Thanks Alvipet. Between the Visaton BGS-40 and Monacor SP-382PA, which would you consider more suitable for PPD ?
I can of course easily try both.
In your opinion, is PPD more critical for Bl / Mms ratio than Ripole ?
I can of course easily try both.
In your opinion, is PPD more critical for Bl / Mms ratio than Ripole ?
If the stated parameters really correspond to the real ones, I would prefer the SP-382PA because their resonant frequency is 25 Hz
Okay, that makes sense. I can determine the parameters with DATS V3. Will check, one of these days.
There is 167 posts, and there was many stuff discussed , there was 2 sides about the design;the old way and the "new" way, so I got lost , that is why I ask, in the other hand if you are over sensitive and feel attacked by somebody asking about it and you will feel exhausted by sharing your holy grail formula cause maybe somebody capitalize on it and stole your profits .... I get it.
I seldom encounter egomaniac beings who enjoy not sharing information, but looks like I found a new one.
I seldom encounter egomaniac beings who enjoy not sharing information, but looks like I found a new one.
There is no "holy grail formula" for the PPD. It is just an unsuccessful experiment based on a lack of physical understanding. The "Ripole" has quite some advantages compared to a simple open baffle and some additional rules. The PPD tries to profit on these ideas, but fails.
Well, (i thought) i found a lazy member, ha. Oversensitive ? It seems you are overreacting, kinda big time. Relax buddy..
So, there's only one 'side' of the design; the other 'side' is the Ripole system, from which this PPD 'side' originated.
Driver wise: Preferably a high Bxl and low Mms. Divide Bxl by Mms; if the outcome is 0.16 or higher, you're fine. You don't need a typical open baffle Qts of around 0.7 or higher, a bit lower is also okay. Low fs is key. High Xmax is good. And considering the low efficiency of the system, a big power capacity is favorable.
You won't find a driver that ticks all the boxes though. That's why i consulted with Allvipet about which of the drivers that i have would be more suitable. Both have their strong points.
Cabinet wise: Make it as small as possible; it should minimally surround the woofer. The front baffle should just leave space enough to let the cone reach its maximum excursion. The hole surface is 1/3 to 1/2 Sd, you can easily calculate the diameter then. The back chamber can already stop where the basket and magnet meet, but for the sake of esthetics, probably most of us won't let the magnet stick out of the back panel. The surface of the hole in the back panel should be 1/2 Sd + magnet surface. Again the hole diameter is easy to calculate.
That's about it. Pretty simple to construct.
So, there's only one 'side' of the design; the other 'side' is the Ripole system, from which this PPD 'side' originated.
Driver wise: Preferably a high Bxl and low Mms. Divide Bxl by Mms; if the outcome is 0.16 or higher, you're fine. You don't need a typical open baffle Qts of around 0.7 or higher, a bit lower is also okay. Low fs is key. High Xmax is good. And considering the low efficiency of the system, a big power capacity is favorable.
You won't find a driver that ticks all the boxes though. That's why i consulted with Allvipet about which of the drivers that i have would be more suitable. Both have their strong points.
Cabinet wise: Make it as small as possible; it should minimally surround the woofer. The front baffle should just leave space enough to let the cone reach its maximum excursion. The hole surface is 1/3 to 1/2 Sd, you can easily calculate the diameter then. The back chamber can already stop where the basket and magnet meet, but for the sake of esthetics, probably most of us won't let the magnet stick out of the back panel. The surface of the hole in the back panel should be 1/2 Sd + magnet surface. Again the hole diameter is easy to calculate.
That's about it. Pretty simple to construct.
You seem quite doubtful of the 'system'. I can understand your motivation from the point of view of wanting to see objective measurements, But on the other hand, there are also people who actually have built PPD subs and are really satisfied with the results. Some of them even have experience with Ripol and can compare, at least by listening. Your attitude towards PPD seems too rigid. Have you tried it yourself, or are you just dismissing it because you don't see all the information that you would like? I did make several Ripols, with 10" and 12" drivers, and always thought that despite some minor flaws it is the most audiophile bass reproduction design. But I am willing and frankly quite eager to try a modification of it. And, in the meantime i am discussing the ins and outs with someone who is totally able to analyze the physical aspects of it.
Hey, I hear you, but I’m not sure I’m the lazy one here—maybe I’m just pacing myself for the long game!
See, after 50 years of speaker building, one should get an idea of the physics involved in driver placement, compression chambers, sound waves canceling out each other, limiting frequencys and all that stuff. The PPD is a slight variation of dipole and Ripole, but with no advantage at all. It looks different and seems to please the "inventors" ego.
He is acting like someone building a light bulb with a square shape of the outer glas and calling it "Ivans photonic sun", or short "IPS". Like it was something new, invented by the great inventor and light artist Ivan himself. In reality it is just an unpractical variation of a very old idea.
If you want to build it, fine, no one has a problem with you doing a PPD. Measure it, then build a correct designed Ripole with the same drivers and measure again. Then you can start to think about the differences and why they are there. We all would be happy if you did this. It's just a few parts and two holes...
All I asked Petrenko Petrushevsky for where objective, practical measurements, but this was something that created agression and insults on the "inventors" side. Obviously I hit exactly the point that ruins the PPD idea. Objective data at a reasonable listening distance. I never speculated for the intentions PP has or his commercial plans or attacked him personaly.
I even looked at the mentioned video of the PPD and found them to be not very realistic for normal use. Not very scientific, too. Not to mention that any audio on YT etc is pure nonsense anyway.
Okay fair. I don't want to judge, i just see an interesting variation on a design that i already know and like very much. Not just because i built some myself but also after hearing Voxativ's commercial Ripol. I'm not 50 yrs into speaker building but close (45) and am very open to new perspectives. You'd be amazed sometimes how much we are restricted by settled 'science' and methods. Furthermore, I am not interested in the inventor and his alleged behavior, just in his idea, which is worthwhile to explore. But i will agree with you that the given information is quite thin. Up to us DIYers then to come up with more substantial evidence !
My line that you quoted just now was merely composed that way in a direct reaction to maxolini's phrasing. Of course i am fully aware that it's all the same thing,
My line that you quoted just now was merely composed that way in a direct reaction to maxolini's phrasing. Of course i am fully aware that it's all the same thing,
How would you position the subs when you have two in antiface? There is the dipole cancelation in front of the area between the two cabinets, how to deal with this.
You just link to the post that I quoted. It's not obvious if the woofer or the space between the woofers is facing the listener
Shown is only an option if you want to use subwoofers side by side and their installation options relative to each other. If you are asking about installation relative to the listening point, then the optimal sound will also be determined by the geometry of the room and the choice of location in the room. The general recommendation for dipole speakers is their distance from the walls of at least 1-1.5 meters. In practice, the easiest way is to listen to different options in different places by ear or if you have measuring equipment and experience using it, then the task is significantly simplified.
I have both equipment and experience. But you can't just turn a dipole 90 degrees. Then you listen to the null. I see that a single PPD the woofer is facing the listener, which is logic. But two woofers facing each other, is not obvious to me. It seems to be just two separate cabinets facing each other, and I can't see a logic way to position it. Will the null shift 90 degrees when two cabinets are facing each other?