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Sub Adjustment With Equilizer

852 Views 7 Replies 4 Participants Last post by  Avliner
I've been reading a lot about people adjusting their woofers with the BFD equilizer from Behringer.

I have an almost brand new equalizer ( TECHNICS Model SH - GE90 ), which is a DSP and also a graphic & parametric equilizer and was wondering whether it'll be possible to use it (as the BFD), in order to make a fine tuning of my woofer.

If so, what's the procedure to run a test and make the necessary adjustments?

Any inputs will be appreciated.

Cheers / Avliner.
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I tried a google search, but couldn't find much info on this product.

One of the most important questions is whether or not you can set the frequencies. For instance, if you have a peak at 29Hz, can you tell the equalizer that you want to cut at 29Hz? If so, then it will work very similarly to the BFD. The very little bit of info I found about it, however, made it sound like there were set frequencies with the lowest one being 31.5Hz. If this is the case, it could probably still be helpful, depending on what your frequency response currently looks like.

You should first use an SPL meter and either the popular excel sheet that floats around or the Room EQ Wizard software to plot your response. Then perhaps some of the experts around here can advise you on what changes to make with your equalizer.

Typically a regular eq can help a bit, but not nearly as well as the BFD. THe BFD lets you pick the exact frequency and then how wide of a "Q" or how far above and below that center frequency you would like to be adjusted. Basically you can really dial in to very specifics, with 12 seperate frequecies. So using it only for you sub you can really fine tune it having 12 settings over a farily small bandwidth of say 20-80hz. A "regular" eq has a set number of frequencies, in this case 8 that must cover the entire spectrum of sound. So in the subwoofer realm, below 80hz, you may only have 1 or 2 adjustment options at the most and they are fixed adjustments. Plus you have no control of the Q--you really don't know how much of a badwidth you are controlling--it could be very small or tight influencing only a few hz or it could be very wide controlling a wide range of hz. I can think of bad scenarios for both. For example, say you have a strong peak at 40hz ( and lets say you are lucky enogh to have a 40hz slide on your eq) If your peak is narrow and the the Q on your eq is wide--you are affecting more frequencies than you want to, introducing valleys or nulls in the 35hz and 45 hz areas. Conversely, if you have a wide hump at say 45-55 hz and your eq only has a 40 and 60hz adjustments. If they both are narrow q's you are actually going to make the problem worse by dropping them. Even in the crazy coincidence that you do get lucky enough to have peaks exactly where you are able to control them with your eq (if that is the case go buy some lottery tickets--odds are about the same) this will only be good for that one very specific placement. If you move anything or change anything in your room, it will change the frequency response. You will not have any ability to flexible in the slightest. I hope this helps. For $100 the BFD is a real bargain for what you can do with it.
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thanks for your speedy reply.

Attached you'll find the tech specs & front view of the EQ.

Perhaps you or someone else can help me out on that.

It seems to be such an interesting thing though, but I must tell you that I need to learn a lot more...

Cheers / Avliner.

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now that I see the specs on that particular model, it looks like it has a better shot at being helpful than the scenario I described above. But still not nearly a useful as the BFD. It has 5 bands in the sub woofer range, and a two position Q. Again, it might be worth a shot if you already have it. Good luck.

thanks for the interest shown. Yeah, it does woth a trial with my current EQ; however I must bother you again and asking if you could inform a step-by-step procedure to perform the test.

According to your comments, it's obvious the you undertand pretty much well about such procedure.

All inputs will be most appreciated.

Cheers / Avliner.
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That EQ says it's a parametric, but the center frequencies appear to be fixed. I guess they can call it a "parametric" because it has adjustable "Q's", even though it's only 2 settings. Anyway, unless you have peaks at exactly the center frequencies of 31.5, 40, 50, 63 and 80, it won't be of much help. However, if you do have peaks at one or more of those frequencies, it may be useful to tame them. Here is the procedure:

1. Get an SPL meter. SVS sells one.

2. Get some test tones. Realtraps has some free ones, with great instructions for use. Also, Avia has test tones and a frequency sweep you can use.

3. Place the SPL meter at your LP as close as possible to where your ears will be.

4. Play the test tones and read the meter. If you use the Realtraps test tones, play track 30 first and set the volume of your receiver so that the SPL meter reads about 70 dB. Then start at track 1 and record the levels. ACI has a spreadsheet you can use to record them.

5. Look at the results. Look especially for peaks above the 70 dB average. If you have a peak at one of the above frequencies, lower the level of that frequency by the amount of the peak. If you have nulls, (frequencies that drop well below 70 dB), don't attempt to increase their level. You can't do much about nulls with EQ.

I think you'lll probably come to the realization that this Technics piece is really a glorified set of tone controls and a Karaoke player. It's not intended as a bass EQ, nor will it do as good a job as a BFD. I'm sorry if that sounds harsh, but it's the reality of the situation.

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[QUOTE I'm sorry if that sounds harsh, but it's the reality of the situation.


Hi Craig,

wow, thanks a lot for a detailed explanation.

I don't feel anything harsh on your comments, you're just telling the truth.

You know, nowadays an EQ is basically not required anymore, so I just tought I could use it to tame the woofer, if necessary.

By the way, I do have an SPL already, so I'll try to follow your guidelines to see what happpens anyway.

Cheers / Avliner.
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