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Discussion Starter #1
Or should I say Part Deux! Due to life's roller coaster ride of events, it has been almost three years since my last post on here. My home theater is long gone but I have started back with a "simple" two channel set up in my bedroom (12' x 14' x 8'). I was enjoying how it sounded but started thinking about ways to make improvements. Then I remembered I still had all my measurement gear (calibrated ECM8000, 802, and UCA202).

The first attachment is a rough layout of the room. As you can see, there is no room for sound treatment panels. So that option is out. There is a floor lamp in the top right corner, two closets, and an office out cove in between. There are heavy curtains behind the bed running the width of the room. There is also a curtain closing off the office space. After not being able to add sound panels, then I started reviewing my old information on parametric eq's. Being applied to mains or bookshelves, the unit needed to be quiet and very flexible. I look at units from Ashly, Symetrix, Klark, etc. I wound up picking up a Sabine GRQ 3102S.

Once everything was temporarily connected and verified to not add any noise, I fired up REW. I am still using an older version (4.x?). So I opened up the REW help files and started the process all over again. I started with recalibrating the soundcard to include the DAC. Sorry I did not save a graph but it looked just like the very first example. After verifying my levels were good, I decided to see what was going on in the room with no sound.

The next two attachments show the RTA of the noisefloor in the room. It was interesting to see the very low end fluctuate so much with the air on and off.
 

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After playing with the RTA, I was ready to proceed with measurements. I only have two listening positions. The first can be seen in the layout. It is the red outline of the chair. I basically move the chair from the wall and in front of the bed. This is my "critical" or primary listening spot. The second is 6' behind it sitting on the bed and relaxing.

After taking many, many, many measurements I was able to get a good before and after graph. The first attachement shows the results of no eq (green) versus adding eq (red). The second shows how I tried to follow a house curve for the room. I was not focused on staying on the line but more so following the trend. It is far from perfect and still a work in progress. I am still listening and evaluating. It is very different from before and taking some getting use to.

The last two attachments show the before and after waterfall plots. Hope they are correct. It has been a long time since I have done any of this.
 

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I have roughly started on the second seating position to just get it started. Here is the graph results from that.

Was very surprised to see very little change in the upper frequencies even with moving back 6'.
 

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I forgot to add this picture of the speakers (Dali Mentor 2's). As you can see, relocating them is not an option too.
 

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Going back and reading the thread on Minimal Eq, there is a lot about cutting filters and no mention about boosting filters. For some reason I remember trying to avoid boosting filters. Is there a "rule" for them too? Something like only +3dB < 80Hz, +6dB < 500Hz, and only +9dB > 500Hz? I see in one example where there is a gain of +9dB at 50Hz and +7 dB at 63Hz. And obviously nothing narrow like a notch filter.
 

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Nice to see you back weverb!

Not sure you’re talking about with the cut-only thing in the Minimal EQ article. I posted EQ settings for the BFD everywhere, using filters boosted as much as 12 dB. Basically there is no rule for boosting. That stuff is mainly floated by people who have little hands-on experience with equalizers. If they did, they’d know that boosting or cutting is academic. In the end, virtually any equalizing ends up taxing headroom, so you have to have it to spare going in, as discussed here.

Regards,
Wayne
 

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Discussion Starter #7
Hey Wayne!

Its been too long since our discussions and research on parametric eq's.

I was referring to your section on "How to recognize perfectly useless filters" where you mention to avoid filters of only 2-3dB and very narrow bandwidth. It seemed like you were only talking about cutting filters.

So how does one know how much headroom is available? In your link, you mention low volumes and subs. Well, these are bookshelf speakers running full range and at low volumes. I cannot recall a time of having the volume past 1/2 way. Is it less taxing on higher frequencies versus lower. I know it takes a lot of power to boost low frequencies by only 3dB.

What has me asking are those two nasty dips (~120 and ~650Hz.). I am wondering if I can add a little boost to each speaker to help those areas. Obviously, if they are regions that are being sucked out by the room then no eq is going to help.
 

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Hey weverb,

There is so much that accounts for how much headroom one has available that it’s difficult to determine it – things like the speaker’s efficiency, how much boost is applied, and where, etc.

The headroom issue extends to any frequency, but a full-range speaker boosted at bass frequencies would make you run out of headroom sooner, since bass demands more power to begin with. However, often bass clipping isn’t readily audible, so you might actually notice distortion in the upper frequencies before the bass.

In your situation, all you can do is try boosting the problematic areas and see what happens. You’ll hear clipping specifically in the frequency range where you applied the boost when you run out of headroom. If that occurs, you’d need to dial the gain down on that filter.

Regards,
Wayne
 

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Thanks Wayne. I always find our conversations very educational. I figured like most things with audio, it was going to come down to trial and error. Both dips look about the same. I guess I will just pick one to try.
 

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Silly question(s) I am sure, but does one of those dips have more musical information than the other? Basically, correcting which one will have the most audible impact? :scratch:
 

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young people and their graffiti! :nerd:

Ok. I will have to see what I can do filter wise to address both. I did try a couple filters today for the 650 range. I did not take any measurements. Just listened at my normal listening levels and I didn't hear anything bad. Nor did the clip lights blink on the eq. Need to verify the new filters with some measurements later.
 

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Discussion Starter #14
:dumbcrazy: Yea, feelin' a little stupid after that comment. I should have known better. Need to check to see if there is any indicator for clipping on the integrated amp or not. The amp did not feel any warmer than usual either.
 

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Just a small non-REW update. Working on setting up and using the Sabine's contact closure switch on the back of the unit. This will let me switch between different presets without having to use the software. Just the touch of a button.

I already tested one button with a multimeter and continuity. I then tested the adapter and button with the actual unit. The preset was verified to switch with just pressing the button. Just need to finish wiring and making it look pretty.
 

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Ok, did a couple more measurements yesterday which raised a question? Which is more important, the individual speakers' response graph or the two combined? I ask because I was able to adjust the dip at around 660 Hz on each speaker's response, but when combined the dip did not change.
 

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Which is more important, the individual speakers' response graph or the two combined? I ask because I was able to adjust the dip at around 660 Hz on each speaker's response, but when combined the dip did not change.
No thoughts? Wouldn't the two combine only effect the center image and mono recordings? :scratch:
 

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It sounds like there is a reflection point that may need to be addressed with acoustic treatments versus eq. I would try putting the frequency back to what it was and then run a series of sweeps a put large objects, such as a person, in different places along the way and see what is affected on each sweep. While this is by no means a scientific process it is a quick way to identify areas that are susceptible to dead spots.
 

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Discussion Starter #19
Thanks Dale, but as stated in the first post, no room for treatment panels.
 

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Ok, did a couple more measurements yesterday which raised a question? Which is more important, the individual speakers' response graph or the two combined? I ask because I was able to adjust the dip at around 660 Hz on each speaker's response, but when combined the dip did not change.
It would be surprising if both speakers individually had the dip at 660, since the room layout you gave us in the opening post shows non-symmetrical placement in relation to the room boundaries. It would be enlightening to see measurements of each speaker separately, but regardless, if there was no change in response after equalizing both speakers at 660 Hz, then there’s nothing you can do about it, short of re-locating the speakers.

Regards,
Wayne
 
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