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DIY bluetooth speaker

audioguru

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Do not allow the amplifier to be turned up too high causing extra high frequency clipping distortion harmonics that will kill the new tweeter.
Also, you might need more than a simple series capacitor to cut low frequencies from damaging the new tweeter.
 

audioguru

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A tweeter is very delicate. It usually plays very short duration bursts of high frequencies. Distortion is extra high frequency harmonics for much longer durations.
Low frequencies and DC will also destroy a tweeter.
 

audioguru

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I guess to play frequencies as high as 20kHz at loud levels, the voice coil in a tweeter must be lightweight which needs very thin wire that burns out easily.
 
Just wanted to say, my friend came pick up his speaker i made for him today. I am really sorry i didnt have a hidden camera because .. well, he is a big guy with beard. And when i put the speaker to max volume playing Prodigy - smack my ***** up and when the first boom hit, he was like a little child. He kept laughing and saying, wtf, r u serious ? You cant be. Later he said, how the hell do you produce so much loudness from such a small box. Well, i cant take the credit for the wonderful dayton TCP115 but my heart warmed when i saw his reaction. I sold the speaker so cheap that i prolly earned a meal or 2 in a restaurant with it, but money is not my motivator, making people happy is. And for that amount of money he would get exactly nothing in stores. I obviously have a loooong way before i could say i actualy made awesome speaker, like fixing the stereo issue, adding more functionality, etc. But for what my friend needs the speaker, it is perfect. He even said that he loves the quality of the music. Well, i wouldn't go so far as the sole cost of parts simply cannot produce high quality sound. But most people are used to crappy pc or car speakers and even my speaker is so much better than that. I know its not nice to brag but i am really proud about making people happy. JBL extreme 2 in my country costs about 4x more than my speaker. And my speaker is so much louder and bassier that u can barely hear the JBL extreme 2. So thx for all the help so far audioguru and stay around, i will need a lot more help from you in the future :))
 
My little Bose BlueTooth speaker has an incredible amount of bass. In fact, too much. A lot of engineering went into it to produce something many people think makes good audio.
 

audioguru

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I heard the good sound of a very expensive Bose little Bluetooth speaker. its lest and right speakers are so close together that it did not produce a stereo effect.
Cheap Bose speakers have "one note bass" due to a strong resonance that is not properly damped.
 

gophert

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My little Bose BlueTooth speaker has an incredible amount of bass. In fact, too much. A lot of engineering went into it to produce something many people think makes good audio.
I think audioguru is right. Bose doesn't spend a lot of engineering money to make great audio, they spend a lot of engineering development money trying to make moderate quality sound systems at the lowest possible cost so they can make the highest profit. Talk to their materials engineers how they manage to make speaker cabinets stiff with the cheapest possible materials and manufacturing methods.
 
I think audioguru is right. Bose doesn't spend a lot of engineering money to make great audio, they spend a lot of engineering development money trying to make moderate quality sound systems at the lowest possible cost so they can make the highest profit. Talk to their materials engineers how they manage to make speaker cabinets stiff with the cheapest possible materials and manufacturing methods.
My little speaker produces a huge amount of deep bass with such little cone(s). That's engineering.
 
To add my part, JBL charge 4 ... see, i am not impressed with JBL extreme 2, not even a little. But JBL charge 4 ... i cant tell you how amazed i am at this speaker, loud, good bass and tiny size. What i dont understand is ... as far as i understand, passive radiators, much like port, the enclosure size still matters, meaning bigger enclosure, better bass. And when you open the JBL charge 4 ... you can see that it basicaly has no free air inside, its all either plastic or electronic parts. It probably has free air the size of small coffe cup inside. So how the hell do they get such bass from it ? Yes, i know, special speaker made for this enclosure and special tuned passive radiators, obviously, i am perfectly aware of that. But there is still physics and so far what i read, no enclosure space, no bass. How do they do it ??
 

rjenkinsgb

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I suspect it's getting in to the realm of fluidics and how pressure waves propagate.

eg. Possibly due to a small speaker with a very long travel, which means the cone moves faster for a given frequency & audio level than a large speaker with a short travel.
That may make the pressure waves / audio more directional, so they get better separation between the front and rear pressure waves from the speaker diaphragm, rather than them cancelling out by airflow "wrapping round" the driven unit.

