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The peak could easily be caused by a room mode. Placing treatments at the first reflection point will address reflections coming from that spot, but reflections and peaks in frequency response are not the same thing. Peaks like the one you have are usually addressed by speaker placement, or by EQ. Are you using any type of EQ, like Audyssey or perhaps a Mini-DSP? If not, have you considered EQ?
 

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The peak could easily be caused by a room mode. Placing treatments at the first reflection point will address reflections coming from that spot, but reflections and peaks in frequency response are not the same thing. Peaks like the one you have are usually addressed by speaker placement, or by EQ. Are you using any type of EQ, like Audyssey or perhaps a Mini-DSP? If not, have you considered EQ?
I do use Audyssey but reading around on web I thought that the best way to make room sound best is to treat it first. So to do that, disable Audyssey and take reading and get good results. That's why I wanted to know how to treat the room???? So far I have this high peak that you are saying that can be taken care by Audyssey. I have room ringing that other member told me is very hard to get rid since its under 50 Hz. Then what can I fix with room treatment and what's the purpose of taking these readings if I'll have Audyssey do the job for me?
 

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OK, let's start with the bass resonance, which is what you see starting at 50Hz and below. The correct way to address bass resonance is with bass traps, which are designed to absorb low frequencies. Bass traps have nothing to do with reflections. A bass trap is typically rather thick, and is usually placed in spots where bass frequencies are their strongest, i.e. at the intersection of walls, corners, etc.

The issue we are talking about is a peak in in your frequency response, not a resonance. If you have Audyssey room correction, you should certainly run it, and then take full-spectrum (15-20,000Hz) measurements to assess how well Audyssey is smoothing the frequency response. As a very general statement, you should have three distinct measurements to assess the quality of audio in your listening room:

- Frequency response measurements to assess the overall flatness of the response. Measure 15-300Hz with no smoothing, and 15-20,000Hz with 1/6 smoothing. Measure with Audyssey on and off to get a complete picture.

- Waterfall and/or spectrograms to assess bass resonance.

- ETC graphs to assess spectral reflections.

Once you have this suite of measurements, you can analyze the results and decide what needs to be addressed. Frequency response issues are addressed by speaker placement and EQ, bass resonance is addressed by subwoofer placement and adding bass traps, and finally, spectral reflections are brought under control by careful placement of appropriate wall treatments.

So, if your immediate concern is that peak, run Audyssey and see what Audyssey does to pull it down.
 
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OK, let's start with the bass resonance, which is what you see starting at 50Hz and below. The correct way to address bass resonance is with bass traps, which are designed to absorb low frequencies. Bass traps have nothing to do with reflections. A bass trap is typically rather thick, and is usually placed in spots where bass frequencies are their strongest, i.e. at the intersection of walls, corners, etc.

The issue we are talking about is a peak in in your frequency response, not a resonance. If you have Audyssey room correction, you should certainly run it, and then take full-spectrum (15-20,000Hz) measurements to assess how well Audyssey is smoothing the frequency response. As a very general statement, you should have three distinct measurements to assess the quality of audio in your listening room:

- Frequency response measurements to assess the overall flatness of the response. Measure 15-300Hz with no smoothing, and 15-20,000Hz with 1/6 smoothing. Measure with Audyssey on and off to get a complete picture.

- Waterfall and/or spectrograms to assess bass resonance.

- ETC graphs to assess spectral reflections.

Once you have this suite of measurements, you can analyze the results and decide what needs to be addressed. Frequency response issues are addressed by speaker placement and EQ, bass resonance is addressed by subwoofer placement and adding bass traps, and finally, spectral reflections are brought under control by careful placement of appropriate wall treatments.

So, if your immediate concern is that peak, run Audyssey and see what Audyssey does to pull it down.
Thx so much. This explains a lot.
The correct way to address bass resonance is with bass traps, which are designed to absorb low frequencies.
I know there are a lot of DIY on it but they are mostly using Owens Corning 703 24"x48"x2" Fiberglass Boards. 2nd post on this tread says that R30 is better for low frequencies assuming one can go beyond 8". Is there any document/post on how one can build a Bass trap using R30?

I started to think that these panels don't do anything because no matter where I placed them, they didn't make any change in frequency. Your post clears out that confusion. I other words, to see the impact of these panels, its the ETC graph that signifies it.

As for taking Audyssey response, do I need to run full (8 point) calibration first since I moved the speakers a bit? I think that since we are working with front speakers, 3 point calibration should be ok???

One more point that's constantly making me wonder is why do we not take reading of center speaker? Even in water fall, when reading the guide, its the Left and Right?

thx.
 

