DIY bluetooth speaker

Oh, just a funny question if you maybe know the reason. I have been painting wooden enclosure with brush. And i also have a paint in spray can. I kindof prefer the brush paint (the spray paint is unbelivably good at making even the smallest uneveness or tiny holes visible).

The problem is this. If i use spray paint, its fine and i can touch the paint in prolly 15 minutes and its dry. Well, the brush color i have says its dry in 1 hour and can be worked with in 10 hours. Well even after all night drying, everything sticks to this paint. Its unbelivable, its dry to the touch and not sticky. But i put it on my table and it will have million of particles stick to it and it will look ugly. With spray paint, nothing and i mean nothing sticks to wood. I even tried applying protective layer over the paint. And it indeed solves the problem of things sticking to it. Sadly, it makes the speaker to shiny and not look good. So what am i missing here ? Why is this happening ?

I doubt that your Killawatt device correctly averages the short duration peak power levels of music.
When you turn up the volume to maximum then the output is probably severely distorted. Distortion is high frequency harmonics that will quickly kill a tweeter. If you cannot hear the distortion then you should have a "clipping indicator circuit" like I have on the amplifier used on my large TV.

I almost had a heart attack today during my speaker testing. So i assembled everything and put on the front and back cover, but only using hot glue gun to temporarily hold it together so i can test it if it works before i seal it well. And i pressed both sides really well and kindof had the feeling that there werent many gaps. Anyway i tested it and there was no bass, literaly, no bass. But good thing was that in the sound, i noticed the similar sound i get when speaker isnt in an enclosure. So then i checked those gaps ... true, they are small but run all around the speaker on both sides which together makes for 1 giant gap.

Anyway i sealed all holes, put the speaker to dry, went to the post office being nervous the whole way. The reason is ... i have to finish the speaker till tomorrow cause buyer needs it tomorrow. And it would be a real bad thing to tell him that whops, my speaker magicaly has no bass.

Anyway once the sealant dried i tested it again and oh my, there is bass, i think it even sounds better then the last speaker. The buyer will be really happy, considering for that price, he can get a keychain speaker from JBL. This thing can be used outside and will cover a decent amount of space.

I will have to decide if i want to use tweeter in the future ... most songs are ok but certain parts sound a bit strange, maybe cause i know left channel is bass and right is highs ... i will test if its any different if i use woofer + full range capped at like 150 or 200Hz.

But i refuse to end this in a pesimistic tone, the speaker is great, plays well and that guy listens to techno mostly and likes the bass and he will have plenty of it. The only problem i seem to have now is paint. I cant seem to paint it in the way that it will look nice. This paint simply shows any uneveness so much and the shiny protective cover i add increases this. I think i will need to invest into a vibrating or orbital sander and next time really sand the surface, no other way. And maybe go to a paint forum and ask around. From DIY projects on youtube, i KNOW i can make it look good. I just need to figure out a way.

SentinelAeon said:

I will have to decide if i want to use tweeter in the future ... most songs are ok but certain parts sound a bit strange, maybe cause i know left channel is bass and right is highs ... i will test if its any different if i use woofer + full range capped at like 150 or 200Hz.

Click to expand...

Why did you do that?, it was always going to sound crap - are you just feeding it with mono?, because if you're feeding it with stereo it's going to sound even worse.

Well like i said, i am using a stereo amplifier and i wanted to use both channels, not to mention i dont have any coils to cap the woofer

SentinelAeon said:

Well like i said, i am using a stereo amplifier and i wanted to use both channels, not to mention i dont have any coils to cap the woofer

Click to expand...

You go on about wanting maximum power, but then you go and through away almost half of it, along with over half the music.

Why would you want a coil for the woofer?.

You're making the lowest quality unit you can (far lower than would be commercially acceptable), and for low quality units (or most PA/music systems) you simply feed everything to the woofer, and have a simple crossover to tap the tweeter off it.

For a start strap it as mono - join the L&R amplifier inputs together - this will at least mean you get all the audio, even if it's only mono.

