New project for a listening room

[marcoc1712]

Hi all,

I was starting with a post in another thread, but Brian courtesly ask me to open a new one, so here i'm.

For Bryan: I was in touch with GIK EUROPE some time ago, and you already received the room description and some measurement made BEFORE any tratement was done.

Now I've put some panels and traps and i'm taking some new meseasure, to see what appened and if i still need some more or wat.

Let me Know if you think is better post here the room description and scketch, or not.

Here again the plot of the today's mesures, BLUE IS LEFT and RED IS RIGTH, FULL RANGE SPEAKER (Monitor Audio Gold 20 SE).

[marcoc1712]

Hi again,

let me decribe a little more about the room and is aim:

It's 5m x 3m rectangle, with an 'extention' on the left side, so it looks like an "L".

The floor is in hard wood, the celing is slanted and cover by wood, as half of the side walls.

I only lissen to music (and read books) in the room, the equipement is a REGA 3 Turntable, TEAC VRDS10 CD + AR DAC1 DAC, Tube Klimo Pre + Amp, Monitor Audio Monitor 20 Gold Speakers, no TV, projector or subwoofer is planned to in place.

here is a sketch of the room as it was BEFORE put on some bass trap and panel:

Pianta.pdf

here the same room today, with bass traps in the front corner and panels in the ceiling and on the side walls (or better, on the rigth wall and free standing in the left, due to the shape of the room).

Pianta_fase2.pdf

In Ligth blu the Traps and the panels added. In the corner are 30 cm thick (15 cm Rockwool 100 Kg/m3 + 15 cm Air) 60 cm x 200 cm, in the ceiling and in the side walls 5 cm Rockwool 70 Kg/m3, 50 cm x 150 cm.

After this, i've reduced the gap between picks and deep from a max of 40 db that was before to the 20 that REW report today, but still remain some huge deep (300 Hz) on the RIGTH channel and some resonance seems still live from the rear wall.

T20 andT30 has been reduced from 0,55 - 0,60 to 0,25 - 0,30.

To my ears, the gain was enormous: Much more bass, clearest sound all over and much more punch.

Still remain some issues:

a) The scene is (less than before but still) shifted to the left.
b) Voices are not always completely natural, some 'metallic' in it and often backwarded related to the rest of the scene.

I'm looking forard for an help in solve also this problems.

Hope is usefull,

Ciao, Marco.

[bpape]

I doubt that it's a rear wall issue since it's only the right speaker. The left actually looks pretty decent. More likely, it's just the fact that you're open on one side and a hard wall on the other. We tried to address that before. You may have better luck without spending much money playing with the position of the speakers in relation to the wall behind them to introduce a peak where you now have nulls to smooth things.

The other thing we need to do is look at the response of both speakers at the same time to see what kind of inter-channel cancellations we might be getting.

Bryan

[marcoc1712]

Hi All,

I did a complete new set of measure and I tried to move the lissening position a little, in this set the position is 20 cm above the previous one (340 cm away from the front wall), same positions for the speakers (133 cm away from the front wall, 88 cm from side wall).

RED is RIGHT channel
BLU is LEFT Channel
GREEN is LEFT + RIGHT playng togheter.

Curve is smoothed at 1/3 Octave.



Now the null at 300 Hz seems to be reduced (in 2 channel playng there is almost no null there) but the one at 45 - 50 hz is deeper than before.

Here the waterfall plot (stereo only)



and here the energy time (stereo Only)



Is from the energy time diagram, looking at the 7s reflection that I presume i still need some absorbtion in the rear corner, Im wrong?

Here the RT60 plot (stereo only)



Any suggestion, request of details or advertise is welcome, thanks a lot to everyone.

Marco

[bpape]

Have you moved the speaker positions? It could be that we can tweak the response by changing the relationship of speaker to side wall vs speaker to wall behind the speakers to help tame the dip.

As for treatment, I don't know that I'd do a lot else and there isn't a lot of space to do additional things in allowable areas.

The 7ms reflection isn't likely the rear corner. General rule of thumb is 1ft per ms. So, something with a total path whose length is approx 7' longer than the distance from speaker to you directly.

