Subwoofer response

[Greg Yeatts]

I built a DIY sub based on a Dayton 12" DVC, an Adire PR15X weighted to 750 grams and a 3.3 ft3 box. I took the following measurements using a Rat Shack SPL meter. The measurements were taken from about 8 ft away. Correction factors were used. The room is 13.5' X 23' and is connected to another 14' X 20' room with a double doorway (no doors). The response is for the sub only with the crossover bypassed. Sine waves were used for testing.

Freq db
20 90
25 90
32 92
40 90.5
50 97.5
63 93
80 98
100 97

When I modeled my sub, It looked pretty flat from 100 hertz to the f3 of 21 hertz. Are the problems in the curve room modes. I located a BFD at Mars Music today for $129. I think I may buy it and give it a try.

[Lex]

Greg, I am not the speaker guru, rather the cable guru. I would guess your probably getting some room nulls, and EQing it is the way to flatten out the response. But Thomas and some of the others are likely to have a better answer.

Welcome to the forum too!

Lex

[ThomasW]

Hi

Yes you're going to need to get something like a Behringer DSP1100P/DSP1124P and use the parametric EQ function(preset filters #4 or 5). This will allow you to flatted the response. The proper way to do this is by flattening the peaks. Don't try to boost the nulls, that's physically impossible




theAudioWorx
Klone-Audio

[Andrew Pratt]

once you get that BFD take a look on Sonnies site for a good instruction manual on the BFD...

[Greg Yeatts]

So, I guess my problem is not that unusual?

[ThomasW]

Doesn't look like a big problem at all. The Behringer will do the job.




theAudioWorx
Klone-Audio

[Lex]

I wound up building Sonnie some custom CATs for his as well. I am sure his site details that too.

If you need to find Sonnie, let us know, he's here, on TTP for sure in Not Ready for Primetime.

Lex

[ThomasW]

?????




theAudioWorx
Klone-Audio

[Lex]

you have a question Thomas? Go ahead, spit it out.

I was just commenting about Sonnie's great writeup on the feedback destroyer for which I built the cables for it. It's worth a read.

Lex

[Sonnie Parker]

Geesh....

sorry Greg... I should have been all over this thread. Where have I been? :roll: :roll:


I might can make a few suggestions for ya.

You used 1/3 octave tones. I would use 1/6 octave to get a better picture. I have correction values for the RS meter at 1/6 octave intervals.

At present, and as ThomasW stated, you don't need to boost anything as far as 1/3 octave measurements are concerned. You have a couple of peaks but the BFD will tame those easily with a couple of filters....... maybe 3 or 4 depending on what your x-over point will be. You can boost if you end up needing to after you re-measure at 1/6 octave and it may help if you have some dips.... but you stand the chance of using up some amp headroom. This would depend on what amp you are using and how serious a boost you try. Some dips can be tamed and some can not.

After you get the response flattened out, you will most likely find your low end has disappeared. This may be fine for music, but for movies you'll probably want it back. Good reason to set up a couple of presets (4 and 5) on the BFD, so you can switch back and forth. On 4 set it up for flat and on 5 set it up for a house curve, which I can explain if you need me to. You may end up liking the house curve for both music and movies.

You can find the following here:

*1/6 octave test tones (10 seconds... 8 seconds full with fade in and fade out first and last second)
*1/6 octave correction values for RS analog meter
*an Excel Workbook already set up with correction values and a graph (all you have to do is plug in your raw measurements)

Anything else you need, you just ask..... if I'm lame and not around, e-mail me and I'll jump back in..... but I'll try to keep up with the thread and not be lazy.






SONNIE

Cedar Creek Cinema

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BFD Comprehensive Setup Guide