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MisterVego

Jubilee / Room Treatment

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Hello everyone, hoping some of the Jubilee experts can chime in.

 

I am currently in the process of finishing up my dedicated listening room and have recently ordered a pair of Jubilees.

 

There has been some scattered talk about the Jubilees needing some acoustical treatment.

 

Is it best to treat the room first, or get the Jubilees installed and take a measurement with REW and go from there?

 

What treatment is recommended and where is the best place to mount the treatments....   Typical 1st reflections on the side walls, front wall etc?

 

If it helps, the room I am building is about 14' wide x 20' x 8.5' tall.     I am planning on putting the speakers on the short wall.

 

Thanks for all your help.

 

Erik

 

Edited by MisterVego
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2 hours ago, MisterVego said:

Is it best to treat the room first, or get the Jubilees installed and take a measurement with REW and go from there?...What treatment is recommended and where is the best place to mount the treatments...Typical 1st reflections on the side walls, front wall etc? If it helps, the room I am building is about 14.5' wide x 20 x 8.5' tall.  I am planning on putting the speakers on the short wall.

 

You can get away with very few acoustic treatments with Jubs.  Some people that own them are looking for higher acoustic performance and are less motivated in absolutely minimizing the size of the loudspeakers and treatments in room. A picture of your room (looking forward and another looking aft) will help others here to make better recommendations.

 

Basically,  you'll know what issues you have when you get them in your room and set up with crossovers/amplifiers. Your ears are your most sensitive measurement instruments for detecting what the issues might be.  REW confirms or denies what your conclusions might be as to the acoustics issues based on first using your ears.  The short wall is what I also use in my room (15.5' wide x 40' deep x 9' height). 

 

I found that the brick fireplace between my Jubs basically nullified the phantom center image in stereo mode.  It turns out that two 2'x2' absorption squares on the side walls at the K-402 horn mouth height strongly increased the phantom center image, but these really became effective only after I placed a DIY TH-SPUD subwoofer behind each Jubilee to push them out into the room very slightly (about a foot)--in front of the brickwork of the fireplace.  I went further and placed absorption squares on the front wall between the Jubs and behind the K-402 horns on the front wall.  This calmed the stereo imaging significantly so that micro-detail from the Jubs became much easier to hear.  It's difficult to verbalize how much a little near field absorption can help the stereo imaging of loudspeakers with such good polar coverage properties.  When you hear it, you'll immediately be sold. 

 

I found that bass traps are also needed in my room to control the "boominess" (tile floor with an area rug between the loudspeakers, drywall ceiling and walls).  One 4" (doubled Owens-Corning 703 fiberglass panels) in a nicer looking bag on top of each TH-SPUD subwoofer across each front room corner is enough for my purposes.  If you want to control booming frequencies below 73 Hz, you'll need to have double length bass traps (8' long) to control down to 37 Hz.  I find that the single-length traps are enough for my needs, although REW measurements show that the room RT60 reverberation time rises below about 150 Hz in the listening areas.

 

From my experience, that's enough in terms of acoustic treatments.  I have good diffusion on each side wall at the front of the room, one side has a 1' bay window expansion starting at 3' off the floor (about the bottom of the K-402 height) that has big wooden shutters to cover the windows and diffuse, while the other wall is largely covered by a CD/DVD/BD case (7' height. 5' wide) that serve to break up the midrange early reflections from the K-402s and the bass bins. 

 

Chris

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I agree with Chris. The Jubilees are much better at controlling dispersion than most speakers. That is huge benefit of that big K-402 horn. The issue of bass traps will be very room dependent and is hard to guess at ahead of time. 

Good luck - this will be a fun project.

-Tom

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51 minutes ago, Chris A said:

 

 

You can get away with very few acoustic treatments with Jubs.  Some people that own them are looking for higher acoustic performance and are less motivated in absolutely minimizing the size of the loudspeakers and treatments in room. A picture of your room (looking forward and another looking aft) will help others here to make better recommendations.

 

 

Chris,

Here are some shot of the room.  

 

Some notes on the room:

Dedicated room built in the basement.   Concrete floors.  Double  Walls with Double 5/8" sheet rock with Green Glue in between.   Sheetrock a fixed to resilient channel.

