DIY bluetooth speaker

[rjenkinsgb]

Just out of curiosity I captured the text off the back of the speaker in the youtube link; it does appear to be the same as your Aliexpress one:

 

[SentinelAeon]

My fault, i didnt put it clearly. I have more than 1 amp. Right now i was using TDA7492P or at least a cheap copy of it. And i got good results. But i was wondering about that stopping power. And its strange, that 24V 4A is used to power things like laptops. And it should be waaay over the top enough for 2x25W amp. As for capacitor, i was thinking using it in parallel between batteries/DC power and amplifier, i have seen the capacitor used that way to suply a steady current to amp. I added a picture of what i mean.

As for TPA3116 D2 ... i ordered it but havent got it yet. I only mentioned it because the guy in the review seems to know what hes doing and he ordered it of ebay/aliexpress and said good things about it.

 

[rjenkinsgb]

HEY! The datasheet shows a stereo (2 channels) amplifier but the video shows a mono (1 channel) amplifier so something is VERY fishy. Maybe the Chinese amplifier has weak wiring so they paralleled the 2 channels. Doesn't your amplifier have 2 channels?

That is a pin selectable option on the TPA3116 - it can run both output stages in parallel for higher power mono operation.

I've got some of the boards as in the video, they do appear to have genuine Texas ICs - they are some of the batch I pulled the heatsinks off because they were on rubber...

 

[SentinelAeon]

Just out of curiosity I captured the text off the back of the speaker in the youtube link; it does appear to be the same as your Aliexpress one:

View attachment 124005

Yes, i noticed that too. Its funny that typing those numbers into google showed me that youtube link with samsung speakers, even though nowhere in the video name are those numbers. Impressive. But it doesnt help me as i still cant find any data on the speakers, like sensitivity, frequency response, etc. I do like the name samsung though, makes me feel like its not a complete cheap thing.

 

[SentinelAeon]

It looks a bit like this speaker:

Order the Peerless SLS-85S25CP04-04 woofer

Buy the SLS-85S25CP04-04 at SoundImports ✓ Same day shipping ✓ Low shipping rates

www.soundimports.eu

 

[audioguru]

1) We talked about the TDA7492Pm amp IC before. It cannot use a heatrsink on its top so it has a low output power so that it does not overheat and shut down (your problem?) and cannot drive 4 ohm speakers.

2) The AliExpress speaker is the same as the Tympany speaker from Parts-Express? Its datasheet shows that when it is in a HUGE enclosure it produces less output below 150Hz so no bass. Your small enclosure will cause boomy sound at 180Hz to 200Hz then less at lower frequencies (no bass).

Samsung probably buys the speaker from the same place as the other places buy from.

I liked seeing the speaker in the slow motion. ANY speaker can do that but not sound good.

 

[SentinelAeon]

Order Dayton Audio PC83-8 Full-range Woofer

Buy the PC83-8 online at SoundImports ✓ Same day shipping ✓ Low shipping rates

www.soundimports.eu

Those speakers seem mighty fine for their price, whats the catch ? Almost 87dB at 8 ohms and going 80-20.000. 13€. What am i midding ?

 

[audioguru]

Look at the spec's of the tiny 3.5" speaker:

 

[audioguru]

Order Dayton Audio PC83-8 Full-range Woofer

Buy the PC83-8 online at SoundImports ✓ Same day shipping ✓ Low shipping rates

www.soundimports.eu

Those speakers seem mighty fine for their price, whats the catch ? Almost 87dB at 8 ohms and going 80-20.000. 13€. What am i midding ?

The datasheet shows the loudness dropping below 100Hz when it is in a huge enclosure. We can hear sounds down to 20Hz and many bookshelf speakers play good down to 50Hz (one octave lower than the little speaker).

 

[SentinelAeon]

Ok i checked it yeah. Its 54Hz at 0.16ft^3 vented. I still think i will order the little speaker just for the sake of hearing it play. Ok so instead of the actual frequency response, i should instead be looking at F3 value and ofcourse sensitivity ?

