Hi there.
For completeness measurements at 1cm from the ports. Purple is front port, red is rear port.
I updated the simulation with what I ended up building. 0.15L front volume, ≈1.8L for the rear volume (2L without the driver). ⌀ 4.4cm front port, ≈116 cm² area for the rear port when the magnet area is subtracted.
It's different, specially above 300Hz... So unless you see something when it comes to the simulation I cannot infer anything other than the need to learn to use HornResp to simulate a Ripole. On the other hand, it's nice to get a guide where the frequency matters the most.
For completeness measurements at 1cm from the ports. Purple is front port, red is rear port.
I updated the simulation with what I ended up building. 0.15L front volume, ≈1.8L for the rear volume (2L without the driver). ⌀ 4.4cm front port, ≈116 cm² area for the rear port when the magnet area is subtracted.
It's different, specially above 300Hz... So unless you see something when it comes to the simulation I cannot infer anything other than the need to learn to use HornResp to simulate a Ripole. On the other hand, it's nice to get a guide where the frequency matters the most.
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Technically, all box alignments are 'band pass'. 😉
Regardless, the box only loads the driver to its upper mass corner (Fhm):
Fhm = 2*Fs/Qts'
Fs: Fhm*Qts'/2
Qts': 2*Fs/Fhm
Obviously though, one needs a much higher Qt for lossy box alignments = a narrower box loading BW, so to get a wide range HF BW also requires extended inductance for higher woofer 'speed'.
(Qts'): (Qts) + any added series resistance (Rs)
On my search for an OB design without a huge baffle i stumbled on this PPD topic and i want to make some test cabs for a pair of Faital 15PR400 i now use in a OB design (OBL-15).
I understand that the volume of the "box" behind the speaker should be as small as possible. Is the example of tu100 in this post a good method to follow? https://www.diyaudio.com/community/threads/ppd-subwoofer.393371/post-7204969
If so, i think the construction could very much benefit if you make it from (solid) wood instead of foam-like material to reduce box vibrations.
One could also make a piston like shape to follow the shape of the back of the speaker thus reducing volume even more and make the construction even more heavy and sturdy. Could that be a good option?
I understand that the volume of the "box" behind the speaker should be as small as possible. Is the example of tu100 in this post a good method to follow? https://www.diyaudio.com/community/threads/ppd-subwoofer.393371/post-7204969
If so, i think the construction could very much benefit if you make it from (solid) wood instead of foam-like material to reduce box vibrations.
One could also make a piston like shape to follow the shape of the back of the speaker thus reducing volume even more and make the construction even more heavy and sturdy. Could that be a good option?
Indeed!
Something like that is whats on my mind.
I see only single cabinets for the woofer for "single" placement. I want to make the PPD part of the baflle with mid (from approx 100Hz) and high above that.
Something like that is whats on my mind.
I see only single cabinets for the woofer for "single" placement. I want to make the PPD part of the baflle with mid (from approx 100Hz) and high above that.
Subjectively: - completely satisfied, low frequencies are very musical, bass is fast, - goes well with electrostats.
My PPD story:
1. The first PPD subwoofer on 10-inch 75 GDN-1-4 speakers, pictured on the left. Very musical, but gets overloaded very quickly.
2. PPD subwoofer with 12" speakers 4A-32, pictured on the right. More resistant to overload, but two of them were required.
I made PPD measurements on 4A-32, all graphs without smoothing. Measurement and display range from 20 to 500 Hz. Subwoofers are connected in parallel to a monotel amplifier with reg. output resistances, through an active filter, cutoff frequency 75 Hz.
1. Left sub graph, near field 10-15 cm.
2. The same for the right subwoofer.
3. Two subwoofers. Distance to subwoofers 1 m.
1. The first PPD subwoofer on 10-inch 75 GDN-1-4 speakers, pictured on the left. Very musical, but gets overloaded very quickly.
2. PPD subwoofer with 12" speakers 4A-32, pictured on the right. More resistant to overload, but two of them were required.
