loud but small, thin audio speaker
Tracy Allen
Posts: 6,656
I have a project where audio clips will be played from a Prop/SD, and the speaker has to fit into a small space constrained to roughly 2" diameter by 1/2" thick, preferably half that. The customer requested something like volume and quality of the iPhone. I have a TPA4861 audio amp that puts out nearly a watt into a bridged 8Ω speaker, and it sounds great with plenty of volume when it feeds into a decent speaker. However, the small speakers I've tried don't cut the mustard, too soft and mediocre quality.
I'm looking at the tiny openings on the bottom on an iPhone and wondering what is under there, and again, looking at the Mouser catalog at offerings from Kobitone and Pui but don't know where to start. Does anyone have suggestions? Thanks!
I'm looking at the tiny openings on the bottom on an iPhone and wondering what is under there, and again, looking at the Mouser catalog at offerings from Kobitone and Pui but don't know where to start. Does anyone have suggestions? Thanks!
Comments
I did a Google for micro speaker and came up with this site: http://www.buzzer-speaker.com/manufacturer/speaker/10-28%20speaker.htm
They have from 10mm dia x 2.7mm thick on up. I would imagine there are other places with similar items. Of course, going back to my early stereo buying days, I always want to hear speakers before I buy.
Maybe all-electronics or some of the other surplus houses?
Any speaker will require a resonant chamber for maximum volume and fidelity. The iPhone housing provides such a chamber. Awhile back, I had a similar requirement, and came up with the MG41S from mgelectronics.com, an enclosed speaker that's 1 1/8" dia. x 1/2" thick. It sounds pretty good for a speaker that small. They may have something bigger in diameter, which would be even better if you've got the room for it.
Here's a link to their PC-mountable speakers page:
-Phil
http://www.warwickaudiotech.com/
I welcome the suggestions. I see that Kobitone does offer "multilayer piezo speakers" that are only 1mm thick and 25mm square, frequency response 300-20000 Hz, +75dBA at 3Vrms drive, but how would it sound?
This project will require about 40 speakers, so I don't know about tearing up greeting cards! I'd like to find what kind of OEM speaker they use.
We can do something in the way of a cavity around the speaker, so that will take some experimentation. The ones from MGElectronics look promising. Phil, what power level were you using to drive them, and how would you compare the volume to, say, an iPhone? It is incredible, the speaker opening on the iPhone is only about 10mm x 2mm on the narrow bottom end, so I wonder if the speaker is mounted perpendicular to the opening, and how much of a resonant cavity there can be?
One that I tried is the Kobitone 253-CE221-RO with the following graph:
The +83 dBA rating (at ?? Vrms) seems to be commensurate with others that are available.
Device:COT-01A
Output:90dB @ 10cm/2.7kHz,3.2kHz
Size(LBHmm):9x9x7
Manufacturer:Star Micronics
http://www.rockby.com.au/Rockby/Mailer/WEEKE192_2.htm
It may be worth looking at that manufacturer to see what else they offer.
The warwickaudiotech flat panels are interesting Leon, out of my league though. They are sketchy on the details. Probably a long shot, I did order one of the flat multilayer piezo speaker from Mouser out of curiousity.
I'm realizing that it does come down to efficiency of translating electrical power to sound power, and speakers are in the 0.1% to 10% range at best. That makes me wonder even more about the iPhone speakers that I am supposed to emulate. Here are a couple of photos of the speaker assembly from ifixit.com--Disassembling-iPhone-4S-Speaker-Enclosure. On the left the speaker openings next to the red circles and on the right the speaker assembly in their chamber. So, I'm still wondering, how do they do that?
Erco, thanks for the offer to ask your friend about the chamber size. Maybe, I will see how this plays out. The sound came up as an add-on late in the game on this project. Thanks all for suggestions, there are so many choices and too many conflicting parameters and no chance to hear before buy!
Flat speakers ... dont get me started!
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-882
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=264-901
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=279-090
http://www.madisoundspeakerstore.com/approx-1-fullrange/aurasound-nsw1-205-8a-1-extended-range/
http://www.sparkfun.com/products/10722
http://www.sparkfun.com/products/10917
The interface started off as a project for wildland firefighters, with this light and sound device that signals quantitative smoke levels with a simple beep and a pattern of light from superbright LEDs, a big red "X" for perilously high levels. The smoke monitor/logger is connected to the "display" by a cable. For this the sounds were raucous and annoying and pretty soon were reduced to very occasional beeps to draw attention to substantial increases.
