Open Baffle Opinions - I Won't go back to Boxed Speakers Evr Again (maybe....)

Sounds to me like you're doing it correctly. No L-pads an absolute MUST.  Would you consider no passive crossover components in the midrange? I like an active crossover in the critical 250 Hz. to 4 kHz. range. I like your approach for the tweeter, simple 1st order passive, but still prefer active with separate amps. Happy listening.

To tell the truth, a single pole and open baffle is gonna be real tough.

The inside of the speaker needs to have a weir between the two. How wide that weir or baffle is, will help to focus the center. It's the rear pole that is causing the issue.  I never could get it right, BUT I did get close by adding 20 inches to the rear pole DEAPTH and quit trying to use OB for the mids and highs.. I use a dipole design just not on the same baffle plane. 

I had a hinge on the inside weir, THAT really helped to focus and help with imaging.. Get the toe in right the set the weirs parallel, they will image a lot better.

Like IRS design from infinity... the center always suffered because of the OB design and ZERO physical separation between the two speaker drivers (left to right). NOTHING, just space...smear is a serious issue THE BLOB... comes to mind... So you toe in and toe in and.. LOL it just can't work...

BUT sound quality IF you can just silence every part of the room.. Reflections are a pure nightmare with OB design and room size...SIZE does matter... BIG time...Small did NOT work for me.....

Cool looking though.. Nothing like DIY

Regards

Great comments from you all (so far). Yes, I thought about using all miniDSP on all the Drivers and I have 3 Balanced version miniDSP 2x4’s that would do the job. The fact is, I’d like to utilize my PS Audio DirectStream DAC Sr. without adding another DAC in the mix (miniDSP non HD is a 48/24 A/D inside). I did start out with all active Xover’s just to get an idea on how they would sound and how best to do the Xover frequencies and Slopes.

Yes, the one big problem is OB’s will tell you immediately how good/bad your room acoustics are. You do "hear" the room. My listening space is not ideal. Basically a square room with the hallway down the left side Speaker and a pocket where the entrance is and a lot of Glass on that side.

I also tried toeing in and it messed the imaging specifically the Phantom Center and the Bass was more prominent on the right Speaker.

Like IRS design from infinity... the center always suffered because of the OB design and ZERO physical separation between the two speaker drivers (left to right). NOTHING, just space...smear is a serious issue THE BLOB... comes to mind... So you toe in and toe in and.. LOL it just can't work...

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Excellent post, 
I agree open back weakens the sound projection imaging

My Seas Thors (minus the Millennium tweeter, just sold the pair off on ebay in 1 hour), has a  *transmission design**  Has this added wall plate behind the  drivers, runs down the cabinet opens at bottom, then the sound runs up to the top with a  opening.
I took out all the white fluff JAMMED tight inside (past 20 yrs!) and now the bass/mids has exploded.
I need to place a  1 inch thick ceiling insulation behind each W18,,
IMHO this transmission design is the best for opening the speakers potential.

Here is the Seas Thor cab design
Genius workmanship.
https://www.youtube.com/watch?v=UaKjlgO3IOE

Hmm... I've only my GR-Research NX-Oticas in one room (my current room) but the center image is quite good. One thing that is different in Danny Ritchie's OB designs is that he uses a side wrong on the side of the speaker toward the center. This reduces the front to back wave interaction on this side of the speaker and may contribute to sharper imaging. 

You could experiment by talking a piece of stiff cardboard on the inside side of your speakers and see if that helps. 

Seal the midbass in a small stuffed box, change the crossover between the mids and woofers to 120. 2500 is fine on top. You are getting that free air woofer out of the vocal range. Leave the woofer free air. Everything will snap into place instantly.  You can dial it in and try it without the midbass baffle, but you will have a hole in your frequency,  the Dynavox won't go down to 120 without the box.  
Be careful experimenting,  use low power, the Dynavox have an xmax of 2mm.  They won't like going down in free air.  

