Boominator Buildlog [DIY audio]

[Lutkeveld]

Welcome to the Boominator buildlog.

 

For the people that are not familiar with this design, a quick rundown:

It is an open-source design DIY Boombox optimized for the best and loudest sound possible in free-field listening.

Main components are 4 pro-audio woofers mounted magnet to magnet, 4 tweeters, one SLA battery and one high efficiency class-D amplifier.

 

Without further ado, our cardboard mockup:

The small holes are for the Monacor MPT-001 piezo tweeters, the big ones are for the P.Audio HP10W woofers.

There will be a removable middle compartiment where all the electronics are located.

 

After thinking everything out we went to the local hardware store and got our wood:

It's FSC certified 12mm 9-ply plywood. Very strong stuff.

 

The result of a dry testfit

As you can see, each cabinet has a centerbrace. The woofers will be mounted magnet to magnet (bipole).

The magnets will be glued to the centerbrace to ensure a rigid structure.

 

And with the top on it: 

You can clearly see where the middle compartiment has to slide in.

 

We're planning on carbonwrapping the electronics module front and back.

This is a test piece, but you get the idea

 

Next stage: construction. Stay tuned/subscribed

[yimello]

Nice. I will follow GL and HF 

[Lutkeveld]

Cutting the centerbraces:

 

One for either side:

 

Draw the side handles, which double as bass-reflex port

 

Cut it out with the jigsaw

 

Glue it to the sides.

 

You don't want square handles, you wan't it nice and rounded so it won't hurt your hands.

So you take a router

 

And round-over the edges

 

To be continued...

[Lutkeveld]

Me and my friend had a lot of fun unboxing today. We are in possession of most of the things now. 

Orders came from eBay, Bax-Shop and Accusafe, we still need to order at Conrad.

We first need to recheck some measurements so we can purchase the right filter components.

 

To kick things off, 4 P.audio HP10W woofers, 95db/w/m, 200 watt power handling.

They scream quality

 

Backside, just look at them ;p

 

The Monacor MPT001 Piezo tweeters

 

From left to right: battery, power supply, amplifier, battery protection

-Battery: 7.2Ah Sealed Lead Acid battery from CSB

-Power supply: 12v 3A MeanWell. Man, this thing feels like quality compared to those china cheapies I was used to.

-Amplifier: MaxAmp20. A lot smaller than it seems from the pictures. 2x15W high efficiency class-D with digital volume control.

-Battery protection: AccuSafe V3.5. Cuts off the battery at 11.5v to prevent damage. Will auto-switch to PSU when plugged in and couple battery to the charger.

 

And last but not least: all the cables, plugs, connectors etc

 

Hope you enjoyed it, stay tuned

[XzzDSA]

Ahh, you beat me to it  

Still havn't abandoned the idea of building this setup as well.
Not sure If I'll be using it much yet, so havn't fully decided if we're gonna make it, but it'll be in the summer if and when it happens

Looks MUCH better than our first try at our half-assed boominator look-a-like.
COOL! :-)

[XzzDSA]

Also, that PSU looks neato.

So do you have an internal charger to charge the battery while plugged in? Or how does this work?

[Lutkeveld]

Heyy @XzzDSA, This one will be bipole (magnet to magnet), that was the reason the bass was lacking in your build

Maybe you can build a Halfinator which is a fair bit cheaper and smaller. You can build it for <200 euros.

Flip it 90 degrees, make the handles/ports on the longest side, make it 1 liter larger to fit the battery etc in it.

Why not build it before it's summer so you can use it in the summer? I'll be your guide

 

It's bad to charge and use the battery at the same time, that's why we went with the charger/PSU setup.

When you plug it in to charge, the PSU will power the amp and the charger will charge the Battery.

It's all auto-switched by the Accusafe, so you only have to plug in the mains cable.