The new project has quite a different audience, education where tobacco smokers are involved, again to signal smoke levels. But now the trick is that they are looking for significant sound clips to be played from SD. I'm skeptical about how that will be received, and am afraid it will get old, fast. But my mission is if possible to fit the lights and melodious sounds into the same 2" by 1.5" x 0.5" Serpac enclosure (or something comparable, can be a bit larger). Erco, do you think your friend's software might help with suggestions for how to baffle the enclosure, placement of the speaker and other openings?
I have six of the little SparkFun speakers mentioned earlier. I have yet to test any of them.
If you think they are worth investigating, I could try making a recording of the sound they produce.
I've wondered about connecting one in place of the S2's speaker and compare how the SparkFun speaker sounds against the stock S2 speaker.
If you want, send me a PM with your address and I'll mail you a couple.
Edit: I purchased these speakers for a project I am unlikely to continue to develop.
-Phil
If you get to speakers that are actually sold for HiFi use, then specs can actually start to tell you a lot. If you're just playing little sound clips, then the user is unlikely to hear the difference in smoothness of response, but you can actually guess how a speaker will sound by its T/S parameters.
For any of the ones listed at Parts Express:
So, there's your rule of thumb. If you want me to do actual enclosure modelling for you, let me know the size of your box, and pick out a driver. I'll let you know how well it'll work in your box. Note, though; even if the box is large enough to not really affect the speaker, you still need to have it well-sealed to the box to baffle waves from the front to the back of the speaker. If there is a path around the speaker, your low frequencies will be limited to the wavelength of the shortest path from the front to the back of the speaker.
As it turns out, the speaker for this project is going to have to be considerably bigger than I had originally intended and the enclosure too will grow to match. The little flat speakers rated at a fraction of a watt simply did not have satisfactory sound quality and volume. The one that came out high in the listening tests was the Cui CMS0401KL-1X. It is on a 40mm square mount and is 4.5mm deep. I have a photo below next to the veho360 speaker that Ken has been extolling in another thread, so I got one of those too to compare sound. The speaker inside the veho360 is very similar in appearance to the OEM Cui speaker on the right,but a little smaller. And they are about the same price, The CUi speaker is $12 from Digikey, while the complete veho360 is just buck or two more and includes the hamburger case, the amplifier, the lithium battery, the cables, etc. (Is that me, saying, "hack the veho!").
The enclosure that I will use for the speaker is dictated by other considerations. It is in the second photo. The enclosure (serpac) is 5"x2"x1", but it will be crammed with other stuff, including a propeller, SD card, XBee and a small LiPo battery. A protective grill over the speaker will be important, and ah, there is that veho again. The grill appears to be a perforated metal that has been rammed into shape. We could use a flat piece, but the speaker would have to be recessed a little with a gasket to separate it from the diaphragm. I'm still open to suggestions.
(a bit like if you set up a camera chart (showing my age now) some git would stand in front of it, although this could be a useful feature if you are unsure if you are the last person on earth)
One other thing, try not to push too much bass through the little speaker, it does little to enhance any thing but very near field response and just forces the cone to its extremes.
Here's a link that deals with lasering ABS:
I've never tried it myself.
-Phil
Obviuously my NEMA enclosure has tons of room compared to yours. Initially the speaker conflicted with the Parallax LCD. I ended up removing the LCD case and epoxied new mounts for the LCD guts alone. No more conflicts.
Never could find a speaker grille to fit. I finally designed and cut my own ABS grilles on my CNC mill. Actually I designed many configurations and opted for the stronger one for an industrial setting. I put the speaker in from the top side, so this reduces how much protrudes into the enclosure.
Although my grille is adequate, it is somewhat expensive to produce considering machine time from the back side, flip and chamfer the edge and countersink from the front side. A high rpm router spindle could do it in 1/4 the time. My VK3 spindle is limited to 4000rpm max. Laser is great for flat pattern work, but not pockets to depth etc.
I will be testing the Velleman audio amp kits K8066 and VM114. Limiting their max output to suit.
Emptybit, those are nice grill patterns the one you chose is artful. The way I have it now with one big hole (Greenlee chassis punch) with SS mesh screen is holding up ok, but it really could benefit from additional support toward the center. I wonder how it would sound with a hexagonal pattern of 7 holes instead of one large hole.
Nevertheless, I'm also looking at the TPA2006 (8 pin dfn), which is a class D amplifier and therefore operates at a higher efficiency in delivering 1.4W nominal. I've had a long interest in class D, but wonder if there might be problems with aliasing between class D pwm and artifacts left from the Propeller duty mode.
Also, since you're willing to expand the enclosure a little, take a look at some of the speakers I listed, especially 1" PolyCone fullrange pair and the HiWave BMR5 Compact speakers. The HiWave one, being a square, will produce more sound per amount of surface area used, and it can probably handle the abuse of being exposed to fingers pretty well, too.