[newvinyl]

Don't know anything about OB speakers, but I'm intrigued.

It seems like there would be a lot of sound from the back of the speaker that would bounce off the wall behind the speaker then get to the listening position after the direct sound. Isn't that a problem? And if so, what is done to mitigate the problem?

I assume that bass would be not as deep as a boxed speaker, but cleaner. I don't see that as a problem.

[Early B.]

This question was asked a few months ago. Maybe someone will find the thread and post the link. Anyway, the two main downsides are size and space. OB speakers are typically very large and they need plenty of space around them (2-3 ft. away from the walls -- the larger into the room, the better). Most people don't have the real estate to accommodate such a speaker. And even if they did, wives and small children would put an end to considering them.

Yeah, and even with 15" OB drivers, you'll still need subwoofers for full range sound. 

[drewm]

Actually the open baffle GR-Research H-frame servo 12" sub easily reaches below 20Hz with enough output, just needed to add a few "wings" to the open baffle. I've listened to them at RMAF and at someone's house, easily the most musical bass I've ever heard.

The space away from the walls is a concern for sure, I run mine 2.5' away from the wall, but I don't feel my open baffle top speakers (AV123 x-statik) are very large at all.

[md92468]

This question was asked a few months ago. Maybe someone will find the thread and post the link. Anyway, the two main downsides are size and space. OB speakers are typically very large and they need plenty of space around them (2-3 ft. away from the walls -- the larger into the room, the better). Most people don't have the real estate to accommodate such a speaker. And even if they did, wives and small children would put an end to considering them.

Yeah, and even with 15" OB drivers, you'll still need subwoofers for full range sound.

FWIW, I have a pair of Spatial M4s...They are not unreasonably large (36"X14"X about 6", including the feet, which is not much larger than many floor standers footprint-wise, or monitors with stands for that matter). The "space around them" factor is definitely true for critical listening...which is why I pull them out for such occasions...the rest of the time I leave them in place near the wall, where they are don't take up too much space.

As far as aesthetics and logistics go, neither my wife nor my small children have had any problems with them...in fact we've gotten many compliments about them from visitors female and male, audiophile and not. And as for "full range sound," while I realize they're not going to reproduce realistic pipe organ ranges, I never feel bass response is lacking in my 26X12 room...in fact, I find bass reproduction (both acoustic and electronic) to be far more realistic in the M4s than in many of the other speakers I've had in here, all of which should have theoretically outperformed the M4s in that regard based on specs alone (which is why you should never evaluate speakers based on a spec sheet, to fan the flame of a conversation in another thread on a related topic earlier today).

I'm not saying the M4s are miracle speakers that defy physics...they certainly have their limitations...but in the end their coherence, their open effortlessness, their ability to convey the emotional impact of music and their ability to pair effectively with everything from an 8-watt SET to a 250W+ class D amp  far outweigh the limitations of their form factor. YMMV, as always. 

[Guy 13]

FWIW, I have a pair of Spatial M4s...They are not unreasonably large (36"X14"X about 6", including the feet, which is not much larger than many floor standers footprint-wise, or monitors with stands for that matter). The "space around them" factor is definitely true for critical listening...which is why I pull them out for such occasions...the rest of the time I leave them in place near the wall, where they are don't take up too much space. As far as aesthetics and logistics go, neither my wife nor my small children have had any problems with them...in fact we've gotten many compliments about them from visitors female and male, audiophile and not. And as for "full range sound," while I realize they're not going to reproduce realistic pipe organ ranges, I never feel bass response is lacking in my 26X12 room...in fact, I find bass reproduction (both acoustic and electronic) to be far more realistic in the M4s than in many of the other speakers I've had in here, all of which should have theoretically outperformed the M4s in that regard based on specs alone (which is why you should never evaluate speakers based on a spec sheet, to fan the flame of a conversation in another thread on a related topic earlier today).