I made PPD measurements on 4A-32, all graphs without smoothing. Measurement and display range from 20 to 500 Hz. Subwoofers are connected in parallel to a monotel amplifier with reg. output resistances, through an active filter, cutoff frequency 75 Hz.
1. Left sub graph, near field 10-15 cm.
2. The same for the right subwoofer.
3. Two subwoofers. Distance to subwoofers 1 m.
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My PPD story:
3. Replaced the 4A-32 speakers with Beyma 12BR70 speakers.
The overload capacity was quite high, but I wanted it to be a little better.
4. I made two more PPDs for Beyma 12BR70 speakers.
Now I'm happy with everything. Organ, piano, double bass, drums sound powerful and without distortion.
3. Replaced the 4A-32 speakers with Beyma 12BR70 speakers.
The overload capacity was quite high, but I wanted it to be a little better.
4. I made two more PPDs for Beyma 12BR70 speakers.
Now I'm happy with everything. Organ, piano, double bass, drums sound powerful and without distortion.
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would a PPD be feasible as a slotted line array?
So N woofers on top of each other and then change the port hole by a vertical slot?
So N woofers on top of each other and then change the port hole by a vertical slot?
Its a vision,
its a pipe dream
But nonetheless I had a thought (that comes in a form of a couple of questions):
How would one go about designing something, which in essence is a 2-way system comprised of a DML-speaker ran as quasi full-range and passively crossed over to a PPD subwoofer?
Is there any data of the PPDs sensitivity?
This thought experiment arises from budgetary reasons (don't have the money for plate amps) and the point of view of everyday use (I would just like to plug everything into my existing amplifier and control the whole thing from there).
In a way I guess this would resemble the amazing "Manzanita" OB(quasi full-range little vifa driver paired to a woofer crossed around 150Hz) which I built (, loved) and eventually sold off when moving.
Being handy in 3D modeling I threw something quick and dirty together, with some quircky design aspects (the wires for the exciter running through the panel and the cross-over being very visible and cast into resin? Wild!!)
Might somebody bother to reply I would be infinitely intrigued to hear about your thoughts about the premise of this imaginary build
Best regards
Sampo
its a pipe dream
But nonetheless I had a thought (that comes in a form of a couple of questions):
How would one go about designing something, which in essence is a 2-way system comprised of a DML-speaker ran as quasi full-range and passively crossed over to a PPD subwoofer?
Is there any data of the PPDs sensitivity?
This thought experiment arises from budgetary reasons (don't have the money for plate amps) and the point of view of everyday use (I would just like to plug everything into my existing amplifier and control the whole thing from there).
In a way I guess this would resemble the amazing "Manzanita" OB(quasi full-range little vifa driver paired to a woofer crossed around 150Hz) which I built (, loved) and eventually sold off when moving.
Being handy in 3D modeling I threw something quick and dirty together, with some quircky design aspects (the wires for the exciter running through the panel and the cross-over being very visible and cast into resin? Wild!!)
Might somebody bother to reply I would be infinitely intrigued to hear about your thoughts about the premise of this imaginary build
Best regards
Sampo
Attachments
PPD sensitivity is low. The same as the RiPol with a single driver.
I have been searching for a suitable 15" driver for a PPD.
Have been searching for a driver with Bl as large as possible and MMS as low as possible to have the highest Bl\MMS ratio.
I will test first with Faital 15PR400 witch has a Bl\ MMS ratio of 16,7\85,2 = 0,196
I found the Precision Devices PD.153C002 with a slightly higher Fs, bit larger xmax, higher Bl and lower MMS. Bl \ MMS ratio of 18,9\67,1 = 28,1
So i have high expectations of the PD driver.
At the moment working on some test cabs and going to try both drivers soon.
Have been searching for a driver with Bl as large as possible and MMS as low as possible to have the highest Bl\MMS ratio.
I will test first with Faital 15PR400 witch has a Bl\ MMS ratio of 16,7\85,2 = 0,196
I found the Precision Devices PD.153C002 with a slightly higher Fs, bit larger xmax, higher Bl and lower MMS. Bl \ MMS ratio of 18,9\67,1 = 28,1
So i have high expectations of the PD driver.