 

Erik

 

Room Front Wall.jpeg

Edited by MisterVego
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That's about as clean as it gets.  I'd just try out the Jubs as-is and listen carefully. 

 

If you want stronger phantom center imaging, using side wall and front wall 2'x2' absorption squares (or other absorption means) will really clean up the imaging greatly.  I had been sold previously on the notion that the Jubs had enough polar control to preclude the need for nearfield absorption, but it turns out that in my room, that notion is not correct.  Like all loudspeakers (especially ones that go on the room boundaries like corner horns), controlling nearfield reflections is extremely important in terms of the psychoacoustics needs of the listening space for small (home-sized) listening rooms.

 

Bass traps are a welcome addition to any home-sized listening room but finding a place for them may be tricky if you've got a lot of stuff in the room already and/or the room has interesting non-rectangular shape (all 6 surfaces) or architectural details that intrude from a basic smooth wall rectangular room shape.  Dr. Earl Geddes disputes that they should go in the room corners, but I find that they are extremely effective when placed across a room corner and one end is covered by the floor or ceiling to form an enclosed resonant volume on one end (open on the other end). 

 

Chris

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Chris,

 

When you mention the nearfield absorption. Are we just placing panels next to (on the walls) next to the mouths of the horn forgoing the mirror trick to place panels on first reflection points?

 

Corner Bass Traps:

Initial thoughts were to place them tight in the corners to gain that last lower octave they can produce.   If done, do i still use traps in the front corners?   

 

Furniture:

Pretty much going to be minimal.   3 Idea Poang Chairs.   Amps on the floor between the speakers and then the stereo rack on the left side wall.

 

Vinyl records will be on the back wall until I build a record room in another corner of the basement.

 

 

As of now, the room is still has a pretty good echo.  The carpet def helped but hoping once the speakers and furniture gets in there it will help some or do you think i will benefit from having a more live type room?

 

Thanks again,

Erik

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Here is a great youtube video from the HomeTheater Geeks that goes into detail on room treatment. Its a bit long but some very good info:

 

 

 

Personally, I had great success using the mirror technique with a laser pointer to control the 4 primary reflection points between me and my speakers for my LaScalas. I think no-matter the setup, this will always make a big difference. 

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3 hours ago, MisterVego said:

When you mention the nearfield absorption. Are we just placing panels next to (on the walls) next to the mouths of the horn forgoing the mirror trick to place panels on first reflection points?

The problem frequencies are the ones that aren't as directional as the very highest frequencies.  You tend to see a lot of advice of placing absorption at the "first reflection points", which is only true for the highest frequencies.  The problem frequencies in this case to be absorbed are the ones that exit the horn's mouth and wrap around the flange to re-radiate off the nearest wall surfaces to the horn's mouth.  The absorption squares that I referred to need to be nearest the horn's mouth exit.

 

3 hours ago, MisterVego said:

Corner Bass Traps:

Initial thoughts were to place them tight in the corners to gain that last lower octave they can produce.   If done, do i still use traps in the front corners?   

Any room placement across room boundaries will do (corners are best, wall-floor or wall-ceiling are next best). 

 

The closer that you place the bass traps to the bass bins, the more effective they will be.  Front corner bass trap placement needs to be controlled a bit in terms of effectiveness by moving the traps left or right slightly while keeping the two walls touching the bass trap edges to form a seal.  That way you're decreasing the entrapped volume of air behind the panels.  Adjust the entrapped volumes to taste.

 

3 hours ago, MisterVego said:

As of now, the room is still has a pretty good echo.  The carpet def helped but hoping once the speakers and furniture gets in there it will help some or do you think i will benefit from having a more live type room?

You can certainly add more absorption to taste.  "Slap" echos are not good.  If you have those, add more absorption to the front of the room, including the front and side walls.  The back of the room can remain fairly live (i.e., this is a "LEDE" arrangement, or "live end, dead end").  Absorbing around the loudspeakers will improve the imaging quite a bit.  The worst imaging loudspeakers I can think of are Bose 901s, which splash acoustic energy around the entire front of the room--which gives the listener a greater sense of space, but actually negates their stereo imaging performance (like a reverse or otherwise called a "DELE" or "dead end, live end" configuration). 

