Yes, it is of course, question is, can it be used to get the same effect in this specific application.
My thinking was that I'm way above the resonant frequency of the PR's. The frequency range I am interested in is 100Hz - 1kHz (Fs is around 24Hz). It looks like the frequency response within that bandwidth of the PR's follows a nice 12db/oct slope, just what is needed. Now if the placement is right on the sides it should lead to a more or less CD response.
Any frequency response quirks on axis can be dealt with by the DSP, as long as the off axis follows the on axis response.
My thinking was that I'm way above the resonant frequency of the PR's. The frequency range I am interested in is 100Hz - 1kHz (Fs is around 24Hz). It looks like the frequency response within that bandwidth of the PR's follows a nice 12db/oct slope, just what is needed. Now if the placement is right on the sides it should lead to a more or less CD response.
Any frequency response quirks on axis can be dealt with by the DSP, as long as the off axis follows the on axis response.
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So the PRs are supposed to follow the pressures behind them, which would be there whether the PRs are or not. So what are you wanting them to do, are they to modify the pressures or simply follow them.
Basically the main function is to act as a sound source to the sides, and also to act as a low pass filter.
A " resistive port" or "acoustic resistance" has the same function in this case, and this has been successfully done by Jag768 and D&D, getting that right seems tricky and difficult to simulate properly.
Full range cardioid
A bit like a passive implementation of the Kii 3 Kii Audio ::: kii_three
A " resistive port" or "acoustic resistance" has the same function in this case, and this has been successfully done by Jag768 and D&D, getting that right seems tricky and difficult to simulate properly.
Full range cardioid
A bit like a passive implementation of the Kii 3 Kii Audio ::: kii_three
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Your link doesn't work because we have different posts per page settings, just mention the post # and I'll look.
I'm afraid I don't see the passive radiators in that thread. If your intention was to point to using ports to create a cardioid pattern, it's ok, that much is understood. The resistive material along the way could stay there whether you were to add passive radiators or not. From this point I find myself back at the questions from my first two posts.
You suggest the PR will simply follow the pressures above resonance, so is it necessary? Damping material is also going to reduce higher frequencies.
You suggest the PR will simply follow the pressures above resonance, so is it necessary? Damping material is also going to reduce higher frequencies.
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Yes I pointed to that thread to show the resistive material / port being used.
Now my idea is to replace these ports with resistive material in them with passive radiators not add PR's to them (hope I was clear about that, sometimes the langues barrier gets in the way).
That would be way easier to implement as a modification to my existing speakers. Simulating it is also easier.
Now my idea is to replace these ports with resistive material in them with passive radiators not add PR's to them (hope I was clear about that, sometimes the langues barrier gets in the way).
That would be way easier to implement as a modification to my existing speakers. Simulating it is also easier.
Well, first get some opinions here on DIY audio if I'm just being stupid with this idea 😉
Next get Boxsim fired up and simulate this using active woofers adjusted to the same frequency/phase response and position as the PR's would be (no PR's in Boxsim). This looks promising.
finally order 4 PR's and cut the holes (2 per speaker), adjusting the DSP for flat frequency response on axis and start measuring the off-axis. Total costs would be about 120 euro's, so that's ok.
Next get Boxsim fired up and simulate this using active woofers adjusted to the same frequency/phase response and position as the PR's would be (no PR's in Boxsim). This looks promising.
finally order 4 PR's and cut the holes (2 per speaker), adjusting the DSP for flat frequency response on axis and start measuring the off-axis. Total costs would be about 120 euro's, so that's ok.
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Funny thing is the idea to use of a passive radiator to create a cardioid came along in another (Dutch…) forum today. Maybe because of some connection I’m not aware of, or sheer coincidence.
What puzzles me is why you would need two PR’s. Maybe one suffices. And it still will be quite a job to get the desired output right by adjusting the damping. Maybe you even should consider using a driver of which you can shortcut the coil in a selective way to control the output.
What puzzles me is why you would need two PR’s. Maybe one suffices. And it still will be quite a job to get the desired output right by adjusting the damping. Maybe you even should consider using a driver of which you can shortcut the coil in a selective way to control the output.
I recall reading somewhere using a higher order rear ported enclosure (double chamber reflex) or possibly bandpass LF alignment coupled with a front facing LF driver to achieve something similar.
In live sound we would simply drive another identical LF enclosure out of phase with multiple enclosures facing forward. This obviously requires active filters, delay and dsp, all of which costs alot of money. Exploded arrays with 90 deg facing perimeter LF out of phase have also been used in the 80s before line arrays. Successful passive implementation of a caridoid LF setup are obviously difficult.
In live sound we would simply drive another identical LF enclosure out of phase with multiple enclosures facing forward. This obviously requires active filters, delay and dsp, all of which costs alot of money. Exploded arrays with 90 deg facing perimeter LF out of phase have also been used in the 80s before line arrays. Successful passive implementation of a caridoid LF setup are obviously difficult.
That's coincidence indeed, I'm not on any Dutch audio forum. Would be a good read probably, do you have a link?
Idea of using 2 came about because mounting a vent/PR on the back is not an option in the current setup, the plate amplifier is mounted in the back. Also because the resistive vents method works this way in the D&D and Jag768 design and gets good results.
That last idea is an interesting one also, using a non powered driver and pressing the voice coil into action purely as damping. That could be made frequency dependent also, gives more freedom in tuning. Something to think about for sure.