The Truth on the Biggest Lie about Open Baffle Speakers

More! Not less!
The open baffle has MORE room interaction than a boxed speaker simply because it's firing out of the back of the speaker as well. Those emissions reflect from the walls in the room almost exactly like the ones from the front.

The "figure 8" dispersion pattern is mostly an "on paper" concept that goes out the window in a real room. By real room, I mean YOUR room - any small room.

As demonstrated with measurements in this video, the room modes are still activated by a dipole speaker. That's because all that takes is for the mode frequency to be present in the room. If it's there, the room will resonate at that frequency regardless of where it's coming from or what's producing it.
My listening room has a very strong room mode at 37Hz, and you can clearly see in the waterfall and spectrograph plots that the mode is being energized. That's because the dipole sub is playing that frequency - it's in the room and the room is resonating at the frequency.
If you can measure output at 37Hz, then that room mode WILL BE activated.
The ONLY WAY to not activate it is to have NO CONTENT at 37Hz at all - zero - a HUGE null.

Also as shown in the video, an open baffle speaker is putting a lot of energy out off axis, even out to 90 degrees to the face of the baffle in the so called dead zone where maximum cancellation is supposed to happen. As I said in the video, the output from the rear CAN NOT be exactly the same as the output from the front, and that weakens that cancellation effect at the sides.

So the truth is that open baffle speakers are not the physics-defying panacea that a lot think they are. They have more room interaction (and that's WHY they sound different and WHY some of us love them) and CAN NOT solve room mode problems or make room treatment unnecessary.

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[IBuildIt]

More! Not less!
The open baffle has MORE room interaction than a boxed speaker simply because it's firing out of the back of the speaker as well. Those emissions reflect from the walls in the room almost exactly like the ones from the front.

The "figure 8" dispersion pattern is mostly an "on paper" concept that goes out the window in a real room. By real room, I mean YOUR room - any small room.

As demonstrated with measurements in this video, the room modes are still activated by a dipole speaker. That's because all that takes is for the mode frequency to be present in the room. If it's there, the room will resonate at that frequency regardless of where it's coming from or what's producing it.
My listening room has a very strong room mode at 37Hz, and you can clearly see in the waterfall and spectrograph plots that the mode is being energized. That's because the dipole sub is playing that frequency - it's in the room and the room is resonating at the frequency.
If you can measure output at 37Hz, then that room mode WILL BE activated.
The ONLY WAY to not activate it is to have NO CONTENT at 37Hz at all - zero - a HUGE null.

Also as shown in the video, an open baffle speaker is putting a lot of energy out off axis, even out to 90 degrees to the face of the baffle in the so called dead zone where maximum cancellation is supposed to happen. As I said in the video, the output from the rear CAN NOT be exactly the same as the output from the front, and that weakens that cancellation effect at the sides.

So the truth is that open baffle speakers are not the physics-defying panacea that a lot think they are. They have more room interaction (and that's WHY they sound different and WHY some of us love them) and CAN NOT solve room mode problems or make room treatment unnecessary.

[nicksamples]

I enjoy people that are not stupid. 😂. Thanks John this channel is helping me to enjoy my hi-fi even more!!

[Thomas..Anderson]

What you get is better interaction with the room with the dipoles. Thing to note is that not every open baffle loudspeaker is a true dipole. It is true that correctly designed dipole radiates as much to the back as it radiates to the front. from lowest of bass to the point where tweeter starts beaming due to size. This puts dipoles into controlled directivity group of speakers. The timbre of reflected sound is the same as direct sound, which is desirable. Also the figure eight radiation pattern puts more energy towards the listener and the wall behind the speaker and nine to the sides, so it actually excites the room less as the classic box speaker. Box speaker is also directional at the top end and omnidirectional at the lower frequencies thereby producing unnatural timbre in room. One downside of dipoles is the need for space. To prevent early reflection (<10 ms) to mess up with listener spatial perception, which id fatiguing they must be put at least 1.2-1.5 m from the front wall. Side walls are not so problematic because dipoles do not radiate to the sides. They also do not excite room modes as much as they act more as velocity source then a pressure source. And yes, real dipoles are not perfect dipoles. Fron back radiation not being equal, different lengths, diffraction also play a big role.
And a side note to mr. Heisz. If the 37 Hz room node is the first node, which most probably is than your room dimension must be somewhere around 4.6 m (give or take). try putting a subwoofer in the middle and see what happens.

