Design Con 2015
Breaking News
Comments
Newest First | Oldest First | Threaded View
hsprr
User Rank
Rookie
Micro Speakers
hsprr   8/6/2013 2:12:16 AM
NO RATINGS
Do we have any mobile phone  using micro speakers which use piezoelectric actuating principle?

Do they use PZT (or any other piezo electric material) as membrane?

I_B_GREEN
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
I_B_GREEN   8/3/2012 11:13:04 PM
NO RATINGS
How about using some of that air pumping functionality to cool the coil? Add a sub chamber and and a mechanical diode (one way valve for the air) and project it along the coil or better inside it. badabing badabong. Now only do this at the exteme travel points and add damping and only pump cooling air when at max power when you need it.

bcarso
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
bcarso   8/1/2012 10:02:10 AM
NO RATINGS
Yes, and not only with temperature but with aging. Ideally, positional determination should be independent.

Tony Casey
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
Tony Casey   7/30/2012 11:06:59 AM
NO RATINGS
That's not something you can rely on either. For example, suspension compliance will change significantly with temperature, changing both the resonant frequency and impedance peak. Moving mass, on the other hand, should remain constant. :-)

calebcrome
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
calebcrome   7/30/2012 6:06:31 AM
NO RATINGS
Good point. But the *rise* in impedance should be linear with temperature. so, if you take a 25C measurement across the spectrum, you should get a nice linear increase across the full spectrum as temperature increases.

agk
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
agk   7/27/2012 12:37:23 PM
NO RATINGS
Author has briefed an important topic and triggered my thoughts. Always there is research going on improving the quality of the sound produce by the loud speakers. This is because the loud speaker efficiency is around 5% maximum. When it comes to fidelity again a quite a lot of limitations. This is because the speaker has to reproduce about more than a 1000 different types musical instruments sounds from a big drum to a smallest string instrument.So naturally it is difficult to design a single transducer to reproduce these sounds.And micro loudspeakers really tough to satisfy.Researchers can think of any other new type of transducer.

tbia
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
tbia   7/26/2012 7:21:27 PM
NO RATINGS
While what the author is stating is true it is much more important to provide a means of acoustic control over the diaphragm. The low frequencies need not be limited by back EMF nor the highs by inductance if a means to provide constant pressure behind the driver is provided. Typically the driver will have a more shallow roll off and not experience as much breakup under these conditions. Pat.7207413 B2 and others pending to allow for dynamic volume modification of the enclosed volume behind the driver. Impedance variations are also not as aggressive and critically damped resonance peaks enhance bass response. These conditions are established pre-electronics allowing for less aggressive DSP requirements to fix the speaker.

AJW in OR
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
AJW in OR   7/26/2012 4:58:23 PM
NO RATINGS
Does this part have any value for piezo speakers?

bcarso
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
bcarso   7/26/2012 4:20:28 PM
NO RATINGS
OK, so as far as I can tell the cone positional information is not exactly acquired in real time (which would be very difficult) but rather developed as a model which resides in the DSP. Brad

Tony Casey
User Rank
Rookie
re: Achieving loud, rich sound from micro speakers
Tony Casey   7/26/2012 8:08:58 AM
NO RATINGS
It is not strictly correct to state that loudspeaker impedance rises linearly with temperature. Only the resistive part of impedance due to the voice coil behaves this way. Over most of the frequency range of a typical moving coil loudspeaker, the impedance is dominated by either the motional impedance caused by back-emf at low frequencies, or voice coil inductance at high frequencies. It is only essentially resistive in a narrow frequency range between these two, where it is largely determined by the voice coil resistance. Any attempt to infer temperature by measuring current, must therefore take this into account (presumably by bandpass filtering the current sense signal).



Flash Poll
Top Comments of the Week
Like Us on Facebook
EE Times on Twitter
EE Times Twitter Feed

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Life
Frankenstein's Fix, Teardowns, Sideshows, Design Contests, Reader Content & More
Max Maxfield

Are Today's Designs Bound by the Constraints of Yesteryear?
Max Maxfield
25 comments
As part of my ongoing Pedagogical and Phantasmagorical Inamorata Prognostication Engine project (try saying that 10 times quickly), I'm working with Jason Dueck from Instrument Meter ...

Jolt Judges and Andrew Binstock

Jolt Awards: The Best Books
Jolt Judges and Andrew Binstock
1 Comment
As we do every year, Dr. Dobb's recognizes the best books of the last 12 months via the Jolt Awards -- our cycle of product awards given out every two months in each of six categories. No ...

Engineering Investigations

Air Conditioner Falls From Window, Still Works
Engineering Investigations
2 comments
It's autumn in New England. The leaves are turning to red, orange, and gold, my roses are in their second bloom, and it's time to remove the air conditioner from the window. On September ...

David Blaza

The Other Tesla
David Blaza
5 comments
I find myself going to Kickstarter and Indiegogo on a regular basis these days because they have become real innovation marketplaces. As far as I'm concerned, this is where a lot of cool ...