With the proliferation of small portable Bluetooth speakers, mini passive radiators have appeared on a scale like never before. I'm searching for information on the use of such small PR units, assuming that there might be slight differences in how they are implemented now and how they function (with lower mass, used in devices that can be positioned multiple ways) and sources for obtaining them.
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Notes:
Here is a source:
Passive Radiators | Tymphany
Design Note:
http://www.d-s-t.com.au/data/Peerless/Peerless_XLS_Subwoofer.pdf
Regards,
WHG
Here is a source:
Passive Radiators | Tymphany
Design Note:
http://www.d-s-t.com.au/data/Peerless/Peerless_XLS_Subwoofer.pdf
Regards,
WHG
1234
1) DSP is being used to tailor the left and right drive signals, and at some frequency above [Fr], right and left source signals are being combined.
2) Drivers for the two stereo channels are working into a single Helmholtz resonator implemented with passive radiator(s) to cover the 'low' frequencies as [Fr] is approached.
3) The fact is, there is no ‘free lunch’ here:
The audible low frequency limit remains a function of the amount of air the unit can displace at [Fr]. This requirement is increasing at a rate inversely proportional to frequency squared (1/f)^2 and is the determinate of where [Fr] is set. This is why there is a "Mini" and "Big" product variants. With the Peerless components, a "Magnum" version could be built as well.
4) I do not know who is building the drive units and radiators, but you could model this system to determine the parameters required to deliver a desired performance in a given footprint.
Regards,
WHG
1) DSP is being used to tailor the left and right drive signals, and at some frequency above [Fr], right and left source signals are being combined.
2) Drivers for the two stereo channels are working into a single Helmholtz resonator implemented with passive radiator(s) to cover the 'low' frequencies as [Fr] is approached.
3) The fact is, there is no ‘free lunch’ here:
The audible low frequency limit remains a function of the amount of air the unit can displace at [Fr]. This requirement is increasing at a rate inversely proportional to frequency squared (1/f)^2 and is the determinate of where [Fr] is set. This is why there is a "Mini" and "Big" product variants. With the Peerless components, a "Magnum" version could be built as well.
4) I do not know who is building the drive units and radiators, but you could model this system to determine the parameters required to deliver a desired performance in a given footprint.
Regards,
WHG
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We may not be that far away from the day when DIY audio enthusiasts may be able to custom 4D print (i.e. multi-material additive manufacturing) passive radiators to spec for any design, any shape, with a range of compliance values.
Until that day, I'm attempting to locate a source for a wide variety of small PRs. These units are in abundance in many commercial (albeit not audio enthusiast grade hi-fi) designs now. The proliferation of small passive radiators does not suggest a hopeful free lunch for maximizing performance relative to size, but rather that they can serve a purpose and are frequently employed in recent years. These smaller PR designs found in numerous Bluetooth devices are somewhat less complex than the PRs of years before. They generally tend to be just a flat diaphragm without a spider or motor structure. The surround is designed to provide the desired stiffness.
Until that day, I'm attempting to locate a source for a wide variety of small PRs. These units are in abundance in many commercial (albeit not audio enthusiast grade hi-fi) designs now. The proliferation of small passive radiators does not suggest a hopeful free lunch for maximizing performance relative to size, but rather that they can serve a purpose and are frequently employed in recent years. These smaller PR designs found in numerous Bluetooth devices are somewhat less complex than the PRs of years before. They generally tend to be just a flat diaphragm without a spider or motor structure. The surround is designed to provide the desired stiffness.
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It's something to toy with perhaps, but what I'm after really, is a source for a variety of small PRs with a range of specs. If one is looking for a 3.5" driver optimally suited to a small enclosure, we're aware of numerous channels to look to. However, to find a functionally compatible PR for that driver, and possibly even an aesthetically pleasing one, the options are virtually nil.
I'm in the process of building one too. I've ordered my amplifier and my 12v to 5v step down for the bluetooth module. I also found a nice battery that comes with charger http://m.aliexpress.com/item/1777958716.html
Also most of the small speakers like jambox and bose use a rectangular pr to maximize space efficiency. I haven't been able to find one on any website though.
Also most of the small speakers like jambox and bose use a rectangular pr to maximize space efficiency. I haven't been able to find one on any website though.
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