# DIY bluetooth speaker

#### SentinelAeon

##### Member
But why is it that i have no problem when i short out the terminals without the button ? Or when using a different button ? Its like that some of the buttons are so old that they make the bms nuts. Btw, is there any procedure that can clean the buttons ? Like a drop of etanol, acetone or something that i can drip directly into a button without spending an hour opening it up.

#### audioguru

##### Well-Known Member
Your intermittent switches and BMS might be too old or were poorly designed.

#### rjenkinsgb

##### Well-Known Member
Like a drop of etanol, acetone or something that i can drip directly into a button without spending an hour opening it up.
Deoxit

Or any general lubricating switch cleaner (not just solvent), or even a drop of 3-in-1 oil / sewing machine oil, if you can get any in.

#### Nigel Goodwin

##### Super Moderator
Deoxit

Or any general lubricating switch cleaner (not just solvent), or even a drop of 3-in-1 oil / sewing machine oil, if you can get any in.

I would suggest WD40, always my choice for a switch cleaner going back decades.

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#### rjenkinsgb

##### Well-Known Member
I would suggest WD40
Great water repellent & excellent for pre-treating such as aluminium antennas to extend their life, but personally I do not like it on switchgear or any delicate items.

#### Nigel Goodwin

##### Super Moderator
Great water repellent & excellent for pre-treating such as aluminium antennas to extend their life, but personally I do not like it on switchgear or any delicate items.
We used it for decades at work, far more effective than the numerous 'switch cleaner' products we used previously.

#### SentinelAeon

##### Member
I have to think whether its worth doing. Those buttons are mighty nice, perfect for what i need (since they are of nice square shape and they cover the hole with "wings"). But spraying wd40 into each one sounds not so much fun. And oil + conductivity somehow dont mix to me. But i have to try it.

The funniest thing. I have 3 speakers of same dimension, same everything except different amplifier. And i test them by playing audio from tablet 24/7 in my workshop. Suddenly i find out that on 1 speaker, the tweeter is hissing in certain tv shows when there is silent and then speech and then silence. I thought alright, tweeter is bust or amp is bust. Then the same happens on a second speaker and on a third one. Smart as i am, i put all 3 speakers apart, make a mess, only to find out that whatever is wrong, is with my tablet. In tablets defence - i repaired it, brought it back from bricked status. But yeah, using that tv over internet program, its hissing. Pretty sure it hisses from internal speaker of the tablet also, but its less heard due to its speaker being small and weak.

Anyway in the end i wasted like 1 hour to put all 3 speakers back together, seal them, glue them, clean them. And im happy to report that on all 3 speakers i get a nice sound when playing from either of my mobile phones (tested that tv over internet program, youtube, music, etc.).

Since all 3 speakers are of completely identical build except amplifiers, i could do some simple tests on them. Well actualy just 1 test: figure out which one is the loudest. Its basicaly 2x50W noname (my favourite of the 3), 2x50W TPA3116 and 2x30W TPA3116. The reason 2x50W noname (or "domestic chip" as its makers call it ) is the favourite to me is ... the TPA3116 ones .. when i turn on the speaker at max volume ... but play no music and have no bluetooth connection, u can hear a hiss. When i connect bluetooth hiss is less heard but still it is heard. Once i play music everything seems to be ok. Now this happened on 2 types of amps with TPA3116 so far. Its not a big bother to me but some people might look at it and say they dont like their speaker hissing. Well, the no name 2x50W doesn't have any hissing.

This is the no name amp i am talking about. I wish you would test it audioguru and let me know what u think about it. Its super cheap:

#### audioguru

##### Well-Known Member
When a very cheap amplifier produces no hiss then it cuts high audio frequencies.
The extremely cheap Wuzhi amplifier has absolutely no audio specs and reviews for it are from guys who do not know anything about audio.
Sorry, I will never buy such a cheap amplifier.

#### SentinelAeon

##### Member
This guy seems to know what hes talking about and he likes another amplifier from them, the TPA3116 one that i dont quite like as much. I really wish you tested the amp just to give me your honest opinion. Because it sounds very pleasant to me. Granted i am not an audiophile nor advanced in this field but to have something cost 5$and sound pleasant and loud, its quite amazing to me. And i tested like 10+ cheap ~5$ amps and this one is by far the best to me. And as a bonus, it doesn't have that generic chinese woman chainsawing it in english when u try to connect with your phone.

#### audioguru

##### Well-Known Member
Did you notice that there are TWO Wuzhi amplifiers but they both come with the same "shell" that is labeled 5V-24V and PK-502L?
The AliExpress one has a pcb labelled Wuzhi and has a Wuzhi IC that has only 16 pins and has no metal top for a heatsink.

The Amazon one has an IC with many more pins and has a metal top for the heatsink it comes with to be attached. The IC is probably the Texas Instruments TPA3116.
The pcb is longer and has 4 inductors on it. The board is labelled 5-27V and PK-502C.

Maybe the original Wuzhi IC was not reliable with no cooling and has been replaced by the Texas Instruments IC with a heatsink.
Which one do you have?

