The Boominator - another stab at the ultimate party machine

[ohman92]

Saturnus, About the hp10t design, when will it be ready? are you going tog use any tweeters? Please tell us as much as you can. Thanks

[danielwritesbac]

Originally Posted by Saturnus

It's obvious you have not tested and measured the HP10T but only run calcs when you can even suggest it for this design. I am however working on another design which will use a pair of HP10Ts but that's for an ultra low cost alternative to the Boominator that still beats any commercially available boombox in sound quality.

Well, I didn't run calcs. Anyway, I am looking forward to your lower cost solution and especially your solution to the amplifier to use instead of the 2024's 12w to 8 ohms.

[rubennn]

For use on a festival I've actually had good experiences with the 12w peak output in 8 ohms. With high sensistivity speakers it will still be very loud just next to you.

[gmarsh]

I *finally* found a local dealer for suitable plywood. 1/2" baltic birch, 9 ply, kept indoors, and only $40 CAD for a 5'x5' sheet. Construction starts soon!

Originally Posted by Saturnus

If anyone wants me to test their amps for the use, they can send me one.

Sent you a PM.

[danielwritesbac]

Originally Posted by rubennn

For use on a festival I've actually had good experiences with the 12w peak output in 8 ohms. With high sensistivity speakers it will still be very loud just next to you.

I suppose that TA2021's 13 watts to 8 ohms looks good for this? You make an excellent point about the area to be covered. Venue size is an interesting thing to mention. Boominator's interesting forwards rearwards covers a large venue if placed in the middle since the distance to the edge of the venue is as short as possible in any direction. I do not know why Boominators sometimes cover greater area when set sideways.

Now how can we get a vendor to include iPhone/Digiplayer suitably higher input sensitivity? It looks like we need to bother some amp manufacturers to let them know that the 90's have passed and nobody is carrying around big black box CD players. I see almost no amplifiers available with useful input sensitivity, unless one cares to solder SMD for a modification. Perhaps we can come up with preamp instead? A preamp seems an easier answer if some were available. Unfortunately, the same power amp manufacturers who cut off the input sensitivity don't have a preamp offering. So, you get very low noise at the cost of insufficient output. lolz!!! And if we could get an amp manufacturer held down long enough for a useful input, then maybe we could also get DC trimmers too?

I would like to mention 4 things about soldering integrity.
http://i1142.photobucket.com/albums/...6062010327.jpg
http://i1142.photobucket.com/albums/...6062010328.jpg
http://i1142.photobucket.com/albums/...6062010329.jpg
1). 30W Iron: When you have a connection that sticks to the iron, you need a hotter iron. I have a 15W/30W switchable, but I wish it was 5W more.
2). 63/37 Solder: When you have a connection that is exposed to vibration, that connection needs 63/37 solder.
3). GEL FLUX: It will flow your solder to a beautiful perfect mirror shine, like a polished chrome Buick bumper. When you have a connection that won't cooperate, that connection needs fluxed and Gel Flux (petroleum jelly+rosin flux) is easiest to work, the lid is beyond impossible, and the circuit board needs cleaned with Simple Green (or Dawn) + 90% (or better) Alcohol to remove excess flux.
4). Tinning: If a connection is especially stubborn, sometimes it is necessary to Flux parts, apply solder (tinning) to the individual parts, and Flux them again before putting them together. It is easier to solder a tinned part to a tinned wire, but it is harder to solder a non-tinned part to a bare copper wire. This can also repair old connections to remove cut-outs and remove intermittent fault static.

P.S.
I really like your cabinetry. They are all so symmetrical and fit. I have not such skill with a saw. Got any tips for me?

[gmarsh]

Originally Posted by danielwritesbac

P.S.
I really like your cabinetry. They are all so symmetrical and fit. I have not such skill with a saw. Got any tips for me?

My opinions might be different from his, but I've built a fair number of similar things (cabinetry, whatnot) and here's my set of suggestions:

Plan everything first. Grab some graph paper, draw the sheet of plywood and start drawing all the cuts you plan to make to get all the pieces that you need. There's one posted already for a 4x8 sheet, I just did one for a 5x5 sheet.

Cut out the main square/rectangular pieces first using a table saw, such that you end up with perfect 90 degree cuts. You won't get that on any other type of saw, and for a speaker enclosure you want perfect 90s so you don't end up with any air leaks.

Before you use the saw, first put a new, finer-tooth blade in it that's suitable for plywood. Plywood tends to flake a bit, using a finer blade and pushing the wood through at a slower speed will minimize this. And before cutting your Boominator pieces, run a scrap of plywood through the saw, measure it and use it to calibrate the guide on the saw to the blade you're using.

Set the cutting width on the saw as few times as you can. If you go 276mm to 300mm back to 276mm, the two 276s probably won't match. Make all your 900mm cuts, then all your 300mm's, then all your 276's, etc...

I'd cut pieces that extend to the outside of the box a bit long (in the case of the Boominator, any 300mm cut) so they overhang the box a bit, and use a flush trim router bit to trim them perfectly flush.

Mark pieces after you cut them, as scrap pieces sometimes have similar dimensions as pieces you're hoping to make and getting them mixed up can lead to plenty of frustration.

Remaining work...

For the detail work on the fronts, ends, center braces, etc... I'm planning to print off paper templates on an 11x17 capable printer at work, tape these to the cut pieces and use them for the speaker/tweeter holes, handles, etc. Do this, or use a straight edge ruler and draw your 'template' directly onto the piece.

For square cuts (handle ports, etc) drill holes first so you can get a jigsaw in, and use a jigsaw to cut them. For square features, holes, I like to clamp a heavy metal bar to the piece and use it to guide the edge of the saw - gives straighter cuts.

For the speaker holes, a router and a circle cutting jig will give the best results. If you don't, use a jigsaw and take your time. For smaller round holes (tweeters) I have a collection of hole saws, which are probably the best tool for the job - it's hard to make sharp curves with a jigsaw unless you have a thin blade, and thin blades aren't really the best thing for cutting plywood, but it's still possible to do.

After that... make a plan for how everything fits together, and the order it goes together in. And test fit everything together first.

[danielwritesbac]

Originally Posted by gmarsh

. . .Set the cutting width on the saw as few times as you can. If you go 276mm to 300mm back to 276mm, the two 276s probably won't match. Make all your 900mm cuts, then all your 300mm's, then all your 276's. . .

Oh my gosh. Thank you!

[rubennn]

I can only agree with gmarsh. Making a plan over every single component and where it should be placed and which cut it belongs to is super important. Otherwise you can end up making quick cutting decisions that may cause fatal conflicts later when joining the wood.

[thenessie]

Hi folks,
I just finished to build me first half boominator (more or less finished). Attached some pics:





I used:

• 2x HP-10W
• 2x MPT-001 Piezo
• 12mm birch plywood (but only the 7 layer type)
• 1x AMP6basic
• 1x bass reflex tube (66mm i.d., length approx. 80mm, has to be tuned)
• 1x SHORAI LFX 12V battery, 7Ah, 483g (Type LFX07L2-BS12)
• some paint (does not adhere very well, used primer first...)

Plays quite nice in my office :-) Will have to test outdoor after finishing all the "outer" parts (battery holder, user panel with input plug, switches and so on...)
Will report afterwards.
Thanks all for all the helpfull thoughts and ideas.

[Bigun]

Originally Posted by danielwritesbac

There's that saying about closing barn door after horse got out...