Experimenting With Open Baffle Subwoofers - Unexpected Results

A bit more detail:
I tried that first dual woofer sub in three different locations at the front of the room, and saw very little difference in the measured output. But that first measurement and the fullness of the bass produced encouraged me to keep going.

In all instances I had to have the tone control on the Yamaha receiver set to boost the bass. While I could do that in Equalizer APO, that generally means cutting higher frequencies to get enough boost in the bass region. The bass control on the Yamaha seems to be doing a very accurate and natural sounding lift.

Without the bass boost there wouldn't be enough bass output from the 2 woofer setup.
The 4 woofer dual subs that I settled on can be improved by adding a lowpass to 2 of the woofers and using those exclusively in the very low bass range (40Hz and down), while the other two operate up to 80Hz. This should extend the bass output even lower, but does complicate things.

You'll often hear that open baffle speakers don't excite room modes, but I saw no evidence of that. The one distinct advantage I saw was that they are easier to place in the room - boxed subs will perform much differently in different parts of the room, while these work the same (more or less) wherever you put them (within reason - they do need to be away from the walls by a certain amount).

As for the quality of the bass, I couldn't hear any difference other than the struggling problems of the woofers pushing their excursion limits. Keep in mind that this is crossed over at around 80Hz.
My isobaric sub was putting out solid, effortless base that sounded accurate and extended down to 20Hz. These are the same except for the depth of the low end, but sound identical to the isobaric sub. My room is 14' x 14' and is well treated acoustically, and these subs easily provide enough thunderous bass for modern movie soundtracks.

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A bit more detail:
I tried that first dual woofer sub in three different locations at the front of the room, and saw very little difference in the measured output. But that first measurement and the fullness of the bass produced encouraged me to keep going.

In all instances I had to have the tone control on the Yamaha receiver set to boost the bass. While I could do that in Equalizer APO, that generally means cutting higher frequencies to get enough boost in the bass region. The bass control on the Yamaha seems to be doing a very accurate and natural sounding lift.

Without the bass boost there wouldn't be enough bass output from the 2 woofer setup.
The 4 woofer dual subs that I settled on can be improved by adding a lowpass to 2 of the woofers and using those exclusively in the very low bass range (40Hz and down), while the other two operate up to 80Hz. This should extend the bass output even lower, but does complicate things.

You'll often hear that open baffle speakers don't excite room modes, but I saw no evidence of that. The one distinct advantage I saw was that they are easier to place in the room - boxed subs will perform much differently in different parts of the room, while these work the same (more or less) wherever you put them (within reason - they do need to be away from the walls by a certain amount).

As for the quality of the bass, I couldn't hear any difference other than the struggling problems of the woofers pushing their excursion limits. Keep in mind that this is crossed over at around 80Hz.
My isobaric sub was putting out solid, effortless base that sounded accurate and extended down to 20Hz. These are the same except for the depth of the low end, but sound identical to the isobaric sub. My room is 14' x 14' and is well treated acoustically, and these subs easily provide enough thunderous bass for modern movie soundtracks.

[KipdoesStuff]

I like that you mentioned how it sounded the same. Too many people get caught up in the numbers and forget that in the end, how it actually sounds is all that matters.

[michaeltablet]

Glad you created this channel! I love your other channels also! Always interesting!

[jackdale]

how about if you reverse one of the woofers like allison speakers ?

[clintbartenstein]

Thats cool! Way to be open minded. My speaker needs to be enclosed bias would have never let me try an open baffle lol

[paulhirst]

I have been told to keep open baffle subs at least 36" away from the wall. In my room I have found that my open baffle speakers are much better suited for music than theatre. You are more than welcome to borrow my Rythmik amps and GR subs so that you can use the options that the amps offer for delay, cross over, etc. Or you can use the amps to drive your drivers to see if the adjustments actually help in your situation. I cannot use them for a while and would drop them off it that helps. Paul

[act..]

This subject always seems to make me fire up my system and give it a listen. It's not perfect, but it is good. It had been so long since I had listened to any Grand Funk Railroad. I loaded Rock and Roll Soul and I suddenly remembered just how good these guys were. Such a tight group of serious professionals.

Of course, now I need to listen to some 2112.

[TheDrake]

Happy to see you experimenting with open baffle. Food for thought: a "w" frame arrangement may also be a good option, as it would cut down on the subs' physical presence and may yield similar results. There's a lot of options out there for tweaking open baffles.

[joeysarmiento]

Just keep producing your ideas on video and thank you for sharing. Until your next informative video, love and a warm handshake from my humble country 💝 the Philippines 🌺💮!!!

[feeterican]

Man, your videos make me wish I can rebuild my speaker cabinets that I designed back in high school. There were some mistakes I made back then that I would like a second chance. One of the main things is in my design I had a Sub built into each cabinet it self and powered separately from the 3 way config. Also, I didn't have the money (being 16 years old) to afford 2X12" woofers and 2x12" subwoofers. But now being old and slightly wiser I'm not sure it would work with only 2 cubic foot of air space.

Side Note: When I built these back in '92 I made them out of 3/4" Birch Ply and everybody including my shop teacher thought I was crazy for using that wood. Now a days it looks like a lot of people are using Birch Ply or Baltic Birch Ply. Looks like I was on to something back then. Also, when they were finished and had the people that thought I was crazy have a listen, they all had the same surprised look on their face. They did end up sounding really good even with crappy Radio Shack speakers and the infamous Realistic 12" subwoofer 😀

[MichaelBeeny]

I assume the frequency response curves shown include the mid and high speakers as well. The bass only I would expect to roll off 600/800hz or less.

[stanykartopet]

I'm so happy to see that You're also considering the Plan Baffle which is part of my religion ! To make simple: Y've been teached that Close to the source, the sound is spreading like a variable pressure with air deplacement. Further in space, the sound moves like a wave, with pressure instant variation. It's like the microphone that is relying to air speed or air pressure, depending on the system. And our ears work the same way, as we also know how to recognize the distance of alarm signals in life ... This concept maybe explains some of Your conclusions.
Personnally, I adore the Plan Baffle for it's Dipole behaviour, leaving energy sensations to a complementary sealed box .

[josephbeltramini]

What is your “go to” recording? I like Yello’s “Of course I’m Lying.”-
I think you’re doing a great job!

[crimsonghost]

Very interesting. I have been wanting to try open baffle in general so thank you

[RambozoClown]

The minimalist approach looks promising. Brings back memories of a lot of musical instrument amps that ran open back.
Now for the other extreme, you can build a folded horn design to test, next.

[mr.purple]

Hi John, I have been impressed with your woodworking and hi fi videos. Would you please share your background in audio?
I am guessing you have worked in the field. I appreciate the knowledge you share. I apologize if you have answered this question before. Thanks

[dougg]

I’ve always been curious about that Swarm subwoofer system by AudioKinesis

[NBC_NCO]

What about selling the rear sound wave totally from the front?
Like speakers in the rear deck of a car.

[peterh.]

I got one Question about the open Baffle Sub: How does music sound when you walk into another room with the door open?

[iliascharis]

Sir u ve got the skills plus the some of danny richie s open baffle designs. He uses one wing - flang per speaker at 110 degrees to separate open baffle cancelations. I belive u will find his designs interesting. Cross overs is a big issue for a flat frequency responce. We are waiting anxiously