from 70 Hz down to 11 Hz. Read it again folks - an essentially flat line from 70 Hz to 11 Hz with no major peaks or dips - in my HT room, without EQ, or a feedback destroyer.
My Preference and Summary:
Although the in room response is obviously more accurate with one port plugged, I actually prefer HT playback with all three ports open. The flat response from 70 Hz down to 30 Hz gives me accuracy with no boom, and the gentle rise and peak at 24 Hz provides reinforcement right where most LFE effects are at their most impressive.
Nonetheless, the accuracy and flatness provided by plugging one port is quite simply amazing for ANY sub at ANY price. But for an $800 asking price - this in room frequency response is almost beyond belief!
Regards,
Ed Mullen
Freq.Test 1 SPLTest 2 SPL
10 65 68
10.6 69 73
11.2 75 81
11.9 76 82
12.6 74 81
13.3 75 80
14.1 75 81
15 75 82
15.8 76 83
16.8 78 84
17.8 80 84
18.8 84 83
20 87 83
21.1 88 81
22.4 88 80
23.7 90 82
25.1 88 82
26.6 86 81
28.2 82 79
29.9 80 77
31.6 81 77
33.5 80 75
35.5 79 76
37.6 78 76
39.8 77 76
42.2 77 76
44.7 78 77
47.3 79 78
50.1 80 79
53.1 80 79
56.2 82 82
59.6 84 84
63.1 84 84
66.8 84 84
70.8 80 80
I figured it was time to verify the in room frequency response of my SVS 20-39PC+.
I burned a CD using a 1/12 octave frequency generator downloaded off the Shiva Sonotube webpage. Each tone is 10 seconds long, and the sweep ran from 10 Hz to 71 Hz.
I am using a factory certified professional-grade Bruel & Kjaer Model 2205 SPL meter which I just calibrated. This SPL meter is accurate down into the subsonic range, and does not need a "Rat Shack" type correction factor for bass tones. Meter settings are C-Weighted, Slow.
I mounted the B&K on a tripod at the listening position, about 11 feet from the sub, pointed toward the front of the room, and tilted about 40 degrees up toward the ceiling.
I set the master volume on my receiver to give me about an 80 dB average volume. I am not using any type of equalizer or feedback destroyer. This is the real deal in my HT room at the couch.
For the purposes of the test, I set the SS filter to 12 Hz, just to see how low this thing can really go.
I ran Test #1 with all three vent ports open, and Test #2 with two vent ports open and one vent port plugged with the factory supplied foam port plug.
I plotted all of this in an Excel spreadsheet which looks really neat, but I can't attach it here, so here are the test numbers. The first column is the frequency, the second column is Test 1, and the third column is Test 2.
Test 1 All Ports Open:
As can be seen from Test 1, the sub holds a nice flat +/- 4 dB from 70 Hz down to about 30 Hz, and then begins a gentle rise, cresting at +10 dB at 24 Hz, and then dropping back down to -3 dB at around 16 Hz. It hangs in there suprisingly well checking in at -5 dB at a staggering 11 Hz.
Test 2 Two Ports Open, One Port Plugged:
As can be seen from Test 2, the sub holds +/- 4 dB from 70 Hz down to 11 Hz. Read it again folks - an essentially flat line from 70 Hz to 11 Hz with no major peaks or dips - in my HT room, without EQ, or a feedback destroyer.
My Preference and Summary:
Although the in room response is obviously more accurate with one port plugged, I actually prefer HT playback with all three ports open. The flat response from 70 Hz down to 30 Hz gives me accuracy with no boom, and the gentle rise and peak at 24 Hz provides reinforcement right where most LFE effects are at their most impressive.
Nonetheless, the accuracy and flatness provided by plugging one port is quite simply amazing for ANY sub at ANY price. But for an $800 asking price - this in room frequency response is almost beyond belief!
Regards,
Ed Mullen
Freq.Test 1 SPLTest 2 SPL
10 65 68
10.6 69 73
11.2 75 81
11.9 76 82
12.6 74 81
13.3 75 80
14.1 75 81
15 75 82
15.8 76 83
16.8 78 84
17.8 80 84
18.8 84 83
20 87 83
21.1 88 81
22.4 88 80
23.7 90 82
25.1 88 82
26.6 86 81
28.2 82 79
29.9 80 77
31.6 81 77
33.5 80 75
35.5 79 76
37.6 78 76
39.8 77 76
42.2 77 76
44.7 78 77
47.3 79 78
50.1 80 79
53.1 80 79
56.2 82 82
59.6 84 84
63.1 84 84
66.8 84 84
70.8 80 80