I'm not saying the M4s are miracle speakers that defy physics...they certainly have their limitations...but in the end their coherence, their open effortlessness, their ability to convey the emotional impact of music and their ability to pair effectively with everything from an 8-watt SET to a 250W+ class D amp  far outweigh the limitations of their form factor. YMMV, as always.

 

[rajacat]

How well do they image? For instance, can you easily pick out the different sections of a symphony orchestra or is it more of a wall of sound? Does the midbass hit you in the chest with a visceral impact?

[Rocket_Ronny]

Generally speaking, you get more "air" with OBs but a more diffuse image when compared to mini monitors. How diffuse depends on a lot of things from the speaker implementation itself, to how far into the room you go, to what the wall is behind the speakers if going closer than 8'. OBs generally have had less "impact, or slam" than box speakers and depending on the listener is a good or bad thing.

Rocket_Ronny

[nicoch]

Yes diffuse ,3d ,wall of sound if you use a full range that go in OB to 7k , open baffle speaker need a big baffle or dps if you want real  bass in the 40hz range , small baffle will got only the superior harmonic ie the punch of 100hz, this is from real experience ,you will find a lot of info in this nice circle

[mcgsxr]

Agree that OB is not perfect, and I strongly believe that people hear differently.

I have, as a recovering basshead, found that a LOT of air in OB needs to be moved to equate boxed sub output.  That can mean multiple large woofers, and correspondingly large baffles.  Many fold said baffle to retain the effective size while minimizing the footprint (at least horizontally).

I would also personally agree that the image is more diffuse.  I would also assert that my Totem Model 1's offered better depth than my Maggie 1.6QR's in the same room with the same gear driving them.

Downsides notwithstanding, I still really like the OB presentation of music.  I have referenced that in my reviews of different speakers over the years.  It is why I came back to OB after a ~3 year exploration of boxed speakers again.

[undertow]

Biggest issue I found was in fact they are slightly more difficult to work with in terms of acoustics. Not just sound quality optimization, or imaging, but fact is if you ever walk behind one you are getting a lot of noise, and distortion in the room from the rear waves bouncing around. Its just hard to control not as easy to smooth out. You get that sorta "Shouting" effect many times people associate with horns etc...Accept its due to all that open sound behind the speaker and whatever barriers are in proximity to them.

I also observed another side effect which was even worse for me. You could hear the speakers more in other rooms of the house, and in fact even in the same room standing next to or behind them which I had a Bar off to the side it was rather loud, and noisy even compared to sitting dead in front of them. All that sporadic sound is just bouncing off the back, and sidewalls since there is no cabinet damping or containment.

So ultimately for my case I would need a lot more damped room, and even soundproofed as the noise transmitted a lot thru the house at a much accelerated pace even at lower volume levels where any box speakers were much more isolated, and easier to get to sound right in the actual listening position.

But before anybody jumps all over this it is in my first hand experience, not saying it's a bad thing, but saying these are things to think about because they are "Noisier" in the environment, and not noisier in a way that necessarily serves to makes the music sound better. So as stated above I think you not only need a rather substantial amount of space to get them off the walls, but probably more acoustic tuning in the room.

[nicoch]

stange effect,  noise can be air noise ? a lot of motor of woofer compress air too much!
OB excite low modal node ed not pressurized the room ,ripole sub are famous for neighbors friendly

[undertow]

No not air noise, just simply when you have an open speaker you get the sound 360 degrees around the driver creating its own distortion in mid air, or bouncing off the wall behind, next to it, etc...

[ebag4]

I find the comments regarding OB issues above interesting.  We all definitely hear differently and there are numerous variables that affect every system, but I have not experienced many of the issues listed above using any of my last 4 OB speaker systems.

To me, the biggest negatives for most OB users is size of the bass section and how far they need to be pulled from the boundary walls, particularly the front wall.

