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How to Solve High-Frequency Suckout in Room?

After upgrading my system including speakers, I'm noticing with more upper frequency detail, that the right channel has some degree of missing high frequencies.  I've confirmed it is my room by swapping speakers, swapping cables for left / right, and of course the cables are all in phase.

My room is quite large, open concept, but my system is to one side of the open area.  Ceilings are vaulted and are 12ft at highest point. The speakers are not near any corners, due to a jut-out on the right side and the other end being completely open. However, there is a partial wall on my right side that has no treatment on it that extends up to 12ft, from the listening position.  This wall starts 3.5 feet in front of the right speaker (about 1.5 Ft to the right of the right speaker) and continues to behind the listening position. 

I've tried putting pillows against the right wall and thought it may have made the problem worse?  There is no wall on the left side, it is completely open.  Does this make sense that there is missing high frequency on the right side, where the wall is?  And, is there anything I can do to fix this?  I will attempt to draw the setup but I'm guessing the alignment will mess up when I post this! 

 

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nyev

Showing 6 responses by theaudiomaniac

theaudiomaniac
87 posts
 

Your left and right are perfectly matched. No issues

theaudiomaniac
87 posts
 

Have you measured it? Perceived lack of highs could be from too much mids.

theaudiomaniac
87 posts
 

The wall is reflecting too much mids from about 1-4 khz, that makes the highs when you listen to that channel alone seem suppressed. Effectively they are in comparison.  You will even get some mids from the left channel reflecting off that close wall too. You need left / right room response measurement to nail it down.

theaudiomaniac
87 posts
 

@theaudiomaniac I think you might be right, in terms of AC voltage output being close enough. That said, there is a 1.2% variance at 5,000Hz, and close to a 1% variance around this frequency. While small, wouldn’t that be audible

 

That is at best 0.1db. Left to right, your system could be off 3,4,5 or more db. It will not be audible.

 

I did read an old forum post that indicated that subtle differences may not be detectable using a voltmeter. The ultimate test is to use a dual channel oscilloscope, inverting one of the channels phases, then using the “sum” function of the scope. Because you’ve inverted one of the phases, the channels should cancel out each other when you sum them, and any variance from 0V that the scope shows would indicate an imbalance. I used to have an oscilloscope that hooked up to your PC but it’s so old it won’t work anymore.

 

Don’t waste your time. A wide bandwidth multimeter is accurate enough. The difference in time between measurements and thermal differences are smaller than what you are measuring. It is your room. Didn't you already say you swapped channels and the issue is still there? That rules out the electronics.

What you need to do is figure out how to measure room response. There are many resources on the web. It will cost you $100-200. If you have a noticeable difference, then then it will be easy to see them. Measure with one speaker, measure with the other, then compare.

 

 

theaudiomaniac
87 posts
 

Welllllll my apologies I misread. That changes everything.

That sounds like a capacitor or resistor in a low pass filter is out of spec, but too many possibilities to guess accurately. Your old DAC will be just fine for testing.

If there is a large enough change in the frequency response to be detectable, a cheap $50 receiver from the second hand store will have more than enough resolution to reveal it. Don't get too hung up on the alternate components quality. This is a significant thing you are experiencing.

 

 

 

@theaudiomaniac , I swapped the cables at the amp end (only) and the problem changes from the right side being too soft in the upper mids and into the treble, to the left side being too soft in these frequencies. This leads me to believe it’s not the room.

That said I am planning to completely rotate my system in the room as a test (setting up my system against the side wall.

Update: I have also questioned if the source material is causing the issue since the problem is not apparent on all music, mildly apparent in some music, and blatantly obvious in other tracks. As above, vocals sound centered but the upper end of vocals seem more fleshed out on whichever speaker is NOT being driven by the amp’s right channel.

theaudiomaniac
87 posts
 

This is such an obvious and good suggestion I feel embarrassed to have not thought of it 🙄   If I am not mistaken, you are using an internal DAC, so alternately, what about finding some mono source material?  Should be easy to find something mono to stream. You can probably even find mono test tracks with a frequency sweep. If the image moves as the frequency changes, you have your culprit.

 

Does your integrated have the ability to play in mono to verity your findings, i.e., that the difference in the left and right speaker sound is from differences in the source material left versus right stereo track recording?

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