Open Baffle Speakers...No Bass??? Try this...

[Popcorn]

I was skeptical about how good an Open Baffle speaker can be. I thought, without a box, you would need a big driver or multiples of it to be able to drive enough volume and for sure a sub-woofer has to be in the configuration plus numerous circuits and maybe separate amplifiers before you can get any decent sound.

That was until I tried my hands on these after much prompting from my brother who said he went through no less than 500 pages of forum postings and found a suitable and simple design.

I built a pair of folded Open Baffle speakers with my Coral 8A-40 8ins drivers.
Each side consists of 3 panels, 32 ins tall. The middle panel on which the driver is mounted 23ins from the floor is 10ins wide; the inner panel is 10ins wide and the outer panel is 12ins wide.

The 3 panels are joined with piano hinges and the driver is braced from behind onto the middle panel in addition to the usual screw mountings.

The construction is extremely simple. Perhaps this is also why I was skeptical in the beginning. Good things just cannot be simple!

Being folded Open Baffles, the speakers presented an almost infinite permutation of positioning and angles by which the inner and outer wings can be folded that would affect how the speakers would sound.
And this is where the fun begins.

The most prominant characteristic of these open baffle speakers is the clear, open and airy sound. The soundstage is life-size, and I was able to get superb holographics. The performance is different from the boxed speakers I've heard.
Because of their size and light construction, they are very easy for me to shift and place to get the optimum effects I wanted.

One might think Open Baffle speakers would sound thin, what more one driven by a single driver. These absolutely don't. The sound is as full and lush as the boxed speakers I have.

So what about the bass which seems to be the weak point of Open Baffle speakers.

I tested mine using Stereophile Test Disc - Track 16 Bass Decade (200hz-20hz) 1-3-Octive Warble Tones At -20dbfs. At the listening position, I hear the warble down to 30hz albeit it is slightly softer.

My floor and sofa vibrated from the bass in Patricia Barber's "Too Rich for My Blood" track in her Cafe Blue album.

The speakers in my room is placed 3 ft from the back wall and 12 ft apart. Of course placement  would be different if in your listening room but it is so easy to move these speakers around to get the right sound you want. The learning point is, closer to the wall does NOT mean more bass. Somehow, there seem to be an optimum distance where you can get the best bass in relation to the room dimension.

Don't take my word for it. Build one and give it a try. Construction is as simple as it gets. I used 15mm Marine plys.

[yeo]

hi popcorn

congrats! i like your bracing used. i believe, once you remove the bracing, you can only hear 30hz "noise" and not music. 

how far off the side walls of your room? how far is listening position?

thx!

yeo

[kkerwin]

i built the dick olsher basszilla platinum, http://store.hifiauthority.com/olsherkits.html, with the main driver being ob.  i am very happy with the speakers.  they sit about 5.5 feet from my back wall and about 3.5 feet from the  side walls with a bit of toe in.  i put phase switches on both speakers because so many, (at least 40%) recordings are recorded out of phase.  when the speakers are "in phase", they are invisible.  the stage is excellent.  i just upgraded the tweeter sections from aurum cantus g2si to aurum cantus g2.  this has improved the smoothness and detail of the highs.  the bass section is a 15" eminence (96db) driver in a bass reflex box.  my jolida 707a doesn't do justice to the low end potential, so i temporarlily have these passively bi-amped driven by my old denon solid state receiver.  this works great. i must add though that with the recent charlize build with my son, the charlize drives the entire speaker very well, with great detail in the bass.  i posted a photo of the speakers in the "mojonica... a giant step closer"  thread.

[assendor]

Hello Evan and Kevin,

Open baffle speakers are very interesting, or at least to me they are.
If this is the absolute best speakers possible? Hard to say, probably depends.

I agree 100% on one thing though. If you take into consideration the amount of Work/Price
ratio compared to they're performance, it is the best speaker option possible PERIOD!!!

I've been listening to OB's for many months now, simply Love the sound.

   Just a statement here that doesn't have to be correct, but still a thought:
""IF OB's where much better than Back loaded horns, it would be hard to understand why someone
with the capacity to Build, Design and Calculate Back-loaded horns properly still would bother doing
just that, if stuffing the same driver in a plank sounded better?""

Even so, many things are being done just because "someone" want to do it differently than the other
engineer did it.
SO it is very possible that someone actually could do this, even if they knew all along it was a stupid
approach compared to OB's.
This is the way of the world and we have to decide ourself what we think/hear/feel and want to spend
of efforts to get the ultimate sound performance into our homes.