For best sound you need to pull the speakers from the front wall a minimum of 36", it is my understanding that this is due to the speed of sound, 36" gives you enough distance that reflected sound arrives at your ear with enough delay to not be misinterpreted as direct sound, closer than 36" and the reflected and direct sound arrive at the ear too close together and can work to blur the signal.  The further you can pull the from the front wall the better, up to a limit I would believe, however I have not had mine in a room large enough to pull my speakers out much more than 4'.

The bass systems tend to be larger than some of the smaller boxed woofers although they do not have to be larger than a large floorstanding boxed speaker.  However, in my experience if you purchase a bass system designed for OB, you will achieve amazing bass without box colorations.  My 2 x 12" GR Research servo bass system (currently in "H" frame however I am building a modified "U" frame currently)per side give me the best bass I have ever heard.

With regard to shouting, distortion and fuzzy imaging, I have not experienced any of these things.  Like any speaker alignment, some designs are superior to others, but the speakers I am currently running are incredible when walking between them front to back, they sound the same, really amazing to hear.  The imaging is fantastic, when the recording allows each instrument has it place, could some boxed speakers image better, possibly, but I certainly don't feel the OBs I have heard are lacking in this department, again, the speakers I am currently running have imaged better than any speaker I have owned previously, and there have been many over the last 38 years or so, many more boxed speakers than OB.

In my opinion, most if not all rooms need acoustic treatments to sound their best.  This is likely more true of smaller rooms, this is what I have seen as one of the differences between my small 2 channel room and my larger HT space.

For me OB speakers offer the best presentation I have heard in my space, of course YMMV.

Best,
Ed

[undertow]

With regard to shouting, distortion and fuzzy imaging, I have not experienced any of these things.  Like any speaker alignment, some designs are superior to others, but the speakers I am currently running are incredible when walking between them front to back, they sound the same, really amazing to hear.  The imaging is fantastic, when the recording allows each instrument has it place, could some boxed speakers image better, possibly, but I certainly don't feel the OBs I have heard are lacking in this department, again, the speakers I am currently running have imaged better than any speaker I have owned previously, and there have been many over the last 38 years or so, many more boxed speakers than OB.

Best,
Ed

I am going to clarify as it seems this was taken out of context from my comments.. I did not say fuzzy imaging, nor "Distortion" in a way that is from musical content... I was simply saying they definitely create MORE control issues adding distortions to the room requiring even greater care in setup or acoustics. Because you have rear firing sound waves period, and you will of course here these specifically being off axis standing on the side, or behind the speaker much more than with boxed speakers.

And again I will say I do not believe this is a deal breaker as many setups or rooms can compensate for this. However, in my experience any thing firing to the REAR of the speakers has more acoustic consequences, and become a bit more tricky to tune in correctly. I also believe I have found better luck with front ported designs opposed to rear vented speakers as well for similar reasons, but to a lesser degree of importance.

BUT this is not limited to just OB speakers. I have also had Dipoles, and simply compound woofers mounted on the backs of full range cabinets that had just as much glare pushing back into the room as OB would. Its simply due to firing ANY drivers in a direction other than toward the listening position will add more noise to the room without cabinets damping the backwave in general... Electrostatic speakers are not the same I am only considering Dynamic Drive systems with woofers that operate on a motor here.

[Early B.]

I am going to clarify as it seems this was taken out of context from my comments.. I did not say fuzzy imaging, nor "Distortion" in a way that is from musical content... I was simply saying they definitely create MORE control issues adding distortions to the room requiring even greater care in setup or acoustics. Because you have rear firing sound waves period, and you will of course here these specifically being off axis standing on the side, or behind the speaker much more than with boxed speakers.

And again I will say I do not believe this is a deal breaker as many setups or rooms can compensate for this. However, in my experience any thing firing to the REAR of the speakers has more acoustic consequences, and become a bit more tricky to tune in correctly. I also believe I have found better luck with front ported designs opposed to rear vented speakers as well for similar reasons, but to a lesser degree of importance.