At the moment working on some test cabs and going to try both drivers soon.
Very first impressions of the ppd cab with the Faital 15PR400.
I did not change anything in crossover, so it is not a ideal setup, but just to listen to differences. I focus on the low frequenties. Listened for about 15 minutes. Then the kids took over
It is different 😅
Bass is deeper, perhaps a bit dryer bass perhaps also faster.
A bit more defined. But also that it comes out of a cabinet (a bit locked in) but not with all songs.
I did not change anything in crossover, so it is not a ideal setup, but just to listen to differences. I focus on the low frequenties. Listened for about 15 minutes. Then the kids took over
It is different 😅
Bass is deeper, perhaps a bit dryer bass perhaps also faster.
A bit more defined. But also that it comes out of a cabinet (a bit locked in) but not with all songs.
Attachments
Listening update after some more time.
All very subjective.
Bass is quite a bit deeper. Also louder especially in the sub bass region where there is quite some gain.
Bass is tight and full. It seems to have some more punch also.
My remark on the cabinet (closed in) i did not hear again on listening position. I heard it yesterday from a side room.
So the sound is very much like open baffle bass but deeper.
Results are good and i will proceed with the PD 153 C002 units with a higher baffle for mid and horn integrating the ppd subwoofer into a single 3 way speaker.
All very subjective.
Bass is quite a bit deeper. Also louder especially in the sub bass region where there is quite some gain.
Bass is tight and full. It seems to have some more punch also.
My remark on the cabinet (closed in) i did not hear again on listening position. I heard it yesterday from a side room.
So the sound is very much like open baffle bass but deeper.
Results are good and i will proceed with the PD 153 C002 units with a higher baffle for mid and horn integrating the ppd subwoofer into a single 3 way speaker.
Sorry, but I don't think that the "PPD" subwoofer idea is anything new, it is simply a variety of the Ripole.
Even the Ripole did not justify a patent (run out anyway), there was just no one who ever contested it. You can not patent something that has been in use for many years, just by changing the build a little and adding a low pass filter, but that's not relevant any more. Axel Ridthaler did a good job in making the result more predictable.
With the Ripole there are two things that define it. First is the separation of front and back to limit phase cancelation, the other one is the different transformation of particle velocity on front and back. If you have a look at the PPD idea, nothing has changed in that regard. It is only a ripole in a different housing, whithout the option to have the very conveniant force cancelation of the 2-driver Ripole.
With the low frequency involved, any resonances in the small, open volumes involved, are no problem.
What I miss is a 1:1 comparison of a Ripole and a PPD, using the same driver. This should show us a slightly better response and level with the real Ripol, because of a better front to rear separation.
All the near field measurements of the PPD, trying to proof some response- are useless and irritating. Such a construction has to be standing on the floor and measured in something like a typical, narrow listening distance. This is part of every "open" system.
For those that like the form better than a Ripole, why not build a PPD, but don't expect any wonders.
Even the Ripole did not justify a patent (run out anyway), there was just no one who ever contested it. You can not patent something that has been in use for many years, just by changing the build a little and adding a low pass filter, but that's not relevant any more. Axel Ridthaler did a good job in making the result more predictable.
With the Ripole there are two things that define it. First is the separation of front and back to limit phase cancelation, the other one is the different transformation of particle velocity on front and back. If you have a look at the PPD idea, nothing has changed in that regard. It is only a ripole in a different housing, whithout the option to have the very conveniant force cancelation of the 2-driver Ripole.
With the low frequency involved, any resonances in the small, open volumes involved, are no problem.
What I miss is a 1:1 comparison of a Ripole and a PPD, using the same driver. This should show us a slightly better response and level with the real Ripol, because of a better front to rear separation.
All the near field measurements of the PPD, trying to proof some response- are useless and irritating. Such a construction has to be standing on the floor and measured in something like a typical, narrow listening distance. This is part of every "open" system.
For those that like the form better than a Ripole, why not build a PPD, but don't expect any wonders.