DIY bluetooth speaker

[audioguru]

You might like the boomy peak of +6dB at about 150Hz or 180Hz. Just now I played 165Hz (musical E3) and my dog barked. My dog does not bark when I play real bass sounds.
83dB at 1W/1m is 77dB at 1W/2m. Then 8W/2m is only 86dB. 8W/4m is only 80dB which is not loud enough.
Which 5W amp did you find?

 

[SentinelAeon]

Well i will test it and see how it sounds. But considering how cheap i would sell them ...

This are the cheap amps, i got them for about 2 dollars a piece. Might sound expensive considering i got the mighty 2x50W for same price, but sadly i couldnt find a cheaper one:

**broken link removed**

 

[audioguru]

The datasheet for the Chinese LPA2171 amplifier used has a little bit of English on a graph.
It produces 5 Whats into 2 ohms at an extremely high distortion of 30%.
With a 5V supply and a 4 ohm speaker it begins clipping at only 2 Watts.
2W into the tiny speaker produces only 74dB (conversation level) at a distance of only 2m.

 

[SentinelAeon]

Here we go with the data. I hooked it up to 10W visaton FR 8 speaker and cranked it to maximum and it sounded ok to me, didnt notice distortion and loudness was quite good considering how small and cheap it is.

In my country, JBL is selling this useless little fart of a speaker for 30€. It is so quiet it cant be used anywhere outside if anyone is speaking. While this little amp is more than loud enough. And JBL can wipe their ass with this bass they seem to love so much. It is useless and i can build useful speaker for 10€.

The only reason i am doing anything to improve bass is other people. I dont give 2 shits about bass and was perfectly happy with my old speaker from 2 30W visatons with F3 of probably 150Hz. All those JBLs were useless around it because when i cranked it, u couldnt hear JBL and the JBL guy had to go away to a quiet spot so he could hear his mighty extreme PVC pipe. And i built the speaker for 30€.

Next time maybe i will tell what i think about people who get excited about a speaker that flashes lights in the rhytm of the music. And those who take their waterprof pvc pipe into the swimming pool.

 

[audioguru]

The 3.3" Visaton FRS-8 is 8 ohms and 82dB at 1W/1m. The little amplifier begins clipping with 2W into 4 ohms which would be maybe 1.1W into 8 ohms that ain't much loudness.

"Cranking it up to max" does not always produce full output power. Only if the gain is high enough for the source input level.

 

[SentinelAeon]

Actualy i tested it on 4 ohm visaton FR 8 and it sounded pleasant and loud. I also tested some other visaton speaker thats more low frequency and it actualy played full range very well and will be great for ultra cheap speaker.

I just realised i will soon have another problem on my hands. My new amplifiers will be 2x50W and i proven they can use over 100W on bassy song. I will use 6S batteries but they are not high amp batteries. This would in theory mean i would draw 4A from them. Now i have no problem draining 4A from them, even if they are rated for 3A. But there is a big problem. If they show 2500mAh at 1A discharge and 2000mAh at 2A ... at 4A they will reach that 2.8V to fast and BMS will disconect it all. So the only solution around this is to either use 12 batteries instead 6S2P or to buy high amperage batteries. Either option will drasticaly make the speaker more expensive.

This amp produces 2x50W when using 24V and 4 ohm speakers. So i might just get around that by using 8 ohm speaker and less voltage. This is the sheet of amp regarding voltage and impedance:


12V--8 ohms/12W+ 12W, 4 ohms, greater than 20W + 20W
15V--8 ohms/18W + 18W, 4 ohms/greater than 30 + 30W
19V--8 ohms/32W + 32W, 4 ohms/greater than 45 + 45W
24V--8 ohms/38W + 38W, 4 ohms/greater than 50 + 50W

 

[audioguru]

50W into a 4 ohm speaker is 14.1V RMS which is 39.9V p-p. Then a bridged amplifier can do it of it has a voltage loss of 4V p-p when the supply is 24V. Your 6 cells lithium battery voltage will be 25.2V when fully charged and drop as it is used. A TDA7492P cannot drive 4 ohm speakers but the original TDA7492 rev 5 can produce about 30W into 4 ohms per channel at fairly low distortion with a heatsink on top and a 25 supply.
Aren't you using a TDA7492 rev 5 amplifier IC with a heatsink on top?

NOBODY plays continuous tones. Music and speech (RAP) has dynamics that average at about 1/10th of full power when drum beats are at full power. Then your battery charge will last for a long time.

 

[SentinelAeon]

I am using more than 1 amp and i if i say 4 ohms 2x50W, take my word for it please. TDA7492 is history and doubt i will use it much anymore.

I will have to test it somehow.

 

[SentinelAeon]

Hmm, u said those full power bass that COULD potentialy take 4 amps only lasts for a very little time. BUT, at that time, when it actualy draws 4A from batteries, they could drop dangerously close to 2.8 or even to 2.8. Even if it happens for a very short time, BMS will cut them off. So i was wondering, how if i could store the power somewhere for those short bass periods. Like .... a big capacitor in parallel with batteries ? So batteries charge the capacitor and capacitor gives power to amp during drummy parts.