What you're saying hasn't been my experience. Here is a real world example -- my friend has a pair of OB monitors and just built GR Research triple 8" OB servo stereo subs and placed them in a basement with horrible acoustics at the bottom end. With his previous box speakers, bass was very boomy and often sounded dreadful. Lots of room treatment helped, but we couldn't rid of it. The OB subs totally eliminated the problems the room was causing. It's the best bass he's ever heard.

[undertow]

Early B.

No offense I note you jump in on my comments every time so here we go... Your experience seem to always be 180 degree to what I have stated in several threads for whatever reason so maybe we live in alternative universes which is fine, but again it has nothing to do with low frequency subs being better or not. That was not my point. The OP asked about the downfalls to OB speakers in general, not just whether you can create better bass or not. We are talking Upper Mids etc... as well will always reflect from any drivers firing out of the rear of a speaker was my point, hence YOU may need better positions, or more acoustic corrections when considering the OB approach in general vs. more standard "BOX" speakers. 

Simple as that... Again this was not a knock at OB or whether they can or cannot achieve better results ultimately. And to reiterate the point of my post it was not about just the difficulty of OB or not, it was pointing out that in fact from experience containing the sound in the ROOM itself has proved more difficult with OB's unleashed not necessarily creating better decibels at the listening position, but simply they seem to transmit a lot more sound thru the structure of the house as well due to being uncontained drivers.

So one more time... My post was not intended to say whether OB was superior, or less superior, but to be prepared that obviously with completely naked drivers you are going to get different acoustic results which may or may not work in certain environments vs. conventional BOX speakers.

[ebag4]

I am going to clarify as it seems this was taken out of context from my comments.

Sorry Undertow, I wasn't trying to misconstrue any of your comments, but instead offer up a alternative view based on my experience. 

One comment you made that I believe could be misinterpreted is

just simply when you have an open speaker you get the sound 360 degrees around the driver creating its own distortion in mid air

, this is simply not accurate.  What typically happens in OB is where the sound waves meet you get a null, sound is typically out of phase at the sides where this occurs and nullifies the output, at least that is my rudimentary understanding of it.

I would agree that if you have a drywall box with no treatment of any kind and have drivers firing into that enclosed space you could very likely experience echos and negative sound artifacts as a result.  I should have qualified that my OB experience is based on results in a well treated room with absorption and diffraction.

Best,
Ed

[undertow]

ebag4

No problem... I was not personally accusing you of necessarily taking it out of context, but I guess I was just making a different point than what was being deciphered from it is all.

As for the out of phase aspect yes with OB it will help. I can say though I also had Horning Loudspeakers which literally fire the rear woofers, face to face, and are mounted in the back, so all you hear is back of the drivers, but from inside, and outside due to a transmission line port on top of it also firing from the back. So you have the back of the woofers firing into mid air, and the transmission line amplifying it out of the bottom of the cabinet from the inside as well. This design was quite different for sure!

Ultimately I got good results, however they were much more difficult to keep the noise from the rear causing other acoustic blending issues. Literally they were actually almost louder standing behind them or to the side than being right in front of them! So you obviously end up with some distortion in the acoustic space from this type of pattern emanating from different sources. Honestly you will still have sound coming out of a different direction from an OB as well, and this can create some havoc on the system balance I don't think we can bend physics to NOT hear the effects in the room from open baffles on the back.

In any case they can still sound very good, but present different challenges is all I am saying, and in some cases may not be worth the efforts for certain rooms or designs.

I never got a hold on Dipole designs either. You would assume the efficiency affect from adding sensitivity from the rear drivers would actually help re-enforce the output, in fact most of the time these designs made me feel like there was a hole in the background, and never really worked well at all being you had a lot of noise being created from the rear of the speakers just as the front. 

[newvinyl]

Thanks for all of the replies. Very helpful.

[rebbi]

For what it's worth, my Spatial M4's (coming from ownership of a long line of mini-monitors) image like gangbusters, but in the context of a large, expansive soundstage (when called for by the recording). Pretty darn close to perfection for my needs and tastes. YMMV, of course!