   I have a pair of Back-loaded horns, 1/4'th wave or something with some Coral Flat8II in there,
they sound FANTASTIC with this single driver in there.
A friend of mine are at the time borrowing them, he is almost in a coma because of they're performance.
He loves them so much is does not have words.

Since I too love the sound of Coral drivers so much, well there is also a pair of FLAT 10's laying around here, so my plan is to put these drivers into a OB JUST like you Evan did.
The "bracing" as yeo so lovely calls it, is an marvelous idea neat and smart.

   The OB's playing in my system today have not less than FOUR (4) 18" Woofer drivers, two on each side.
Then Midrange 8" and a 4" Tweeter.
For a long time and liters of drool have been spilled on the Aurum Cantus tweeters G1.
What bothers me is the PRICE, ERR; it is OK if they are OK in my system, if not, HA HA HA!! NO FUN!"
Reason why not G2, well sadly the sensitivity is too low for my setup.
OR else it the pick would have been the same drivers as Kevin has in his setup.

You do mention Eminence, I was supposed to use Eminence Beta 18" in my system,
but due to impedance matching it fell on some other similar 18" drivers with even lower
FS = 23Hz.
These work fantastically good in OB's have a sensitivity of around 99dB/W/M, and so with two on
each side we add up to 101.5dB/W/M or so. (Think this is correct, like with antennas ))

BTW Evan,
I had no idea that the bass would behave like you mention here.
SO the bass will first increase in strength and depth the further from the wall, and then weaken again
when too far away.. Interesting, very interesting.

   Oh one other thing here,
yeo I agree with you in many things, and it is beneficial to do so, because you are so often right.
Still I'm disagreeing with you when it comes to the use of HUGE BEAST Woofer drivers.
You I'm sure, think that these speakers of mine will blow my hair off, they certainly could even if my hair
still is hang'n in there pretty well.
The Woofers are rated 800Watt/RMS each, so a total of 3200Watt/RMS and a sensitivity of 99dB/W/M.
approximately 45KG of drivers...
Yes you are correct, or you might at least not be wrong, it may seem EXTREME!!!

Truth is, maximum power these drivers ever have seen is about peaking 4watt.
Now we can discuss if they're break-in time and so then can be achieved.
YES, Swipe and pink noise for day's with a 2x600WATT/RMS PA amp on  low frequencies have done this.
Only maybe up to 7W/channel, or else the police would show up.

   OK, what do they sound like? The sound, the low frequencies are wonderful.
It is so detailed it is hard to believe. IT is especially the imaging, holographic 3D in bass region that
is the most impressive part.
HOW deep frequencies can they deliver with a couple of watts, "simple" they do all instruments fine.
Cello, Contrabass, Timpani, they are all sounding like what they are.

I never get the feeling they play thundering bass, they just reproduce the instruments perfectly.
Even Thunder, like in Roger Waters Amused to Death (Thanks for the special one Jochen),
the thunder sounds and holographic positioning is breath taking.
The rolling of the thunder reproduction, like it is outside in mountain areas is wonderful.

It probably gets even more wonderful with some proper HUGE beast hard to build horns,
but compared to ALL other speakers, including the horns available to me, this is a very good solution.
Synthetic bass with long sinus wave 20Hz frequencies they cannot reproduce.
(Haven't tried it with the tone generator, but can hear it on horrid music.)
Other simple Bass reflex speakers makes this Rumbling distorted sounds when fed with this music.

IT is also possible this may be differently when the distance to wall experiment will be carried out.
Then maybe they will do 23Hz or so?

OH this was a lot..
Please comment, there should be enough to comment here.. .HA HA!!!

-Jonas

[Popcorn]

Hi Yeo, Kevin, Jonas,

This is my first attempt with OB and thus am still very early in my learning curve.
I started this not expecting much...I was a non-believer, but I was amazed with the results. The clarity, soundstage and holographics simply won me over.  I was able to achieve more in those areas compare to my other boxed speakers using the same driver in the same listening environment.

The bracing, I believe did alot for the sound and imaging. It's a must-have.
Perhaps mine needs some refinement, a narrower block maybe.

My listening position is about 14ft from the speakers. The right side wall is about 22ft away while the left opens to a balcony.

The bass behaved as you have described Jonas, The speakers are obviously interacting with the room.  The room becomes perhaps a big resonance box now with Open Baffles.  Even the spread of the side wings has an effect on the sound.  Many hours has to be spent in getting the positioning, tilt, wing angulation right. The effort however is well worth it.

These speakers gave me a new experience to the sound and music. I am beginning to ask the same question as to why the bother with difficult boxed designs and construction.  I am not quite an OB convert yet but this one I have seems to be holding its ground and convincing me.

