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I use my Seeeduino V4, DFPlayer mini, and this speaker module from AliExpress to create an automatic doorbell. The problem is that it seems that this speaker module's Yurobot amplifier is not powerful enough to create a noise-free loud sound. Also, the bundled speaker is 0.5W, 8 Ohm.

There is a volume selector on the speaker module. If it is selected to a value a bit higher than 0 then the sound's quality is quite high (click here to listen), but the volume is not enough by far for a doorbell, even though the DFPlayer's programmed volume is set to maximum. But if I increase the amplifier's volume selector to something near maximum, I start hearing some very scary noises (please click here to listen).

How can I increase the volume without having hard-to-listen-to noises? Maybe I need to buy another, better amplifier?

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  • The DFPlayer already has a 3W amplifier on it you can connect a 3W speaker to. If you connect an extra amplifier to the DPlayer and turn the volume of the DFPlayer up, the second amplifier will probably clip. You could try how the DFPlayer sounds when you connect a speaker directly to it; a 3w speaker would be good for this.
    – ocrdu
    Dec 12 '20 at 11:07
  • I don't have a 3W speaker currently at my's, so I can't do such a test. Also, my only speaker has a unique connector that is compatible with the speaker module I talked about in the question.
    – Starter
    Dec 12 '20 at 11:13
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    If you want a load sound, you should buy a speaker with the wattage of your amplifier (here the 3W amp of the DF player).
    – chrisl
    Dec 12 '20 at 13:26
  • @chrisl, otherwise I'll get rasps and hard-to-listen-to noises?
    – Starter
    Dec 12 '20 at 13:29
  • I think that is because your extra amp module is clipping the sound, since it reached its maximum amplification. In that case you get distorted sounds (that how the distortion with e-guitars works). But with the 3W speaker you could enable to full potential in the DF player and then see, if that is load enough. On aliexpress there is mostly few to none documentation, so we cannot know, how strong the amp module is. But judging from the speaker, that came with it, I would say, that it is weaker than the DF player.
    – chrisl
    Dec 12 '20 at 14:08
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The DFPlayer already has a 3W amplifier on it, so you can connect a speaker directly to the DFPlayer. There is no need for an extra amplifier.

If you do connect an extra amplifier to the DPlayer, and turn the volume of the DFPlayer up too far, the input of the second amplifier will clip and it won't sound good. Also, the output of the DFPlayer is probably from a class-D amplifier designed to be connected directly to a speaker; it won't play nice with other amplifiers.

You should try how the DFPlayer sounds when you connect a speaker directly to it. The 0.5W speaker you have is not a good fit; it can't handle the power of the DFPlayer's amplifier.

A 3W (or more), 8Ω speaker would be good for this if you want to use the maximum power the DFPlayer can deliver. According to most publications on the interwebs a 2W, 8Ω speaker will also do, but I would be careful with turning the volume all the way up.

Note that the DFPlayer can pull a fair bit of current (about 25mA in standby, and in the order of 200mA when playing) and it needs a power supply that can deliver that.

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  • 1
    I'm probably going to be playing with a couple of these soon and this contains some useful information to me. Welcome to 1K.
    – timemage
    Dec 22 '20 at 13:54
  • @timemage: Thanks! Note that if you only need to play short sound bites for a user interface or something like that, the memory and DAC of anything SAMD21-based will also do.
    – ocrdu
    Dec 22 '20 at 14:15
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    The problem has been solved by buying a YD103-O4B 8Ohm 4W speaker. Thanks for the help!
    – Starter
    Dec 28 '20 at 1:53
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Interesting! The wattage rating of the speaker does not affect its loudness, the efficiency does at a given wattage. Wattage is the maximum amount of power you can drive the speaker with, that does not indicate the source can provide more or less. The SPL (SPL stands for sound pressure level and is also commonly referred to as efficiency and sensitivity. This parameter represents how loud a speaker is. A higher SPL equates to a louder speaker). To get more volume out of a speaker you have to put more power in. Ohm's Law explained this. The impedance (AC Resistance) of the speaker varies with frequency but typically a nominal number such as 8 ohms is used. Looking at Ohm's law the only way to get more power is to lower the impedance or increase the voltage with voltage being the most popular as well as the easiest. Putting more power into a speaker then it is rated at will eventually destroy it as well as distort the sound. This may not be noticeable to the human ear at low amounts but it is there. Also the sound coming out is directly related to the signal going in. Clipping is a common occurrence when the amplifier is being over driven ie. it is asked to put out a higher voltage then it is capable of. There is an old saying garbage in garbage out. That includes the components as well. To solve your problem you probably need an amplifier capable of doing what you want and a speaker that will at a minimum handel the worse case power you will send it.

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  • I am sorry if my questions are stupid, but is it possible to calculate the SPL of a speaker? Actually, this answer is very interesting, but it actually seems like I will need to experiment with multiple speakers... This will take a long, according to AliExpess' shipping durations. I actually hope that a 2W 8Ohm speaker will work correctly without an amplifier, but directly connected to the DFPlayer, as had people suggested some time ago.
    – Starter
    Dec 15 '20 at 1:02
  • It is relative involved with math. The easiest is to use a calculator. A good one is found here: myhometheater.homestead.com/splcalculator.html This works quite well. Have fun with it!
    – Gil
    Dec 16 '20 at 2:36

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