[Bumpy]

My communications with GIK and Clayton said without a doubt get bass traps in a small space like mine.  Then absorb side reflections.  Only then add diffusion.  I think if you're serious about this, you shouldn't trust opinions on threads, but talk to a couple people who do acoustics for a living.  Sure, they want to sell you something, but you can usually distinguish the BS from a company with a good track record who doesn't even really need your business and are attentive to your concerns.  I felt that was the case with Mike.  He wasn't in the least worried about me sucking bass out of the room. Nor was my speaker manufacturer, for that matter.  Both said the bass would be cleaner and paradoxically stronger in a good way that balanced out the tone across the spectrum.  Also, the bass traps I purchased don't just absorb low frequencies; they are full spectrum. Time will tell if this was the right move.  About 7 weeks.

I will wait patiently for your response. Please don't forget to tell us 

[Bumpy]

This guy talks a lot of sense.

https://www.youtube.com/watch?v=vvoDuBnElao&feature=youtu.be&mc_cid=6eea52a425&mc_eid=c486149bf1

[Rusty Jefferson]

Jesco is very knowledgeable, but keep in mind his emphasis is helping folks with home studios.  Mainly taming room issues for near field control of a mix. Getting a natural or organic sound in a home listening room in the mid/far field is very different.

Relevant article touching on the subject released today.
https://www.stereophile.com/content/my-room-2

[Bumpy]

Jesco is very knowledgeable, but keep in mind his emphasis is helping folks with home studios.  Mainly taming room issues for near field control of a mix. Getting a natural or organic sound in a home listening room in the mid/far field is very different.

Relevant article touching on the subject released today.
https://www.stereophile.com/content/my-room-2

Useful reminder Rusty

[sockpit]

I will wait patiently for your response. Please don't forget to tell us 

Here is more on my communications with Mike at GIK. He gave me permission to post this. Again, my newish OB speakers are Spatial M5 Sapphires and my room is 11 by 14 by 8.

"Thanks for sharing the post.

It’s not that I don’t think diffusion can be used with these speakers but you need to have the space that warrants it. Bass trapping is always the first thing to address, along with first reflections. Those two areas are the cornerstone of getting a room into balance. Diffusion is wonderful if it’s implemented right but I think too many people leap to diffusion as the first step because they look cool. Seriously. I am pretty specific about where I use diffusion because I want to hear the speakers first…and that requires getting the bass under control making sure the first reflections don’t blur the image and mess with the frequency response.

Your room is pretty small so using diffusion is not easy. You have to use the right ones (our Alphas can work) in the right places (rear wall if there was space) and maybe between the speakers on the front wall (but you have a bookshelf there). I’ve done them on the ceiling behind the listening position as well but you really need to have the space and orientation to make them work.

Bottom line: most speakers sound really good on their own and all rooms do is ruin that. Acoustic treatment is used to allow the listener to hear their speakers as they were designed so the music becomes more enveloping and sounds more like it’s supposed to. I don’t subscribe to the idea of the room being a contributor to the listening experience. Even a room with good dimensions has reflections, uneven frequency response and serious decay issues."


I (sockpit) am not saying this is gospel truth, but I have no reason to doubt he knows his business. And as I said, it's Clayton Shaw thought this strategy would do the trick. We'll see.

[Bumpy]

I spent a bit of time trying to think this through.

The reason many OBs are light in the lower frequencies is because of the cancellation of the front wave by the rear. Perhaps bass traps behind the OBs will 'mop up' some of the low frequencies from the rear and allow the front signal to perform.

[matevana]

The reason many OBs are light in the lower frequencies is because of the cancellation of the front wave by the rear. Perhaps bass traps behind the OBs will 'mop up' some of the low frequencies from the rear and allow the front signal to perform.

You will likely end up "mopping up" mid and high frequencies to a greater extent, negating much of the OB magic. Have you considered putting the Altecs in a sealed or aperiodic (leaky box) enclosure instead?  I'm a fan of well integrated bass enclosures with open back mids/highs. 

[Bumpy]

Have you considered putting the Altecs in a sealed or aperiodic (leaky box) enclosure instead?  I'm a fan of well integrated bass enclosures with open back mids/highs.

Moving off topic a bit for this thread, but yes thanks it remains an option for future development.

[FullRangeMan]

I'm a fan of well integrated bass enclosures with open back mids/highs.

+1 on that.

[Les Lammers]

Pi Audio Group has treatments for open baffles.

ABB1 Mr. 'T' Hemispherical Radiation:  47.5" X 23.5" X 6" - Perfect for open baffle use: Unpainted / Box of 2 pairs (M & F) $180.00 Painted / Box of 2 pairs (M & F) - $220.00

Standard colors are Behr Black and Behr Swiss Coffee.  Other colors are available for a small upcharge.