All I can say is for everyone to just build one and give it a try..it doesn't take much cost nor time in building. However, you must have patience in trying different placements in your room to find that one where the music simply come together.

Finally, there is definitely bass.... though that is not the only thing we look for in the music.

Evan

[kkerwin]

hi all
i purchased the aurum cantus g2 tweeters recently from parts express.they wer running a sale for about $110 us. a piece.  typically these are around $180 a piece.  they are 96db sensitivity.  i am running eminence 15" definimax in bass reflex enclosures.  they are also 96db.

dick olsher's design is actually very complex due to crossover and notch filtering for the fostex 208ez.  in this design, the g2si and g2 are interchangeable. however, due to the excellence of the entire design by dick olsher, i have no desire to tweak.  i also cook for a hobby and will not modify a thomas keller recipe.  i simply don't know enough in these areas.

i have found the i can tune the midrange of my ob's by placing small sounding boards at the room corners behind the speakers.  so a 5" by 24" board can actually change the location of singers in the soundstage.  i was fiddling with this quite a bit for a while when we were working thru the monica mojo improvements.  i have found that this is not necessary with the latest improvements and since the amb labs sigma 11 power supplies are in use, i have actually been taking some of the previous adjustments out of the system.  i was probably to some degree compensating for things that have now been significantly improved in the mojonica source.

i'm now a bit conflicted after hearing the charlize that my son and i built.  the detail in the bass is so fabulous however i still love the sweetness and smoothness of my tubes, so now i'm trying to figure out how to get both!

thanks
k

[yeo]

hi kevin

sweetness and smoothness of tubes without sacrificing the bass? not easy...

try riken as i/v resistors. they are quite rich.

yeo

[kkerwin]

hi yeo,
i already have the rikens on the mojo! i'm open to other suggestions for locations though.
thanks
k

[kkerwin]

i've been thinking about simply replacing my denon ss that i have been driving (passive bi-amp) my woofers with the charlize.  i think this would have great results, however, the way i have been running the denon is from a "pre-out" on the tube amp.  this way i set the bass at a volume that i like on the denon and then  control the overall volume from the jolida volume control.  this doesn't work well with the charlize because i suppose i have impedance differences that don't allow charlize to play loud enough to match the volume of the tube section.  i think the volume control on the jolida is 100k ohm (not sure, i might be less, but not less than 50k ohm).   

so.....  i either get a separate volume control for charlize and then i have to adjust both volumes each time i want to change volume (this would make me crazier),  or, (this is beyond the limits of my electronics knowledge) i figure out some kind of circuit than will bring these two to some kind of match.  is this an active pre-amp situation? nelson pass b1 buffer??  and then, have i just created so much circuitry that i'm compromising some of the musical gains i was hoping for? 

the nice thing about this is i can experiment a bit with my son's charlize to figure out if i can get it to work, and then get another charlize.

any thoughts? 

thanks
k

[gvimhoof]

Hello Popcorn,

Congrat's on discovering the "open" sound of open baffle!  I won't dismiss all the other designs out there because different tastes dictate different wants (ears are like fingerprints:  unique to the individual), but I love my OB's!

[Popcorn]

Hello Gvimhoof,

As I listen more to the OBs I just made, I am getting to prefer them more than my other boxed speakers.
I am not dismissing other designs and you are right about different tastes and wants.

Your OBs look very good. And that is a big woofer you have on it.

[KenC]

How about this
http://www.troelsgravesen.dk/PMS.htm

[vmps]

hi bro

i love the design

gab

[Popcorn]

10 months on since I've switched to these OBs, I'm still enjoying these speakers tremendously. It is not just the bass. The soundstage, imagery, holographics, realism these speakers are capable of when correctly placed is amazing. It has been a great deal of fun experimenting various placements with these speakers and discovering their true potential.  I'm an OB convert! I'm not going back to boxes.
I encourage anyone reading this to just make a pair and try. The placement shown in the photos above ala centre baffle toe-in and  side wings angles would be a good place to start. I found my sweet spot with the speakers 7 ft apart and centre baffle about 3.5 ft from the back wall.

I used Roger Waters' "Amused to Death", Track 3 - Perfect Sense, Part I, alot when trying out different placements of the speakers to get the best holographics. The opening voices are heard directly about 80degrees to my left and about 45degrees up and the inital piano is directly 80degrees to my right.

Just sharing.

[Paul_Hynes]

B200 open baffle line array. This reduces room interaction considerably and moves enough air, with very low distortion, to reproduce a convincing illusion of a live concert, classical or rock, from a few watts of class A power. Would I go back to boxes of any description? Definitely not!

http://i700.photobucket.com/albums/ww7/paulhynes/Picture036.jpg

Regards
Paul