# 2 Channel Room Needs Treatment



## z3scott (Sep 30, 2010)

Hello Bryan and other interested parties. I would like to post some pertinent REW charts to begin analyzing and correcting my "man cave" 2 channel room which is dire need of some treatment. I am interested in bass trapping, diffusion and reflection treating in fairly bare room.

What REW charts are useful to start the discussion, SPL and Waterfall? In what range? My speakers are getting usable output into the low 30Hz range in room.

I am using REW with a RadioShack analog meter (from my reading may not be useful much higher than 3k) if that is helpful to know.

I also have a very rough layout of the room (using Paint).

I have been playing with REW and various seating locations as well, (basically distance from the back wall).


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## Dale Rasco (Apr 11, 2009)

SPL and frequency response will help as will the diagram. Just save as a JPEG with at about 600-800 MP wide. You have to make five posts before being able to upload.


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## z3scott (Sep 30, 2010)

I just uploaded some jpg images although I think they aren't ready to attach yet. This will be my 5th post anyway. I think I actually had access to posting images by virtue of my donating status.

I'm a bit rusty on forum protocols so have to figure the system out for attaching them when they are ready.

I have a room layout and 3 waterfalls and 3 spl graphs from different listening position distances.

Thanks


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## Dale Rasco (Apr 11, 2009)

Sorry Scott, I missed the Gold Supporter title. You should be able to post the pics by putting in the url and wrapping it with


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## z3scott (Sep 30, 2010)

Ok I'll try this again...

Here is the room layout








Three different listening positions 











































I find it interesting that prior to my getting a hold of REW I gravitated closer to the rear wall listening position due to the filling in or smoothing of the bass response that the graph's clearly show. However too close and the boom/echo is muddying up things.

The room is totally untreated except for a 8'x10' rug so it has quite a lot of slap echo.

I have pretty free reign on what I can get away with in this room. One consideration is that we will eventually be putting sofa/hide-a-bed against the rear wall for emergency guest overflow and probably for me on occasion.

I plan on properly testing as I incorporate room treatments to verify and optimize with guidance from folks.

I am also curious as to the effect of the large closet. There is over an inch gap between the hardwood floor and the bottom of the doors is this effecting things as well?

Thanks,
Scott


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## Dale Rasco (Apr 11, 2009)

Are you using any type of sub EQ like an AntiMode or Behringer DSP1124?


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## z3scott (Sep 30, 2010)

No I'm not using any EQ and would prefer not to add it at least at this point in my 2 channel setup. I think I'd like to take things as far as I can correcting the room issues passively first.

I am aware if them and may be checking them out for my home theater where I'm running dual subs.


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## bpape (Sep 14, 2006)

Ideally, you'd be just under 6' from the rear wall to seated ear position. I know that seems close to the speakers but you have plenty of space behind them unless they're something special that requires that much distance. What are the speakers?

Waterfall is fine. Can you post a FR that has 5db increments on the left and runs from say 20-300Hz on the X axis?

Bryan


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## z3scott (Sep 30, 2010)

Hi Bryan, the speakers are Reference 3A Episode they are rear ported which can be problematic getting too close to a wall. They typically seem to need some breathing room to blossom in sound stage depth. Manufacturer recommends pulling them out into the room. But I'm willing to try things. 

The back of the speakers are about 38" from the wall. I might be able to squeeze them back about a foot or so, maybe slightly more. I neglected to show a corner glass shelf system that holds a printer and a my sat receiver in the back left (top right corner on drawing).There are two stacked Power Var transformers that take ac off from dedicated lines that take up some space on the floor next to the turntable. The right speaker (bottom right on drawing) has my VPI record cleaner behind it also. I'll have to doctor the room drawing to reflect these items.

Are you requesting a waterfall of any of the specific distance adjusted or all three?

Thanks


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## z3scott (Sep 30, 2010)

Here's the revised room layout with additional items along back wall behind speakers

Note this drawing isn't to scale!


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## bpape (Sep 14, 2006)

More concerned with FR from a seating and speaker position perspective. Then we can look at the waterfall from an overall decay time perspective.


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## z3scott (Sep 30, 2010)

Here are the revised fr graphs per your 5db increment from 20-300Hz. I have included additional distances I tested at with the speakers at 38" from the wall.









































I did move the speakers back just to listen at 26" and definitely have the sound stage depth shrinking noticeably. I crude listening tells me I need them out at 33" minimum. I now have them at 34" and moved them to 29 1/2" off sidewalls. I haven't measured at this point.

Not to jump to any conclusions so early in this but wouldn't some treatment behind the speakers help to allow me to move the speakers back closer to the rear wall.

I'll do measurements with the speakers in this new location.

Thank, Scott


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## z3scott (Sep 30, 2010)

Bryan I have been moving things around and extrapolated your 6' to fit dimensions of the speaker locations. Tash at Ref 3A suggests 1.1-1.2 x speaker separation to lp distance. When I had the speakers in a monster room up north we settled on 8' apart with the listening position 9-10' away. That room was substantially larger and the ceiling was 10', the rear wall behind the speakers was 4-5' away and the wall behind the lp was about 12-14'.

