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Measurements - what to do next

ppataki

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Sweep - left only
Managed to flatten it to this:

1666336905595.png


I suggest trying it at least to hear how it sounds (doing the same with the right channel too)
If you attach here the right channel too I can send you the convolution file with the flattening filter
 

ernestcarl

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View attachment 238564

Edit: quickie in Paint.NET. Not 100% sure about the alignment. The overlay could have been a fraction more up maybe. Added the source files for you or anyone to play with it further.

Depending on distance, it may have been better to compare with a PIR or estimated in-room response curve — of course, the link you gave did not have them anyway.

BTW, there’s a really handy tool in VituixCAD to trace SPL from plot images. Same one I use most of the time… Not a lot of effort is required to learn how to use that specific tool.
 

LTig

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Moving mic - RTA - periodic pink noise. Left channel (right looks similar).

Why such a high Q value of 7 for the filter at 860?
I would EQ down the peaks at 44 and 62 Hz with rather sharp filters, also the peak at 900 Hz, and try to raise the region between 100 and 300 Hz with a wide filter. So 4 filters should do.
 
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brk

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Thanks everyone. Ppataki - I cannot find the right measurements so will have to re-do. If you send me the correction for the left I should be able to easily adapt. You can see the current EQ strategy I chose on that first graph - with sharp reductions around 44 and 62. Will try a broad filter from 100-300 hz to see how it sounds.
 

ppataki

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holbob

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have you tried pointing the speakers straight ahead rather than just at your ears? May bring some of the high frequencies down a bit.
 
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brk

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Thank you for the file. I see that you use multiple high Q filters to get the response- are the "rules" about avoiding steep filters beyond the bass region and staying away from areas of high phase shift just recommendations? Also, you EQ to a flat frequency response - as this is at the listening position should I be creating some slope in the response?
 

ernestcarl

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Just keep in mind: Although you can linearize the FR with convolution, this really does not change the speaker’s directivity and the room’s reflection decay characteristic. The former is baked in the design while the latter can be improved by physical adjustments like acoustic room treatment. Non-flat or relatively even reflection decay pattern will add its own coloration the sound that you hear despite achieving a “flat” looking FR curve.
 

ppataki

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Thank you for the file. I see that you use multiple high Q filters to get the response- are the "rules" about avoiding steep filters beyond the bass region and staying away from areas of high phase shift just recommendations? Also, you EQ to a flat frequency response - as this is at the listening position should I be creating some slope in the response?

Well, there are 'rules' and there is your ears - I suggest listening to it and then you can judge for yourself ;)
Yes, forgot to mention that you shall apply a high shelf to tame the highs and a low shelf to increase the lows on top of the filters that I sent
Also you can consider a high-pass filter if needed to get rid of frequencies that would overload the drivers
 

Hipper

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Hello room acoustics wizards,

After some time measuring and working with REW I have managed to get meaningful improvements in the measurements and subjective sound of my two-way speakers- see attached. Space limitations require set up along the long wall of a 22 x 14 foot room, so they are only two feet from the back wall and about 10 feet from me. Within limitations, moving them around does not help these measurements very much. The attached responses represent averages taken from four positions around my left ear location using a UMIK and a fixed stand (the right speaker looks very similar). Note that some of the bass EQ strategy is intended to mimic the analog EQ box that originally came with the speakers (boost at 35 hz plus a subsonic filter),

1. Would a subwoofer help? (possibly add deep extension and fill in a touch more around 80hz)
2. Ever since seeing that ugly 100-300 hz region I stayed away from it and do not EQ. Is this correct?

Thanks very much,

Bryan

Unless there's some major fault with your speakers or input you should be able to make quite big alterations by positioning.

Can I just make sure I understand how your speakers are positioned.

In your first post you say that they are set up on the long wall. I take that to mean that the wall behind the speakers (normally called the front wall) is 22'. They are 2' forward of the front wall and also 10' from your listening position (LP). They are therefore 12' from the back wall. In a later post you say that they are 6 feet apart. which means they are 8' from each side wall. Is this correct? Let's assume it is. Your LP is therefore about 2.5' from the back wall (using Pythagoras!).

One positioning idea is The Thirds. This would locate the inner front edge of your speakers 7'4" from the side walls and 4'8" from the front wall with your LP (specifically your ears) 4'8" from the rear wall. That makes the speakers about 7'4" apart and your distance from ear to one speaker just under 6' (more Pythagoras). It might look silly but it's worth a try. If it's too silly or impractical for you, you could try The Fifths.

http://www.barrydiamentaudio.com/monitoring.htm

The coffee table is probably not good - it will reflect sound upwards. Test that by removing it. Generally you should have no obstructions between you and the speaker. Leather chairs may also reflect more than fabric ones. Also I found that having equipment on the front wall - amp etc, or a screen - will also impact what you hear at the LP. I don't have a screen but put my gear on the side wall (it needs longer speaker cables but this also reduces irritations from LED lights).
 
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brk

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Thanks! I rechecked the numbers and found a mistake. Here are the true dimensions:
The room is 19 x 13 feet with the speakers set up on the long (19 foot) wall. Their outside edges are 70 inches from the side walls. Their backs are 22-24 inches from the back wall - 22 for the outside edge and 24 for the inside edge due to toe in. They are 6 feet apart tweeter to tweeter. I sit 9 feet from the mid-point - the back wall is 18 inches behind my head.

I tried measuring just the left speaker at a range of distances from 12-40 inches from the back wall. At about 36 inches out, the dip gets a little smaller but that is too far out into the room. Have not tried varying the side wall distance mostly because a tweeter-tweeter distance of 6 feet apart seems to provide optimal imaging. Gear is on side wall as you mention.

The rule of thirds will not be practical. Will see about fifths. Thanks,
 

Doodski

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the back wall is 18 inches behind my head.
A large absorption panel right behind your head will help with imaging. I've done this one before using 2, 6 foot x 3 foot panels and the entire room changed for the better.
 
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brk

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Any ideas for an absorption panel that does not look ridiculous? Can you cover it with a picture?
 

Doodski

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Any ideas for an absorption panel that does not look ridiculous? Can you cover it with a picture?
I used 2 of those thick heavy office divider panels behind my head. @ 6 feet high and 6 feet wide with 2 of the panels they are a bit obvious but you could put tapestry over them or a large picture. They can be expensive as new but they do work and come in varying sizes and shapes. If you are on a budget and don't mind buying them used then scope out auctions where they sell for way less than a new price.
 
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