 

[audioguru]

F3 is when its output is at -3dB which is half the power and sounds a little less loud.

 

[SentinelAeon]

Yay, i am learning new things ) Well, i will keep looking for the perfect speaker but still try to do some nice speakers with the parts i got. I might just aswel go for a stronger amplifier and put those daytons i got to use. I will keep posting new things, tomorrow i hope i will put those speakers i just got to use

 

[SentinelAeon]

I would like to create a test speaker, using 1 of those new speakers i got and also a tweeter i got. I would like to put 1 speaker on left channel and 1 speaker on right channel. I dont have any coils and those new speakers seem to handle high frequencies just fine. Would it be ok if i just use capacitor for the tweeter ? And also, how low can i go on a tweeter ? I was thinking something like 1000Hz, which at 8 ohms would mean 20 uF. Would that be ok ?

 

[audioguru]

A tweeter is fragile and is destroyed if it is fed low frequencies. A woofer has "cone breakup" at mid-high frequencies. Therefore a crossover circuit is needed.
Many tweeters use a 3kHz crossover frequency. Use a 6.8uF capacitor for your 8 ohm tweeter if you can find one. It must be non-polar like a film type, but there are some non-polar electrolytic capacitors available.Since you will have two sources producing the same mid-high frequencies then their distance from each other will cause additions and cancellations of some frequencies.

 

[SentinelAeon]

Hmmmm. Can i ask why i need non-polar ? All i have is bipolar ones, so i will need to order more. As for woofer, i dont want its cone to break. So i need coil for it also. As for canceling their frequencies, i will leave that alone for now.

 

[audioguru]

Audio is AC, an ordinary electrolytic capacitor works only with DC, not AC. It explodes with AC. A non-polar electrolytic capacitor is marked "NP" with no minus bar marking.
Cone breakup of a woofer is not a physical breakup, it is a disturbance of the frequency response.

 

[SentinelAeon]

Oh, ok. i will get some unipolar capacitors then, they are very cheap anyway. Cone breakup i will ignore for now and deal later.
I made a new tiny speaker from some leftover speaker i had. I only used 1 speaker and it is very loud. It plays quite decent. But as soon as i close the sides, it sounds kinda strange. There is more bass but also i think playing frequency shifts. I have perfect pitch so i can say that for instance it changes from playing note C into playing C major. Also its kind of echoe-i, i mean u can hear that its in a pvc pipe. Is this normal, can i make it sound better ? This pvc pipe is perfect because it saves me so much work as opposed to a round pipe. I added an image so u will know what i work with. I might add that i didnt notice that when i used the round gray pipe, which is alsopart pvc but looks more like ordinary plastic. U can tell also when u cut it with rotary tool - the gray pipe, when cutting, things were flying at high speed into my face. While at this pipe, there is only tiny dust.

 

[SentinelAeon]

Another picture

 

[audioguru]

"Uni" means "one" that you do not want. Ordinary electrolytic capacitors are uni-polar. You want non-polar (NP) capacitors.
Your speaker enclosure looks to be too small so when the sides are closed then the speaker resonance frequency and resonance amplitude are increased causing a higher pitched "boomy" resonance. Echoes can be reduced by using an enclosure with a certain ratio of dimensions, or by using a sound-absorbent stuffing.

It is wonderful to hear that you have "perfect pitch". When I was playing a trombone in my high-school band I worked on it and almost got it. My grandfather was an orchestra conductor. Google says 1 in 10,000 people have perfect pitch, but it can be learnt by some people. They say that Mozart had perfect pitch.
Just now I thought of musical A and Audacity played the same pitch so I got perfect pitch now.

 

[gophert]

Google says 1 in 10,000 people have perfect pitch

it seems I've met two dozen people in my lifetime who have claimed to have perfect pitch. I may have met a quarter million people in my life to keep the statistic true - or, those two dozen people may have varying definitions of "perfect".