Following are some fr graphs with the speakers 65" apart 27" from the wall and 37" from the side walls.

















That's all I'll be able to work on for a few days.


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## bpape (Sep 14, 2006)

Just to be clear. Did you move seating distance and speaker location at the same time for those 2 measurements or just the rear wall seating location?


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## z3scott (Sep 30, 2010)

The last two graphs were with the speakers locations changed dramatically from the earlier graphs. As noted the speakers are 65" apart rather than the original 80-86". They are now 27" from the wall behind them and 37" from the side walls. The lp was measure at 61" & 72" (your suggested) distance from the back wall behind lp.


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## bpape (Sep 14, 2006)

Gotcha. My problem is that since we changed LP, and distance to front and side walls, we've changed 3 things so no telling what did what.

72" is definitely better for the first low null but some of the rest isn't as good as before. We just need to follow the scientific method and change only one thing at a time so we can see what is and isn't impacted.

For instance, keep the seat now at 72" and change the speaker positions slightly to see what changes.

Bryan


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## z3scott (Sep 30, 2010)

I made the above relocations to fit your suggestion of a 72" (from rear wall) lp and keep the normal speaker symmetry of an equilateral triangle.

When you say slightly how much is slight? A couple inches, half an inch?

Monday I'll be able to move the speakers and provide results for you.

Thanks, Scott


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## bpape (Sep 14, 2006)

I would pull them forward maybe 6". Take that measurement. Next, pending what that does, we will play with side wall position. 

Bryan


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## z3scott (Sep 30, 2010)

Ok Professor "Shirley" following are plots with the speakers moved forward 6" thus 33" out from the wall and still at the 37 1/2" sidewall distance.

I did four graphs: 72"; 61 1/2"; 56" and 78" lp from back wall of the room.

































The experience is rather enlightening> I'm starting to grasp the room effects much more. The focus and instrument placement have greatly been enhanced getting the lp out into the room. 27" was a bit stifling on the sound stage depth. Still room for improvement :T

Scott


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## z3scott (Sep 30, 2010)

Hey Bryan, I went ahead and varied the sidewall distance and measured since you didn't comment on the last post. It seems I'm not making much progress raising those nulls they basically just shift around in frequency.

This first graph is at the 37 1/2" sidewall distance as the previous post with more toe-in on the speakers.








The remainder progressively move closer to the sidewall.





























Any thoughts?


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## bpape (Sep 14, 2006)

Sorry - been really busy at work. The first plot looks better to me than the rest.


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## z3scott (Sep 30, 2010)

I hate how work gets in the way sometime... 

I think I'll try moving moving the speakers back 3" to split the previous 27" and 33" distance from the wall and vary the toe-in some for comparison. Due to the high frequency dispersion characteristics of the speaker they can't be toed in as much as most speakers.


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## z3scott (Sep 30, 2010)

I tried 30" & 31" with various toe-in and measurements didn't improve. 30" is when the soundstage starts compressing quite noticeably. 

These three appear to be the best of the many measurements I've been taking.

This first one is the last one you picked:







This one has just a slight bit of toe:







This final graph is with the toe-in between the first and second:








Looks as if I can't pull much more out of the nulls. The middle one with just a slight amount of toe is best correct?


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## z3scott (Sep 30, 2010)

For giggles I decided to measure with the closet open both doors and with just the front doors open with speakers unchanged. I thought you should see these.


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## z3scott (Sep 30, 2010)

Both closets open


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## bpape (Sep 14, 2006)

Well, the lower peaks got better but the null at 90 got deeper again. Might have to move the chair a little to see if you can avoid that now with the doors open.


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## z3scott (Sep 30, 2010)

Knockin' down that 75Hz peak is definitely a plus.

I'll try 78" (although every time I've tested at that distance those nulls between 100-200Hz increase), 66", 60" and see what happens. I would think I'd need to balance the speaker seating location side to side in the room. Or, at least move things towards the closet side somewhat. Wait and see I suppose for the results first.

Thanks,
Scott


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## z3scott (Sep 30, 2010)

Here are the measurements taken with closets open and speakers position stable. Each one represents strictly lp distance change from the back wall.






























The 66" lp excepting the 90Hz worsening shows some potential the dips in the 100-200Hz range are not as drastic; slightly better than the open closet 72" graph at mid 40Hz, worse at mid 60Hz. 

Time to try moving speaker location relative to the _new _centerof the room with open closet configuration?

Thanks, Scott


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## z3scott (Sep 30, 2010)

Bryan I need a sanity check... I've removed the cabinet doors and been measuring various speaker locations from 16"-41" depth (speaker to wall), varied the distance from the side walls and listening position from the back wall. Please take a look I think the 18",36" & 41" (speaker depth to wall) show the most potential for more experimentation. Am I making progress?:scratch:


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## bpape (Sep 14, 2006)

41 looks best to me.


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