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subwoofer test.......


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#1 of 22 Cam McFarland

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Posted July 02 2004 - 08:46 AM

Ran my Avia to check levels, then put in my copy
of sinewave tones. Here is the result when tones played at
volume setting netting me 75dbs at my listening position which is 14 ft from sub & where I had the spl meter for this test.

10 - 88
15 - 84
16 - 91
17 - 93
18 - 94
19 - 95
20 - 97
25 - 102
27 - 112

At this point i had to back down the volume by -5 for the next 4 tones as I felt the sub was gonna come apart & I didnt want to damage anything. I was hitting levels over 115dbs....

28 - 107
30 - 112
32 - 112
35 - 107

Here I went back to original volume setting...

40 - 97
46 - 96
50 - 93
56 - 93
60 - 93

and this is where I stopped, I left out several of the tones
I tested.

These numbers were taken off the RatShack SPL meter with no changes made as I am not sure how they are to be adjusted.


What the heck does this mean....lol

#2 of 22 Aaron Gilbert

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Posted July 02 2004 - 09:08 AM

Cam,

Those are some fairly impressive numbers there. Let me see if I understand you correctly. The 28, 30, 32, and 35Hz numbers were measured with the volume 5dB below all the other measurements? If so, it would seem you have quite the peak from 25-35Hz. Other than that range, it looks pretty smooth.

Aaron Gilbert

#3 of 22 Cam McFarland

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Posted July 02 2004 - 09:31 AM

Hey Aaron,

I dont know if it would be 5 decibels less, but I backed the receiver volume down from -10, which is where it was set to run the AVIA test, to -15.


Now all I have to do is hook up my BFD thats been here for about a week....what is the ultimate goal, highest db rating
with the lowest db range??

#4 of 22 Jeff B.

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Posted July 02 2004 - 09:36 AM

Cam,
What exactly are you running for you sub setup?

#5 of 22 Cam McFarland

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Posted July 02 2004 - 09:41 AM

I have a Tempest, & am using the Adire Alignment in a ported box.
I am using the 360w from CSS, but it is way overkill, I think even 250w is way overkill for this set-up, actually.
It was my first attempt, already planning a sonosub...Posted Image

#6 of 22 Jeff B.

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Posted July 02 2004 - 09:47 AM

Nice, I think that is what I am going to end up with, except 250w pe amp. The last couple of days my head has been spinning with bigger and bigger ideas, but I think for my first DIY project a ported tempest will be fine.

If its not enough output for me (I doubt it won't be) I can always make something else. Posted Image

Oh ya, very nice numbers btw. Amazing how much performance you can get making your own sub.

#7 of 22 Cam McFarland

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Posted July 02 2004 - 09:48 AM

I dont even know what good numbers would be...

#8 of 22 Wayne Ernst

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Posted July 02 2004 - 10:09 AM

Quote:
Now all I have to do is hook up my BFD thats been here for about a week....what is the ultimate goal, highest db rating

Cam, Thanks for posting the numbers. It's my understanding that with the BFD, you'd want to "tame" some of the peaks to level things out a bit. It's easier to reduce the dB for the higher frequency points as opposed to greatly boosting the dB for the valleys - because doing so will create a lot more strain on your receiver or amp.
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#9 of 22 Cam McFarland

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Posted July 02 2004 - 10:16 AM

Here is a pic pardon the mess, was looking over some goodies for the truck I've had & need to put in.....

#10 of 22 Aaron Gilbert

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Posted July 02 2004 - 10:19 AM

Cam,

Yes, ideally you would have the most output with the lowest variation between all frequencies. As I think has been mentioned in another thread though, I believe the Radio Shack (and other) SPL meters have some inaccuracy, which should be factored in. Over 115dB is quite impressive to me. My subwoofer peaks at 114dB (also in room, like yours). However, due to my 11Hz tuning, I have quite a bit more output from 10-20Hz, which says nothing other than our choice of tuning. Posted Image Most receivers these days are calibrated in decibels, so 5dB change on your receivers display SHOULD correspond to a 5dB change on your SPL meter, assuming you are within your speakers capability.

You should be in great shape once you get the BFD hooked up.


Aaron Gilbert

#11 of 22 Felix_F

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Posted July 03 2004 - 02:35 AM

Quote:
What the heck does this mean....lol

They don't mean much, as they weren't all taken at the same amplitude. I've read quite a few of your posts, Cam, and I hope you don't mind if I make a suggestion. There's a plethora of material available on the web that can be found by doing a few simple searches. Seeing how you mention having a BFD, you may want to first research equalization and understand exactly which constraints are effected by an adjustment of a given parameter. And, please keep in mind that there are no easy answers to complex questions.

Best,
Felix

#12 of 22 Bryan Michael

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Posted July 03 2004 - 04:20 AM

your amp could have a bost on the 25-30 hz range

also a good test is the lotr fotr ring drop sens. try and get a max reading with no audible distorshon and no botoming
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#13 of 22 Cam McFarland

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Posted July 03 2004 - 02:43 PM

Actually, only 4 of the tones were reduced by 5 dbs.