 

[audioguru]

My radio controlled model airplanes use small lightweight Li-PO batteries that have a capacity of only 280mAh. They deliver 6A many times in a 5 or 10 minute flight and the low battery warning does not trigger until the battery voltage drops to 3.5V (warning) and 3.2V (main motor shutdown) per cell.
Your 18650 cells are much larger but if they cannot produce 4A without dropping voltage then they have very poor quality. A large capacitor would help.

 

[SentinelAeon]

 

[audioguru]

Good, the speaker produces the sounds very well.
Which speaker is in it?

 

[SentinelAeon]

Its the one you heard distortions the last time when i played ultra bass song. That ultra bass song plays strange on all speakers, even my big hi-fi. The speaker in the video is dayton TCP115 8 ohm and some cheap tweeter from aliexpress capped at about 2800Hz.

 

[rjenkinsgb]

You may find this article & the video linked in it interesting?
A 3" sub claimed to work to 40 or 35 Hz.

"HexiBox" Tang Band W3-1876S Subwoofer Enclosure by HexiBase

Print & demo video: https://youtu.be/4_4tu4rAtgIThis is a subwoofer enclosure for a Tang Band W3-1876S mini subwoofer which you can purchase here: https://www.parts-express.com/tang-band-w3-1876s-3-mini-subwoofer--264-909Usable frequency response: 38Hz-200Hz.Power handling: 30WI printed mine...

www.thingiverse.com

 

[SentinelAeon]

I saw that before, its interesting, though not practical for me atm due to cost of 3d print, etc. But in the future it would be interesting to just order a box like this with the right speaker and voila, you have a speaker

I just wanted to say some news about comparison of my new calculated enclosure vs the old one that was pure luck or 1 tone bass or whatever. Anyway, i listened to them both one after another, and while the non calculated sounds OK and has bass, the new one is on a whole different dimension. The bass is just so much more powerful and deep. What is more ... for some reason this new one sounds a lot better to me. Which is amazing considering it uses a 4 dollar tweeter for highs while the old speaker uses visaton frs 8M, which is supposed to be a good bang for buck. Now im not gonna explore why this new one sounds better but i am just happy that it does. And while i realised if the speaker was tested in a studio for parameters, it would score very bad, it just feels awesome that its that easy and cheap to create something very decent. Ofcourse the real test will be how people respond. Afterall, that is the goal, if people think it sound pleasant and has good bass, its a pass. If not, back to the drawing board.

Tnx for all the help so far, i really appreciate it

 

[audioguru]

The Tang Band 3" woofer is expensive, has low 15W max allowed power and has VERY low 76dB sensitivity. It will provide "a solid bass kick" only if you wear one on each ear. "Useable" frequency response means nothing without saying how many decibels it varies.

The bass in the first song in the video was "one note" 55Hz and 58Hz. The little woofer had a long a delay before it produced each bass tone then it also had a long delay for it to stop each bass tone.

 

[SentinelAeon]

Just wanted to say i sold the speaker, the big black one that you commented on. I sold it for a fair price but still half the price remained as profit. Again it was amazing to see the buyer when that part of prodigy song came on with bass - like a little child. He needed a loud and bassy speaker with great battery life for his drinking parties. And i am confident that for that price, nothing he could buy in my country new, would come even close. I did show u what JBL sells at that price range - keychain rings. Also, he has 1 year complete guarante no matter what, and lifetime guarantee where he only pays for the part that gets damaged. I think he will be very happy

 

[SentinelAeon]

I ordered parts for new speakers and have a few questions:

1) https://www.soundimports.eu/en/grs-pz1165.html

Instead of ordering cheap aliexpress 15W tweeter for 4 euros (with which i am happy btw) i ordered this. PIezo horn words confuse me. Will this work as normal tweeter for my needs ?

2) this tweeter i ordered is 60/120W which is a lot more than i need since none of my amps puts out more than 50W per channel. But what about that tiny 15W tweeter ? If i put that on 1 channel and woofer on 1 channel. Wont that 50W per channel kill the tweeter ? I guess i should use resistor then, which means lost battery life ?

 

[audioguru]

If you connect a resistor in series with your little tweeter then it will produce less sound level, last longer and the battery life will be a little longer because less power is used. The series capacitor or crossover network must match the total impedance.

All audio speakers have a frequency response graph. This piezo crap (it says from days gone by) does not because its output level vs frequencies is all over the place. A piezo tweeter produces many peaks and nulls in its frequency response that sounds awful. The horn makes the sound directional but a normal dome tweeter has a smooth frequency response and spreads its sound around fairly well.
Here is the horrible frequency response of an ordinary piezo transducer without the horn:

 

[SentinelAeon]

Well that kind of sucks. Its so cheap, i was really happy. The problem is with the other cheap tweeter with which i am happy btw, that its rated only 15W. And if my amp produced 50W per channel which i suppose will fry the tweeter, even if i cap it at 2000Hz. And if i use resistor in series like you said, sure, its fine. But that means battery energy is used to produce heat. It would be great to see how much does tweeter actualy draw. Cause i know the woofer can draw that 50W. Maybe the tweeter actualy draws a lot less since its high tones and it will be only up to 15W ?