Avantgarde Acoustics Duo XD - first go at measurements and EQ

Bergm@nn

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Aug 14, 2021
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First adventures in room measurement and using the Duo XD parametric EQ, and would appreciate a bit of hand holding and advice from the experts to help me to learn and better understand how best to approach getting it right.

The software in the Duo XD allow you to do 10 point adjustments from the screen below in the XD control software when linked to each speaker using USB/ Ethernet -

1653408988279.png

First job was to take a simple measurement using a calibrated mic connected to the XTZ soundcard and then using REW get a couple of consistent measurements from my listening position (so single point rather than average).

This is what you see between 10-200 Hz -

1653409234501.png

What I hear from my seat with no EQ applied is some boominess when I lean forward about a foot, less so if I lean back or stand behind the sofa. As the volume goes up the boominess then seems to travel back and reach my listening position without leaning forward.

Where do I go from here then?
 

sbnx

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Mar 28, 2017
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Hello,

Out of curiosity, how far is the mic from the speakers? One thing I notice is that your measurement volume is not very loud. You want to be well over the noise floor of your room and excite the room. I usually shoot for an average of 85 dB with pink noise. Does the software allow you to adjust each speaker independently or the same EQ is applied to both speakers? Depending on how symmetric your room is the left and right speakers might have very different response.

How much smoothing do you have applied in the frequency response graph you showed? In the bass you should smooth to 1/24th octave so you can see what is going on. The response you posted is actually pretty smooth being +/-5dB within a pretty large range. Was this response before or after EQ? I am surprised you think it is sounding "boomy". One point to note that EQ is really only applied at the one location. You are actually making other locations in the room potentially worse depending on what the EQ was compensating for.
 

Bergm@nn

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Aug 14, 2021
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Hello,

Out of curiosity, how far is the mic from the speakers? One thing I notice is that your measurement volume is not very loud. You want to be well over the noise floor of your room and excite the room. I usually shoot for an average of 85 dB with pink noise. Does the software allow you to adjust each speaker independently or the same EQ is applied to both speakers? Depending on how symmetric your room is the left and right speakers might have very different response.

How much smoothing do you have applied in the frequency response graph you showed? In the bass you should smooth to 1/24th octave so you can see what is going on. The response you posted is actually pretty smooth being +/-5dB within a pretty large range. Was this response before or after EQ? I am surprised you think it is sounding "boomy". One point to note that EQ is really only applied at the one location. You are actually making other locations in the room potentially worse depending on what the EQ was compensating for.
Thanks for your reply @sbnx

So the room is pretty symmetrical, except for furniture layout (there's a 3 seater sofa on one side of room). However yes I can measure each speaker indepenently.

This was pre EQ so maybe the measurement capture wasn't taken at high enough volume.

I'll retake these this evening hopefully and share how they come out.
 

ecwl

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Mar 20, 2021
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If the boominess is more distinct 1 foot in front of the seating position, you can try putting the microphone at that position and re-measure to see what frequency the boominess is coming from.
Another way is to go to the waterfall plot or spectrogram plot of REW to see which frequency lingers excessively in the room as that frequency is likely the cause of the boom.
Providing the room dimensions sometimes can also help us calculate where the boomy frequency is coming from.
My guess is that you do have a room mode, maybe even the longitudinal one which is causing the boominess. It’s just that your current seating position is well chosen which is why the boominess is reduced. You’re unlikely to be able to completely able to get rid of the boominess in that frequency but you can mitigate it by
1) choosing a good seating position (which you probably already did based on your measurements)
2) put in a lot of thick (>4”) absorbers all over the room along the walls that’s causing the problem (which I don’t do as I don’t want to turn my home into a hi-fi shop and it may or may not cause other sonic issues)
3) lower that boom frequency slightly by EQ but it will never completely correct the problem
 

Bergm@nn

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Aug 14, 2021
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So finally found time to do some more measurements!

1654686385628.png

Green curve is the LH channel; Blue is the RH channel

As per original post, the Duo XD has 10 points of EQ adjustment up to c 500Hz.

So, any comments on the graph and/or suggestions for EQ adjustment very welcome!
 

sbnx

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Mar 28, 2017
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OK. So this makes a lot more sense on why you hear "boominess". You have that huge peak between 70 and 90Hz (centered on 80Hz) in the left channel. Here is what I would suggest for an EQ filter to address that. Choose a "bell" filter for the Left speaker only. Set the center frequency to 80Hz. Set the Q to somewhere around 6. and set the gain to -10. Then measure and see what that gets you. you may have to adjust the gain further -- -12 or -15 until you get it to where you like it.