[acreguy]

John, I could listen to you and your theories all day. You explain things so well. I too am a hobbyist designer and have had a few victories and some losses.
Question: Are you familiar with a man named Bill Woods? He was from Warkworth, ON, Canada. He was an expert designer who started on his own but was hired by Yorkville sound to help bring their PA gear to a much higher level. Sadly, he passed away a few years ago. A terrible loss to the industry.
Thanks for another great video!

[markjohnson]

I've never understood waterfall plots. You made it clear to me in like three sentences. 👍

[Jorge-Fernandez-Lopez]

I appreciate this technical content. I like to surf room modes; walking helped me to feel these standing waves and have a better understanding of my room. Thank you John.

[luxxer]

Hey John, cool to see that you keep doing stuff on the whole topic of speaker room interaction.
One thing i have to add. A dipole only has cancelations if the front and rear wave hit each other. In the midrange you need a 10 or 15cm wide baffle for that to happen. The LX521 or ME Geithain speakers have a narrow midrange baffle for that reason. In the case of the wide baffle you have a dipole at lower frequencys and two halfspace radiators front and back at higher frequencys. Thats why you have a wide radiation pattern. With a narrower baffle the radiation gets tighter and the nulls get deeper.
Edit: The best way to see how much room interaction a speaker has, is to calculate the directivity at a certain frequency. There are tools for that.

[soothingbeats]

I’m so glad I discovered this channel. I need this knowledge so bad.

[Ro-ninm]

Room interactions can be broken down into 2 x categories, pressure and reflections.

[bartvanransbeeck]

Your experience you're sharing is of high value, nothing is better then concrete real life testing ....thanks a lot😊

[paulhirst]

One of the GR Research OB servo subwoofer options is rare in that the twin driver has one 12" driver facing forward and one back and the enclosure is designed so that they are in the identical position. Servo subs are a topic all to themselves and this is the exception rather than the rule as far as speaker/sub design goes. Perhaps the reflections from the sides of a well designed OB speaker add to their ability to create a good soundstage. This is sheer speculation on my part. I really enjoy these insights/opinion John. Thank you for your willingness to challenge dogma.

[Bigirondoug]

Looks like even Bass has been affected by CANCEL culture.🤣

[magnusdens]

Hey John,

What about first reflections? Since a room's sidewall is often within the null of the figure-eight, there should be at least some impact on the first reflection's arrival time and amplitude at the listening position? If so, might this fall into the "less Interaction" camp? :)

[bartvanransbeeck]

Very interesting test, agree, but what is different between open en closed is the coloration due to sound in box return to cone,

[brucermarino]

Thanks for another great presentation. Like you, I am a fan of dipoles. I think the great advantage of open baffle speakers is the reduction of early reflections at mid-range-ish frequencies. Hence, one is hearing less of the room at these critical frequencies. Put another way, open baffle speakers alter the time interaction with the room at certain frequencies allowing one to hear more of the first arrival sound unaffected by early reflections while still allowing a degree of ambience from late reflections. Thanks!

[dceldeen]

Very well put! Every speaker regardless has room modes and best placement. Just different more or less based on the design.

[samhalsey]

You are correct, of course you are getting more reflections!

[Aswaguespack]

You add much clarity and detail to dispute and dispel audio myths. Many people make simple suppositions about listening experiences without any actual measurements to justify or refute their conclusions based upon impressions and not facts. Good stuff John. BTW “Stupid” seems to be the biggest “pandemic” in the world today, it’s expanding and spreading globally so your “watering hole” of reason draws us here to get sips of clear understanding of practical & truthful information. Looking forward to whatever is next.

[edjackson]

I agree. My lack of room boom when moving from ported box subs to OB subs is probably due to less bass below 30hz. Makes sense. Ironically I don't miss that extension into those low frequencies at all. Even with bass heavy modern music I can still feel the bass punch in my body without all that low extension

[JohanEngstrand]

I really enjoy your videos, calm approach, full of knowledge 🙏.
Are your baffle speakers available as plans?
Crossover and baffle.
Yours sincerely Johan.