 

Most people aim for an RT60 of the room between 0.2 and 0.45 seconds vs. frequency--the lower RT60 values more like a home theater, and the higher values more like a 2-channel setup.  My room's RT60 as measured at 1 metre in front of the center loudspeaker:

 

1892000477_ChrisAsListeningRoomRT60-1MetreCenter.thumb.jpg.a80bf7904ba4b25a61b985352c104af3.jpg

 

Once you set up and measure the room using REW, you'll have that data in hand to see if the total amount of room absorption is too much, or too little, or just right.  This is a function of frequency, so it will also tell you if you've got enough bass trapping in the room.

 

Chris

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3 hours ago, Chris A said:

The problem frequencies are the ones that aren't as directional as the very highest frequencies.  You tend to see a lot of advice of placing absorption at the "first reflection points", which is only true for the highest frequencies.  The problem frequencies in this case to be absorbed are the ones that exit the horn's mouth and wrap around the flange to re-radiate off the nearest wall surfaces to the horn's mouth.  The absorption squares that I referred to need to be nearest the horn's mouth exit.

 

Chris,

Again, more great info!

Can you post a picture of your room so i can see what your talking about in regards to the 2x2 panels?

Thanks,

Erik

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Here is a picture from about 3 years ago when I was using a center three-way "JuBelle":

 

gallery_26262_6_1571719.jpg\

 

and a more recent picture with the K-402-MEH center (pardon the state of the absorption tiles and coverings that have been moved around a bit by my two border collies and the cat):

 

Chris A's Main Setup.jpg

Chris

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14 hours ago, Chris A said:

 

 

Chris,

Thanks for the pictures, they def help!

 Do  you suggest 2", 4" or 6" panels?   OC 703, 705, FRK or Non FRK?

 

Did you choose 2'x2' panels just for easier placement?

 

Also, why did you choose to straddle the bass trap panel in the corner rather than doing what some might call a super chunk type bass trap?

 

Slap Echo:  Did the test this morning and there is a wicked slap echo on both the front and rear walls. Will need to address that.

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If you are concerned with using fiberglass...try Roxul Rockboard. I used r60 2" and 3" thick with 2' x4' panels made of 1x4 redwood. I found the redwood was significantly lighter, and worked great for ceiling first reflection panels as well as wall panels. We also covered the whole front wall with 2" Roxul, and found it made a nice improvement in soundstage, improved clarity. A friend of mine did the same (but used 1 layer of Roxul instead of 2 like I did), but spaced his panels out a couple of inches from the wall where I made mine flush, and he said his panels made as big of a difference as my 2 layer ones did. I listened to his fully treated room, and it sounded great!

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I think Chris did the bass panels like he did to let the sound reflect off of the rear corner, and have to go through the panel a 2nd time... I have heard some people it works better that way. I am curious if this is why Chris did it, and if he agrees.

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@Chris A ... AWESOME :D  Showed this to my wife and she just stared at me :(  (But ... did get KPT-904's in our TV room :D )

Chris A's Main Setup.jpg

 

Cheers, Emile

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5 hours ago, MisterVego said:

Did you choose 2'x2' panels just for easier placement?

If you look at the Jub bass bins and the sides/top of the JuBelle, you'll see more Auralex Sonofiber material there, too.  I wanted something that I could place on the walls and also cut with scissors to fit in tighter areas.  The Sonofiber material is just lint that's been processed a small amount to be fire retardant. 

 

5 hours ago, MisterVego said:

Also, why did you choose to straddle the bass trap panel in the corner

When you form an enclosed volume by using the corners of the room, that volume becomes like a Helmholtz resonator (without the neck restriction) that significantly increases its effectiveness in capturing midbass and upper bass frequencies.  That's called a corner bass trap.  It also works along a floor/wall boundary, but one end of the trap needs to be closed off using a wall or something else like a bookcase (or the top of a TH subwoofer, like I use). 

 

5 hours ago, MisterVego said:

Slap Echo:  Did the test this morning and there is a wicked slap echo on both the front and rear walls. Will need to address that.

As you put furniture, loudspeakers and equipment in the room, and pictures on the walls, CD/record cabinets, etc., much of that slap echo will fix itself.  I'd wait until you get everything into the room and rerun the slap echo test before adding general absorption to the room.

 

Chris

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