Bryan

[marcoc1712]

bpape wrote:

Have you moved the speaker positions?

No I've just moved 20 cm ahead the microfon (and the chair)

bpape wrote:

It could be that we can tweak the response by changing the relationship of speaker to side wall vs speaker to wall behind the speakers to help tame the dip.

Let's try, i've already had some good result before (but not mesured) rotating the speakers some degree inside, (now are more or less 30°) and moving it upward few cm, the results were better stereo image and voice, less bass. What shall we try first? Move them away from side wall, from the rear wall or what else in your opinion? How many cm by time?

bpape wrote:

The 7ms reflection isn't likely the rear corner. General rule of thumb is 1ft per ms. So, something with a total path whose length is approx 7' longer than the distance from speaker to you directly.

7' = 2,13 m. .... Still reflection from the ceiling? or maybe from the wall in front/beside the left speaker? This reflection appears in both R and L channel, but is a little more evident in R, so it would not be the wall i suppose.

Waiting for your indication, i'm going to move the speakers 5 cm backward and take some mesure.

Thanks a lot

Marco.

[bpape]

If you can write what the dimensions are:

Front of speaker to wall behind speaker

Center of right speaker to wall beside speaker

That will help.

To pin down where the reflection is approximately, measure the distance from the speaker to you directly. Then, find a reflected path that's approx 7' longer than that direct distance.

Bryan

[marcoc1712]

Some new mesures:

First a set of new one taked moving the speakers back to te rear wall in step of 12 cm (max delta 48 cm):



the same, but "separated"



It seems to me few o no differences in the 20 - 200 Hz, much more in the Higher Fq.

Then I've "fixed" the new position, 36 cm back to the old one (means 110 cm away from the back wall and 98 from the side wall) and moved the lissening position in step of 20 cm:




the same, but "separated"



The difference between a position and the other is bigger. May be the best one is the nearest to the front wall, but is not practicable.

I've noticed that the second better is the farest from the front wall, so i figure that in between there are some problems.

I'm going to Try a new set starting BACK from the original sitting point.

Marco

[marcoc1712]

bpape wrote:

If you can write what the dimensions are:

Front of speaker to wall behind speaker

Center of right speaker to wall beside speaker

That will help.

For the first set of measure the FRONT was 146 cm from the front wall, the side wall was 88 cm far, the space in between the speakers was 144 cm.

The lissening position was 340 cm from the front wall.

Then I've tried moving the speakers a litle bit to the center of the room, so the distance from side wall and rigth speaker was 97 cm, the space in between 130 cm.

Then I've start moving the speakers by 12 cm step nearest to te rear wall, ending at 110 cm.

Then I've fixed the new position and start to move the lissening point, by step of 20 cm, until 240 cm far from the front wall.

I've just posted this set of measures.

It seems to me that no major changes happen in the 20 - 200 Hz zone moving the speakers, biggest one moving the mic.

Unfortunatly, the better result is not practical (the chair is very very near to the shelf in the front), the one that looks the second to me is with the chair quite far, so i'm going to try some new, starting back from the old sitting position but moving ahead the speakers, in order to maintain the same relative distance between me and the speakers, is a good idea or not?

Thanks

Marco

[bpape]

That's a good plan. When you're trying things keep in mind that USUALLY, we don't want any measurement the same. So, watch things like:

- Distance between speakers
- Front baffle to front wall
- Speaker center to side wall
- Speaker face to listening position
- Listening position to wall behind

Try to make sure those things aren't the same or multiples of each other. That's not a hard and fast rule but it usually works well.

Bryan

[marcoc1712]

HI All,

i'm back after some days and a Flue, with some new data about my lisseninig room.

First, I tried moving the speakers or the listening position 5 cm by step and taking measures each time, searching the position that seems better to me looking at the plots.

After this, I started lissening music for a wile, again moving the position and/or the speakers searching the 'better sounding' configuration.

At the end of the day, the better result to me is at this position:

- Speakers (Baffle) from front wall: 133 cm
- Speakers (centre) from side (rigth) Wall: 81 cm.
- Space between speakers (centre) : 158 cm.
- Speaker (face) to listening position: 228 cm (212 from the middle)
- Listening position to wall behind: 144 cm

Bass are good enought, the balance between the two channels is the better i've founded in any other configuration and voices are pretty natural.

