Problem with a DIY bluetooth speaker

Thread Starter

Martiio

Joined Apr 2, 2020
6
Hi everyone
I would like to ask you about my DIY bluetooth speaker.
I bought 2 speaker 2x4 ohms, 2x3w mini stereo amplifier,18650 batteries,usb step up module, 18650 battery charger and bluetooth receiver and made a speaker.The speaker works generaly,but when I turn up the volume to the max level or even 80% of the level the sound stops,but the speaker is still on.I have to turn the speaker off and then again on and it works again. What might be the problem?
 

KeithWalker

Joined Jul 10, 2017
798
What is the output current rating of the usb step-up module? At high volume, the amplifier may use more current than it can can supply, putting it into overload protection mode. You may need a boost converter that can supply more current.
Regards,
Keith
 

Audioguru again

Joined Oct 21, 2019
1,272
You forgot to provide us with any details about the amplifier. A link to its sales sheet or its datasheet should have some details.
Many little amplifiers are using a PAM8403 IC that produces 3.2 Whats per channel into 4 ohm speakers with 10% of horrible clipping distortion when the power supply is 5.0V. Its output is 2.5 watts per channel with fairly low distortion and is 2.0 Watts per channel with very low distortion. Its absolute maximum supply voltage is 6.0V.

What is the output voltage of your boost converter?
 

Thread Starter

Martiio

Joined Apr 2, 2020
6
What is the output current rating of the usb step-up module? At high volume, the amplifier may use more current than it can can supply, putting it into overload protection mode. You may need a boost converter that can supply more current.
Regards,
Keith
What is the output current rating of the usb step-up module? At high volume, the amplifier may use more current than it can can supply, putting it into overload protection mode. You may need a boost converter that can supply more current.
Regards,
Keith
That is the step up module: https://www.aliexpress.com/item/32612173159.html?spm=a2g0s.9042311.0.0.27424c4dcxm13I
Maximum current output: 2A

That is the amplifier: https://www.aliexpress.com/item/32392563588.html?spm=a2g0s.9042311.0.0.27424c4dQPoMYs
 

Thread Starter

Martiio

Joined Apr 2, 2020
6
You forgot to provide us with any details about the amplifier. A link to its sales sheet or its datasheet should have some details.
Many little amplifiers are using a PAM8403 IC that produces 3.2 Whats per channel into 4 ohm speakers with 10% of horrible clipping distortion when the power supply is 5.0V. Its output is 2.5 watts per channel with fairly low distortion and is 2.0 Watts per channel with very low distortion. Its absolute maximum supply voltage is 6.0V.

What is the output voltage of your boost converter?
It is 5v
 

Audioguru again

Joined Oct 21, 2019
1,272
Nobody turns up the volume of an amplifier to 80% or maximum but you do. Then the amplifier and voltage booster are overloaded. At maximum, the power of distortion is the same as the power of normal sounds then the total output is almost 6W per channel.
Again, what is the output voltage of the voltage stepup module? The amplifier will be destroyed if it is higher than 6.0V but the PAM8403 datasheet recommends a max voltage of 5.5V.
 

KeithWalker

Joined Jul 10, 2017
798
You are driving two 4 Ohm speakers from a 5 volt supply. At maximum volume, the peak current will be 1.25 amps per channel. That exceeds the current limit of the supply. That is why it is shutting down. As I stated above, you need a supply that can provide a higher current if you want to play music at maximum volume.
Keith
 

Thread Starter

Martiio

Joined Apr 2, 2020
6
Nobody turns up the volume of an amplifier to 80% or maximum but you do. Then the amplifier and voltage booster are overloaded. At maximum, the power of distortion is the same as the power of normal sounds then the total output is almost 6W per channel.
Again, what is the output voltage of the voltage stepup module? The amplifier will be destroyed if it is higher than 6.0V but the PAM8403 datasheet recommends a max voltage of 5.5V.
As I said, the output voltage of the stepup module is 5v !!! I have a original bluetooth speaker and when I turn the volume of the phone up to 100% the speaker doesn't turn off and there is no some kind of distortion! Can I do my diy speaker as my original speaker?
 

Thread Starter

Martiio

Joined Apr 2, 2020
6
You are driving two 4 Ohm speakers from a 5 volt supply. At maximum volume, the peak current will be 1.25 amps per channel. That exceeds the current limit of the supply. That is why it is shutting down. As I stated above, you need a supply that can provide a higher current if you want to play music at maximum volume.
Keith
All right KeithWalker. Thanks for the answer.So I should buy a more powerfull stepup module for example 5amps.I hope that will fix the problem!
 

Audioguru again

Joined Oct 21, 2019
1,272
Your original Bluetooth speaker might have a much more powerful amplifier and power supply than your DIY system has. It also might have much higher quality speakers in it.
Every amplifier has a different amount of gain, then the volume control of the phone will be at a different position to produce the same output loudness. Your original Bluetooth speaker "doesn't turn off and there is no some kind of distortion" when "the volume of the phone up to 100%" because its gain is less than the gain of your DIY amplifier, or because it has more output power.

The volume control of your phone is expected to be turned down when distortion is heard.
 

Audioguru again

Joined Oct 21, 2019
1,272
Your little amplifier begins to produce distortion when it produces its maximum of only 2W into each speaker. Some portable bluetooth speakers produce 15W or more into each speaker. Increasing the current from your voltage stepup module will not increase the amplifier power.
If they are working very poorly then maybe your cheap Chinese modules are defective?
 

Thread Starter

Martiio

Joined Apr 2, 2020
6
Your little amplifier begins to produce distortion when it produces its maximum of only 2W into each speaker. Some portable bluetooth speakers produce 15W or more into each speaker. Increasing the current from your voltage stepup module will not increase the amplifier power.
If they are working very poorly then maybe your cheap Chinese modules are defective?
All right .Thanks for the information! Have a nice day!
 
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