[sockpit]

This is a great topic for a thread, but a bit frustrating because none of us consumer types have any more expertise than what we can glean from the internet and puzzle out in our private theories.

There seem to be two schools of thought so far:

1. OBs are special enough in their dipolar design that they defy the almost universal advise of acoustic engineers that you need to address bass modes and other sins by putting base traps in the corners (at least) and addressing first reflections, including ideally the ceiling. This is the line of thinking that says doing so will ruin in the magic of OBs, deaden the room, etc. so one should go for Mr. T or diffusion not absorption. (Linkwitz seems to belong to this school.)

2. The other school of thought is that while OBs are less omnidirectional with bass and therefore create less problems and more articulate bass, they are not so special in their physics not to require attacking the bloated bass and reflections that are the bain of every average listening room.  There is a another thread on this Circle that ends with the owner of GIK, saying the principles of treating a room are not that different with OB speakers.

I've decided to go with 2) because both Mike at GIK (see above) and Clayton Shaw, the Spatial owner who sold me my M5s, said full-range bass traps in all corners and also at first reflection point was the way to go.  I'm quite sure Mike would have laughed at the idea of putting a piece of styrofoam diffusion behind my speakers, given his view on the way in which bass reflections kill a small room's ability to render the music clearly. Time will tell if I've just parted with more $ for this hobby without any benefit. 

But what would be great is if Glen at GIK or Clayton could take a moment to talk about the physics of a typical OB design and under what circumstances, if any, bass trapping is to be avoided. Otherwise it's just speculation . . . 

[sockpit]

sorry, duplicate.

[Rusty Jefferson]

....But what would be great is if Glen at GIK or Clayton could take a moment to talk about the physics of a typical OB design and under what circumstances, if any, bass trapping is to be avoided. Otherwise it's just speculation . . .

What would be great is if the speaker folks and the treatment folks got together and demonstrated in videos how to get the best performance from say 3 or 4 different rooms. Small, medium, large, extra large.  "If your room is like this, here's how we suggest setting it up, and here's why."...

Show measurements and discuss the subjective aspects of making the best of what is commonly a bad situation.  Speaker vendors would sell more speakers, and acoustic treatment companies would definitely sell more products if they could make it relatable. 

[JTF]

I'm finding bass traps to be beneficial. I had a huge hole between 100-200hz and the low bass is lacking with my X5s. The room is a little challenging, the main area is a little less than 13' x 22', but it's open on one side and in the back to another room. After discussing with Clayton, and with GIK, and after some research, I tried a few things. Clayton and GIK cited my rooms modal response as playing a role, and suggested bass traps as the first step.

So I built some traps and tested them out on the front wall, and I'm happy with the results so far. Below is a photo of the traps (excuse the fabric, it's temporary), they are 30 x 72 x 6 in, filled with R19 UltraTouch recycled blue jean insulation. Then on the back I attached a 2x4ft piece of rigid fiberglass, centered on the lower part of the trap.

You can see in the REW graph below, measured at the listening position, the response smoothed out a bit, notably filling in some of that 100-200 crater. I plan to build two more for the rear of the room and test again. Edit: I also note I turned down the subs a bit for the measurement with the traps, so it's not exactly apples to apples. I didn't save the other measurements, but it followed along pretty close with the green line below 50hz before I turned it down.

Here's one of the traps installed.



Here's the graph, green is before, orange with traps.



Here's a sketchup model of the room for reference.

[Bumpy]

I'm finding bass traps to be beneficial. I had a huge hole between 100-200hz and the low bass is lacking with my X5s.

Very interesting thanks. What were the theories as to why you had that big black hole in the frequencies?

[JTF]

Very interesting thanks. What were the theories as to why you had that big black hole in the frequencies?

Room modes, boundary reflections and speaker position. FWIW, the first thing I did was move the speakers around, I tried everything short of moving the whole system over to the long wall. I even put them up against the wall to try and minimize the front wall reflections. That did help the response and actually I got the best results by corner loading the speakers with more extreme toe in, crossing in front of the listener. The sweep looked similar to the orange line in the graph I posted, the 100-200hz null was smoothed out.

Getting a time out in the corner. If you're wondering, placing the sofa cushion there was worthless.

[Bumpy]

Thanks JTF. I think we can all glean a bit more info from other peoples experiences.

Attached is a picture of the REW scan at my seating position (3 way OB). I am very happy with the sound at present but will be tweaking the room, seat, and speaker positions to try and flatten this a bit.