 

It's beginning to look like something, but the coolest thing(s) still have to come

[XzzDSA]

Heyy @XzzDSA, This one will be bipole (magnet to magnet), that was the reason the bass was lacking in your build

Maybe you can build a Halfinator which is a fair bit cheaper and smaller. You can build it for <200 euros.

Flip it 90 degrees, make the handles/ports on the longest side, make it 1 liter larger to fit the battery etc in it.

Why not build it before it's summer so you can use it in the summer? I'll be your guide

 

It's bad to charge and use the battery at the same time, that's why we went with the charger/PSU setup.

When you plug it in to charge, the PSU will power the amp and the charger will charge the Battery.

It's all auto-switched by the Accusafe, so you only have to plug in the mains cable.

 

It's beginning to look like something, but the coolest thing(s) still have to come

If we do decide to build it - we'll build a full blown boominator like yours.

 

[Lutkeveld]

Dry testfit of the 'skeleton'

 

 

 

Beginning to look like something.

[XzzDSA]

Aww mann.. This looks SOOO much better than ours did - HA!
Gj.. Might need to get a hold of some proper tools for our next attempt.

[Lutkeveld]

@XzzDSA Thanks! Actually, it's not a whole lot of tools you need.

Required:

-Jigsaw (we got a secondhand Black&Decker for €10)

-Drill (battery powered is nice to work with) with hole saw

-Soldering iron 

-Side cutter

 

Recommended:

-Router (On my birthday, 15dec, I'll get a brand new one )

 

@vinyldash303 Thanks, we're making nice progress indeed

[XzzDSA]

@XzzDSA Thanks! Actually, it's not a whole lot of tools you need.

Required:

-Jigsaw (we got a secondhand Black&Decker for €10)

-Drill (battery powered is nice to work with) with hole saw

-Soldering iron 

-Side cutter

 

Recommended:

-Router (On my birthday, 15dec, I'll get a brand new one )

 

@vinyldash303 Thanks, we're making nice progress indeed

We didn't really have proper hole saw for our drill, so we used a hand-drill with a size which was aprox. the correct size.. Man, that was ALOT of work, lol.

How do you make sure to make the holes for the woofers, round? 

We just drew out the woofer on the plank and free handed it with a jigsaw. (Wasn't the prettiest thing though).

[Lutkeveld]

We didn't really have proper hole saw for our drill, so we used a hand-drill with a size which was aprox. the correct size.. Man, that was ALOT of work, lol.

How do you make sure to make the holes for the woofers, round? 

We just drew out the woofer on the plank and free handed it with a jigsaw. (Wasn't the prettiest thing though).

 

You knew that there was a centerbrace, but you didn't know that there were two woofers per side?  :blink:

It took us 10-15 minutes total with the hole saw on the electric drill. The woofer  cutouts will be done using a router and a circle-jig. Perfect circles within minutes. 

 

If you don't have a router:

Draw it with a compass tool, take it easy with the jigsaw, sand off the rough edges and you have near-round circles.  

We will use this technique for the piezo cutouts.

[XzzDSA]

You knew that there was a centerbrace, but you didn't know that there were two woofers per side?  :blink:

It took us 10-15 minutes total with the hole saw on the electric drill. The woofer  cutouts will be done using a router and a circle-jig. Perfect circles within minutes. 

 

If you don't have a router:

Draw it with a compass tool, take it easy with the jigsaw, sand off the rough edges and you have near-round circles.  

We will use this technique for the piezo cutouts.

We knew that actual design of an actual boominator. We just didn't know how much all of it mattered

 

[Frankie]

This looks awesome ! Good job *sigh* I need to get more tools...

[Lutkeveld]

Small update, more coming up in a couple of days. Christmas holiday. Finally.

We're going to put blue led strips around the perimeter of the woofers that flash on the beat.

This will look absolutely amazing at night

 

[Lutkeveld]

*Holiday Update * 

 

I got a router for my birthday, which we used A LOT today.

