DIY bluetooth speaker

SentinelAeon said:

I thought about adding a resistor if necesary to make them match. The only problem is that i run on batteries and it seems a shame to waste battery life like this

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You're not wasting anything, as little power goes to the tweeter anyway - but try it first and see if it's to 'trebley'.

Hmm so from all that, would i be better off with a tweeter instead of full range visaton ? So that means dayton TCP115 on 1 channel, maybe with crossover that will cap it at 3000Hz and then a tiny tweeter with crossover for 3000-20000Hz ? The reason i wanted to include full range visaton is that i know it plays nice and its very very loud. Oh, and yes, i already have it and have to use it somewhere

If it's full range, you may as well just use it as such - you can get better with properly designed tweeters and crossovers, but you're looking for volume here, not quality.

I will test it and see how it sounds. I will also see how it acts at very high volume. As far as i remember, the visaton can start "farting" at high volume, i dont know if that is the poor amp i used to use or it simply cannot handle that much low frequencies. If that is the case, i might use 250uF or 200uF capacitor on it, to make sure it doesn't go to low

Of course the Visaton "full range" speaker is loud, because its cone is lightweight so it produces no bass. It also produces a louder shrill peak of sounds from 7kHz to 13kHz.
Like any full range speaker, its high frequencies are very directional, unlike a tweeter that spreads out high frequencies.

The low frequencies can be reduced below 425Hz with a series 47uF capacitor that must be non-polarized.

I got 2 tweeters but they dont have poles writen on them, how do i know which is + and which is - . Even the connectors are both the same

Sometimes the + connection on a tweeter has a red dot.
On a normal speaker the cone moves out with a 1.5V battery cell connected. I never tried it on a tweeter but I doubt you would see it move.

SentinelAeon said:

I got 2 tweeters but they dont have poles writen on them, how do i know which is + and which is - . Even the connectors are both the same

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It doesn't really matter, although I tend to like to connect them both the same way - where they are marked, it's relatively common to connect them the opposite way to the bass units, because of phase inversion in some crossovers.

But the reason for the polarity of speakers is to ensure bass units are connected the same way, as you get phase cancellation and lack of bass if they are opposite to each other. This only happens at low frequencies (but is very pronounced), so I doubt anyone could tell if the tweeters were connected the same phase or not.

I once had a right struggle at a gig, not only were the speakers either side of the stage out of phase, but individual speakers in each stack were out of phase!

In the end I nicked a PP3 out of an effects pedal, and checked the phase of each speaker and corrected them all.

Its really funny. I needed capacitors with no polarity for crossover, yet i only had 2 polar capacitors from old power suply units, motherboards, etc. And since shops are closed i had no way of getting them, i even tried on some forums if someone would sell, couldnt find anyone. And then i remembered something:

At my old job, outside we had a trashbin for electronic things. And everyday during lunch i would go there and pick out the things i thought were still usable or i might need them or can sell them. My coworkers said it doesn't suit my education level to pick the trashbin but i still couldnt watch usable gear go to waste. Well, funny thing is i earned like 110€ with that gear from trashbin and kept lots of usable things for me. 1 of the thing i picked from that trashbin was bag of 500 non polar 1uF 160V capacitors ! This will last me a lifetime of making speakers. Its amazing how some silly thing i did months ago actualy saved me now and i can make more speakers.

For my dayton woofer + tweeter, one on left channel, one on right channel and i used 7 of those caps in paralell to give me 7uF - and if u look at the graph of 8 ohm dayton, it starts going quiet somewhere between 2500 and 3000Hz and since tweeter is 8 ohm, this will do the trick. I already tested it and on max volume, the tweeter made my head hurt, its really loud and annoying. When played together with dayton it doesnt sound half bad.

One thing i have to ask. In this program, i enter volume and enter resonant frequency of box and it chooses the port diameter and length. Then if i change the port diameter it will change the length. BUT. If i change resonant frequency again, it will change port diameter to a bigger one again. So for my volume and resonant frequency, it decided that 3.20cm diameter is the best. But, i dont have anything 3.20cm in diameter. I do have nice thick plastic cups with 3cm diameter and wanna use that. Will that still be ok ? Obviously the length will be a bit shorter becuase diameter is smaller, program calculates it. I guess it bothers me that when i change resonant frequency it changes the diameter of port, kind of like saying that my diameter is wrong. Why cant it just adjust length for my chosenport diameter. So will 3cm diameter be ok ?

Tweeters are usually more efficient (louder) than woofers so they usually need a series resistor or adjustable variable resistor to match their level to the woofer.
Then if you find a 4 ohm resistor the capacitance for -3dB at 2.67kHz into 12 ohms is 5uF.

If 2 polarized electrolytic capacitors are connected back to back in series they equal one non-polarized capacitor that is half the value of one one them.

I think you need to calculate the volume of a port so that you can calculate any length or diameter.
Years ago I had speaker enclosure design software called Boxplot and a free demo for it is here: https://www.diamondcut.com/boxplot.htm

This program calculated it all for me.

