# DIY bluetooth speaker

#### SentinelAeon

We will fix that in the next speaker, i am learning as i go. Its kind of funny cause we are like a student and his mentor. And i, as student, am happy of my progress and you aren't easily pleased. But look at this video, this actualy made me smile. Obviously there is a million things wrong with it but i made it for under 30$, 12.000 mAh battery, some bass, capacity display, etc. Please, be at least a little like, hmm, well ok, it plays music #### audioguru ##### Well-Known Member Most Helpful Member You can go to an online frequency response test and record it. It starts at 20Hz and slowly sweeps up to 20kHz. It might show that your speaker makes one loud tone at about 200Hz. It is called one note bass. I looked up "Bass reflex speaker with passive radiator" in Google and copied some important parts but not enough to scare you: #### Attachments • 131.5 KB Views: 2 • 155 KB Views: 2 • 177.7 KB Views: 3 • 28.8 KB Views: 2 • 103.4 KB Views: 1 #### rjenkinsgb ##### Well-Known Member Most Helpful Member For a speaker cabinet alone, packing the enclosure with a fibre material to reduce internal air resonances and provide some damping can improve performance, but you cannot really have that too close to an active amp module or the batteries as it would also trap heat... One of the common types is called BAF Wadding - it's a bit like a denser version of the filling in a bed quilt or quilted jacket: You would need a divider between the electronics and the speaker section to use that safely. I don't know how much effect it would have with such a small enclosure though; it would probably need quite a dense packing to have any effect, if it did anything at all?? It could, just possibly, reduce the "bounciness" of the passive radiators a bit though, whilst not affecting true low frequencies. Or it may have absolutely no effect... #### SentinelAeon ##### Member I will test frequencies when i have time with this app, it will be interesting to see if there is anything below 100Hz. It sure sounds deep when i play it, but the true test will be today when we go out with friends. Like i said, with people talking and beers, we really arent that much about audio quality. We want loud and they want bass. We will see #### SentinelAeon ##### Member I have some good news and some bad news. I didnt screw in the full range speaker, only glued it with epoxy. Which worked fine till now. But this speaker has bass so strong that it kept moving and falling off the bench. And well, this is a result. Since there is no option to completely take apart the speaker, i will have to use some tricks to screw it. #### SentinelAeon ##### Member The good news though is that people really liked the speaker. They liked the bass, they loved the looks and the way it plays they also liked it. I recorded a video just so you will understand where i use the speaker. So maybe you will understand why i am not so concerned with audio quality, or frequency response, or dampening and such. Its just a bunch of people on friday evening, having drinks, talking, singing, u can even hear my friend playing a strange instrument he bought. Next to me was my friend with his 300$ sony speaker. And my speaker cost me under 30$. And obviously his speaker is superior to mine in every way but i can tell you, we had just as much fun with my speaker as we did with his. Here is the video: #### audioguru ##### Well-Known Member Most Helpful Member My local shopping mall installed large expensive ceiling speakers that sound fantastic. Because of this the mall has more customers and the stores sell more stuff. Whenever I go into a Costco store I turn on the good-sounding tiny Bose very expensive demo portable speaker. They sell lots of them. #### SentinelAeon ##### Member I repaired the speaker, i used screws to screw full range speaker and it should be ok now. While doing it i accidently unhooked 1 wire from charging port and only found it out when i already sealed the speaker. Sadly had to put things apart again and fix it. I hope now things will work ok. I did learn lots of new things building this speaker. I really have to plan things better in ahead, test them before i put speaker together, etc. I have trouble finding the right material to make speakers. The only plastic i found in store is PVC which costs a lot. I would like to find plastic of same type as speakers are made of. Then i could just use dremel to cut pieces and glue it together. #### SentinelAeon ##### Member I have a question. I am trying to make the speaker air tight. I push in the speakers and the passive radiators go out, but then they slowly go back in, which means there are still tiny holes somewhere. Is it possible that air goes through the speakers themselves since they are from cardboard ? Another question. I have seen some ppl gluing coins to passive radiators. Is it worth trying if this changes the bass itself ? #### audioguru ##### Well-Known Member Most Helpful Member When you push the speaker and the passive radiators go out then slowly go back it means you have a very small air leak that does not matter since it will not affect sounds. The resonance of the passive radiator must match the resonance of the speaker so usually they are the same size and same construction. If the passive radiator has a weight that is less than the speaker then adding some weight will help match them. But adding weight might make the matching and resulting bass become worse. Try it. #### SentinelAeon ##### Member Well i can tell u right away passive radiators are a lot lighter then speakers, that is if i take the speaker as a whole, metal frame, magnet, etc. Well, i will play around with it and see what happens #### audioguru ##### Well-Known Member Most Helpful Member It is the moving parts of a speaker or a passive radiator that produce sounds, not the magnet or the metal frame. The speaker and passive radiator must have the same acoustical spec's. #### SentinelAeon ##### Member Could u help me find some nice speaker for my next project ? Something between 70-20.000Hz of small factor and lots of allowed movement in and out. Something similar to the speaker in charge 4, its a very small speaker that still produces bass. #### rjenkinsgb ##### Well-Known Member Most Helpful Member These may possibly be ok for bass, but you need a crossover and midrange/ fullrange speaker (or mid and tweeter) to get the full frequency range. You can get them on ebay and amazon. #### SentinelAeon ##### Member I ordered not 1, but 4 of them !! Why ? Cause then shipping is free. Amazon wanted 20 bucks of shipping so i found some strange website and ordered 4 of them, 10 dollars a piece + 10% discount, so i got 4 of those little buggars for 38$, shipping included !! I used this page and this item:

I cant wait to get their hands on them to test them. You said crossover. What if instead of that i just put woofer on left speaker and full range on right ? I know its not the right way but i really dont mind not having stereo and it seems soo much easier.

#### audioguru

##### Well-Known Member
Most Helpful Member
The tiny Drok speaker has no detailed T+S audio spec's. The missing spec's are needed to plan the enclosure size.

What is "Effective frequency range"? Is 90Hz at -30dB and you can barely hear it? Or is 90Hz at +12dB and sounds like a bongo drum?
For how many milli-seconds can it survive 25W?

Drok's sales sheet is exactly the same as Amazon's sales sheet.
Drok (website) says they are closed during the Chinese Spring Festival and have no address, just Amazon so I think they are simply an Amazon Seller, not a manufacturer.

Two resistors at the input of each amplifier mix the left and right stereo channels into mono so that you do not miss hearing half the sounds.

#### SentinelAeon

##### Member
Can you draw a scheme with resistors only ? And how big resistors i need ? I will just test the drok thingy and see

#### audioguru

##### Well-Known Member
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Connect together the inputs of both amplifiers. Connect together one end of two 10k-1/4W resistors and connect the joint to the inputs the amplifiers.
Connect the other end of one resistor to the Left channel audio source and connect the other end of the other resistor to the Right channel audio source.

The weird supplier (also with no address) you found mentions 4 ohm speakers and mentions 8 ohm speakers in their ad. Which ones will you get??

#### SentinelAeon

##### Member
U know i cant do that because my bluetooth IS on my amplifier board. And even if i did, i have no idea what ur talking about without a scheme. It would be really great if u helped me pick the speakers. Everything i show u say is bad ok, but how about u give me a link to good speakers ? Surely u know more about them than me and it would make it much easier on me.

#### audioguru

##### Well-Known Member
Most Helpful Member
You are stuck with the Chinese stereo no volume controls and no mono Bluetooth/amplifier module.
Parts Express has many good speakers but you want cheap no-name-brand Chinese ones that have no spec's.

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