Ok so I am going to be building my first DIY bluetooth speaker. I may be thinking about this all wrong, but here is what I have planned.

I picked out a bluetooth amp board that is 2x30 watts, and is rated from 4-8 ohms. I picked a pair of drivers that are 4" full range 30watts RMS 8 ohms.
I am thinking I want to add 2 tweeters into the mix, and wire them in parallel with the main drivers. I am not sure which tweeters, but they will be 8 ohms
as well. This should if I understand correctly make each set of speaker 4 ohms with the tweeters.

The main questions I have are this. What CAP do I need to wire to the tweeters, and will the CAP change the impedance of the speakers wired in parallel?

The last questions are this. Do I even need tweeters, or will they be a waste of time and money. I am making the speaker for my wife so she can listen to
music in the kitchen while she is making me sammiches. It's going to be her christmas present. Never wired anything like that up before. Most of it is plug and
play, but I get confused when it comes to numbers, and math with all this audio stuff. Below is a list of components I plan on using for the build.  

I NEED HALP!!!!

Bluetooth amp board

4" Dayton Drivers

18650 battery board

These tweeters are the ones I want, but they are 6ohm. Will they work??? Remember I am also needing to know which CAP
to use in conjunction with these.

tweeters


Thanks in advance for the help.

https://www.diyaudioandvideo.com/Calculator/SpeakerCrossover/


Google, it's your buddy.

"crossover designer" and "crossover design software" are relevant keywords to search by.

Ok that shit's got me more confused than I was before. What the hell is a 1st order butterworth?

It's a design for a frequency filter.

If you use multiple drivers, you have to separate the appropriate/desired frequencies that you are sending to each driver, ie, high frequencies to the tweeter, everything lower to the woofer/midrange. You can't just hook them up in parallel, as you'd just be sending all frequencies to both drivers thus defeating the purpose. A circuit that's a combination of frequency filters to split incoming audio into parts to send to different drivers is a "crossover". The exact construction of the filters depends on the impedance characteristics and frequency responses of the drivers.

However, you would likely be just fine with the 4" full range driver by itself, especially if it's relatively non-critical listening to streaming music or something like that. After all it's "full range" for a reason.

If you really want to do a two-way speaker, I would suggest a kit type speaker with drivers and crossovers which are all matched up in parameters so will work correctly and sound good.

You do, because the crossover will only work correctly with the correct impedance drivers. If you connect (for example) 4 ohm drivers to a crossover designed for 8 ohms, you will get a very different crossover frequency.

The higher the order, the sharper the cutoff slope will be.  A first order crossover has a gentle slope, 6 dB per octave, or 20 dB per decade.

A second order filter will have a slope of 12 dB per octave.   There will be much less overlap of frequencies between the two drivers.

87 ohms.

No, no, not 87,... 42!

I bet those tweeters will sound really nice.  

If it were me, I'd buy them and wire them in parallel with the 4" speakers and see if it was acceptable to my ears.  If so, you are done.  No capo, no Butterworth of any order, no nothing, done!

Build the enclosures and install the drivers.  Test them for their sound quality using your (subjective) criteria - do they sound good?.

Do that much, get a feel for it and go from there.  




P.S. - you can buy crossover units pre-built.

What are the power requirements for that amp?  Where do you plan to get the power, from disposable batteries?  Get a small power supply, instead.

nm, that battery board with rechargeable Li ion batteries seems the way to go.

What, no vacuum tubes?

Looked at the specs on the 4" full range driver. I don't think I'd bother with trying to put a crossover and tweeter in.

If you wanted to do a 2-way speaker build in that size range I'd take a look at the "C-note" kit on that site.

I agree but have never heard these speakers.  Those soft dome tweeters usually have a very nice sound to them.  A 4" speaker does not and will never qualify as a woofer, so trying it by itself is quite rational.

Crossovers are a set of filters that put frequencies into the desired speaker while making sure the impedance seen on the various ports is still correct.

A 2-way crossover handles two speakers per channel.
A 3-way crossover handles 3 speakers per channel.

Crossovers can be active with a direct power connection to operate or passive.

Passive crossovers can be completely passive or steal some power (semi passive) from the audio and appear passive but have a small power draw from the audio.

Completely passive often has lower power handling and some loss in audio power.

If this audio power is used in a semi-passive design the output volume can often be made higher than fully passive.

You steal power from more of the band and spread the loss out so it is less noticeable.

Powered crossovers are used for sub-woofers and higher power applications.

Ok so after reading all this stuff, and doing a little more looking I decided to just go with the 4" drivers by themselves. I am however
very interested to learn the other stuff. I plan on building more stuff in the future, but I don;t want to buy a "kit" and just plug stuff
in. I want to build it, and design it myself. Guess I better get reading.

Good luck.

It is a bit of a PITA the first few times.

After that you will be able to just shuffle around the equations and solve them for different frequencies depending on the individual speaker requirements.

It does work better with some computerized circuit modeling to optimize things.

You can make a network that flattens out speaker response for better sound without having to use a larger equalizer in the system.