Hello there,
First of all I would like to say that I am a complete beginner when it comes to building speakers (incl. all the technical know-how). So forgive me if I mention anything stupid/crazy.
I looked around the forum about similar projects, but did not find the kind of info I wanted (but correct me if I am wrong). So I decided to start a thread myself.
I want to build a small wireless (and rechargeable) speaker:
When I look around at parts-express I see a lot of 2" inch speakers. But since I will be using batteries I have no clue to look out for: ohms, wattage, something else?
I was thinking about using a:
Dayton Audio AMT Mini-8 Air Motion Transformer Tweeter 8 Ohm
Tang Band T1-1942SB
Or is this too much or not even possible?
Also any suggestions in terms of amps (small of course around 2"-3") are welcome.
First of all I would like to say that I am a complete beginner when it comes to building speakers (incl. all the technical know-how). So forgive me if I mention anything stupid/crazy.
I looked around the forum about similar projects, but did not find the kind of info I wanted (but correct me if I am wrong). So I decided to start a thread myself.
I want to build a small wireless (and rechargeable) speaker:
- - 2" inch (5cm) sized speakers (the parts, not the size of the casing).
- - built-in amp
- - built-in bass (since the enclosure will be small, I doubt if this will be possible/useful)
- - no cheap parts (budget around 300$)
- - dimensions around 3" x 3" x 10" - 8cm x 8cm x 30cm (roughly)
- - Li-Ion battery (around 10.000 mah should do the trick right?)
When I look around at parts-express I see a lot of 2" inch speakers. But since I will be using batteries I have no clue to look out for: ohms, wattage, something else?
I was thinking about using a:
Dayton Audio AMT Mini-8 Air Motion Transformer Tweeter 8 Ohm
Tang Band T1-1942SB
Or is this too much or not even possible?
Also any suggestions in terms of amps (small of course around 2"-3") are welcome.
Hi roquestar
You should also look at the sensitivity of the speaker you want to purchase. The TB T1-1942SB has a sensitivity of 82dB 1 watt at 1 metre (1W/1m) and a maximum power input of 4 watts. For every doubling of power you get another 3dB, so from 1 to 2 watts you get a 3dB increase and then from 2 to 4 watts another 3dB. This gives a maximum output of only 88dB.
Don’t be fooled that this speaker can provide a good output at 75Hz. The cone diameter, the amount the cones movement (x-max) and the internal volume are too small. You can do better than that! Other specifications to consider are the speakers free air resonance Fs where frequencies below this will drop quickly.
Even though the internal cabinet volume you have chosen is small (and will get smaller with the addition of the battery and amp etc.), I would look at a separate speaker and passive radiator and use the internal volume left in the cabinet to your advantage.
If you could manage to fit this driver in from Dayton Audio. Check out the reviews, especially the second one:
Dayton Audio ND91-4 3-1/2" Aluminum Cone Full-Range Driver 4 Ohm
Peerless 830878 3-1/2" Passive Radiator
For the ND91 you will need about 30 watts RMS
You will also need a crossover if you are going to add a tweeter.
You should also look at the sensitivity of the speaker you want to purchase. The TB T1-1942SB has a sensitivity of 82dB 1 watt at 1 metre (1W/1m) and a maximum power input of 4 watts. For every doubling of power you get another 3dB, so from 1 to 2 watts you get a 3dB increase and then from 2 to 4 watts another 3dB. This gives a maximum output of only 88dB.
Don’t be fooled that this speaker can provide a good output at 75Hz. The cone diameter, the amount the cones movement (x-max) and the internal volume are too small. You can do better than that! Other specifications to consider are the speakers free air resonance Fs where frequencies below this will drop quickly.
Even though the internal cabinet volume you have chosen is small (and will get smaller with the addition of the battery and amp etc.), I would look at a separate speaker and passive radiator and use the internal volume left in the cabinet to your advantage.
If you could manage to fit this driver in from Dayton Audio. Check out the reviews, especially the second one:
Dayton Audio ND91-4 3-1/2" Aluminum Cone Full-Range Driver 4 Ohm
Peerless 830878 3-1/2" Passive Radiator
For the ND91 you will need about 30 watts RMS
You will also need a crossover if you are going to add a tweeter.
I would start by googling "boominator". It's one of those evolving designs that a lot of people have built different variations of, but the design and goals are consistent.
The Boominator: 360° of 115dB music
www.diyaudio.com/forums/class-d/104402-boominator-another-stab-ultimate-party-machine.html
https://www.reddit.com/r/Boominator/
Boominator MINI (development thread) - Speakerplans.com Forums - Page 1
https://www.facebook.com/theboominator?fref=nf
The Boominator: 360° of 115dB music
www.diyaudio.com/forums/class-d/104402-boominator-another-stab-ultimate-party-machine.html
https://www.reddit.com/r/Boominator/
Boominator MINI (development thread) - Speakerplans.com Forums - Page 1
https://www.facebook.com/theboominator?fref=nf
You could go with a pair of these mounted together as a boombox. The amount of bass from these guys is surprising.
Overnight Sensations MT Speaker Kit Pair
Many folks use a Lepai amp to power something like the Overnight Sensation with good results. A 12VDC amp would work great with a battery set-up.
Lepai In Stock At Parts Express With Free Shipping
Mike
Overnight Sensations MT Speaker Kit Pair
Many folks use a Lepai amp to power something like the Overnight Sensation with good results. A 12VDC amp would work great with a battery set-up.