Just noticed that autocorrect changed "wing" to "wrong" in my post. Meant side wing on the inside side of the speakers. 

Yes, the one big problem is OB’s will tell you immediately how good/bad your room acoustics are. You do "hear" the room. My listening space is not ideal. Basically a square room with the hallway down the left side Speaker and a pocket where the entrance is and a lot of Glass on that side.

You mentioned center fill as an issue. The way an OB system is supposed to work is that the rear firing information bounces off of the wall behind the speaker and thus arrives at least 10mS later than the first arrival.


If it does that the ear uses the delayed information to echo-locate, IOW to help out the sound stage. If it is less than about 10mS then the information contributes to harshness. As a general rule of thumb you want such a speaker to be at least 5 feet from the wall behind it. If less than this it won't image right because of the reasons I stated.

I wonder if the center image problem is because of the deep walls on either side of the midrange drivers. I have never seen an open baffle speaker that looked like that before. 

Ralph's (atmasphere) advice matches my experience with planar loudspeakers. The common wisdom for dipole/wall spacing is at least 3' from the front wall (behind the speakers), but that is incorrect. As Ralph said, we want the rear wave to reach our ears no less than 10ms after that from the front of the speaker. Any less than that, and the rear wave in effect sounds like a smearing of the front signal, rather than a separate event. As sound travels at approximately 1' per ms, that requires the dipole be 5' from the wall (5'/ms from speaker to wall, 5'/ms from that wall back to the speaker). 

And diffusers on that wall can help disperse rather than absorb the rear wave, a good thing if your room is on the warm side. Absorption on that wall will reduce the amount of life and energy the speaker produces, which can be good if your room is too live, and perhaps cold/bright.

As sound travels at approximately 1' per ms, that requires the dipole be 5' from the wall (5'/ms from speaker to wall, 5'/ms from that wall back to the speaker).

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The main reason I had a difficult time getting a Dipole common baffle to work.  You cannot get the timing correct front to rear. The further you get from the front wall the WORSE the timing will be not better. Lets move it closer to the wall. HOW will you ever get the timing correct. Front to rear. 

The only way is to separate the poles and add drivers to the rear pole also.

A rather sloppy way is to add a WEIR, to the inside of both monitor sections. I chose to hinge mine and set the toe on the baffle face. After the phantom speaker is kinda figured out you set the inside weirs parallel to each other.
 
What about the outside of the baffle adjacent to the outside wall, where do you think all that "out of time" stuff is going.. NOT WHERE YOU WANT.. I assure you..

So a box (It has to be a box it can't be open) has to be DEAPER and that distance from the front wall to the rear pole is the distance from the rear pole the front pole BUT only if the distance is the same. So a 20" deep speaker would be 20" from the FRONT wall. The further you pull the speaker into the room the more of a 3/D effect you get BUT loss of imaging. There will be a point where your ears will just QUIT making sense of the music. A sound effect chamber...

The numbers you quote are arbitrary. I've never heard the "within10ms rule" I've found in speaker building that it to be just the opposite.

If you want to smear the image and ruin the sound stage, let like firing drivers fire at different distances from your ear as you're proposing with a common Dipole baffle. You will get one thing "SOUND EFFECTS"

OB Look cool though..

Excellent comments from all of you once again.

Here's my responses (so far) and thanks for the good advice :