Yes, the problem is i would need to use 2 sets of speakers to use the full power. As soon as i get the mono amplifier, i will do the crossover like that, woofer and tweeter connected together, with capacitor to protect the tweeter. Sadly i dont know how to mix stereo (left and right) into mono and feed it to speaker and tweeter

Nigel, his bridged class-D stereo amplifier module has a wireless stereo Bluetooth input made with tiny surface-mounted parts and even its volume control is not analog, it is a digital pushbutton. Therefore he cannot simply join the L&R into mono.
Maybe that is why most expensive portable little wireless speakers are stereo even though the speakers are so close together that you hear mono.

In the future with a separate stereo Bluetooth module and a mono amplifier he will be able to add a resistor from each Bluetooth output to mix the channels together into mono.

Yes, either that, or i will just buy a strong mono amplifier and it will be fine. Stereo when speakers are so close together sound pretty useless to me, but to each his own. Btw, for my latest project i used this amplifier, it does indeed have an analog button for volume. But its so small i wouldnt even know where to begin looking for things i need.

If you can figure out how to make mono from this amp, it would be great, like i said, i love this amp.

But apart from that amp, i also found cheap 60W mono amp:

**broken link removed**

And i ordered a 100W mono amp:

**broken link removed**

And i ordered this bluetooth receiver:


Sadly, the receiver is stereo, so i am hoping u can tell me how to mix that into mono and feed it to amplifier.

The "100W" mono amplifier has its stereo channels paralleled for more output current. Then with a 22V supply it produces 100 Watts into a 2 ohm speaker, 50W into a 4 ohm speaker or 27W into an 8 ohm speaker with 1% distortion.

Take two 4.7k resistors, one in series from each output channel of the Bluetooth module and join together their other ends for mono to feed the mono amplifier input.

The Bluetooth receiver and the mono amplifier do not have volume controls. Will to add one?

Thank you for the help with making mono, sounds easy enough !

As for volume control. Sure, i would prefer to have that, but its hard to find cheap amp with what i need. So what i ordered now, what u see in previous post, is only to test how this things work. If i am satisfied with the result, there is plenty of amps with speaker knob included, some even have bass knob. It all comes down to how the gear will perform. Its just problem that its more work for me, as it is i need 2-3 days to make 1 speaker and if i separate more components its extra soldering.

Btw 50W into 4 ohm speakers sound fine to me. The Dayton TCP115 is 40W speaker with 80W max. And part of that 50W will be used by tweeter. Or full range if i decide to go that way.

I dont even need to go that high. I used the old 2x25W amp with tcp115 8 ohm and tweeter and it was plenty loud. TCP115 4 ohm should be here in a few days so thats another 20 or so percent of extra loudness. When i go into 50w and up, battery wont last long at that volume.

Ok, the speaker finished. I think my friend will be very happy, hes into techno and music like that, so he wants the bass, which he will get. The song is wierd, i tried listening to it on my hi-fi and still it sounds strange lol, i just picked it because i wanted a bass song.


I do feel like this speaker is a tad less loud than my previous one. In my previous one, i set the resonant frequency high. Which resulted in few Hz higher F3, but in turn raised loudness at 70-100Hz. I will have to decide what i prefer. Considering this speaker is like 3L, i still think the bass is good. One thing that bothers me is that the first speaker i made from logitech woofer and 30W visaton is still louder and bass sound probably about the same. Bothers me because that thing was not calculated, i just put in 2 speakers and 2 passive membranes. It is probably the 1 note bass but i really cant say which i like better. This bass will go much lower when i test frequencies, but in the songs ...

ps: its amazing how bad mobile phone is at recording sound. This song sounds soo much cleaner in real life, so much louder and bass is muuuuch stronger. At first i was even unsure if i should record a video or not becuase it is not doing justice to the speaker.

ps2: what is amazing with this amp is ... it doesnt have any distortion i can hear even at maxximum loudness. Dont mind the video, im talking about real life. I cant detect it. While on other speakers before i used dayton + tweeter combination, i could hear baaad distortion at maxximum loudness. One thing this amp doesnt have is filter. That is why its so small and cheap i guess. Filter as i read is supposed to improve music quality. Though i really cant say i can hear the difference compared to that other more expensive 2x25W board i used that has a filter.