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If all you are doing is using Audyssey to assess the impact of a small distance change on one or more speakers, then running a three-point calibration is probably OK. However, once you have finished moving things around, you should run the full eight-point calibration.

As far as measuring the center channel, by all means it is appropriate to measure it. Especially for bass frequencies, you should measure center+subs and Left+right+subs, 15-300Hz, no smoothing, with Audyssey on. Then look at smoothness of the frequency curve, as well as the waterfall or spectrogram graphs. Since bass is essentially mono, bass appears in the center channel, and is re-directed to the subs by bass management. This is why measuring the center channel is so important when assessing bass response.

And for determining the effectiveness of your treatments in addressing spectral reflections, place the reflection in what you think is a good spot, and then run full-spectrum (15-20,000Hz) sweeps of the left, right and center channels individually, and then examine the ETC graphs (Audyssey off or on doesn't make a big difference for the ETC measurement). There are a number of "best" placements for full-band absorption panels--the left and right first reflection points on side walls, on the back wall immediately behind the MLP, and the first reflection points on the ceiling.
 
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If all you are doing is using Audyssey to assess the impact of a small distance change on one or more speakers, then running a three-point calibration is probably OK. However, once you have finished moving things around, you should run the full eight-point calibration.

As far as measuring the center channel, by all means it is appropriate to measure it. Especially for bass frequencies, you should measure center+subs and Left+right+subs, 15-300Hz, no smoothing, with Audyssey on. Then look at smoothness of the frequency curve, as well as the waterfall or spectrogram graphs. Since bass is essentially mono, bass appears in the center channel, and is re-directed to the subs by bass management. This is why measuring the center channel is so important when assessing bass response.

And for determining the effectiveness of your treatments in addressing spectral reflections, place the reflection in what you think is a good spot, and then run full-spectrum (15-20,000Hz) sweeps of the left, right and center channels individually, and then examine the ETC graphs (Audyssey off or on doesn't make a big difference for the ETC measurement). There are a number of "best" placements for full-band absorption panels--the left and right first reflection points on side walls, on the back wall immediately behind the MLP, and the first reflection points on the ceiling.

Thx for the explanation. I'll try them out and will post the findings.
If all you are doing is using Audyssey
Are there better ways than Audyssey?
 

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You are reading something into my reply that is not there. I am a huge fan of Audyssey for room correction. Are there alternatives? Sure--Trinov, Dirac Live, AccuEQ (the new Onkyo RC technology), and a bunch of simple solutions like MiniDSP. But if you already have Audyssey, that's what you should use for now, IMO.
 

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You are reading something into my reply that is not there. I am a huge fan of Audyssey for room correction. Are there alternatives? Sure--Trinov, Dirac Live, AccuEQ (the new Onkyo RC technology), and a bunch of simple solutions like MiniDSP. But if you already have Audyssey, that's what you should use for now, IMO.
Just wnated to confirm to to have a clear path. I'll be busy tomorrow but the day after I'll perform the readings and will post the result. I'll do to the following

1 - Calibrate 3 point with Audyssey.
2 - Take Left+Right+Sub reading.
3 - Take Center+Sub reading.

Which output in Preferences in REW points to center? I think I tried all the options but none pointed out to center.
thx.
 

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... I have room ringing that other member told me is very hard to get rid since its under 50 Hz. Then what can I fix with room treatment and what's the purpose of taking these readings if I'll have Audyssey do the job for me?
SherazNJ,

I've been looking for ways to treat low frequency bass and have stumbled across a thing called DIAPHRAGMATIC ABSORBER. If you're a handyman and like to build things, there is a DIY kit available here from Acoustic Fields: http://www.acousticfields.com/product/bda-broadband-diaphragmatic-absorber/

I've ordered the kit and looking for someone nearby where I live to build one for me - don't have a workshop unfortunately. I've also ordered their acoustic foam which will be used inside the BDA.
 

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SherazNJ,

I've been looking for ways to treat low frequency bass and have stumbled across a thing called DIAPHRAGMATIC ABSORBER. If you're a handyman and like to build things, there is a DIY kit available here from Acoustic Fields: http://www.acousticfields.com/product/bda-broadband-diaphragmatic-absorber/

I've ordered the kit and looking for someone nearby where I live to build one for me - don't have a workshop unfortunately. I've also ordered their acoustic foam which will be used inside the BDA.
Awesome. I"ll explore it a bit more. A friend of mine who is a good handy man and also quite knowledgeable built his bass traps using Mineral Wool http://www.buyinsulationproductstore.com/servlet/the-326/4%22-Thick-Roxul-Mineral/Detail. Basically for bass trap, he doubled up the layers to get effective absorption at lower frequencies.
 

