The Boominator - another stab at the ultimate party machine

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#1,301
Can I just stop you guys before you start doing something silly and possibly destroying your amp.

If you have a stereo amp that feeds into two 8 ohms speaker, that will give the same power as a mono amp fed into the same two speakers paralleled. In fact it will give a tiny bit more because the efficiency is slightly higher.

Also you should never run piezos alone on a class D/T amp output without changing the output filter and zobel network. It's simply not designed to run highly impedant capacitive loads. The only way to do that safely is to have a power L-pad that emulates a speaker before the piezos.

So by making the box mono you get less output and you risk destroying your amp. Make it as drawing 3 above with each side playing one stereo channel.
 
#1,302
Buckapound said:
Running the battery charger while you are drawing power from the battery is not a good idea for a number of reasons. Wire a switch that when in one position charges the battery and runs the boombox off a mains-powered regulated supply, and when in the other position, the mains power is off and the amp draws power from the battery.

Wiring diagram is attached. Four-pole, dual-throw switch is required, at least the way I did it.

--Buckapound
Click to expand...

This is great. Just what I was looking for.

I'm a bit of an electrical idiot, but I think I can make this work. What confuses me is there's two bits to the diagram. The top I get (I think), the bottom I don't. Could you clarify?
 
#1,303
Saturnus said:
Can I just stop you guys before you start doing something silly and possibly destroying your amp.

If you have a stereo amp that feeds into two 8 ohms speaker, that will give the same power as a mono amp fed into the same two speakers paralleled. In fact it will give a tiny bit more because the efficiency is slightly higher.

Also you should never run piezos alone on a class D/T amp output without changing the output filter and zobel network. It's simply not designed to run highly impedant capacitive loads. The only way to do that safely is to have a power L-pad that emulates a speaker before the piezos.

So by making the box mono you get less output and you risk destroying your amp. Make it as drawing 3 above with each side playing one stereo channel.
Click to expand...

Thanks for clearing that out Saturnus, probably saved me some serious headaches 😱

I can follow the original boominator "build-scheme" quite close with drawing #3 right?
 
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#1,310
ThokN said:
And from what I've read, it should sound incredible stereowise because of some special principle. I too am building a 2-speaker boombox, and wondering if the Stereolith thing could be copied, but I have no idea if it's good for outdoor use.
Click to expand...

It's basically the same as half a Boominator but with a center tweeter that outputs the summed signal for both channels at half volume (-6dB) and in reverse phase (180 phase shift). It's hardly anything new or existing really.
 
#1,312
ThokN said:
Alright, but couldn't it be a good thing to place one tweeter in the middle as they have done? Or do you think a tweeter on each side sounds better? Or maybe louder?
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The principle is meant to have a tweeter on each side, or the drivers on those sides being full-range. What the top/center, whatever mounted tweeter does is make a narrow wave cancellation beam of high frequencies so that in a room you'll hear reverberant sound over direct sound. The center tweeter has no (positive) effect outdoors.
 
#1,313
I just have to say that I made half a boominator for a friend having him pay the materials. Once again I was a bit stressed with finishing it before the 1st of May on his request. But the sound... of what I heard (it was just a quick test)... was pretty good. Though it probably plays less loud that the original boominator, it still plays surprisingly loud for people not having heard it before - and that was my friend 😉

Unfortunately, I haven't got all the pictures of the finished project because of the fact that it needed to be done before May 1st. I will ask my friend for some pictures and post them here soon. It's not a perfect build, a lot of visual flaws are present but I definately like that it has the same sound quality, less weight and that it doesn't take up much space.

If there's one thing I would like to do differently, it is to use a tube as port next time and place it in the front/back of the half boominator to be able to sit on it while the side that originally has the port is facing the ground. Portability also means a lot to me.

Have a good one 🙂
 
#1,314
rubennn said:
If there's one thing I would like to do differently, it is to use a tube as port next time and place it in the front/back of the half boominator to be able to sit on it while the side that originally has the port is facing the ground. Portability also means a lot to me.

Have a good one 🙂
Click to expand...

Why not just put it on the side while playing like a full size Boominator? Or is it more convenient with the roughly 50cm height compared to 30cm?
 
#1,315
Hallo everybody. 🙂
I'm about to build my new boomblaster for Roskilde 11'
I have thougt about makeing a "double boominator" with 8 hp-10w, 8 horn bubble tweetters, 2 amp6basics and of course a twice as big cabinet.
But I'm not sure about how much more sound i get in proportion to I double up all the parts, and if it is possible to use two amp6 in one system at all, I have just thought about using a jack splitter like this:
Itech Minijack splitter kabel 0,2 meter
Are there any other considerations i should have in mind?

Jonas
 
#1,317
jonasvj said:
Hallo everybody. 🙂
I'm about to build my new boomblaster for Roskilde 11'
I have thougt about makeing a "double boominator" with 8 hp-10w, 8 horn bubble tweetters, 2 amp6basics and of course a twice as big cabinet.
But I'm not sure about how much more sound i get in proportion to I double up all the parts, and if it is possible to use two amp6 in one system at all, I have just thought about using a jack splitter like this:
Itech Minijack splitter kabel 0,2 meter
Are there any other considerations i should have in mind?

Jonas
Click to expand...

Maybe you sould just consider making a regular boominator design with a more powerful amp, like the AMP9 (if it's more output you seek)

EDIT: Or maybe 2 seperate boominators running on the same signal.
 
#1,318
rubennn said:
Maybe you sould just consider making a regular boominator design with a more powerful amp, like the AMP9 (if it's more output you seek)

EDIT: Or maybe 2 seperate boominators running on the same signal.
Click to expand...

Oh, you edited it. I was about to say the same thing. Build 2 separate Boominators. It'll be easier to transport, and you have a lot more options for placement. And if you're going to the park or beach or somewhere not being Roskilde then just having to haul one Boominator will be a lot easier to manage.

EDIT: in any case, 2 Boominators will be twice as loud as one. That's a no-brainer. A Boominator with a 24V amp is also about twice as loud as one running on a 12V amp. So if you really want it loud then 2 Boominators on one 24V amp would be insanely loud. In fact one amp9b could run both.

You should note that a standard Boominator already plays louder in average SPL at 2 meter distance than what Roskilde Festival is allowed to have as maximum average SPL in front of the stages.
 
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#1,319
rubennn said:
Yeah I was thinking that it would be more convenient. Also you can only sit one on the boombox when using it the way I described (which I dunno is a good or a bad thing), but then you just tilt it to the other side.

Also it has the advantage when wanting to make a lid like this drawing:

An externally hosted image should be here but it was not working when we last tested it.
Click to expand...

I'd probably make sure to have the piezos in the top instead of the bottom.
 
#1,320
Its time to close the lid, all the connections are made, secured and tested.
I will seal the lid with silicone (the rest of the box is glued) to be able to open it in the future.

Saturnus: What about dampening material, do I put anything in or let the box be "naked" on the inside?
 
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