There are some odd effects with speakers & restriction.
Try connecting a small bare speaker to an amp and listen to it while held in mid air; then hold it face down, half over the edge of a desk or bench.

There is still a very short path around the front of the speaker - but the frequency response & bass are dramatically different, despite nothing being sealed or volume-related.
 
I would love to at least try to make some small speaker. Obviously i will not be looking for ultra low bass, i think even F3 of 80Hz would be great and if i somehow managed to get the "1 bass note" thing that would be great. I did some reading on passive membranes and while its a science of itself to make it perfect, i saw many people really did very simple thing, only took into the equation the surface of the membrane and its weight and then added weight slowly to make the resonant frequency lower. I will try it just for the fun of it and i wont be disapointed if the result is very bad, its all about trying new things, learning as i go :) I found this interesting site, i wonder what the result would be using this equations:

 
I received the cheap chinese bluetooth receiver board and can now finaly make a first proper mono system. There are 2 problems though:

1) the chinese woman trying to speak english when ur connecting, it's just, i dont know what they were thinking. It should be different beeps telling you whether its connected or not. It will really not look good on my speakers. But on the positive side, it will sure make people laugh when they hear it so thats good, i like making people smile.

2) there is a 3.5mm jack on the receiver like i wanted but it turnes out its an output rather than input like i wanted. I wanted people to plug their computer 3.5mm jack into this receiver and play music from their computer. Instead, this 3.5mm jack is meant to connect to the amplifier. So my question is (and i know this might sound dumb), can i simply take a female 3.5mm jack and solder the wires directly to amplifier input, the same way i will be connecting receiver to the amplifier ? So then the person can decide either to use the bluetooth or to connect 3.5mm jack directly to the amplifier and can therefor use the computer to listen to music ?
 

audioguru

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I am still laughing at your cheap Chinese woman trying to speaky zee English.
A bluetooth receiver does not have an audio input. Its input is bluetooth.

With a jack on the amplifier input then the amplifier can play whatever is plugged in. The output of the Bluetooth receiver or the headphones or line level output from the computer.
 
Alright, what if i dont have an amplifier with 3.5mm jack ? Can i just solder wires from 3.5mm jack on the same pins that i will use to make connection between receiver and amplifier ?

As for the chinese woman, you can hear it at 4:35. Cudos to her for speaking english, its so much different from Chinese. But couldn't they just ask some american woman to send them a mp3 of her saying this things and they send her an aliexpress cupon or something ? Other than that, i read some reviews and they said audio quality is GOOD, whatever the **** that means. I will test it and if it doesn't show any serious problems like hissing and stuff, i will be happy.

 
Someone on forum seemed to have found a simple solution so i could have mono and still keep my WUZHI which i love so much. He said there are 2 options:

1) Simply solder the 2 signal pins together on the pot and test if you get much distortion at higher levels (image in the attachment)

option 1.JPG

2) remove the knob and just do a stereo mixing as i would with separate receiver and amplifier board. I dont really need the knob anyway, never used it. I made a scheme of stereo to mono and would like you to comment if i did it right ? ()

stereo_to_mono.png
 

audioguru

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You do not need to add resistors since the volume controls already have the resistors in them. Connect the volume control sliders together to make mono and turn down the volume controls maybe 10% from maximum so that the Bluetooth channel outputs are not shorted to each other.
 
The problem is sooner or later someone will turn the knob all the way and short it. Can you verify that the second scheme image is correct ?
 

audioguru

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It might be impossible to cut traces on the Bluetooth receiver and add the resistors so I guess you must add a little circuit board with the added resistors, then the little circuit board is connected between the Bluetooth receiver outputs and the amplifier inputs.
 

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