Look, this is a DIY forum and I have shared a private development with the community. This is a non-commercial product without a patent. There is no documentation, only the experience of developers and users. So you can take part in an exciting study and add your own experience to the general knowledge base.
I only have U baffles to test, but acoustics will be the same. The PPD is "just" a U baffle with loading on front, and very little rear extension.
I have attached the set-up I will use. Two PPD facing each other, and woofers in antiphase. Listening position in front of the "gap" between woofers.
I'm not sure how cancellation will behave, but my logic tells me I have only have bass to the left and right and not in front of the set-up.
I have attached the set-up I will use. Two PPD facing each other, and woofers in antiphase. Listening position in front of the "gap" between woofers.
I'm not sure how cancellation will behave, but my logic tells me I have only have bass to the left and right and not in front of the set-up.
Emerald Physics also makes something similar. But always stacked or side by side with multiple woofers. I'm really wondering how PPD will work with the woofers facing each other. Ripol/W/N baffle I understand, but for PPD there is nothing stopping the bass frequencies to wrap around the baffle
i wish there was like a thermal imaging camera but that can display the sound waves, so you can see in real time, like the predator, what change will make if moving the baffles.
Sound waves are quite simple buddies. You can simulate them perfectly. Sure, to get a 100% picture you need to add all data of the room, its boundaries material and surface reflectivity. Put in all that stuff and you will see what happens. Anyway, if you build a speaker and add some magic mushrooms to the listener describing their performance, anything is possible. Maybe some spririts will have the same effect, if it is not mushroom season.
PS Deep freezing can get around the problem if vodka gives you a headache
PS Deep freezing can get around the problem if vodka gives you a headache
Yes, very much Ripol-like. There's a very similar design in Germany with 8" Dynavox drivers, called Dynapol. I will build that too.
Maybe this page would provide some information on the arrangement and wiring of two woofers. The PPD enclosure may add a little difference. https://edsaudiopages.blogspot.com/
I had a similar arrangement with a common slot and it played well lower than any simulation would suggest with proper EQ - at the expense of high energy and high excursion. But so did a sealed box with the same woofers and EQ. No free lunch there, it is a nice and compact way of putting the woofers in a box with holes on both sides. One could do a "clamshell" arrangement without any box at all with a very similar result. There is no replacement for displacement and baffle width (for dipoles) at LF.
I had a similar arrangement with a common slot and it played well lower than any simulation would suggest with proper EQ - at the expense of high energy and high excursion. But so did a sealed box with the same woofers and EQ. No free lunch there, it is a nice and compact way of putting the woofers in a box with holes on both sides. One could do a "clamshell" arrangement without any box at all with a very similar result. There is no replacement for displacement and baffle width (for dipoles) at LF.
I did a similar experiment and it gave a negative result. Now, after all the material presented, it should be clear why.
Apparently, your front is removable. Try replacing it with a version with a calculated hole in the center and compare the sound. It should be noticeably better.
I checked the whole threat and didn't find any information about your experiments with different front openings. On the other hand I found informations of a YouTuber who did some experiments on his OB-speakers. He recommended this kind of circular slot for being better than a hole in the center.
What was your experience when you compared both options?
If you take a microphone and measure output at exactly the same input power you will see that the woofer with no restriction plays louder. =higher efficiency. And has less distortion.
EQ is your friend to make response flat. You need EQ anyway for dipole compensation 6dB/oct
EQ is your friend to make response flat. You need EQ anyway for dipole compensation 6dB/oct