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Which output in Preferences in REW points to center? I think I tried all the options but none pointed out to center.
thx.
Output 3 is the CC. :)
 

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I had posted this in the Marantz 7701 pre/pro owners thread but it was suggested to pose this question to the august body of experts on this thread ;)

I'm just a bit surprised that while overall Audyssey MultEQ XT on the Marantz does a great job in mid range - it doesn't seem to be doing much in lower bass range. I'm using crossovers set at 60Hz.

I've attached my results.
-With No EQ you can see my room problems of a large 25Hz peak (room width), 40Hz-50 dip and also in the 60-80Hz range (orange)
-Audyssey does bring the 60-80Hz up a bit, but doesn't do anything with the 25Hz peak or the 40-50Hz dip(GREEN)
- On the Other hand, the Anitmode 8033 I had used separately does a good job by knocking down the 25Hz peak, allowing me to bring up the overall level to counter the 40Hz dip.

Why doesn't Audyssey MultEQXT with its "8x higher number of filters for bass" and "thousands of points" help with that, do you think?
 

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I had posted this in the Marantz 7701 pre/pro owners thread but it was suggested to pose this question to the august body of experts on this thread ;)

I'm just a bit surprised that while overall Audyssey MultEQ XT on the Marantz does a great job in mid range - it doesn't seem to be doing much in lower bass range. I'm using crossovers set at 60Hz.

I've attached my results.
-With No EQ you can see my room problems of a large 25Hz peak (room width), 40Hz-50 dip and also in the 60-80Hz range (orange)
-Audyssey does bring the 60-80Hz up a bit, but doesn't do anything with the 25Hz peak or the 40-50Hz dip(GREEN)
- On the Other hand, the Anitmode 8033 I had used separately does a good job by knocking down the 25Hz peak, allowing me to bring up the overall level to counter the 40Hz dip.

Why doesn't Audyssey MultEQXT with its "8x higher number of filters for bass" and "thousands of points" help with that, do you think?
How many positions did you measure and how far apart were the spacings?
 

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Why doesn't Audyssey MultEQXT with its "8x higher number of filters for bass" and "thousands of points" help with that, do you think?
Read this for an explanation on the differences between XT32 and it's predecessors (incl XT). Note the major differences in the preout measurements in the bass region. Suffice it to say that XT just isn't doing enough in the bass region.
 

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Hmmm...it looks like XT is doing nothing for your bass. In my room, XT makes a very noticeable difference (Denon 2113ci).

Has to be your Audyssey technique (or a bad mic). Did you follow Keith's awesome Audyssey Guide?
 

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Hmmm...it looks like XT is doing nothing for your bass. In my room, XT makes a very noticeable difference (Denon 2113ci).

Has to be your Audyssey technique (or a bad mic). Did you follow Keith's awesome Audyssey Guide?
Based on these preout measurements from @rickardl, it's really no surprise that XT isn't doing anything in the bass region:

In this graph below, XT32 Flat/Music is RED, XT32 Reference/Movie is GREEN and XT is BLUE. Remember this graph is showing the pre-out measurement not the in-room measurement, so it is showing the amount of correction that will be applied. Observe the almost non-existent low end correction for XT in the graph below! It is interesting to see that the XT32 curve is so much smoother at the higher frequencies vs the very jagged curve of XT. Note the extreme amount of 'hair' at the HF end in the XT graphs.

Image uploading. Refresh page to view
 

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How many positions did you measure and how far apart were the spacings?
Thanks for the responses. I measured all the 8 positions available following the FAQ pattern. 1 at the listening position. 2 and 3 about 2 feet to the left and right of 1. Then 4,5,6 about 2feet in front of the first three. finally 7 and 8 about 6 inches behind 1 and about a foot away from 1.

I did follow the Audyssey set up FAQ except that I didn't use a tripod. I used a wooden stool with a set of rubber coasters.

The subwoofer distance came out about right. I did have to set the sub to a little less than 3 o clock to get a level of -2db. It seemed quite soft while "chirping".
 

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Here's what XT does in my room. Although I don't have as many peaks as the OP, it actually does something. :)

 

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Based on these preout measurements from @rickardl, it's really no surprise that XT isn't doing anything in the bass region:

In this graph below, XT32 Flat/Music is RED, XT32 Reference/Movie is GREEN and XT is BLUE. Remember this graph is showing the pre-out measurement not the in-room measurement, so it is showing the amount of correction that will be applied. Observe the almost non-existent low end correction for XT in the graph below! It is interesting to see that the XT32 curve is so much smoother at the higher frequencies vs the very jagged curve of XT. Note the extreme amount of 'hair' at the HF end in the XT graphs.
Dang JK...like I didn't want XT32 bad enough, you just had to post that. ;)
 
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