1. The side wing (a la NX-Otica's - Danny Richie - I watch his Video's too) idea is one I will try 1st and foremost. Makes sense and he gives an excellent explanation why as you mention too. It's the center focus problem. I have enough material that I can temporarily make a side wall on top of the 1.5" thick side panels of the H-Frame Woofers.
2. Build a box around just the Midwoofers leaving just the 12" Woofers and the Tweeters Dipole. Changing the crossover points from 250Hz - 2500Hz to 120Hz - 2500Hz won't be hard. I have lots of Inductors laying around that I can cobble something together. Lowering the 12" Woofers LPF  to 120Hz is a snap with miniDSP.
3. Placement currently is 5ft. exactly from the "front" (TV) wall to the back of the H-Frame Subs (5', 9" to the Midbass/Tweeter Baffle). Right side is only 2.5ft. from the room's side wall and the left side is a whopping 7", 4" from the entrance/side pocket opening/WINDOW (I have to draw it out for you Guys), Also on the right side the Speaker face a Hallway. Also the swinging doors to the kitchen are wood in a glass frame window embedded. I'll take some pics and a floor plan with room dimensions.
4. Toe-in on most box Speakers friends have lent me gives me a great center phantom image when placed straight out into a room except for a pair of KEF R3's that worked best with about 10deg of toe-in.

Thanks again for the kind words of encouragement.

BTW, I'd seen a lot of OB designs that that either integrate an H Frame stacked or not stacked Woofer cabinet below the OB Panel so my panel was tall enough (barely) to accommodate. The difference is I have no top brace/shelf in my design.

I also saw a Video with Clayton Shaw (Spatial) who suggests the upper Woofer be crossed over higher while the bottom one is X'd at 90Hz.

Baby steps but I can hear the potential.

I have owned 2 Spatial audio labs speakers ,and currently 
saving for the Exceptional X3s. They have a great minimal Xover only 3 parts, the CustomBeyma AmT midrange-Tweeter,is excellent and there is no Xover in the critical midrange from 1k on up , very efficient 97db-1watt, 12 inch mid bass , and from 90 Hz down to 25 HZ and is powered for deep clear Bass.

1. Build a box around just the Midwoofers leaving just the 12" Woofers and the Tweeters Dipole. Changing the crossover points from 250Hz - 2500Hz to 120Hz - 2500Hz won't be hard. I have lots of Inductors laying around that I can cobble something together. Lowering the 12" Woofers LPF to 120Hz is a snap with miniDSP.

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man you are way ahead of my DIYer skills. I have no idea what you are talking about. 
However , though i do lack the science and deeper understanding of these things,,does not mean i am not willing to do some DIY stuff on my own. 
I just shipped back the Seas Fa22rcz after 15  minutes of testing .
So I am back to the drawng board,
Going witha  Davidlouis Lowther/Voxativ clone. The 2020 version,  the 8 incher. 

so my New Thor design will be dual W18 E001's + the Lowther/Vox clone 8. 
Adam at Madisound on <my> new Thor said of it,~~sounds like you got a  real Frankensteinspeaker going on there~~~lol, Yep, hope the 87db midbass pair up well with the 95db FR..

jimob18 posts05-10-2021 8:16pmI have owned 2 Spatial audio labs speakers ,and currently
saving for the Exceptional X3s. They have a great minimal Xover only 3 parts, the CustomBeyma AmT midrange-Tweeter,is excellent and there is no Xover in the critical midrange from 1k on up , very efficient 97db-1watt, 12 inch mid bass , and from 90 Hz down to 25 HZ and is powered for deep clear Bass.


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Sounds really nice what you got going on there.

I just cked out Beyma's cp750TI horns, weighing in at 15 lbs each!!!!
Really nice, 
But have to pass up these massive  and tempting , horns. 
Staying with a  FR + midbass design. 
The FR goes up into the 10k-15k range, and thats all I need.
I have no interest at all past 15k as 99% of classical music has nothing at all past 15k.
Sure a horn goes right up to 20k. 
But for what purpose????
zero interest. 
As well  these  , high tech compression mid tweets , have incredible sensitivity at 100-120 db sens. 
Again for what purpose??
My amp is a  true 100 watt PP.
On midrange/highs I look  for 94/95 sens. Even 97db is too high. 
I listen extremely near field in my small room  , so anything higher than 95db is a overkill.