The bigger concern I see in your measurements is that the left speaker is louder across the entire range from 60 to 200Hz by 5 to 10 dB. I don't think this is really an EQ problem. There are two likely causes. First is you have the gain turned up more on the left channel by 5 to 10dB. I would first try turning the gain down on the left channel and measure as you go. I would try to get that flat area between 120 and 150 Hz to be the same loudness level. The other thing is that the speakers are not aligned properly. Meaning the left speaker is closer to the mic than the right. The two response curves are not very similar at all. You said your room is symmetric but the data doesn't suggest that. Can you include a picture that shows the front of the room. (e.g. stand with your back against the back wall and take a pic of the front wall with speakers.)
 
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sbnx

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Continued... Based on the data I would expect the stereo image to be pulled to the left. Is this indeed what you are hearing. Try putting listening to the now show favorite "Death Row" by Chris Stapleton. In the intro the bass should sound centered with equal pressure coming right at you. When you listen on your system do you hear the bass coming from the left?
 
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Bergm@nn

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Aug 14, 2021
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The bigger concern I see in your measurements is that the left speaker is louder across the entire range from 60 to 200Hz by 5 to 10 dB. I don't think this is really an EQ problem. There are two likely causes. First is you have the gain turned up more on the left channel by 5 to 10dB.

Continued... Based on the data I would expect the stereo image to be pulled to the left. Is this indeed what you are hearing.

Yep, nailed it. This confirms my suspicion that my current preamp is off balance - the balance dial has no centering and behaves oddly so getting the musical image centralised is somewhat tricky.

When I took the measurements of each channel I had the balance dial fully cranked either way left and right - even under those conditions the measured sound shows that it is quieter through the right channel.

Thus confirming that I need a new preamp! Currently looking/ auditioning and hoping to find a replacement in the next few months.
 

ecwl

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Mar 20, 2021
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Hmmm... I think we all have different takes on measurements.

First, I presume we are dealing with an asymmetric setup of the speakers in a room? Because you can see that it's not consistent across all frequency ranges (which it would be if the problem is the preamp or speaker alignment). The fact that the dips for the left & right speakers are different also suggest an asymmetric setup.

I personally also have an asymmetric setup so some of the issues you just have to live with because without extensive DSP/parametric EQ of each speaker, you simply can't get rid of the issue. In fact, tweaking left speaker gain can sometimes make things worse because you're fixing one set of frequencies but making another set of frequencies worse.

Because I presume you've listened to music in an asymmetric setup for a while, chances are, your ears are already used to it. Moreover, since bass is generally less directional (although I would still say it matters), it doesn't matter as much.

Moreover because of room acoustics, you're lucky in that most of the peaks on the left speaker is actually compensated by dips on the right speaker. That's why your combined speaker measurements were relatively flat by comparison.

To me, your 100Hz and 155Hz left speaker peaks are balancing the right speaker's dips so I don't think you should even try to DSP the problem. Moreover, I suspect when you crank up the volume and hear a boominess, it's probably as sbnx said earlier coming from the 80Hz peak. Because at lower volumes, the left and right speakers balance each other out in volume but a higher volume, because the 80Hz peak is a big room resonance, it simply overwhelms and the right speaker's dip no longer cancel out the boom.

The issue to me is whether you can even do parametric EQ only to the left speaker on the Duo XD system. If so, I completely agree with sbnx's approach. But if Duo XD only allows you to parametric EQ both speakers at the same time, that's a bit trickier. You can still use that approach but you may only want to start at -3dB and see how everything sound and then slowly increase the dB to see what is optimal.
 
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sbnx

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I was initially suspicious of the measurements posted in the original post as the response was far too smooth and regular (unless a lot of EQ had already been applied). Something was not right with the measurement setup. There is no way to get the left & right speaker measurements to sum to that. For example, the combined measurement in the OP is very smooth going all the way down to well below 20Hz. but in the individual measurement the output is dropping rapidly below 30Hz. The other area is the frequency band between 70 and 90 Hz. The left channel has a huge 20 dB bump and the right channel is relatively flat with a 5dB dip at 85Hz. This area would still sum to show a large bump between 70 and 90 that is not shown in the graph in the original post. I feel the graph in the OP should be ignored.

@Beergm@nn -- Can you repost a measurement with both speakers playing. Also please post further measurements as you make changes and improvements. A picture of the room would also help.
 
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ecwl

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I was initially suspicious of the measurements posted in the original post as the response was far too smooth and regular (unless a lot of EQ had already been applied). Something was not right with the measurement setup. There is no way to get the left & right speaker measurements to sum to that.
So for the longest time, I don't have a dip at 80Hz for my left and right speakers independently but when combined, I do. Now that I use Acourate to create my DSP filters, I have a better understanding of why that is happening. It is not possible to estimate the summation of the left & right speakers by looking at their individual frequency response curve, particularly in an asymmetric setup because the problem is that even if you can see the volume at specific frequencies at the listening position from the left & right speakers, you are not seeing the phase of that frequency coming from the left vs the right. And if the left & right speakers are in phase at that frequency, then yes, the summation would be as expected by just doing a simple addition. But if the left and right speakers are not in phase (and usually it is because of room acoustics shifting the frequency out of phase since obviously the direct sound from the left & right speakers are in phase), you can get significant cancellation.