What I find difficult is knowing whether its the peaks or the troughs that are the anomalies.



Out of interest I know my mid ranger is measured by the manufacturers as flat from 100 Hz to 10 KHz, almost certainly in an anechoic chamber. So everything I measure is down to something I have created in the OB or room.

[pompon]

Your measurement is not bad.

Mine ... with and without a basic EQ.
Start with 20dB swing to 10dB swing
I can do +-2dB with Acourate






The position of the speakers is to have the best image ... not the best frequency response in your room.
With 3 pts of EQ, you can have something pretty sweet.

What matter the most is your room resonnance.
Do the waterfall with my param to see how your room resonance is actually.
My room have basstraps and panels but it's a small bedroom.
I have a mode at 60hz probably because I have nothing on the ceiling.

[radarnyc]

JTF - your room is my room's doppelgänger. I have the X3s in a basement room that is 14.5x22 (7'7" ceilings); has an opening to the back and to two sides. Perhaps unsurprisingly I have the same null and I'm exploring room treatments with GIK. You didn't end up purchasing treatments from GIK? Can you describe what put you on the DIY path? Also, how far off the front wall (wall to front baffle) and side wall (wall to side of speaker) are your X5s?
Thanks!
Mike

My room


My Measurements (untreated room)

I'm finding bass traps to be beneficial. I had a huge hole between 100-200hz and the low bass is lacking with my X5s. The room is a little challenging, the main area is a little less than 13' x 22', but it's open on one side and in the back to another room. After discussing with Clayton, and with GIK, and after some research, I tried a few things. Clayton and GIK cited my rooms modal response as playing a role, and suggested bass traps as the first step.

So I built some traps and tested them out on the front wall, and I'm happy with the results so far. Below is a photo of the traps (excuse the fabric, it's temporary), they are 30 x 72 x 6 in, filled with R19 UltraTouch recycled blue jean insulation. Then on the back I attached a 2x4ft piece of rigid fiberglass, centered on the lower part of the trap.

You can see in the REW graph below, measured at the listening position, the response smoothed out a bit, notably filling in some of that 100-200 crater. I plan to build two more for the rear of the room and test again. Edit: I also note I turned down the subs a bit for the measurement with the traps, so it's not exactly apples to apples. I didn't save the other measurements, but it followed along pretty close with the green line below 50hz before I turned it down.

Here's one of the traps installed.



Here's the graph, green is before, orange with traps.



Here's a sketchup model of the room for reference.

[JTF]

JTF - your room is my room's doppelgänger. I have the X3s in a basement room that is 14.5x22 (7'7" ceilings); has an opening to the back and to two sides. Perhaps unsurprisingly I have the same null and I'm exploring room treatments with GIK. You didn't end up purchasing treatments from GIK? Can you describe what put you on the DIY path? Also, how far off the front wall (wall to front baffle) and side wall (wall to side of speaker) are your X5s?
Thanks!
Mike

Mike, I looked at the GIK panels, but ultimately decided to build my own for a few reasons: I wanted custom sizes. Variety of fabric and the ability to change the fabric easily. Also these panels may be temporary, I'm planning to gut this room down to the studs and build the absorption into the walls and ceiling. Cost wasn't really a factor but it is cheaper as well, the material cost for 4 bass traps, the TV panel and the 2 side panels was less than $250. I also enjoy DIY.

Right now the speakers are 55 in. from the front wall, measured to the center of the baffle, and 22 in. from the side walls to the edge of the speakers. The speakers are 78 in. apart edge to edge.

Since my earlier post in this thread I've built and installed 5 additional panels. 2 bass traps in the rear of the room (not shown), same size as the front 30 x 72 x 6. A free standing panel to place in front of the TV, 60 x 36 x 4in, and the side panels which are 30 x 48 x 4. I also rewrapped with a different fabric, and I stuffed more of the recycled cotton insulation into the bass traps. My main takeaway so far is that surface area and the depth of the bass traps needs to be significant to improve the low bass.

Here's the room right now:





Here's some pics of how the panels are constructed, it's very simple. I used cheap 1x pine boards, recycled denim insulation batts, R13 for the 4in and R19 for the 6in deep panels. I covered the backs with landscape fabric, then wrapped the fronts. The batts are sized to fit inside typical 16in oc wall studs, so I added the central supports. This is also why I used a 30in width for most of the panels:





The R19 is only slightly thicker than the R13 but much denser, the lighter blue batts in the photo are the R19. If you compress it slightly or leave the backing off the R19 will fit in the 4in deep panels. I may swap it out in the future. I did remove the backing from the bass traps and they now have a layer of R19 and a layer of the thinner stuff.