Over 95db on a  full range, this would mean gain on the linestage would be set very low, which would not allow the W18E001's to open up..
The dual W18E001's are acting like a  bass floor for the Full range.
Really  is a Frankenstein of a  speaker
I havea  pair of open baffle,, well honestly, they have 1 screw hopding the driver to the top of the Thor cabinet,, The Millennium spot is now open as a  front baffle, , took out most of the stuffing fill and placed a 1 inch pad behind each W18/
Lots of bass and sounds super. The Diatone 6.5 is far superior to the Millennium tweeter for full rich midrange/highs. Even a bit lo nice solid upper bass. 
We need to begin thinking outside the box. 
I should have made this Frankenstein pre-upgrade on the Thors. 
The loss in that upgrade project  really pushed my bottons and I came up with this New Thor design in frustration and despair. 
Suffering is the root of creativity. 

I don't process some of the technical jargon in this post but isn't the open baffle concept what the Dahlquist DQ 10 was trying to accomplish?  I own a pair and they sound fabulous..  Just curious....

Very fun and interesting project you've done!

If the three drivers were sealed as stated above, based on the specs for the drivers, they will naturally have an F3 of 130hz, with a 0.105cuft which should make crossing over at that point quite simple.  With a QTS for these drivers being .34, and an EPB of 137, I think they could benefit from being boxed in. Although, they would prefer a ported design, which is not a good idea for an OB speaker :)

Would be very curious to see what the difference would be having the 3 drivers in the same sealed cabinet vs having them in their own sealed enclosures. 

I'm a bit confused as to the reasoning behind the H frame and how it dissects the top woofer. Asking because I have been wanting to build some open baffle speakers for myself, but 4x15" woofers, 2x6.5" full range drivers and a (possibly) rear firing super tweeter (not to mention crossovers) they can get quite costly as an experiment.  The wings and associated math to sort out baffle step is something I have not wanted to take on quite yet either.

Decwares approach with the curved edges is an interesting design approach, but again, either math, or a LOT of wood being cut to experiment with.

@bdp24 , @atmasphere - I have also found that moving the speakers further into the room and adding some diffusion behind the speakers helps a lot with the imaging and soundstage. I have two 2x4' GIK panels with diffusor plates behind each speaker and have the speakers placed such that the front of the baffle is about 7ft from the front wall.  This creates a deep sound stage with nicely focused imaging. I wouldn't say it's the sharpest imaging I've ever heard, but I really like the overall presentation. 

@sejodiren - yes the DQ10s were one of the first speakers to popularize open baffle, although these speakers used a conventional box enclosure for the woofer. 

@rajugsa. Very interesting design and their specifications make for wanting to hear them.
I also have a pair of open speakers (if you expand my avatar you can see one in my room. They are Kyron Audio Gaia’s. for a better look check out
www.kyronaudio.com.au under speakers /Gaia
They are sublime with a huge stage. Interesting characteristic is the louder you turn them up, there is a point where instead of volume, you get fullness. Like listening to a full orchestral then adding more instruments. Wonderful!
Do your open speakers open up the sound rather than a box?
AG 🇦🇺

@jayfor Diffusers are next on my list. I have 6  sponge type absorptive panels at the 1st reflection points in the room, above the listening couch, and as you see in the pictures, placed in the corners like Bass Traps (which I know they are not). two 20"x 20" behind each Speaker may do the trick. If not, it's Amazon so I can return them & get my money back.

I'll let all of you know. Thanks again. Great tips so far.

FWIW

While I am aware of wings, my Emerald Physics OB 3.4s are wingless, but image just fine. MAYBE it’s because the 12" driver has a 1" polyester concentric tweeter. Remote passive XOs are some 2ft away from each speaker. I replaced the CRAP OEM jumpers with Wire World OCC, which by-it-self was HUGE. Speakers are ~ 7ft from my front wall and ~ 9ft on center with a 20-30* inward tilt. My powered 12" subs are 65" behind the speakers

It's your speakers' position. Dipoles follow a simple rule for high frequency front/rear integration. If your are enjoying the low frequency coherency, you're not far away. LF is easier to find direct/rear. (But can still be optimized)

You describe your problem as lack of focus, then go on to say have great soundstage and imaging. Can you clarify/rectify these statements? Feel free to contact me directly.  