But yes, it is probable that the original measurement was excessively smoothed. But I suspect it was still reasonably representative of what the frequency response of both speakers playing simultaneously are.

Another way to say this is that you've probably heard people say that to smooth out the bass, you can have multiple subwoofers at different locations so they won't trigger the same room modes. Well, if you have an asymmetric setup, then your speaker woofers are basically different woofers at different locations that have completely different room acoustic effects so you'll actually get a fairly even bass.
 

Bergm@nn

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Aug 14, 2021
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Yes I would ignore the first measurement. I now have a calibrated minidsp umik 1 mic which I used for the latest graphs.

Here is my room. The differences are that there is a 3 seater sofa on the right, and a fireplace on the left.

Behind the sofa where the picture was taken is a large floor to ceiling shelving system full of vinyl and tapes.

000067E5-1F60-43AB-A9E5-2D5A26712282.jpeg
 
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sbnx

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Nice room and nice view. You might try pulling the speakers out from the wall just a little bit more (1 - 2 inches) and see what that does for the bass. Since you have them in the corner they are exciting the room modes. The best thing would be to pull them out a little bit (1/8") at a time and see if you can find a happy spot. The sofa being where it is relative to the right speaker is going to cause some frequency response aberration but I don't see anything you can do about that other than removing the sofa.

you are on a good path to start. Get the balance control with the preamp sorted out first as you need to be able to trust that what you are hearing/measuring isn't beign skewed by the preamp. Then you can come back and adjust the EQ on the speakers.
 
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matakana

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Yes I would ignore the first measurement. I now have a calibrated minidsp umik 1 mic which I used for the latest graphs.

Here is my room. The differences are that there is a 3 seater sofa on the right, and a fireplace on the left.

Behind the sofa where the picture was taken is a large floor to ceiling shelving system full of vinyl and tapes.

View attachment 94349
I dig the wallpaper !
 

Bergm@nn

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Aug 14, 2021
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So I resolved the definite 10db drop in measured output from the right hand speaker (firmware update).

This is now the latest in room measurement showing both channels.

1657459902866.png
 

sbnx

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Mar 28, 2017
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Much improved. Now you can proceed with speaker positioning and bass eq. You have that big bump at 85dB in the left speaker. And the broad dip between 100 and 200 Hz to try and fix.
 
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sbo6

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May 19, 2014
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First adventures in room measurement and using the Duo XD parametric EQ, and would appreciate a bit of hand holding and advice from the experts to help me to learn and better understand how best to approach getting it right.

The software in the Duo XD allow you to do 10 point adjustments from the screen below in the XD control software when linked to each speaker using USB/ Ethernet -

View attachment 93491

First job was to take a simple measurement using a calibrated mic connected to the XTZ soundcard and then using REW get a couple of consistent measurements from my listening position (so single point rather than average).

This is what you see between 10-200 Hz -

View attachment 93492

What I hear from my seat with no EQ applied is some boominess when I lean forward about a foot, less so if I lean back or stand behind the sofa. As the volume goes up the boominess then seems to travel back and reach my listening position without leaning forward.

Where do I go from here then?
A frequency sweep won't give you the full picture; you need to frequency response over time to see the decay. Generate a waterfall plot or spectrogram will help fill in the blanks. Also, our ear/brains don't hear the way our tools measure, for lower frequencies in particular worry less about narrow peaks and troughs and more about larger trends.
 
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ecwl

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Mar 20, 2021
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I suspect for the 100-250Hz dip, you won‘t be able to make a huge difference by moving the speakers. If you can move your listening position forward or backward, you can try re-measuring at 0.5’, 1’, 1.5’ in front and behind the current listening position to see if it smooths out the 100-250Hz dip more. If so, you can move your new seat to that position. If you can’t move the seat, you’ll probably have to live with the dip.

If you can DSP the left 80Hz peak at +8dB, that’ll definitely be worth correcting and give you cleaner sound. REW can calculate that for you so you don’t have to guess the Q, dB or even the exact frequency in Hz.

Overall I think everything already measures pretty well. Should sound pretty awesome.
 

sbnx

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Mar 28, 2017
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One thing I forgot...I believe the crossover point for the Duo is adjustable. At least some of the dip between 100 and 200Hz appears to be phase cancellation. Can you measure Just the woofer on the right and just the mid-tweeter on the right. Then we can get an idea of how the crossover is working.
 
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Blue58

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The dip could also be boundary wall cancellation. Moving the speakers away could lower the frequency where the dip occurs, potentially taming the 80hz peak in the process.

There are some frequency/wall calculators out there somewhere.
 
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