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Topic: Need help determining which speaker is louder (Read 2373 times) previous topic - next topic


so i have a project where i have a audio amp built .. and due to size contraints im trying to find them best and loudest speaker possible.. i bought a 4ohm .2w speaker at 40mm by 6.5mm

so would this be louder?

or this?

i dont know which rating makes it louder.


I have my doubts about the 1st one being 2 Watts.


The thing that has the biggest impact on loudness is the speaker housing.


Well one is rated at 2 watts max and the  other at 0.2 watts max power consumption. Neither gives what it's audio output is at their rated max power (SPL rating), but I would suspect the first can be driven louder then the second based on the very limited information given in the product descriptions.


You need a sensitivity or "efficiency" rating.    For example this speaker (which I just selected randomly) is rated at 91dB @ 1 meter with 1 Watt.    If you double the power, you'll get 3 more dB.   

Most amplifiers are "constant voltage", which means the output-voltage doesn't change when you change the load impedance (as long as you stay within the specs).     This also means that if you use a 4-Ohm speaker instead of an 8-Ohm speaker, you'll get twice the current, and therefor twice the power, with 4-Ohms.     If the 4-Ohm speaker and the 8-Ohm speaker have equal sensitivity, the 4-Ohm speaker will be 3dB louder.


I have used those micro round speakers in your first link, they are not well suited for music they have a "tinny" sound.
Much better in a situation for sound effects, like in a toy.
It's all about the skills


I've done a lot of stuff with speakers in my projects, trying to get the most out of small and large speakers.

There's several things you'll want to pay attention to.

First there's the audio file itself.  Have you maximized the peaks?  Run it through a compressor?  You can double the volume this way.

Next, there's the impedance.  If you've got a little 3W amplifier running on 5V, then a 4 ohm speaker (or two 8 ohm speakers in parallel) is going to allow twice the current to flow, and you will get twice the power out of it.

Then there's the sensitivity.  All other things being equal, the sensitivity, measured in decibels, is how efficient the speaker is at converting power into volume.  A 6db increase is a doubling in volume. 

But the sensitivity does you no good if the speaker isn't good at reproducing the tones you want.  Look at the datasheet for the speaker if you can find one for a graph.  Or at the very least, there should be a range for frequencies the speaker can reproduce.  You can hear between 20Hz-20kHz, so you want as wide a range as possible.  For a tiny speaker, if it can go down to 300Hz then that's great.  But make sure it isn't limited to something like 8Hz on the high end if you want the best audio quality.

Finally, there's the size of the speaker.  You'd think the other factors above would tell the whole story but in my tests, that doesn't seem to be the case.  A 3" speaker is going to sound a hell of a lot louder than a 1x2" speaker, even if the latter is listed as having a higher sensitivity, and has half the impedance.  Perhaps this is partly due to the larger speaker's ability to play lower frequency sounds, but it seems like it's across the board that a larger speaker will be louder with the same power input.

Unfortunately if you're buying your speakers on Ebay instead of a site like Digikey or Mouser, then you're not really going to have much of this data to base your decision on, and you can't really trust what's there anyway.

So, I'd suggest getting a speaker from Digikey and paying close attention to the specs, or else it's just going to be pot luck what you get.  That said... the 5pc auction looks like that would be the louder speaker.  But neither looks like a very good speaker.  Not a fan of the mylar.


Oh and as Grumpy mentioned, the speaker housing is important.  The waves from the back side of the speaker are 180 degrees out of phase with the ones from the front and they cancel eachother out like noise canceling headphones.  The speaker cabinet prevents that from happening.  They sell tiny speakers on Digikey with plastic housings.  I haven't tried them myself as they are fairly new, but I would imagine they'll give you the most bang for your buck with minimal effort. 

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