Cheap, bulk source of good quality speakers?

Blazemaguire

Senior Member
Hi all,

Looking to develop an improved portable speaker project for my electronics students (well.... now D&T, but still doing as much electronics as I can under the new GCSE specs). The kind that plugs into am MP3 player or mobile phone.
It will be linked with a PICAXE (to control lighting) and also either an LM386 op-amp or TBA820 circuit for driving the audio. Does anyone have any suggestions or links to a good, cheap 8 ohm speaker (between about 30mm - 60mm diameter)

In the past I've brought these speakers from Rapid,

https://www.rapidonline.com/primetone-lp400-0-1w-8-ohm-40mm-ultraslim-speaker-0-1w-35-0120

but not only are they expensive (In my opinion, given school budgets!) they're also very poor audio quality as I think their rated RMS Wattage is very low.

Just experimenting with various old recycled speakers from my shed I've managed to get notably better sound quality (and louder volume, without distortion) using 9V to 12V supply into the LM386 and cruddy speakers from old recycled kids toys / radios etc.

This will be the next project with circa 50 Students. In an ideal world, I was also going to run 2 x LM386 circuits and 2 speakers per student to give stereo sound as well.

The kids are all willing to chip in £5 for the project (and I have £3 per head from my capitation to add to that), so I need to get 2x op-amps (about 50p each), 2 speakers, the PICAXE and all the caps/resistors/LEDs in for that budget. (case and PCB material is already brought and paid for)

I guess I have about £2 - £3 to get 2 speakers, but I want something that's better than the version above and would appreciate any reccomendations.

Any ideas? Audio/amp circuits are not my specialty at all. I just want to improve upon the current version I run, and the speaker is certainly a weak point. Though, the audio amp itself could also do with being beefier (any ideas on that front).

The traditional version I build using a single TBA820 and the Rapid speaker above is eclipsed by most internal mobile phone speakers nowadays, so makes it kind of irrelevant to the kids!

Rob
 

Blazemaguire

Senior Member
Cheers, they seem a stupidly good price. But It seems almost criminal to destroy something 'new' to make something else new (and probably worse, because kids are making it) As a last resort, I will look at that. It doesn't teach much about sustainability either! I'll buy one just for testing purposes.... I guess, if the amp and battery is good, we could always just hack the internals completely and rebuild it into their own enclosure design, with the PICAXE and LED Lighting.
 

AllyCat

Senior Member
Hi,

I haven't bought a speaker for many, many years but those 0.1 w from Rapid do seem particularly pathetic. I would have thought you could get an acceptable speaker (or "driver") for a Pound or two, perhaps something like this (just the first I found). But as stan says, the "enclosure" is really the important part.

As for the amplifier, take a look at the PAM8403 modules, a maximum 6 volts supply but that would be compatible with a PICaxe, and its H-bridge output means it can drive as hard as a normal 12 volt supply transformerless amplifier. Less than 20p each from China, so you should be able to source/invoice a quantity for less than 50p each in UK, if you must purchase locally? At least a watt (per channel) into 8 ohms from 4.5 volts (e.g. classic PICaxe 3 x AA cells supply) should give a decent volume in stereo, or one channel could flash a couple of bright LEDs (1 Amp pullup or pulldown). ;)

I'm using them for a rather different application but they seem quite easy to use and reliable (I won't say indestructable as children are involved).

Cheers, Alan.
 

Blazemaguire

Senior Member
Thanks all,

This is why I posted here!, I knew you guys would have some ideas.

AllyCat, those speakers from CPC look in budget (just) and 2W RMS should be more than enough, particularly in stereo. I also like the idea of that PAM board, I can stick it on some SIL header pins and make it piggy back onto a PICAXE PCB that the kids are designing anyway.

Just need to find a UK seller that can get them here quick now!

As a side note, its kind of a shame that the electronics is now dumbed down to the point of just being an 'accessory' to add in to product design, thus teaching the theory of how an op-amp works is no longer part of the exam content... this would have been a great oppotunity were I on the old electronic products spec.

I guess they just need to know "this thing make go louder"... (sorry, I've grown very cynical since the GCSE reforms!)

Thanks Stan, that website you've linked has given me an excellent idea for a home work task. 50 Kids will be thanking you begrudgingly for that one!

Rob
 

AllyCat

Senior Member
Hi Rob,

Just need to find a UK seller that can get them here quick now!
I got a couple to test for significantly less than £2 delivered from booskibits, and several UK sellers on ebay will send one for 99p. Note that some pads (in particular the supply pads) are not quite on a 0.1" grid; the boards I sourced (later) from China seem slightly closer, but we're only talking a small fraction of a mm anyway.

Eclectic's link has a couple of speakers at just under £1 each from bitsbox. 500 mW might be a little low, but if finances are tight! ;)

Cheers, Alan,
 

stan74

Senior Member
I was into it once Rob. Explaining why a speaker unit sounds tinny then putting it on a baffle,then in a box,called an infinite baffle but the air acts like a spring to resist the speaker so use a tube so that the air in it acts like a piston etc... quite interesting...and why swapping the speaker polarity loses bass...kids love bass.
 
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