Here some plot:

RIGTH CHANNEL:



LEFT CHANNEL:



BOTH CHANNELS:



BASS ONLY:




WATERFALL (R, L, R + L):







RT60 (R+L):



ENERGY TIME (R + L):



Could you help me commenting the measures?

How I have to read the 4db difference in the Right vs. LEFT Plot? Do you think I'll need some Balance compensation?

As Bryan posted, there is no much space left for other room treatment, but any advice or comment is welcome.

Thanks to anyone who helped or will help me in this project.

Marco.

[bpape]

Obviously, there's still a boundary issue on the right channel that's not positional for seating, sub, etc. That means you need to kill that boundary pretty hard

There's a little extra gain on the right as opposed to the left but that's not surprising looking at the bass response. Same problem as above.

Bryan

[marcoc1712]

Hi Bryan,

an ocean is in between me and you, first in Knowledge... what you mean with: "you need to kill that boundary pretty hard" ... Hope I've not to broke down a wall...

Marco

[bpape]

Hi Marco

Sorry. I was just saying that we need to kill boundary reflections on that side to make it act more like the wall that ISN'T there on the other side. Likely can't do it completely but we can make it better hopeully.

Bryan

[marcoc1712]

Hi Bryan,

here some pict of the room with the treatment i've done:

FRONT:



REAR:



LEFT SIDE



RIGTH SIDE:



RIGTH SIDE Full view:



The "Yuta totem" you can see are 60 x 200 x 30 cm bass trap made by Rockwool (15 cm + 15 cm air gap), the little one is 60 x 100 x 20 cm.

The panels in the ceiling and in the left side are 60 x 100 x 5 cm.

The 'box' on the rigth side is a BASS TRAP in Wood (1/4" plywood in front and 5 cm Rockwool inside) 100 cm x 60 cm x 15 cm.

As you can figure, I could not find any more room in the rigth side to add absorbing material, if not replacing the one that i've put in place (I could arrange this, if necessary and make sense).

Looking at the plot serie that I've took in different speakers and chair positions (you could look at the previous post) , seems to me that moving the speakers has little or no effect on the peack at 40 Hz and deep at 50 and 160 Hz, moving the chair has much more, but to my ears the actual position is the better.

In your opinion what are the symptoms on the plot that are the worst (peak at 40 Hz, Deep at 50 or at 160 or what else?) and we have to point first?

I'm asking this becouse i've noticed that moving the chair to the front I could reduce the peack at 40 Hz and the deep at 50 Hz, but I'll increase the deep at 160 and lower all the 60 - 140 Hz zone (less bass punch over all).

Moving it in the other way, I grow up the peak at 40 and the deep at 50 Hz, I could almost eliminate the deep at 160, but I'll get one at 300 Hz and all the spectrum over 300 Hz will be like a mountain, more than this, I hear a lot of reflection coming from the rear, voices became 'metallic' and the scene is shiffed to the left.

Any advise is welcome, just I would like to be sure that we are at the best compromise before to give up...

Thanks a lot for your precious time, and please forgive my ignorance.

Marco

[bpape]

Looks like you've done what you can.

I personally wouldn't move at the expense of making the null worse. Just for giggles, try moving the panel that's on the left side back into the recess corner and see what happens.

Bryan

[marcoc1712]

Hi Bryan,

As You suggested, I've tried to move the left side panel back into the recess corner, and this is the result:





very little changes if not at all in the 20-200 Hz.

Ok, I think we've squeezed the best from the room, at the and of the day the sound is far better than before!

Just to know, in your experience, a response like the one we reached, is poor, medium or good for a domestic listening room?

Thanks a lot for all the help you gave to me.

See you again on the net.

Marco.

[bpape]

I'd say moderate. We've helped a lot of things and you can hear the difference. There's still something going on that we haven't found yet. It could be the structure itself has a resonance. It could be something up around the wall/ceiling junctions. We've tried seating and speaker positioning.

Seating is still making a difference but at the expense of something else. If you want, we can make the seating move and try to specifically identify the null.

Bryan