[-Richard-]

Hi Robin ~

You are quite right... my apologies!!!!

Warmest Regards ~ Richard

[satfrat]

Hi Robin ~

You are quite right... my apologies!!!!

I removed my thoughts from my above post... and again... sorry for my misunderstanding.

It is strange what can happen sometimes in ones mind when reading a post... or reading anything for that matter... there is always the potential for a misreading... admittedly... I was tired.

Warmest Regards ~ Richard

Likewise I removed mine, I only wish others would have removed their comebacks everytime I've made a mistake. No worries bud!

Cheers,
Robin

[JLM]

Open baffles are not all alike.  Most are dipole radiators, meaning that an open driver is mounted in the plane of a simple baffle which produces out of phase front and back sound waves.  Some use sealed drivers (like a dome tweeter) that has no rear wave signal.  Others (like found in many applications of the Hawthorne Audio Silver Iris drivers) use virtually no baffle.  And finally a few are bipole designs where matching drivers are front and back to produce in phase waveforms in each loudspeaker.  All are characterized by their large “wall of sound” presentation.  And nearly all lack deep bass response without the aid of an enclosure.

On the other hand open baffles are simple to construct and without “box constrictions” can provide very good dynamic response (similar to horn loaded compression drivers).  Driver selection starts by looking for high Qts ratings (ideally above 0.7.)  However it can be seen that few musical instruments (including human voice) are recorded using baffled microphones or emit from both sides of a baffle, therefore lending to the diffused soundstaging.

The lack of a well defined stereo imaging is due to out of phase front and back sound waves.  Note that because of the relatively low mass and un-braced nature of open baffles, the baffle itself produces significant amount of sound.  Also note that due to the large surface area of most open baffles, reflections of sound off the baffle from the other speaker (in the case of stereo applications) can further diffuse/confuse imaging.

As dipole radiators open baffles result in the lower frequency waveforms being out of phase front and back waves cancel in the plane of the baffle.  They room load mid/bass signals differently than point source radiators.  So if given sufficient open space (I recommend 3 – 5 feet behind) they have less room interaction than “box speakers”.

Yes, integration with a sub is more of a challenge with open baffles than most speakers to the dynamics mostly.

Magnapans are the quintessential example of dipoles.

[opnly bafld]

The lack of a well defined stereo imaging is due to out of phase front and back sound waves.  Note that because of the relatively low mass and un-braced nature of open baffles, the baffle itself produces significant amount of sound.  Also note that due to the large surface area of most open baffles, reflections of sound off the baffle from the other speaker (in the case of stereo applications) can further diffuse/confuse imaging.

I have heard OBs with a well defined stereo image.
There are designs that are braced well enough that the baffle produces no more sound of its own than box speakers and some builders magnet mount the driver so it is not mechanically vibrating the baffle.
Most of the baffles that I have seen from experienced OBers at @18" or less are no wider than a lot of commercial designs that for example use a 15" driver. I heard a pair of 18" drivers in 24"? wide baffles in a narrow room (no choice) and noticed no problems with the soundstage. I attribute this to the driver/baffle relationship, if the baffle is not more than @ 2 times the width of the driver many of the "problems" with open baffles are greatly reduced or eliminated.

JAPO (just another persons opinion),
Lin

[MJK]

Is an open baffle speaker difficult to place, ie more difficult than a rear ported speaker?

I don't think so, each has a very different spacial sound field property. Most people focus on distance from rear and side walls with OB speakers. I believe it is a combination of distance and angular orientation of the speaker with respect to the walls. Since a dipole has a sound radiation pattern that has nulls at 90 degrees from the dipole axis, if you rotate the speaker with respect to the reflecting surfaces and listen at close to on axis I believe you can cut down on the distance requirements from the rear and side walls. The other interesting thing I have found, at least in the way I design dipole speakers, is the lack of a serious floor bounce null that I have always seen/heard in boxed speakers.

With an open baffle speaker, is sound quality as dependent on room treatment as in driver selection?

I don't know, I don't use sound treatments beyond the furniture and normal room decorations my wife desires. Seems to work for me.

With respect to imaging, I find that dipoles do just fine. Again, just like box speakers there are designs that do better then others and some that probably don't image as well. It is all about trade-offs in design goals.

Driver selection and in my opinion crossover point selection are key variables in OB design. I have my own recipe that I have formulated using analysis and experience which does not seem to be consistent with most other OB speaker designs.

