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DIY bluetooth speaker

I know JBL charge 4 says its 30W but i can tell you that my speaker was quite a lot louder then it. Granted, it didnt have good bass but it was a lot louder. Maybe the speaker inside JBL charge 4 is 30W and amplifier is only feeding it 15W or something like that. Anyway i will have to do some testing and find some proper material. I cant seem to find the right plastic to make my own speaker cases, i only found pvc sheets in store and they are so expensive its crazy, not to mention that unlike this nice plastic, pvc will break often when cut with jihsaw.
 

audioguru

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A good speaker enclosure has sides that do not flex.

The loudness sensitivity of a speaker is measured at 1W and at a distance of 1m. A sensitive speaker is 93dB and a speaker that is not sensitive is 83dB.
2W is +3dB. 4W is +6dB. 8W is +9dB and 10W is +10dB that sounds twice as loud as 1W.

Maybe the JBL speaker has a flat frequency response but your louder speaker has a peak in its response?
Maybe the JBL speaker amplifier output is 30 peak Watts which is only 15 real Watts?
Maybe the JBL speaker's amplifier produces 7.5 real Watts plus another 7.5W of awful clipping distortion?
 
The wierdest thing. I connect my batteries to amplifier and suddenly i read 3V on my BMS instead of 24.7V. Then i turn the button off and on again and its same, only this time the amplifier wont turn on at all. I have to physicaly unplug the power from amplifier and then bms shows 24.7V again. I will try with a resistor now to see if the same thing happens.
 

audioguru

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Most Helpful Member
The BMS is limiting the power-up current surge of the main filter capacitors in the amplifier.
The BMS is designed for connecting only battery cells that have no load.
 
Well interesting, it does seem to be a little spark whenever i connect power to this amp. Doesnt matter if i connect batteries or external DC.

Anyway it seems i connected everything fine. You know what was the fault ? A simple button i salvaged from old computer power suply. I used this buttons on all my projects and never had any problems. This time though, for some strange reason this button made battery pack act strange, sometimes it showed 3V instead of 25V, sometimes it was jumping between 10 and 30V. I have no idea how this button could do it, since its a normal button that either connects or doesnt. All i know is that i disconected everything and only left the button and it wasnt working. Then i used another button and suddenly its working. Connected all the other things and its still working. Electronics never stop to amaze me. Would u care to speculate how this button could do what it did ?
 

audioguru

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If your "button" was the on-off switch then it was worn out or was overloaded.

All two-way speakers (woofer and tweeter) I have seen have the tweeter with a sealed rear so that the vibrations caused by the woofer do not cause the cone of the tweeter to move and damage it, or cause the woofer to perform poorly like the tweeter cone is just a big hole in the enclosure.

It looks like your "tweeter" is actually a little full-range speaker. What is its manufacturer's name and part number?
 
Yes, it was an on-off switch. It is funny because when i unplugged the batteries from amplifier, voltage was fine. But as soon as i plugged it in, voltage dropped. Anyway it was annoying cause i had to unglue things to open them and replace the button but something new learned which is ok, as its written in a book i am reading: there are no failures, just lessons.

That speaker is indeed full range speaker:

Visaton FRS 8M 30/50W
 

audioguru

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I can't remember. What is the manufacturer and part number of your woofer?
 
It doesnt have anything written on it. I took it from a cheap logitech woofer, its 9W, when i crank up the volume over 90% it starts clipping or stopping. For my next project i will find a powerful small woofer :)
 
Sadly i have no microphone that will record low frequencies well, in reality it actualy has good bass, with good i mean, it is 100x better then previous speaker but far from perfect, faaar. I will keep improving and learning as i go. This is so much fun. Yesterday my friend said, why dont u just replace batteries in my JBL extreme and we can have good bass speaker. And i said, you just dont understand. My motivation is not that i am to cheap to buy JBL extreme. My motivation is that i love making new stuff and learning new things. Today when i tested the speaker for the first time with all holes sealed, and saw those membranes moving out like crazy, i was like a little kid when he gets his favourite toy.

 

audioguru

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Your video shows the passive radiator vibrating a lot after each bass beat. Then it has very poor damping of its resonance.
 

audioguru

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The spec's for the woofer and passive radiator must match and the enclosure be sized for those spec's.
The full-range speaker should be in its own separate enclosure.
 
Specs and passive radiators will be hard to match, because the ones i have, there probably doesnt even exist specs for them. As for full range being in its own enclosure, do u mean just separate compartment, or seal it off completely, meaning closing it in a box so it has no contact with woofer. But wouldnt it make it not affect the passive radiator either ? Meaning it wont contribute to bass that passive radiators produce ?
 

audioguru

Well-Known Member
Most Helpful Member
You are making a speaker that has random spec's.

Since your two speakers have no crossover network then the full-range is acting like a mid-range and tweeter. Usually a mid-range speaker has its own enclosure that is sealed off completely inside the speaker box and usually a tweeter has a sealed rear.
If you want the woofer and the full-rasnge speaker to both drive the passive radiator then they should be replaced by one woofer that is a little larger than you have. Then add a tweeter and filters.

The crossover network does not need to be passive with a capacitor and inductor feeding the speakers. Instead it can be a capacitor or filter circuit at each of your amplifier channels.
 

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