DIY bluetooth speaker

Way more complex than need be. I used a cheap 5$ BT from BIGBOX store and bridged some TDA2050s. Bought some 4cell battery packs and charge them individually and replace.

TDA2050 IC is obsolete and is not made anymore.

Thats true but decent copies can be had. Ive tested the 20 i bought and they work just fine. Its an easy circuit to build and they sound good for the price. Probably not so good with a battery because of the drain but a fuzz of effort then its fine. I used an 8ohm 10watt computer speaker and housing and it lights up the house with sound. I didnt bridge that one. I use multiple cells that i charge in a multi cell charger and made the case easy to open to remove and replace. it plays for around 10 hours at what i call "grilling and drinking" levels.

This thread uses a modern class-D stereo TDA7492P amplifier IC. With a 21V supply it produces 18W per channel at low distortion into 8 ohm speakers and its high efficiency allows a small battery.
The old TDA2050 was mono and with a 21V supply produced only 4W or 5W into an 8 ohm speaker. Nearly half of its output power was heat.

Yes the power is reduced but to provide 21v in a small battery isnt going to be a small battery i dont believe.
TDA205032W Hi-Fi AUDIO POWER AMPLIFIERHIGH OUTPUT POWER(50W MUSIC POWER IEC 268.3 RULES)HIGH OPERATING SUPPLY VOLTAGE (50V)SINGLE OR SPLIT SUPPLY OPERATIONSVERY LOW DISTORTIONSHORT CIRCUIT PROTECTION (OUT TOGND)THERMAL SHUTDOWNDESCRIPTIONThe TDA 2050 is a monolithic integrated circuit inPentawatt package, intended for use as an audioclass AB audio amplifier. Thanks to its high powercapability the TDA2050 is able to provide up to35W true rms power into 4 ohm load @ THD =10%, VS = ±18V, f = 1KHz and up to 32W into8ohm load @ THD = 10%, VS = ±22V, f = 1KHz.Moreover, the TDA 2050 delivers typically 50Wmusic power into 4 ohm load over 1 sec at VS=22.5V, f = 1KHz.The high power and very low harmonic and cross-over distortion (THD = 0.05% typ, @ VS = ±22V,PO = 0.1 to 15W, RL=8ohm, f = 100Hz to 15KHz)make the device most suitable for both HiFi andhigh class TV sets

4 or 5 watts?? Im by no means promoting any IC but i dont think ignoring any is fair. TS original issue was charging his batteries. Even with my neanderthal methods, it still provided clean sound and fairly decent battery life in a small package. possibly all TS needs is a battery and charger compliment?

Each little Lithium battery cell is 4.2V so only 5 of them makes 21V. Each cell is a little bigger than an AA battery cell and has a capacity of 3Ah.

That is a surprise to me. I didnt know something like that was available. Point still stands that surely there are available chargers for them on the market

Sorry, i didnt see there were 2 amps in the link. Anyway i have the 2x25W one without any buttons. Anyway, if it is to complex i will just leave it as it is and just put volume to lower on mobile phone. Yesterday we were outside, cranking the speaker to 100% and while u could hear some distortion, it certanly didnt seem to bother anyone, we had many beers and it was lots of fun. What does bother me is that speaker lasts a lot less time then it did before and i mean a LOT. So either some of the batteries suddenly became bad, or they became badly unbalanced. But i wont open the speaker until i have a backup unit ready.
What did bother me though is the bass. I will really have to look into the bass thing because this is just crazy. My speaker is not small. And yesterday a friend brought a speaker the size of mobile phone. It was so tiny. And it actualy had better bass then mine, even though i use 2 big speakers with 2 passive radiators. So a lot needs to be researched and tested to improve bass. But thats ok, thats why i do this, to test, learn and if in the end i actualy get decent bass, i will be very happy. If not, well, what can u do

Two little speakers in one enclosure produce stereo if you have the enclosure on your chest. At any distance then you hear mono, not stereo.
One larger speaker (a woofer) makes much better bass than two little speakers even when the enclosure sizes are the same.

Many good-sounding little speakers use one woofer and two little tweeters but since the tweeters are so close together then you do not hear their stereo, a single tweeter will sound the same.