What is a good mainstream open baffle loudspeaker I could go listen to as an example of the tech?  Where should I go listen?

Some of the popular onea are the Hawthorne Audio designs, Linkwitz's Orion, John K's NAO designs, and the Maggies. I have not heard any of these speakers. My guess is that you would need to find an owner who would let you audition his system or visit one of the big audio shows that happen a few times a year around the country. I bet that just like box speakers, each will have strengths and weaknesses.

How is the bass extension in a 2.0 listening environment?

For a classic flat OB system I believe that 40 to 50 Hz is doable but it would be rare to find something that goes lower without a lot on complexity. For an H or U frame dipole woofer system 20 to 30 Hz should be easily achieveable.

Is there an issue with separation between the sound of the open baffle portion of the speaker and the sealed sub beneath often seen in this type of speaker, alla electrostats?

I don't know, I have never used a boxed sub. My system is for music only so maybe my bass requirements are less dramtic then a HT set-up. I use dipole bass in my OB systems and I have not had a problem with it not meshing well with the rest of the system. My current system easily gets down below 40 Hz, measured to have bass donw inot the 20 to 30 Hz region, and can shake the house during the 1812 Overture or any other recordings that have those deep bass frequencies.

[Rudolf]

I'm not a big fan of electrostats because, it might just be me, but the sub and the mid/hi have a totally different sound character.

Integration of a sub should be much better if the sub has a dipole radiation pattern too. I wonder if you ever heard dipole subs in conjunction with ESLs.

But I have a weird room, my speaks have to go in basically a corner, I have been looking at front ported towers.

You can put dipoles into a corner. Deciding, whether that is feasable in your case would need more information regarding those corners and the distances of your listening position WRT to the corners. Apart from that you never can stuff a dipole speaker in between the furniture without some place to breath to the back and/or left and right.

[David Weil]

Also note that due to the large surface area of most open baffles, reflections of sound off the baffle from the other speaker (in the case of stereo applications) can further diffuse/confuse imaging.

Since a dipole has a sound radiation pattern that has nulls at 90 degrees from the dipole axis,

Isn't that a contradiction?

[Bob in St. Louis]

Hey Rick,
Like our moderator Brad here, I've also got a pair of HawthorneAudio 15" Silver Iris Coaxials, and some 15" Augies.
I live less than 30 minutes from Scott and his wonderful sounding Acrylic Lowthers.
In a single day you could hear both versions. "Two birds with one stone kinda thing....."

Bob

[Scott F.]

Is there an issue with separation between the sound of the open baffle portion of the speaker and the sealed sub beneath often seen in this type of speaker, alla electrostats?

I can only speak to my experiences which are limited (for the past 2 years) to my Lowthers and previous to that using a pair of 30" Carver ribbons over a vented enclosure (for about 3 years).

Rick, I've heard 'stats' and ribbons integrate well and also integrate poorly. Certain models of stats do an extremely good job like Blackmore's Innersounds and Adrian's ML Monoliths (both are local guys). Other, lessor models you can definitely hear the poor integration of the woofer. I had this with my Carvers. Eventually I gave up on that DIY design because I could never get it to integrate properly.

For the past couple of years I've been doing the Lowthers. When I finished the latest design of the clear baffle is when I finally got the woofers (not subs) to integrate seamlessly. These are crossed over at 125Hz and you literally can't hear where the woofers kick in.

When it comes to placement, all that I've played with are fairly sensitive to placement. Not that they don't sound fine if they are relatively close to the wall, its just that the soundstage collapses. To get the best out of any I've played with, they like to be out into the room a fair piece. I've got a big room (almost 40' deep) so I can afford to pull them out to about 6'.

I have to respectfully disagree with JLM on a couple of items. When it comes to imaging and soundstage using an open baffle. I've not had any issues with focus or placement, you'll hear that when you come over. When it comes to sympathetic vibrations of the baffle, I can see it if you are running them down to the lowest octaves but if you design a reasonably rigid baffle taking its resonant frequencies into account, it becomes far less of an issue. In my case, cutting the speaker off at 125Hz and then using 3/4" acrylic makes these baffles dead.
 
I'm not convinced about a 'true' OB design where the woofers extend into the 40's and below....but I'm open to the concept. Personally and in my room and with my system, I think using a box woofer with an OB extended range driver on top gives you the best of both worlds. Rock solid, room filling, deep bass and that monstrous, open soundstage. Others will disagree but thats OK, to each their own.