You are absolutely right Felix....... Posted Image



Bryan, it seems like it could as there were a couple different options with this amp, but I ordered
the amp with no boost......

this is the amp I got.

#14 of 22 Cam McFarland

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Posted July 04 2004 - 05:47 PM

I guess these are my corrected numbers.
I went by the numbers on another post.


xxxxxxx.....corrected
10 - 88.....108
15 - 84.....96.75
16 - 91.....102.5
17 - 93.....103.5
18 - 94.....103.5
19 - 95.....103.5
20 - 97.....104.5
25 - 102....107
27 - 112....116.33

At this point i had to back down the volume by -5 for the next 4 tones as I felt the sub was gonna come apart & I didnt want to damage anything. I was hitting levels over 115dbs....

28 - 107.....111
30 - 112.....115.33
32 - 112.....115
35 - 107.....110

Here I went back to original volume setting...

40 - 97......99.5
46 - 96......98
50 - 93......94.5
56 - 93......94.5
60 - 93......94.5

does this look right, or am I all screwed up on what I did?

#15 of 22 Felix_F

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Posted July 04 2004 - 06:14 PM

Cam, you may want to download some tones in 1 Hz or 2Hz (max) increments, burn them to a CD, and run the sweep to get a better picture of what's going on.

Felix

#16 of 22 Cam McFarland

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Posted July 05 2004 - 02:30 AM

Felix, I tested 10-35 in 1Hz increments, & 35-60 in 2Hz increments, just didnt post all the numbers as I figured nobody wanted to see that many.
How would that tell me something different?
Did I adjust my numbers correctly? All I did was add to my Radio Shack numbers the amounts stated on this thread....

Jeremy Stockwell Interpolations

#17 of 22 Felix_F

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Posted July 05 2004 - 03:16 AM

Cam, not knowing where you have the sub's x-over set, it's difficult to say how high you should run the sweep. To be on the safe side, I'd probably run it up to 100Hz. In terms of interpreting the data, I suggest the same thing as I did earlier in the thread. You may want to read-up on the subject and try to get an understanding of the constraints involved.

I also suggest that once you become familiar with the BFD and begin working with it, that you set several curves. As an example, you may want to set a "flat" curve which would be based on the data you get by measuring the sub's FR and adding the posted correction coefficients, as well as a house curve (do a search on the subject). Then listen and decide which you like best. Personally, I use a modified "flat" curve during the rare occasions when I play music on the HT rig and a house curve for movies. I don't know where you were positioned when you took the readings, but I prefer to measure from the listening seat. Make sure, though, that you record the sweep without altering the volume and measure, measure, measure after every change in BFD's settings. HTH

Felix

#18 of 22 Lee Carbray

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Posted July 05 2004 - 05:29 AM

Felix is giving some good advice, although 1-2 hz intervals makes for too many measurements for my liking. 1/6 octave is good enough. If you have not already, download the spread sheet program form here .


Re-run your tones at a lower, constant volume and go up to at least 100Hz like Felix has mentioned. There is no need to keep the master volume at the value you used with Avia.
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#19 of 22 Felix_F

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Posted July 05 2004 - 06:22 AM

Quote:
...although 1-2 hz intervals makes for too many measurements for my liking. 1/6 octave is good enough.

I found that when I setup the EQ with 1/6 octave tones and achieved +/- 2dB results, and then measured the sub's FR in 1Hz intervals, there were quite a few peaks and valleys that weren't being addressed by the corrections. Even though it takes quite a bit longer to setup a curve for 1Hz resolution, for me the time spent is more than worth it. Plus, it's a fun and productive educational experience. That said, it's a personal choice that hinges solely on one's ultimate goal.

Felix

#20 of 22 Cam McFarland

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Posted July 05 2004 - 09:37 AM

Guys,

Got the BFD hooked up & here are new numbers (uncorrected).
I was able to keep volume at one setting. These readings were ALL taken at reference level volume setting .

Felix, as I stated in my original post, ALL readings are taken from the listening position ~14ft from the sub.
Sub crossover is set at 80Hz.

Original numbers are first....New numbers are second

10 - 88 - 87
15 - 84 - 85
16 - 91 - 92
17 - 93 - 93
18 - 94 - 95
19 - 95 - 95
20 - 97 - 93
25 - 102 - 96
27 - 112 - 97



28 - 107 - 97
30 - 112 - 98
32 - 112 - 100
35 - 107 - 94


40 - 97 - 87
46 - 96 - 88
50 - 93 - 93
56 - 93 - 98


I ran new tests at 60, 63, 65Hz and numbers were
WAY up.....around 105 or so.

Even with gain for these 3 Freq. set at -10, it made absolutely NO change......what would cause that?

I dont have Excel on my home computer......

And I still dont get the bandwith part on the EQ!




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