Very decent product for only €65. 

 

We started the day by drawing out all shapes on the wood.

Just for reference, final radius will be determined by our DIY circle jig.

 

As seen here

Perfect circles in no-time.

 

Stacks

 

 

Testing all woofers and tweeters. We removed the stickers on the back of the magnets so the chemical metal will adhere better.

 

Filled the groves on the piezos with sealant to reduce the plasticy resonance.

 

Woofer+grill+wood

 

Woofer+grill+wood+ledstrip 

 

And a dry testfit to see how far we have come in a day 

 

 

That's was it for today. Tomorrow my friend will swing by for another day

[Lutkeveld]

180 leds in one picture

 

Phone cam doesn't really do justice. You can see the woofer IRL, looks awesome.

 

Mounting the speakers on the baffle using acryclic sealant.

 

Letting it dry

 

So we started assembly on the AccuSafe (protection board and auto-switch between mains and battery)

 

Done

 

Removed three of the five capacitors on the MaxAmp20, high pass is now on 40hz and acting as a sub sonic filter.

Looks nasty, I know. We don't have any flux to clean it up. Doesn't hurt performance in any way ofcourse.

 

Testfitting the bipole driver setup. Can you see why it's so strong when assembled? It can't flex in any way.

 

Next stage: Assembly

 

 

[Lutkeveld]

We got the terminals to the centre in place:

 

All cables soldered and ziptied in place

 

Top down view

 

We've tested it with a towel between the top and bottom and weights on top. Not exactly airtight but we can already hear how loud it can go

 

And a pic of the LED sweetness. Current consumption per strip is around 190mA at 12v according to my multimeter. So total consumption should be 760mA or 9,12W. Pretty significant, double the consumption of the amp, but most of the time they will be off or flashing on the music.

[Nup]

man this is a cool project! 

[Cheesebaron]

No crossover needed for this build?

[Lutkeveld]

Thanks guys!

 

No crossover needed for this build?

 

Actually, yes. Can you spot the resistor in series with the tweeters?

'Normal' tweeters are resistive and need a capacitor to create a first order RC highpass.

Our piezo tweeters are capacitive and they need a resistor to create a first order RC highpass.

 

You could use a coil on the woofer, but the midrange already has a very controlled rolloff.

Crossover frequency is around 3.5kHz.

 

There is also a highpass on the input of the amp at 40hz. It's to prevent the woofer from playing frequencies it can't properly reproduce anyway.

[Cheesebaron]

Thanks guys!

 

 

Actually, yes. Can you spot the resistor in series with the tweeters?

'Normal' tweeters are resistive and need a capacitor to create a first order RC highpass.

Our piezo tweeters are capacitive and they need a resistor to create a first order RC highpass.

 

You could use a coil on the woofer, but the midrange already has a very controlled rolloff.

Crossover frequency is around 3.5kHz.

 

There is also a highpass on the input of the amp at 40hz. It's to prevent the woofer from playing frequencies it can't properly reproduce anyway.

 

Now that you said it I can see the resistor, it was hard to spot though. What is the reason to put sealant onto the tweeters? Aren't they already in a closed enclosure?

 

Anways, it looks pretty nice.

 

What amplifier are you going to use for this? Tripath?

 

Edit: Nevermind about the amp. Found it in the OP  

 

-Amplifier: MaxAmp20. A lot smaller than it seems from the pictures. 2x15W high efficiency class-D with digital volume control.

[Lutkeveld]

.

 

Yeah, they don't have to be so large (metal film 2W), we spend €3 total on crossover components

Tripath TA2020, the 41Hz AMP6 to be exact, was the recommended amplifier for a long time.

The new amplifier, based on a Maxim chip, offers a smaller footprint, better thermals, higher efficiency, digital volume control and slightly increased sound quality.

[Lutkeveld]

Unleashing the beast for an outdoor test

Everything is glued together now. Next up will be painting