I'd suggest listening to Bob's (Bob in StL) OB Hawthorne setup (I haven't made it down yet either but need to). Bob does a 'true' OB.

If you are looking to hear a nice sounding pair of front ported, affordable floodstanders, I've got the new Aperion 6T's that I use in my combo HT5.1/2.0 system in our living room. Never know, they might punch your ticket. Follow the links in my signature line and you can see some pics of them.

[JoshK]

I too would have to disagree, respectfully with some of the things JLM said, based on my experience.  First, while its true that magneplanars are dipole, they are very different in sound radiation then a dynamic driver on a flat baffle.  They are line arrays for one, which is more about the wall of sound comment then OB has anything to do with.   Second a planar is a flat wide surface which will have cancellation affects starting at 1/2 or 1/4 wavelength, I forget which.  This is what gives it the prototypical flower pedal radiation pattern and also gives it the head-in-a-vise imaging.  This is not the same with a dynamic OB.   The radiation patterns have more differences then the obvious similarity in my experience. 

Second, while it is true that an undampened flat baffle has resonate itself, my limited experience suggests that they adds less sound radiation then even a well braced box speaker's box.  By design, the speaker's box creates standing waves inside it, which blackhole or equivalent can do little to attenuate given the wavelengths and the thickness of the treatment.  You best bet is to try and cleverly use this resonance as MJK's TL speakers do. 

Its my opinion, and I cannot give any supporting data for this, that the boxlessness of a dynamic OB speaker is what gives the spacious soundstage to these designs, not the back reflection.  A box naturally creates a means for the backwave to get reflected back through the cone, especially at wavelengths defined by the front to back length. Below the bafflestep (around 800hz in many traditional modern box speakers, iirc), sound is becoming omni-directional, so regardless of OB or box, the sound is getting reflected off the back walls.  The fact that midrange sound isn't being reflected back through the cone, instead, its left to propogate freely backwards until colliding with the rear wall or whatever at significantly greater time is what leads to the purity of midrange of an OB from my experience.  This also gives it the soundstage openness in my guesstimation.  I think it really has to do with lengthening the time that back wave interferes with the direct signal.  Its like early room reflections versus late reflections only on a smaller scale.

So that is just my $.02, but I read JLM's commented like someone who is strongly in the box camp.  I have heard and enjoyed speakers of both technologies, line arrays too.  But I think the thing that is addictive about OB speakers is something that is uniquely OB from the ones I've heard and I postulate my reasons why above.  Its also something that gets messed up with maggies in my experience.  Or maybe I am too opposed to the head in the vise sound to listen and enjoy it with maggies.


To BigRick,

You might also consider corner horns, like Klipsch or Pi-speakers or homebrew if you have good corners and need to use the corners.  I don't think OB is the solution to all music enjoyment and your situation might be a perfect time for another solution like a corner horn. 

[Magnetar]

For me it's two things

1) No box, no secondary resonance less fake sound

2) They drive my room better. - What's even better is line arrays without boxes in my room AND dipole from the bass past 15K

I also feel to realize the full potential you need to bi tri quad or penta amp - You need a lot of high efficiency upper QTS drivers to overcome the liability of no box IE in my current system I use two 21" woofers, six 15", fourteen 10" and 26 high efficency electrostatic panels and a serious 18" driver loaded in the horn below 40 cycles in nearfield - Configured properly with enough drivers you can approach a low distortion fully horn loaded sytem in dynamics but have far less coloration - stil compromised (it's BIG) but less then most

Surely my goals are different from most judging by the compromises I see sold commercialy and posted on these forums. So first look deep into what you desire as a result before throwing drivers on a board or baffle. To be unconvential can bring unconvential results - this can be a very pleasant thing.

[opnly bafld]

To BigRick,

You might also consider corner horns, like Klipsch or Pi-speakers or homebrew if you have good corners and need to use the corners.  I don't think OB is the solution to all music enjoyment and your situation might be a perfect time for another solution like a corner horn. 

Hornshoppe is another one to consider for corner loaded (or not) horns.

Lin

[Magnetar]

Are you talking about those little single driver speakers? If you are those aren't horns.

Hornshoppe is another one to consider for corner loaded (or not) horns.

[opnly bafld]

Hornshoppe is another one to consider for corner loaded (or not) horns.