Modern class-D amplifiers do not need a filter because they use a very high frequency waveform that does not need filtering for excellent audio and high efficiency. A small filter helps prevent radio interference to other products. The AliExpress amplifiers have small inductors.

Any hifi amplifier produces distortion when the output level tries to exceed "clipping". The distortion is very low up to the clipping power level. The input level, amount of voltage gain and the power supply voltage determines the clipping level. If you are able to turn up your volume control to maximum and do not hear clipping distortion then either the "music" is acid rock that is already full of distortion or the input level, gain or supply voltage does not let the output level reach clipping level.

Your last song demo has very slow compression of the high frequencies at each beat that I do not like to hear. It might be caused by the original song or by You Tube. It is good to see that the power supply voltage does not drop for each bass beat.

How do you know the power suply voltage doesnt drop ? To be honest, i havent been looking at the voltage display and even so, its prolly to slow to notice fast drops. And on the video you cant see the display anyway, how did u notice that voltage is stable ? Its quite expected btw, this time i used 6 high amperage batteries, they can deal with 10-15A per battery so those puny 2 amps demanded of the whole pack is nothing for them )

Btw, here is the song:

Ok, so i sold the speaker to my friend and i have some good news and some bad news.

The good news is ... everyone was really impressed. We prolly spent 90% of the time talking bout it and we were there for hours. Some wanted to help me in the "business", some kept asking how i made them, if i can make them for themselves. When the friend first heard the bass, he had this look on his face as a child that gets a toy, it was amazing. Then there was a funny thing when someone said, i like that it sounds better than JBL. Which clearly isnt true lol, its far from truth, but the fact that he liked the sound was good to hear. It is the best speaker i made so far and cant wait to see how much i can improve it with the crossover etc.

The bad news ... well i dont know if its bad but it is to me. At one point when everyone was a bit drunk and talking a lot louder, being outside etc. One really drunk guy said, put it more loud. And i wanted to do it only to see it was already at 100%. Other ppl were like, its to loud, put it more quiet. But the guy that said put it more loud, well that remained with me. So after a while the friend went home with his new speaker so i put out my old non calculated wierd speaker. And yes, its louder. Bass is less deep but bongy and its more loud. So my next speaker has to be more loud. And that wont be easy to achive. Granted, this was a 8 ohm version of speaker and i calculated that 4 ohm version of dayton tcp115 will give me about 5dB more. But i dont know if that will be enough. I wanted to make it a lot louder than those JBL pipe type speakers. But its hard as i am already in the 50W area and improving this wattage will net me more battery drain. And finding better than tcp115 for this price will be hard. There are some, but less bass and more sensitivity. I will check them out.

One idea i got btw was ... well this visaton FRS 8 M are really really loud. A lot louder than that tiny tweeter i got. And louder than Dayton. So if i used them together, i would certanly need to use resistor with the visaton so it wouldnt be to loud compared to dayton. Soo, i was thinking. What if i get a kind of a switch, that will be able to switch between various resistors. Like the default mode would be visaton and dayton perfectly tuned together for best sound quality. But if the person ever needed loudness more than bass, u could just move the switch and get more "treble", meaning it would switch to resistor of lesser value and that would get you a really loud noise. How does that sound ?

You said that the volume control(?) was already at 100% then was the amplifier producing clipping distortion? If the amplifier was not clipping then the input level was too low or the amplifier's gain was too low for the amplifier to produce its maximum output power.
+5dB is about 3 times the power is noticeable but not a lot more. +10dB is 10 times the power and sounds twice as loud.

The FRS8 speaker is not a dome tweeter, instead it has a cone so its high frequencies are in a narrow beam. A dome tweeter spreads out its high frequencies better.
The TCP115 speaker is a mid-bass woofer and needs a tweeter.

