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Discussion Starter #1
I just want to make sure that I eqed my system correctly. I used REW and ran sine waves from 0 to 20k, my speakers are Swan T900F and my sub (Emotiva Ultra 12) is crossed at 80hz. I used my UMC-1 to eq and my Radio Shack Digital SPL meter to record.


This is my graph:

http://img844.imageshack.us/img844/8...eakerseqed.jpg


Did I do everything right?
 

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To understand if it done correctly, you need to give us two graphs - before and after. It also helpful to know how much equalization did you apply.
 

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I noticed you're boosting +5,+6, and +7 on several frequencies on your subwoofer. That can be bad. Have you tried placing the sub in another location so you don't have to boost those lower frequencies as much? At higher SPL levels you could run into distortion faster and you will take away headroom on the subwoofers amplifier boosting that much.
 

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Discussion Starter #6

Quote:
Originally Posted by Secret Squirrel /forum/post/21508312


I noticed you're boosting +5,+6, and +7 on several frequencies on your subwoofer. That can be bad. Have you tried placing the sub in another location so you don't have to boost those lower frequencies as much? At higher SPL levels you could run into distortion faster and you will take away headroom on the subwoofers amplifier boosting that much.

The subwoofer in general doesn't do well below 30, I just figured I couldn't be hurting much, what db would you suggest I don't pass? (For my speakers I had to +5db the sound so that instead of raising any frequencies I would just turn them down (UMC-1 has a distortion issue when it comes to raising frequencies))


EDIT: I raised my subwoofer volume 2db's and lowered everything that would made it equal to my original eq (I made 4db my barrier). It sounds better so I assume I was hearing distortion beforehand, however I want to make sure that this eq isn't pushing any limits.

http://img20.imageshack.us/img20/556...ooferneweq.jpg


Also, playing the subwoofer in a different part of my room is pretty much impossible, no other space but this one corner. (My room is small as is, 12ft x 12ft x 8ft tall)
 

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Since you already know that subwoofer doesn't do very well below 30hz I wouldn't boost at 22hz and 28hz at all. Boosting at 22hz and 30hz is making the sub try and do something it's not good at. The lower frequencies are the most taxing as the SPL goes up. If you take the boost off those lower frequencies I don't think you will even notice the difference. Our hearing tapers off at about 25hz. Everything below that is just felt and not really heard with our ears.
 

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Discussion Starter #8

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Originally Posted by Secret Squirrel /forum/post/21508395


Since you already know that subwoofer doesn't do very well below 30hz I wouldn't boost at 22hz and 28hz at all. Boosting at 22hz and 30hz is making the sub try and do something it's not good at. The lower frequencies are the most taxing as the SPL goes up. If you take the boost off those lower frequencies I don't think you will even notice the difference. Our hearing tapers off at about 25hz. Everything below that is just felt and not really heard with our ears.

Alright, I removed the 28 and 22 bands.


Any one know the specific reason as to why I have such a hump at the 44 hert range? Or is it that my room placement just happen to have it boost around that frequency?


Also, the 89 band is -9 cause its the only way I could even out the 80hz range without lowering the 70hz range.
 

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I would never put any gain more than 3 DB. You better increase overall sub level. 40 and 90 Hz anomalies are likely due to room modes. You may try to move sub around to reduce them. You can try to use software like RoomEQ Wizard to generate filters for you. There was room mode calculator somewhere in the Internet (I lost link), which computes room mode frequencies based on dimensions.
 

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Quote:
Originally Posted by Secret Squirrel /forum/post/21508525


The hump at 44hz is most likely due to the room or where the sub is placed in the room.

It's most likely the room. There is a prominent axial mode in a 12x12x8 room along the length and width at 47 Hz (See Ethan Winer's ModeCalc program at RealTraps; it's a free download. You just enter the dimensions of the room and it instantly calculates your modes and tells what they are in each axis). I have a listening room with very similar dimensions, and there's not a whole lot you can do with it other than to tame the modes with lots of thick bass traps. Finding the optimum place in the room for the sub can help, but those modes are going to be there regardless.
 

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Quote:Originally Posted by Khaos

I just want to make sure that I eqed my system correctly. I used REW and ran sine waves from 0 to 20k, my speakers are Swan T900F and my sub (Emotiva Ultra 12) is crossed at 80hz. I used my UMC-1 to eq and my Radio Shack Digital SPL meter to record.

Did I do everything right?

Feel free to ignore the advice about not using any boosted EQ filters. At least as far as subwoofers are concerned, it’s a myth that just won’t die.

The situation is that you had a peak at 45 Hz that needed to be tamed. However, your subwoofer calibration (i.e. its level relevant to the main speakers) was based on that peak. Once you eliminate the peak with equalization, you will find that the sub’s level is now too low, and you have to increase it to compensate for the equalization. Well – say “goodbye” to any headroom you thought you “saved” by using only cutting filters. Gain is gain as far as the signal that passes to the amplifier is concerned. It doesn’t matter if it comes from EQ filters or the sub’s level control.

What’s apparently escaped some folks is the electrical response of the equalizer as filters are added. Let’s take your case for example, with the 45 Hz peak. If you had used a bunch of filters to boost everything above and below 45 Hz up to the level of the peak, the electrical response of the equalizer, passed to the sub’s amp, would look something like this:

 
 



However, if you had merely used a single filter to cut the peak, then re-adjusted the sub’s output to compensate, the electrical response seen by the amplifier would look like this:
 
 


For all practical purposes, what is the difference between the two? Nothing, really: In both cases, the signal passing to the amp has a big hole where 45 Hz “used” to be, and is relatively flat on either side of it (save for the natural roll-out of the filters in the first picture).