Lepai In Stock At Parts Express With Free Shipping
Mike
@pop4richard - Thank you for your elaborate explanation. I have learned some new things there 
@zettairyouiki - Thanks for those links. These will help me a lot.
@mikejennens - Thanks, but I mean to build a portable speaker that you can put in a backpack. These parts you mention are simply too big.
@sreten - The reason why I choose the 300$ dollar budget, is because I would like to know if I can build a superior product then those commercially available at that price (or less). And what would the fun be of just buying something in a store? And I don't mind walking through a minefield... it is a good way of learning. I am not afraid to fail miserably. I can always use the parts for something else.
But thanks everyone for your input. I will try and update this thread with my progress.
@zettairyouiki - Thanks for those links. These will help me a lot.
@mikejennens - Thanks, but I mean to build a portable speaker that you can put in a backpack. These parts you mention are simply too big.
@sreten - The reason why I choose the 300$ dollar budget, is because I would like to know if I can build a superior product then those commercially available at that price (or less). And what would the fun be of just buying something in a store? And I don't mind walking through a minefield... it is a good way of learning. I am not afraid to fail miserably
. I can always use the parts for something else.But thanks everyone for your input. I will try and update this thread with my progress.
This is a really fun and educational project, so have at it! Here are a couple of thoughts.
- You'll probably get a lot more bass from a 3" than a 2", and even more from a 4", but they start requiring a bigger cabinet. I have 2 x 4" in a box 16.5" x 7.5" x 7" and it sounds pretty good and has a decent amount of bass, but I added a DSP board (Mini-DSP) to equalize it and boost the bass.
- The small speakers have a lot of top end, and may not require a tweeter unless you like a lot of top-end sizzle. Actually, many designs use a "crossover" network of coils, capacitors and resistors to tame resonances at certain frequencies.
- As somebody already suggested, looking at existing small speaker plans is a good place to start with this. You can change them somewhat in shape as long as the internal volume remains the same. You can even make two small cabinets and use them connected together by a frame/handle, or separate them for parties, etc. and to get better stereo.
- I would suggest Lithium Iron Phosphate (LiFePo) batteries. Can't overcharge and catch on fire and MUCH longer useful life that ion type. Initially, they don't quite hold as much charge as ion type, but the latter degrade pretty rapidly and then store less charge. LiFePo charge very rapidly, another benefit.
- The class D boards are pretty efficient. A battery the size of your fist will play all day. They are rated in amp-hours. That fist-size one may be 4-5 AH.
- It's a nice convenience to add a USB charging port somewhere. You'll need a small regulator to drop the voltage to 5v or you can just cannibalize a car charger.
- Look at the nominal 25 watt class D amplifier boards, there's ton of them out there. at low distortion levels, they'll put out closer to 10 watts per channel, which will be plenty. If you go higher wattage, you'll need to go to 24 volts, a more complicated setup.Most of the amp board have input impedance that can be adjusted by changing a resistor, so you can make sure you have the right amount of amplification for an iPod or other input source you're using. They're not all the same.
- You will need a charger as well as an AC power supply if you want to run the thing plugged, which you most certainly will. Add a switch to route appropriate power to the board, and charge to the battery when it's in charge mode.
- Make sure it's easy it's easy to access the internals. I tinker with mine endlessly.
Let us know what you're doing.
- You'll probably get a lot more bass from a 3" than a 2", and even more from a 4", but they start requiring a bigger cabinet. I have 2 x 4" in a box 16.5" x 7.5" x 7" and it sounds pretty good and has a decent amount of bass, but I added a DSP board (Mini-DSP) to equalize it and boost the bass.
- The small speakers have a lot of top end, and may not require a tweeter unless you like a lot of top-end sizzle. Actually, many designs use a "crossover" network of coils, capacitors and resistors to tame resonances at certain frequencies.
- As somebody already suggested, looking at existing small speaker plans is a good place to start with this. You can change them somewhat in shape as long as the internal volume remains the same. You can even make two small cabinets and use them connected together by a frame/handle, or separate them for parties, etc. and to get better stereo.
- I would suggest Lithium Iron Phosphate (LiFePo) batteries. Can't overcharge and catch on fire and MUCH longer useful life that ion type. Initially, they don't quite hold as much charge as ion type, but the latter degrade pretty rapidly and then store less charge. LiFePo charge very rapidly, another benefit.
- The class D boards are pretty efficient. A battery the size of your fist will play all day. They are rated in amp-hours. That fist-size one may be 4-5 AH.
- It's a nice convenience to add a USB charging port somewhere. You'll need a small regulator to drop the voltage to 5v or you can just cannibalize a car charger.
- Look at the nominal 25 watt class D amplifier boards, there's ton of them out there. at low distortion levels, they'll put out closer to 10 watts per channel, which will be plenty. If you go higher wattage, you'll need to go to 24 volts, a more complicated setup.Most of the amp board have input impedance that can be adjusted by changing a resistor, so you can make sure you have the right amount of amplification for an iPod or other input source you're using. They're not all the same.
- You will need a charger as well as an AC power supply if you want to run the thing plugged, which you most certainly will. Add a switch to route appropriate power to the board, and charge to the battery when it's in charge mode.
- Make sure it's easy it's easy to access the internals. I tinker with mine endlessly.
Let us know what you're doing.
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