Nope, there was no clipping or distortion to be heard, which is kind of amazing and very good if u ask me. And i tested the amp with killawatt and with 3 ohm speaker i actualy managed to get 65W per channel, with dayton i also got near 40W. Ofcourse i used that non realistic bassy song ... other music doesnt go that high ever. What im trying to say ... amp draws like 2W in idle when no music plays. And that peak power draw is how much amp draws. I am guessing most of the power goes into speakers.

As for visaton frs 8 ... i know its not a tweeter but i used this speaker a lot and its pleasant sounding, much more then my tweeter. If i ever make a new speaker for me, i will not use tweeter but visaton. It has a really pleasant sound and thats more important to me than its graph being flat line. But its also louder than the tweeter.

As for the db and power, i know it now, i know I just said i will get about 5dB just by changing to 4 ohm version (i triple checked the numbers and it comes to about 5dB). Its not much but its something. Then i could gain another 5dB by raising the resonant frequency. The F3 will be about 5Hz higher, but that will mean frequencies from 70 - 100Hz will be about 5dB louder.

Anyway, on some forum, they showed me another cheap speakers, i think from dayton. They said they have less bass than dayton but have higher sensitivity. I will have to test them to see if bass is still acceptable.

Btw, the speaker is not quiet by any means, its loud. But my old speaker is still louder, arbeit it has less bass. But i really like it when i come with friends to a place, crank the speakers and see people from all around coming near, dancing and listening to music. U cant do that with a not loud speaker

SentinelAeon said:

Btw, the speaker is not quiet by any means, its loud. But my old speaker is still louder, arbeit it has less bass. But i really like it when i come with friends to a place, crank the speakers and see people from all around coming near, dancing and listening to music. U cant do that with a not loud speaker

Click to expand...

You mess about so much, and most of it makes no sense, but didn't the old one use both channels of the amplifier? (with two bass units) and this one only uses one channel of the amplifer and one bass unit (and only half the music as well), so it's going to be a lot quieter. And of course you've halved the power only using one channel, then halved it again by using an 8 ohm speaker onstead of 4 ohm.

I am sorry i make no sense, sometimes its hard to put my fast thoughts into sentences that make sense. I will try to explain it more.

The speaker i made for my friend is using 2x50W amplifier. It has dayton tcp115 8 ohm on left channel and the tweeter on right channel. And u r right. Since tweeter uses like 5W and the dayton is 8 ohm so it uses less power (amplifier sheet says at 4 ohms its 50W per channel, at 8 ohms its 38W per channel). I already said i will fix that in my next speaker when i get the parts.

My old speaker, the speaker i still use .. it is using 2x25W amplifier. On left channel it uses a bass speaker i took out of ultra cheap logitech system (and on the back of it, it says 9W woofer - i dont know if that means amp is 9W or speaker is 9W. But in anycase it is working on 25W with no distortion even on max volume). And on right channel i use visaton FRS 8 M 8 ohm 30W. There is no crossover and there is no physical barrier between woofer and visaton (i know that will kill visaton in the long run. Didnt know that when i was building the speaker). Anyway, this speaker is louder but has less bass then the upper speaker. I belive that loudness comes from using visaton instead of tweeter.

I would like to test many setups to see what i like most. Like i said, i really like how visatons sound. My first speaker was 2x visaton frs 8M. It was really really loud but had almost no bass. It didnt bother me, but friends seem to like bass so i gave them bass. I am toying with the idea of using Dayton TCP115 4 ohm + visaton FRS 8M on mono amplifier, and do a crossover that will cap the visaton at either 200Hz or even as high as 2000Hz. The visaton distorts at max volume even on 2x25W amplifier. They said its cause of low frequencies, so if i cap at 200Hz, it shouldnt do that anymore.

I hope i made a little more sense this time. Btw, i talked to my dad today and we decided i will make him speakers for his pc. Since he only has audio outputs on motherboard and no amplifier, i decided i will make speakers using this amplifier and each speaker will have a woofer and either tweeter or full range. This way dad can use 3.5mm cable but also has the ability to connect through bluetooth. He only listens to classical music so i will have to go easy on the bass ... or do some research on what speakers classical music sounds best. I kindof cant imagine him listening to classical music on some boomy bassy speakers. Maybe i am wrong.