I will test today how and if the port works considering this is quite small enclosure. Well the program said it would so we will see. If i cover the port hole, that should remove its effect right ? So i can compare port to no port. It says that non ported at my volume i will get F3 at 98Hz and ported is supposed to be F3 at 62Hz. I am guessing the difference should be easily heard, but i havent heard it yet so cant comment. All i can say is that even sealed only with hands and no port and some holes still existing, this thing bangs quite good. So if it trully will go down another almost 40Hz, well, that should be awesome.

I tested it and i am very disapointed. Not sure what i expected but certanly i wanted it to be better than my previous non calculated speaker. But it isnt. Its not all bad, it still produces decent bass and it is a LOT better than the first few speakers i made which were basicaly tweeters. It still packs a punch and head to head, volume at maximum, it will blow those, i wont mention which, company plastic speakers away. But yeah. The fact that when i cover the port, it makes almost no difference (when in reality it should change F3 from 60 to 100Hz ..) shows that i didnt do something right. It is an acomplishment that i got this bass from enclosure that is probably 2.5 - 3 times smaller than the enclosure of my previous speaker. So that is good. And the material is also dirt cheap. Also good. Also it got me thinking if its possible that the cheap amplifier is simply not sending enough bass into the speakers, i will test that theory with my new amplifier and we will see.

Infact i know i didnt do everything right. I calculated battery volume, battery volume and other things volume and removed them from the equation. But i didnt know i have to remove port volume also, it never crossed my mind, didnt see it mentioned in any video tutorials i saw. Is this the reason i dont get the best results ? I dont know, probably. Right now i am wondering if i can still fix that. Open up theside on which i have port, calculate its volume, put the new enclosure size into equation .. i will probably need to cut the port so it will be shorter due to lower volume.

Also, this PVC really cant handle the bass im putting into it, u can see it rattling madly and only stops when i squize the speaker enclosure. I would be happy of some pointers on what i did wrong and how to correct it.

Yes, the enclosure must be rigid so it does not expand and contract with the bass and cancel it.
The volume of the enclosure is larger if the port is on the outside of the enclosure. The port can be rectangular, the width of the enclosure and a narrow opening.

Thank you for your answer, maybe we can yet improve the speaker, though after a 2 hour nap, i dont think it plays bad, considering it is really really compact. Lets go together over the things that can be the reason the speaker isnt giving its best:

1) didnt count in the port volume. Will have to do that, put the numbers into QSpeaker and calculate again, probably cutting the port

2) i tried including the volume of all the wires and amplifier as best i could since they were already glued in when i found out i have to calculate that too. Do i have to subtract also the size of the speaker since its inside the enclosure ?

3) Do u have any good ideas how to solve the enclosure not being rigid ? I came up with few quick solutions. I could surgicly drill a few holes in it and put in wooden sticks that would hold apart the sides. Glue them with some epoxy and see if it helps. The other would be tocover the outside with something without making it to thick. Like paper covered in wooden glue + water mixture, that makes quite strong thing in few layers.

4)Is there a way u could double check my findings in a program, just to make sure the program is giving me the right numbers and to make sure it isnt a problem that i changed diameter from 3.20cm to 3cm.

5) U said i can make port any shape i want. So if its giving me port dimension in diameter and length, how would that translate to lets say rectangular ? Do i have to match the length, or do i only have to match the volume of port? Still dont know much bout this.

Of course the speaker reduces the volume (space) in the enclosure. Many speaker datasheets show how much volume (space) they have.
A port has a length and an internal diameter which makes its volume (space). If its diameter is too small then you hear the air huffing and puffing.
I would design a hifi speaker that would displease you since you want a boom-box.

Great speakers also have volume that i have to remove. Ok i just checked, volume occupied for this speaker is 0.02L. Which is almost nothing considering i have a 2.3L enclosure. Ok so 1 option would be to cut open the thing and cut the port but i was thinking like this, wouldnt it be easier if i just cut open the side without the port and just add some volume ? I can easily do that since i have this pvc pipe.


I calculated port to be 0.139L and speaker is 0.02L. So together this is 0.159L. So i just add this volume to my enclosure and i should be getting better results ?

Edit: btw, my port is made from small plastic cups made to store photo microfilm. Glued them together, covered them with 2 layers of duct tape, is that ok ?

I decided i will leave the speaker as it is and sell it for cheap and just learn from my mistakes in the next speaker. Since i got a bunch of things inside the speaker, like amp, wires, batteries, bms .. i think i will pack all that into a little box that will be easy to measure and then i can subtract the volume from the box.

edit: or, i might open it up and add the volume i need to add. I need to open it anyway to reinforce the enclosure so it doesnt vibrate so much.

I opened it up and added volume and it sounds better. It really packs a punch now, i cant belive i thought the daytons will be to quiet. Its really awesome. The problem with vibrating pvc remains though. Which is really a shame because otherwise the speaker is awesome. I will try to screw a wooden panel to 1 side of the speaker and see if it makes any difference.

I decided i will take the components out of the speaker and put it into wooden enclosure. This thin pvc simply cannot handle that power