I will experiment with different speakers and setups. I have lots of speakers from hi-fi systems and cant wait to dig into it and test it. Oh, and i dont really care much about stereo so i might try a setup with woofer on left channel and tweeter on right channel

Bass is usually mono so it is produced on both stereo channels, but not always.
But high frequencies from tweeters are often playing different things from each channel so one tweeter should have the stereo channels added into mono.

It is simple to convert stereo to mono, also for the woofer. A series resistor from the left channel signal source and another series resistor from the right channel are joined to make mono. Then the woofer plays all the low frequency sounds and the tweeter plays all the high frequency sounds.

Constructionk88 said:

That is a surprise to me. I didnt know something like that was available. Point still stands that surely there are available chargers for them on the market

Click to expand...

There are countless chargers for them, and for pretty well any number of cells you might care to use - and quite reasonably priced.

Could you show me a scheme of what you meant so woofer plays lows and tweeter plays high ?

A tweeter is fragile and low frequencies damage it. A woofer makes shrieking high frequencies so a two-way speaker has a tweeter, a woofer and a crossover network:

I have 2 question and i would like you to help me with them:

1) You can see my speaker. It is a lot larger then charge 4. U can see i have 2 passive radiators and 2x25W amp and 2x30W visaton speaker. Why the hell do i get no bass from this ? Speaker is totaly closed (no holes, on pic it is obviously opened, otherwise its closed). Also i did notice that those visatons dont move much. If you remember my previous speaker, the speaker cones moved a lot, this ones dont move that much. Its the same amp, same power. So, double the size of charge 4 and no bass ? What is going on ?

2) I have this 6S BMS and balancing board, i think its balancing at 45mA. Could someone please explain to me how this is working exactly, how does it balance? And also what will happen if my charger is 25V instead of 25.2V or 25.3V. I am ok with losing capacity, i am just wondering how it will affect balancing of the board:

**broken link removed**

If your speakers are real (not Chinese copies) Visaton 3" 30W speakers then their resonance is 120Hz and they will produce no bass.
The enclosure appears to be too small which increases the resonant frequency and cuts more of the bass.
The passive radiators with no part number appear ro be too small to do anything, or are they little tweeters with no part number?

Please explain what these things are:

Its not old sock, its foam that holds the speaker in place in case glue gave up xD I removed it now.

The big thing is visaton 30W and its supposed to be real, i ordered it from respectedshow in my country. The middle small things are passive radiators yes.

Ok so charge 4 uses different speakers ? Maybe i could order similar speakers? As for the size of the enclosure, it clearly doesnt matter when jbl charge 4 plays - its 2 times smaller then my speaker and has 100 times more bass.

The spec's for the JBL Charge 4 says that it has a single 50mm x 90mm transducer (2" x 3.5") and produces bass down to 60Hz. So it is mono and it mixes together left and right stereo channels. Its enclosure size is suitable for its single fairly small speaker and its two passive radiators are much larger than yours.

Since its 30W is used for only one speaker then it probably has bass boost.

The size of a speaker enclosure must be suitable for the speakers in it. It seems that your enclosure is too small for two of your speakers then it raises the resonant frequency from 120Hz without an enclosure to 240Hz or higher in your enclosure. Bass sound levels drop steeply below the resonant frequency.

Ok, thank you. I found an old logitech woofer and it is quite small. Im gonna play around with it, first test it in plastic speaker box i found at home with adding passive radiators. If all else fails, i will just use the original woofer box that has a port and just add another hole for another speaker and play woofer on left channel and full range on right speaker.

Ok now i have a question. That woofer is 4 ohm and it produces distortion. I read online that i could add 4 ohm resistance to make its impedance higher but that would mean a lot of battery power wasted as heat. So i was thinking. I have 4 ohm full range and 4 ohm woofer. If i add them in series that makes 8 ohm. But i remember someone saying adding different speakers in series is bad but i forgot what was the reasons. Lets say i dont care much about quality, only about loudness and bass. What will happen if i put different speakers in series, apart from the fact that they will be 8 ohm. Also another question. What if i put 2 same speakers in series to get 16 ohm. Will that mean that there will be less volume and less distortion when volume is at 100% ?

Today i tested 2 speakers from same hi-fi. One is 8 ohm and one is 16 ohm. They both had the same distortion. And i dont quite understand that. Shouldnt the 16 ohm speaker be a lot less loud, with higher impedance draw a lot less power then 8 ohm speaker ? I would really like to understand how this works.