And - it should be a no-brainer that multiple cutting filters leave you with peaks between the filters!

 
 





So at the end of the day, cut-only filters accomplish nothing as far as “headroom saving” is concerned. The simple truth is, virtually any equalization taxes amplifier (and driver) headroom, so you have to have enough to spare going in.

That said, I agree with Secret Squirrel about boosting down low in the 22-28 Hz range in your case. As I noted, in order to effectively EQ you have to have a capable sub to start with. Poor extension is typically a sign of a lower-performance subwoofer, or perhaps one that’s trying to fill a room that’s way too large for it. Either way, you’re most likely going to overdrive it if you equalize, and for sure by trying to force low freq extension via EQ. The exception would be if you typically run the system at low volume levels.

Regards,
Wayne A. Pflughaupt


 

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Quote:
Originally Posted by Wayne A. Pflughaupt /forum/post/21516881

Are you sure you posted the right graphs? There's virtually no difference between your before and after graphs. Your before graph, if it is the right one, doesn't need any equalization at all. I don't see anything at 1 kHz that needed adjustment, and your before and after graphs show no noticeable change after EQ.


Feel free to ignore the advice about not using any boosted EQ filters. At least as far as subwoofers are concerned, it's a myth that just won't die.


The situation is that you had a peak at 45 Hz that needed to be tamed. However, your subwoofer calibration (i.e. its level relevant to the main speakers) was based on that peak. Once you eliminate it with equalization, you will find that the sub's level is now too low, and you have to increase it to compensate for the equalization. Well - say goodbye to any headroom you thought you saved by using only cutting filters. Gain is gain as far as the signal that passes to the amplifier is concerned. It doesn't matter if it comes from EQ filters or the sub's level control.


What's apparently escaped some folks is the electrical response of the equalizer as filters are added. Let's take your case for example, with the 45 Hz peak. If you had used a bunch of filters to boost everything above and below 45 Hz up to the level of the peak, the electrical response of the equalizer, passed to the sub's amp, would look something like this:

However, if you had merely used a single filter to cut the peak, then re-adjusted the sub's output to compensate, the electrical response seen by the amplifier would look like this:

For all practical purposes, what is the difference between the two? Nothing, really: In both cases, the signal passing to the amp has a big hole where 45 Hz used to be, and is relatively flat on either side of it (save for the natural roll-out of the filters in the first picture).


And - it should be a no-brainer that multiple cutting filters leave you with peaks between the filters!

So at the end of the day, cut-only filters accomplish nothing as far as headroom saving is concerned. The simple truth is, virtually any equalization taxes amplifier (and driver) headroom, so you have to have enough to spare going in.


That said, I agree with Secret Squirrel about boosting down low in the 22-28 Hz range in your case. As I noted, in order to effectively EQ you have to have a capable sub to start with. Poor extension is typically a sign of a lower-performance subwoofer, or perhaps one that's trying to fill a room that's way too large for it. Either way, you're most likely going to overdrive it if you equalize, and for sure by trying to force low freq extension via EQ. The exception would be if you typically run the system at low volume levels.


Regards,

Wayne A. Pflughaupt

Great advice.
 

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There is a difference between busting and trimming if it is done in digital domain. When too much bust is applied, you can get into digital clipping. For 6dB bust you need at least one more bit in processing. If you do equalization before volume adjustment, you may not have any spare bits of resolution left. Digital equalizers usually have overflow protection, but it involves signal compressing, which you unlikly want to happen too.
 

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Discussion Starter #15

Quote:
Originally Posted by Wayne A. Pflughaupt /forum/post/21516881

Regards,

Wayne A. Pflughaupt

Thank you very much for taking the time out to make this. I do however have a few questions.


Firstly, unless I'm not understanding the point of the 45hz filter, are you claiming that I would be better off moving the -8db band up? I have started looking into bass traps if that is my only solution.


Second, I'm not quite sure I follow how my before and after are not different. The after has a much more linear response then my before. Do people not eq often? Would you have any recommendations in eq regarding the before graph? I open to testing a few things as I really am novice when it comes to the eqing aspects of audio.


EDIT: I noticed just having my speakers flat tends to sound best atm. I'll keep it like that till I can figure out how to eq these properly. Any help would be greatly appreciated xD.
 

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Quote:
Originally Posted by Khaos /forum/post/21557926


Firstly, unless I'm not understanding the point of the 45hz filter, are you claiming that I would be better off moving the -8db band up?




No, I was merely making a point that there really isn’t any functional difference between EQ boosting vs. cutting, for the benefit of the people who think EQ should always be cut-only. I have no idea how your particular sub should have been equalized, since you didn’t give us a sub-specific graph.
Quote:
Second, I'm not quite sure I follow how my before and after are not different. The after has a much more linear response then my before.




My goof, I just noticed that you have your graphs generated with a huge 220 dB scale. That tends to make all graph traces look fairly flat. We’d have a better idea of what you had accomplished before and after EQ with a graph that’s scaled for something like 60 dB. And there's no reason to scale beyond ~15 Hz, unless you have a sub that digs lower than that.


Regards,

Wayne A. Pflughaupt
 
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