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Old 16th May 2015, 04:06 PM   #1
ribs is offline ribs  Norway
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Default DIY Class D "portable" speakers

Been looking at various threads here for a while now (read all of the boominator posts) and I think it is time to start putting a plan together for a build of my own.

Years ago a did multiple builds for home, car and my first home theater. But a lot has changed since then also because of the class D amps.

I did like most of the ideas of the Boominator design and choice of hardware. But at the same time the boominator was first and foremost a portable party boombox chasing party sound level over refined top end and deep low end.

From other projects I have too much left overs in form of resin and carbon fiber. I also have access to vacuum infusion so I think I will try to mould a cabinet of some sort of carbon fiber sandwich. CF is tough and has little to no flex giving speakers optimum work conditions.

I have previous used Seas, and Scanspeak elements with great results. But as I have been out of the game for a decade or more I am not up to date. I am not set on final config. 2 way system or 3 way? Both have benefits and drawbacks.

For speakers I picture using some long throw speakers that sounds good in small space cabinets. Not sure if I will use master/slave bass or harvest the benefits of woofers playing back to back.

Regarding class D amps I am green and totalt noobie. I have no idea what to look for or who has good reputations. What I have seen is the wealth of different class d boards and at great prices. Anyone feeling for giving advices is welcome.

As the plan matures and make the choices for hardware I will make sure to update thead. For now I hope to get feedback for usable hardware for my project.

Sound quality over quantity. Not looking to do a boominator although I was inspired by that thread.
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Old 16th May 2015, 05:40 PM   #2
nijunge is offline nijunge  Denmark
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Im looking forward to hear your plans and execution as im looking into doing something semilar

Im saing
compact transportable
including battery power (and out let for phone charge)
Bluetooth
mini jack input

I got this tip from another forum on speker design that I like

http://www.lencoheaven.net/forum/ind...?topic=19778.0

Build into one case with a center of batteries, dock , amplifier all build in wood (im actually thinking MDF or ply)

And I thought about changing the speakers to a set of Fostex FE 83 en that I know sounds great (in my opinion)

Class D Im thinking TPA3118D2 based thing

Im thinking about hos to make the bluetooth part but I know that SURE has some.

how does that sound
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Old 20th May 2015, 07:19 PM   #3
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I'd be tempted to go 4-way fully-active just to make it that much easier for each driver and more controllable. 4 amps per full-range signal with the very bottom one possibly summed to mono to make a 3-way mains + sub arrangement. That's pretty much the practical limit in terms of quality vs. complexity.

Short of finding an anechoic chamber to calibrate them in (probably not going to happen), the next best thing would be outside on a calm day away from traffic, or a very carefully defined procedure to ensure that you get a good measurement before the first reflection arrives. The whole point is to prevent reflected sound (room reverb) from affecting the test. Make the speakers sound as good as they will on their own, and then use them anywhere you need without modifying the calibration. Any new problems at that point are from the environment or the placement, not the speaker itself, so don't try to "fix" the wrong thing. Ears and brains are very good at separating direct sound from reverb; microphones and software are not yet.

I want to build an outdoor live concert set on a 50 pound budget per stack, so I'm interested to see how the CF thing works. Never used it myself.
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Old 21st May 2015, 02:31 PM   #4
nijunge is offline nijunge  Denmark
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It may be that im slow but that answer I really do not understand at all.

4 ways ? or 3 ways with sub and multible amps ?? for a simpel 50 pound budget ??

or is the answer to something different ;-)

N
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Old 22nd May 2015, 07:51 PM   #5
nijunge is offline nijunge  Denmark
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I found this
HiFi TPA3116 2.1+CSR4.0 Bluetooth 4.0 Digital Amplifier Class D 100W+2*50W+CASE | eBay

does anyone know that one it sounds on what ever you can read as ideal for a portable project ???
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Old 26th May 2015, 12:34 PM   #6
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Producing ample quantities of deep bass in a small box without drawing too much power would be my main concern. I'd choose a FAST system(fullrange with a woofer). I chose mono sound in my last boomblaster build and that helped with keeping the budget small. Also the filter cost in a FAST setup would be really low. Just a single cap for the fullrange and some filtering for the woofer(or a bandpass box without filters->really cheap). Funny that you mentioned a master/slave cause I used that principle in my setup. I used cardboard concrete tubing, tube/5mm rubber sheet inbetween/tube and active/passive speakers in each end. Plays pretty loud and low enough for bass guitar The active part is a high end car component 2 way setup with tweeter and a 5.25" speaker.
The slave was made from an old bass speaker. Sawed off the magnet and reinforced/added weight to the cone-->free long throw slave
I have heard that this board has decent sound; TPA3116 2 50W Class D Digital Amplifier Board | eBay. If you bridge this amp and build a low ohm speaker setup that will give you plenty of power( handles 2-4ohms in bridged mode).
Maybe you could build a slightly hornloaded/recessed fullrange in that carbon enclosure you mentioned. That would give you cleaner midrange at high spl and you could choose a smaller cheaper fullrange.
Most of the bluetooth cards I've tried doesn't cut it! I've tried 2 diy bt 4.0 aptx cards and both had big problems. This one is the best I've found so far: Bluetooth V4 0 NFC Aptx Music Receiver Adapter Handsfree Car Aux for iPhone 6 PC | eBay. Plays loud and has a full rich sound which is what you need match the acoustics outdoor. Easy to pair and gives about 3 hours on the inboard battery. Runs off a 250mAh battery which easily can be soldered to something way bigger..
I hope this gives you some ideas and I tried to utilize the fact that you can create an advanced speaker box but with simple low cost electronics which would give really good sound

Last edited by impuls60; 26th May 2015 at 12:53 PM.
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Old 26th May 2015, 05:07 PM   #7
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I buy this one, it is much smaller in size and can use car lead acid battery.
TPA3110 + blue tooth.

蘑菇迷你蓝牙功放机功放板大功率电视音响2.0声道包邮 堆拦Ψ虐-淘宝网
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Old 27th May 2015, 07:36 PM   #8
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The tpa3116 can also be driven from a 12V car battery or even lower voltage It's just less powerful at lower voltage.. To produce deep bass from small speakers you need all the power you can get from higher voltage batteries. Size of the inductors also matters when pushing large currents trough them. They distort the sound pretty bad when overdriven. Chokes are expensive so I like to buy class D amps with decent size inductors from the start.
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Old 27th May 2015, 09:18 PM   #9
ribs is offline ribs  Norway
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I have yet to get started with the project. Still doing CF work trying to find the best sandwich material. I get some sheets of balsa woods tomorrow and that might work.

Has anyone any idea of the bandwidth usage for flac files? Someone told me blue tooth might not work well with flac files. What other wireless standards are possible to use? Would prefer not to use wifi. But for all I know maybe there is no problem at all transferring music in flac format via blue tooth. What do people think?
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Old 27th May 2015, 09:26 PM   #10
ribs is offline ribs  Norway
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Quote:
Originally Posted by impuls60 View Post
The tpa3116 can also be driven from a 12V car battery or even lower voltage It's just less powerful at lower voltage.. To produce deep bass from small speakers you need all the power you can get from higher voltage batteries. Size of the inductors also matters when pushing large currents trough them. They distort the sound pretty bad when overdriven. Chokes are expensive so I like to buy class D amps with decent size inductors from the start.

I really liked this - have you tested the tpa 3116? Wonder if one uses one of those L speaker and one for Right speaker and transferred via blue tooth would one experience any out of sync or phase errors?

That amp was so nimble it seemed like a good choice if someone here have tested it.
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