Lin

Are you talking about those little single driver speakers? If you are those aren't horns.

You are late to the party, that has been argued about a lot around here and other places, regardless, they still sound real good.

Lin

[planet10]

I am using the Hawthorne Audio Silver Iris.  The 15" coaxes can go down to 50hz or so on their own and they have a nice midbass punch. 

I've been living with a set of SI for the last month or so. Not the greatest example of how an OB can free you from ther sound we usually associate with a box. The self noise on the paper cone is sufficien t to make the speakers, for lack of a better description, sound boxy. I'm working to fix that.

dave

[Bob in St. Louis]

Interesting Dave. Can't say I've heard that comment from any owner (or casual listener) of the SI in the 26 months I've lived with mine.
Please elaborate.

Bob

[-Richard-]

Open Baffle speakers are a way for all of us to enter into the process of learning what audio is all about.

It is relatively simple to experiment with... starting with a flat baffle and a wide-range driver with good overall functional characteristics and high sensitivity. Leave room on your baffle for a large "woofer" driver below that you can add once you understand what you are working with.

I am using an Eminence Alpha 15A crossed over at around 1200+ with a Visaton B200 wide-range driver (allowed to operate full-range) in a simple flat baffle. I use different combinations of amps, preamps and dacs to further experiment with. My completely rebuilt Heathkit 151A (now out for repairs to Sam Kim the designer) has tone controls that work very effectively with my OB's... the bass tone control easily brings the bass into the 30 Hz region.

I have owned several speakers that I thought all sounded good... until I began to experiment with OB's... that is when I realized that there is a somewhat generic sound that each kind of speaker design has... and that designers try to work around in order to get their chosen design approach to exceed the limitations inherently "built-into" whatever paradigm they are working with.

The Open Baffle design approach immediately solves some of the most fundamental flaws in some speaker design approaches... like box speakers for example.

You will encounter some problems as you begin to experiment... and some patience and a good measure of curiosity will move you along the learning curve toward understanding what you are listening to and what you need to make it work better... and that is where the fun is... and that is where the greatest measure of "learning" takes place... we all learn to "listen" carefully, sensitively... and we learn how-to-listen... we learn to stop thinking like consumers and all that implies... and we begin to listen on an entirely different level of "recognition."

Deborah and I love our Open Baffle speakers... with the right equipment the sound is deeply satisfying... and music is projected into our space very close to how it sounds when it is a live performance. But one must be willing to do some experimentation and be willing to make changes in your amplification devices and source components (although I use a cheap CD player that sounds quite wonderful).

Most of the writers in the OB forum know far far more than I do about the science of OB design... which creates a marvelous resource for us amateurs who need help in our designs... but I know what live music sounds like... and I know what happens when music is absorbed by the body in a form that is close to the organic rendering of real music by real instruments... something extraordinary happens... one is transported into a different zone of perception... one is buoyed into an emotional plan that is exciting and stimulating and emotionally cathartic. That is what we hear with our OB system.

Warmest Regards ~ Richard

[jkelly]

Richard,

Interesting comment on the Heathkit 151.  I love my Jolida 102B with Mullard EL-84
on the Alpha 15 and B200 combo.

Jeff

[doorman]

Yup, speakers are but one link in the chain. The upstream bits are tres important!
(That'll be a lot of those "little dots" on those big dogs, Dave!)
Don

[mcgsxr]

I continue to be very happy with my combo of Visaton b200 and a 12 inch helper woofer per baffle.  The b200's get fed from an old EL84 Magnavox amp, and the 12's have fun with a 300w BASH digital sub amp.  Xover duties performed by the Reckhorn active unit.  All fed by the Bolder modded SB3.

Room is a large unfinished basement, but I look forward to rectifying that.  The pool table in there now has be unsure when I will ever want to though, I have 90% of the functionality the finished room will ever have (missing a bathroom down there) and as a boys retreat (and place for my little girls to ride their bikes in the winter) it is great.

OB speakers have been a revelation for me.  I used boxed monitors for years (Totem) and loved them.  I find that OB speakers sound better for me, in this room.  I have had them in another room too, and liked them there.  Eventually, I will rebuild them, and move them upstairs to my living room, once the design is finalized, and veneer thought out etc.

I like them as they are relatively simple to get 80% right.  And what an 80%!

I do find that they want 3+ feet from the rear wall, to allow bass to bloom, but other than that, simple to locate.