I finally plotted down my FR !

[Vaughan Odendaa]

I have wanted to measure my FR for a long time now but never had the chance because of time contraints. This morning I tested Ethan Winers test tones from approximately 20 hz to 170 hz.

Further info :

* X-over at 80 hz
* Phase at 360 degrees
* Seating position : 2.8 m from source (I am sitting the short way in my rectangular room)
* Pink noise set to 70-71 dB

I have not measured my FR with phase set to 0. But I noticed more deep bass when set to 360. To be sure I'll measure with both. However I did notice that my mid-bass was severely lacking at 360. At the 0 position I had a much fuller mid-range. I don't know why that is nor do I know which is more accurate.

Here is my frequency response :

hz - dB

20 - 86
21 - 91
22 - 90
23 - 89
24 - 87.6
25 - 85
26 - 84
27 - 84
28 - 82
29 - 82.1
30 - 82.2
31 - 82
32 - 82.1
33 - 83
34 - 84
35 - 85
36 - 87
37 - 89
38 - 88
39 - 85.4
40 - 83
41 - 83.1
42 - 84
43 - 83
44 - 83
45 - 82
46 - 81
47 - 79.2
48 - 75
49 - 73.4
50 - 72
51 - 72
52 - 73
53 - 73
54 - 74
55 - 78
56 - 79
57 - 80
58 - 80
59 - 81
60 - 81
61 - 82
62 - 82
63 - 82
64 - 80.5
65 - 75
66 - 70
67 - 73
68 - 74
69 - 76
70 - 81
71 - 81
72 - 79
73 - 72
74 - 70
75 - 72
76 - 72
77 - 70
78 - 69
79 - 69
80 - 69
81 - 69
82 - 69
83 - 70
84 - 72
85 - 74
86 - 76
87 - 79
88 - 81
89 - 82
90 - 82
91 - 83
92 - 83
93 - 83
94 - 82
95 - 81
96 - 80
97 - 75
98 - 69
99 - 73
100 - 75
101 - 77
102 - 80
103 - 82
104 - 84
105 - 85
106 - 85.3
107 - 86
108 - 85
109 - 86
110 - 86
111 - 86
112 - 87
113 - 88
114 - 88
115 - 87
116 - 84
117 - 84
118 - 84
119 - 84
120 - 83
121 - 83
122 - 82
123 - 82
124 - 82
125 - 82
126 - 81.8
127 - 81.4
128 - 81.6
129 - 82
130 - 82
131 - 81.6
132 - 81.7
133 - 82
134 - 81.7
135 - 81.6
136 - 82
137 - 82
138 - 81
139 - 79
140 - 75
141 - 73
142 - 75
143 - 79
144 - 82
145 - 83.2
146 - 84.1
147 - 85
148 - 85
149 - 85
150 - 85
151 - 85
152 - 85.1
153 - 86.1
154 - 84
155 - 88
156 - 89
157 - 89.1
158 - 89
159 - 89
160 - 89
161 - 90
162 - 91
163 - 91
164 - 92
165 - 93
166 - 94
167 - 95
168 - 95.2
169 - 95.3
170 - 93

Perhaps someone can explain to me how to chart this down on Excel or something. It might help me a little bit. Comments will be most appreciated.

Thank you.

--Sincerely,

 

[sploo]

Hi Vaughan,

Well, one fairly easy way is to copy your text into an editor (Notepad etc.) replace all instances of " - " with the tab character, and paste into Excel.

You could also probably save it as a text file and load it into Excel, telling Excel which character(s) you've used as the delimiter.

I've attached an xls file (in a zip).

To be honest, recording the low frequency response of your room manually isn't really worth your time. You almost certainly will need some room treatment, as pretty much every room has issues.

If you were planning on getting a Helmholtz resonator (tuned to a particular problem frequency) then it might be worth doing. The problem of course, is that it takes so long!

If you have an SPL meter with an output phono (like the Radio Shack digital meter) you can use a program called ETF to automatically measure your room response - in a matter of seconds.

This is very useful, as you can look at the entire 20-20k range, and spot, amongst other things, reflections.

 

[Vaughan Odendaa]

Sploo, thank you very much for creating the Excel file ! As I said above, this is the very first time that I have measured my rooms response. I would love to use ETF and I've heard great things about the software, but well, I've also heard from several people that it's complicated to use properly. That kind of scares me. The last thing I want to do is spend $100 + on software that I can't use effectively.

Unless I get serious help of course.

Manually taking down readings is a long process. It took me almost one hour to complete the tones manually up to 170 (including a few mishaps along the way ) but I guess that the majority of people without special software have to endure the same thing. I guess.

Concerning treatment, I know I need it. Definitely. I just don't have the money to buy nor do I have the space at the moment.

So what do you think about my FR results ? Thanks.

--Sincerely,

 

[Vaughan Odendaa]

Sploo, do you have ETF software ? If you do, please tell me what your experiences are with it. BTW, on the excel file, is the region along the 80 point on the graph supposed to represent the ideal flat response ?

Thanks.

--Sincerely,

 

[sploo]

Hi Vaughan,

Well, it was over a year ago when I last used ETF, so it's probably changed a bit.

You could use it in evaluation mode to take basic readings, but not save the results.

I found the setup a little problematic, as it wouldn't work with the soundcard on the first machine I installed it on. Once it's installed though, it was easy to use.

Here's some info about the readings I took, and on the treatment panels I built:

http://spikyfish.com/acoustics/
http://spikyfish.com/acoustics/panels.html

Some more info on recording with ETF:

http://www.ethanwiner.com/density/density.html

Lots and lots (and lots) of info on room treatment:

http://www.ethanwiner.com/acoustics.html

Your low frequency response looks pretty typical - there's a maximum peak to trough (null) of around 26dB. Mine was 30dB, and I got it to under 20dB.

I believe that within 15dB is pretty good, and the pros are satisfied with 6dB in a proper studio (if memory serves me right).

In short - you'll never get a perfectly flat response in a real room, you just hope to get it as good as practically possible. For me, it was the removal of the reflections at higher frequencies that made the most difference to the sound.

 

[bpape]

If you are willing to play with seating, speaker, and sub position, and then do an analysis and properly treat the room, you can get things relatively close.

My goal is to shoot for +/- 5 in a real room with little or no EQ. Sometimes you can't get quite there but it's one pesky frequency that's holding you back.

In general, when you play with positioning, shoot for the locations that yield the fewest and shallowest nulls as those are the hardest to deal with via EQ and the most noticable. Peaks are much easier to deal with.

Bryan