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Why such a big difference in sound? (Speaker position)

Toblerone

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So I've had the KEF LS50 Metas since February of this year and had them pulled out to the very front of my entertainment center to reduce any reflections from the entertainment center and side wall next to the speaker on the left (see pic) and I would pull them even further out when I wanted to have a serious listening session.

Well the down side to where I placed the speakers is having 2 kids who like to do gymnastics. A few weeks ago one of them fell into the speaker and dented the cone. I got it fixed and decided to push the speakers back away from the front (maybe 5-6'' back) to reduce the chance of that happening again.

Unexpectedly the sound stage opened up and became a lot wider and deeper and blended better with the subwoofer, which is the opposite of what I expected. Also, to my surprise there was no noticeable change in the overall frequency response in the room (pre-correction as measured by the Audyssey multeq-x windows app) and the sound is almost as good (enveloping around my ears) as if I had the speakers pulled out a few feet (which I no longer feel compelled to do).

So how am I suppose to understand the difference in sound? Just placebo? Why isn't anything showing up in the measurements? Is it the timing of the reflections lining/timing up better with my listening position which is about 8 ft away from the speakers and 5 ft from the back wall behind my listening position.

Any feedback would be appreciated!

PXL_20221119_001640359.jpg
Speakers back.jpg
 
Last edited:

UltraNearFieldJock

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Unexpectedly the sound stage opened up and became a lot wider and deeper
The sound stage is the effect of the stereo signal on us (our brain) and is very difficult to measure: to measure it you need the artificial head in any case. So far, I have not found any standardized method on the net. In any case, the simple measurement of frequency response does not help here. This aspect is the most important for me, therefore also my experiments with UNF... - here 10 cm sometimes make the big difference.
 

anotherhobby

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Every single room is different, so all of those guidelines you hear about placement and toe-in are all just good recommended starting points. You have to mess around with your setup, take measurements, and listen. Often times it's good to let a change sit for a bit to see if you like it. Sometimes we think different means improvement, but not always. I've definitely changed things with my audio, immediately thought it was better, only to realize after enough listening that it was not actually better. Other times a bunch of listening confirms that improvements are real, especially if you switch back like a month later after you are really used to it.

Also, if I zoom in on those graphs, there are differences in the bass. Both the left and the right speaker trend closer to the red line when they are back vs. forward, especially in the bass region. The MultEQ-X app graphs are harder to analyze being side by side and small vs using REW when you can over lay them and go full screen, but the measurements do look a little better pushed back, so I don't think you are just hearing things.
 

RobL

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Distance from the rear wall affects SBIR. Genelec recommends no greater than 2’ from wall to front of speaker to keep the cancellation dips out of the bass frequencies. Not sure if this is causing the effect you notice, but maybe?
 
OP
T

Toblerone

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Distance from the rear wall affects SBIR. Genelec recommends no greater than 2’ from wall to front of speaker to keep the cancellation dips out of the bass frequencies. Not sure if this is causing the effect you notice, but maybe?
Yea the Genelec guide is kinda what I had in mind. I have the speakers crossed at 80hz on the Audyssey app with a low pass filter applied, the same as before.

I've been listening to all my go to songs for the past week and I just can't get past the way the sound extends so far out (and wide) and has so much more depth/dimension like I'm sitting a few feet from the speakers and they are pulled all the way out away from the wall.
 

RobL

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Yea the Genelec guide is kinda what I had in mind. I have the speakers crossed at 80hz on the Audyssey app with a low pass filter applied, the same as before.

I've been listening to all my go to songs for the past week and I just can't get past the way the sound extends so far out (and wide) and has so much more depth/dimension like I'm sitting a few feet from the speakers and they are pulled all the way out away from the wall.

149C55C2-23E6-447E-B84C-37C39BCC08C3.png

This chart also recommends avoiding the 2’ - 3’ 6” distance front-of-speaker to rear wall measurement for bass managed speakers.
It’s from a studio design website.
 

truwarrior22

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So I've had the KEF LS50 Metas since February of this year and had them pulled out to the very front of my entertainment center to reduce any reflections from the entertainment center and side wall next to the speaker on the left (see pic) and I would pull them even further out when I wanted to have a serious listening session.

Well the down side to where I placed the speakers is having 2 kids who like to do gymnastics. A few weeks ago one of them fell into the speaker and dented the cone. I got it fixed and decided to push the speakers back away from the front (maybe 5-6'' back) to reduce the chance of that happening again.

Unexpectedly the sound stage opened up and became a lot wider and deeper and blended better with the subwoofer, which is the opposite of what I expected. Also, to my surprise there was no noticeable change in the overall frequency response in the room (pre-correction as measured by the Audyssey multeq-x windows app) and the sound is almost as good (enveloping around my ears) as if I had the speakers pulled out a few feet (which I no longer feel compelled to do).

So how am I suppose to understand the difference in sound? Just placebo? Why isn't anything showing up in the measurements? Is it the timing of the reflections lining/timing up better with my listening position which is about 8 ft away from the speakers and 5 ft from the back wall behind my listening position.

Any feedback would be appreciated!

View attachment 245963View attachment 245962
Back wall reflections? They say if you can pull them out far enough into the room to put them close to the back wall then.
 

Steve Dallas

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Distance from the rear wall affects SBIR. Genelec recommends no greater than 2’ from wall to front of speaker to keep the cancellation dips out of the bass frequencies. Not sure if this is causing the effect you notice, but maybe?

SBIR frequency should show up in his measurements, though.

I have smaller rooms in my current house, and I push the speakers as far back to the front wall as I can and use a 5" broadband absorber behind them. The goal is to nudge the SBIR frequency up to a point where reflections can be absorbed.

Here is part of a handy SBIR spreadsheet I made some years ago. At 24", we are at 139Hz, which is absorb-able, and is a good thing.

Distance (in)Distance (m)SBIR Frequency (Hz)
40.10837
50.13669
60.15558
70.18478
80.20418
90.23372
100.25335
110.28304
120.30279
130.33257
140.36239
150.38223
160.41209
170.43197
180.46186
190.48176
200.51167
210.53159
220.56152
230.58145
240.61139
250.64134
260.66129
270.69124
280.71120
300.76112
320.81105
340.8698
360.9193
380.9788
401.0284
421.0780
441.1276
461.1773
481.2270
501.2767
521.3264
541.3762
561.4260
581.4758
601.5256


This is a chart of the KEF R3s in my home office as I experimented with absorption behind the speakers. Light purple is no panels. Darker purple is a single 24x48x5" panel behind the speaker. Green is two panels behind the speaker. Baffle distance to the front wall is 22". SBIR center is 152Hz.


KEF R3 Right SBIR Treatment - Copy.png


My guess as to what the OP is hearing is a change in side wall reflections due to the change it distance to the MLP.
 

voodooless

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You clearly gained some between 50 and 100 Hz. That should be quite audible.
 
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