#### Attachments

• Wuzhi amplifiers.png
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#### Nigel Goodwin

##### Super Moderator
This guy seems to know what hes talking about and he likes another amplifier from them, the TPA3116 one that i dont quite like as much. I really wish you tested the amp just to give me your honest opinion. Because it sounds very pleasant to me. Granted i am not an audiophile nor advanced in this field but to have something cost 5$and sound pleasant and loud, its quite amazing to me. And i tested like 10+ cheap ~5$ amps and this one is by far the best to me. And as a bonus, it doesn't have that generic chinese woman chainsawing it in english when u try to connect with your phone.

Decent sounding amps are fairly easy to make, either discrete or using IC's, it's speakers that make the HUGE difference.

#### audioguru

##### Well-Known Member
To be portable, the small woofer is 4" with a free air resonance at 53.8Hz.

#### SentinelAeon

##### Member
Did you notice that there are TWO Wuzhi amplifiers but they both come with the same "shell" that is labeled 5V-24V and PK-502L?
The AliExpress one has a pcb labelled Wuzhi and has a Wuzhi IC that has only 16 pins and has no metal top for a heatsink.

The Amazon one has an IC with many more pins and has a metal top for the heatsink it comes with to be attached. The IC is probably the Texas Instruments TPA3116.
The pcb is longer and has 4 inductors on it. The board is labelled 5-27V and PK-502C.

Maybe the original Wuzhi IC was not reliable with no cooling and has been replaced by the Texas Instruments IC with a heatsink.
Which one do you have?
Wuzhi has many types of similar looking amps. The one with no-name chip is the one i like, that one is called ZL-502L, thats the mini version. Then you have ZK-502L with the TPA3116 chip. This one is tiny bit louder and bassier. Then for both of them you have mini and normal version, then you also have 2x100W version and lately they seems to be a bunch of new designs, all having that nice black matte look. Anyway i wish there were some proper reviews because this things look decently built. And if you compare them to some of the amps for 5$that i tried .. i remember 1 amp was 2x3W or 2x6W and it had a terrible hiss, it was weak, it sounded terrible .. i remember when i first got that "wuzhi" amp for like 4$ i thought that there must have been some kind of mistake.

edit: forgot to mention difference between mini and standard is 3.5mm jack

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#### SentinelAeon

##### Member
I have a question. I keep having the issue with 1 speaker and different buttons. I tried many types of buttons, some new, some old, some work, some don't. I tried different amps. I will try a different battery pack + bms, just to see if maybe this one bms is to sensitive and cuts the power to soon.

I noticed that on all the amps, if i use a knife to connect two wires, i get a visible and "soundable" spark. Quite big. Now i am guessing this is the sudden current flow that fills the caps on the amp and also i am guessing this sudden surge is what triggers the "snowflake" bms. Now mind you, this amp should prolly be connected to power first and then turn on the knob, while in my usage, i have the knob turned to 100% all the time and connect the power via the button. Prolly not the best idea but i did that with all my speakers and didnt have problem till now.

My question: is there a way to somehow limit this spark - to somehow fill the amp calacitors slowly over a second or two. Obviously i dont want this solution, whatever it is, to limit my speakers SPL and battery life.

#### audioguru

##### Well-Known Member
It could be the BMS that detects a massive current surge when the supply capacitor in the amplifier suddenly charges. But it also could be the battery that cannot supply such a high current and drops its voltage during the current surge then the BMS correctly detects low voltage and shuts down.

Try using a battery/BMS with a higher mAh or C rating. Some Li-PO batteries sold in local hobby stores have a 300mAh to 2000mAh rating and a C rating of 70 which means a max allowed current of 21A to 140A.

#### SentinelAeon

##### Member
I am using 10A batteries. And the problem is i can only detect this in 1 speaker. So for now, i will first try replacing a BMS (to rule out the faulty BMS), then i will try a different battery pack. But it is really strange. Didnt have this problem before and im using the same type of amp and bms, and same kind of button (i even tried a new button i bought and this kind never gave me problems before). I will report back

#### SentinelAeon

##### Member
Just to make sure this isnt causing any problems. On the left is the original connection scheme - how it should be connected. Notice the yellow wire being exactly in the middle between + and - pole. I connected it directly to - pole. I figured it doesn't make a difference. Am i being wrong ?

#### Attachments

• connection.png
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#### audioguru

##### Well-Known Member
The wiring is fine if the wires are fairly short and have no voltage loss with a current of 10A.
Is the battery name-brand (please post its spec sheet) and is it fully charged at 12.6V?

#### SentinelAeon

##### Member
I only posted part of the scheme - its a 6S one, 25.6V. I tested battery capacity at 2A discharge and they give me about 1500mAh with the cutoff voltage at 2.4V. Like i said, i built a bunch of speakers with same parts - only this certain speaker is giving me problems. So im guessing its either faulty bms or faulty batteries. Tomorrow i plan to get to the bottom of this. Cause now i dont even care about the speaker working anymore, i just wanna find out who the culprit is !

#### Attachments

• 20220117_020447.jpg
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#### audioguru

##### Well-Known Member
I think your batteries are old, damaged from being discharged to less than 3.0V each or fake. The 22P is probably a 2200mAh rating.
I put some old Panasonic 18650 cells in a portable vacuum cleaner and their power is fairly low and for a short duration.

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