OP follow the ping pong ball.. To the sides of the baffle!.. The outside and inside are going to be the killers. A small room and OB?

Diffusers? You want absorption and dampening.. NOT scattering the sound.. OB? OP.. OB!! We are talking about imaging right?

Second raising the XO point on the UPPER bass unit causes issues too. Ringing.. The larger the driver (usually) the lower in the frequency range it occurs. 12 - 15" drivers are limited by their physical size to reach higher frequencies. Just a physical thing. In theory it works, practically it may not.. The room size and how it pressures up, change a lot of things.. 

A simple window being opened can change how an OB system works and sounds. Fruit for thought... No veggies please :-)

Regards

This is a very interesting read...

http://www.enjoythemusic.com/diy/0911/slot_loaded_open_baffle_speaker.htm

@pekri. My Wife would kill me but yes, I did read Nelson Pass' article  a while ago. Interesting design and I'm sure it's a mindblower.

@rajugsw   

Yeah, I understand! There are not many who would be happy with that in their living room :)

http://www.jantzen-audio.com/poor-mans-strad/

I added a side panel (behind the baffle) on both Speakers facing inwards to each other with acoustical foam. 10° of toe in and the Phantom Center is back baby !

It's not razor sharp but it's better than it was yesterday. The Treble is a bit subdued now. But that's to be expected. My ears will adjust. To me when someone says the Treble or the Speaker has lots of air, that's a hot Tweeter. This is great when you want to hear the Fart of a Knat, but to my ears it can be fatiguing. No Tinnitus here, just 51 1/2 years of age.

So long as the vocal sibilance's stay dead center along with the Kick Drum & Snare Hits, I'm good. I have some mono DSD files legally purchased/downloaded and will try them out tonight. Right now, it's a 70's Vibe, CSN, & Y, The Eagles, James Taylor, Joni Mitchell, Carole King, and whatever else I'm either Streaming (AmazonHD/Bluesound Node 2i) or Spinning (SACD/CD).

Thanks for all the encouragement and advice folks. I still have tinkering/tweaking to do. 

After reading this post yesterday, I decided to rearrange the placement of my 4 Argent Room Lenses. 2 are now ~ 5ft directly behind the drivers and 2 are closely butted up against the inside of each speaker. I must say, this significantly improved imaging


hth

Again, my Wife will kill me if I DIY’d 3 PVC pipes taller than the Speakers and placed one in the middle of my room (see pic link on my original post).

I am building some calculated Diffusers from 2x2’s cut to specific lengths using QRdude and chose the design frequency of 300Hz (human voice). No clue if I’m gonna fail or pass but I have lots of 2x2’s doing nothing in my garage and some cheap thin plywood to glue the pieces on to. I’ll try them behind the Speakers first (plan A), then replace the foam panels at my first reflection points with the diffusers if plan A doesn’t work (plan B).

Or build more of the diffusers and reuse the foam panels as fake Bass Traps that will raise the height of my current.

Is my frequency selection correct since it’s the female/male voice that’s the problem ? Drum Kicks/Snare are pretty centered.

Diesis Audio is the best for the open baffles, you must give a try for them.
https://www.youtube.com/watch?v=S7XZvXYFFXY
https://www.youtube.com/watch?v=EgLDqriZIlE

OP,
Tinnitus (on average) starts at around 55 years of age...I got it at 54. Dont count your chickens just yet. Enjoy your unaltered hearing every day!!

Lovely design and execution.

Try active crossovers and amping.  Try it, don't speculate it in an online forum where 90% of the input will be from individuals that don't have any firsthand experience.

Not analog, but decent digital so you can achieve phase alignment via delay and FIR filtering.

That will take you to the next level and give you a much higher degree of control over the system.  :)

@quadprod :

You make some excellent suggestions regarding using active X-overs and Finite Impulse Response Filtet also can more precisely help with some of my issues.

But as I’ve stated earlier, I don’t want to feed the Analog output of DAC into another DAC (of sorts).

Fixing my room problems for me is the key to getting that damn center image sorted out.

I’m almost there. Built a 2’x4’ Skyline Diffuser for the back wall behind the sofa and an building two smaller 2’x2’ Skyline Diffusers for behind the Speakers (preferred WAF) or on my 1st reflection points where I have absorbers currently.

Try active crossovers and amping. Try it, don't speculate it in an online forum where 90% of the input will be from individuals that don't have any firsthand experience.

agreed, and I do have experience with this. Pure Music and Pure Vinyl are  excellent options. Built in crossovers 2-3, or 4 way with adjustable amplitudes and delays for time alignment. They also accept AU plugins so you can EQ, I used Fab Filter and  recommend it but there are many others. Next you need a Pro Audio interface to get the active outputs. Again, many excellent options at various price points. Lynx, Antelope, RME, and others. I triamped my system with great results. The interface is your DAC which is what the pro's use to mix the music you listen too. Many excellent choices at a fraction of what you pay for overpriced "audiophile" DACs. 

To expand a little on Ralph and bdp's comments, many years ago Bell Labs research found that a delay of at least 10 ms between direct and and reflected sound increased clarity and definition.  Any time less that that leads to smearing of information.  So it is important for any dipole distance from the front wall.

As mentioned, sound waves travel at something very close to 1' per ms. So 5' minimum distance out from the front wall is recommended.  When that distance is not possible then diffusion panels should be utilized.

This applies to all speaker designs for sidewall distance.  The distance from front baffle board to the first reflection point on each sidewall should be 10' greater than the distance from drivers to the listener's ears. 

I agree with the OP. Once you’ve experienced OB’s you’ll never listen to a box again. Fact is, my first set of speakers were boxes but featured a Heil AMT. I enjoyed them immensely. Since 1980 I’ve owned electrostatics. In 2010 I discovered OB’s made by an audiophile whose main gig was producing 30’ boardroom desks here in Seattle. The man had serious woodworking skills, and his OB’s were sensational. He began building speakers which had a following. He built the Hawthorne Rainiers which featured a huge Heil version in their center. For woods he’d use Sapale or the finest Birch you’ve ever seen. I owned two different pair over the years which featured 15” woofers. It’s the finest natural sounding bass I’ve ever heard. Yes, once OB, never back. Fact is, there’s a ton of OB options nowadays.

@coltrane1 That's so cool. My woodworking chops ain't the greatest but all my DIY Speakers have always had a DIY look and feel to them. Not by choice. I am not a Carpenter (but I wish). Here the rear wall Diffuser just completed and hung today. Two more smaller one's are going up this week either at the 1st reflection points or behind the Speakers on the front wall. 

Phantom Center is much improved but add smaller diffusers should tighten the Phantom Center. Or that's the hope anyway.

https://photos.app.goo.gl/bJQNygLXcWffuGKg7

Beg, borrow, or steal the $2K, but these are amazing
https://www.audiogon.com/listings/lis9e665-emerald-physics-ep2-7-black-full-range

I believe Clayton Shaw the owner of Spatial audio was the designer for Emerald Physics prior to starting Spatial Audio.  I have the Spatial Audio X5s and will never go back to a box speaker again.  Everything in my opinion is just better in regards to open baffle sound quality.  Problem is many have not heard open baffles and I only just heard an open baffle speaker after being an audiophile for close to forty years.  But the X5s have exceeded my expectations and well just make most box speakers sound closed in and boxy.  The bass on an open baffle is vastly better as well in my opinion with no bass bloat, just clean fast and tight with lots of texture.