The Boominator - another stab at the ultimate party machine

[Sjanten]

Hi all

Saturnus, I have great respect for your workmanship, it looks great!

Janoch, as Saturnus said, horns would not work, not that they're not great in many ways, but they do not come in small packages!
I've build some designed by Bill Fitzmaurice that we use for the festival, and with a sensitivity at approx. 110dB they do give a lot af bang for the buck!
But as you can see in the pic, the total package is 180 x 170 x 80 cm total, and weighs 400 kg...
KILOWATTGRUPPEN.DK

 

[Saturnus]

Those HP-10W's seem to be way ahead of the alternatives for the price (~30 euros ea). I've been searching high and low for something smaller with similiar sensitivity at a decent price (say <€150 for 4), but to no avail.

That's the real problem, I have yet to find anything that is even remotely as good as an alternative to the HP-10W. I've used them for various projects for many years. And for the price they offer exceptional quality. I've tried many other, and much more expensive drivers, but I constantly return to this one for it's natural sound and exceptional voice detail.

Like most PA drivers they don't like very low volume levels but being used outside where there's lots of background noise that's not a problem. They also don't like high excursions and start to sound really bad when forced to do that but cutting out the extreme low end and the limited power output of the amp6basic makes sure that doesn't happen either.

Put simply, I can wholeheartedly recommend the HP-10W, for this specific purpose they're in a league of their own.

 

[janoch23]

2 x HP10W is too big and heavy. And you're right, there are no cheap mono Class D amps.

I don't know why I didn't notice these from Hifikit before: RILA BW818 for just €20 ea. However they sound "too cheap" and I don't know enough about speakers to draw conclusions from the T/S numbers.

8" Paper cone, impedance 8 Ohm
Freq range 55-4000 Hz
200 unspecified watts
Sens: 94 dB/SPL
Resonance: 55 hz
Vas: 392 L
Qts: 0.31
Weight: 1.5 Kg

Nothing else is specified! Other threads say RILA specs are not to be trusted either.

Anyway, 97 db at 3 kg / €40 sound like it would suit my needs. Could these work in a boombox 2 x 8" ?

Next step up is >$100 for 2x8".

 

[Saturnus]

They might work

At that price it can't hurt to buy a couple and test it, if they're no good ... no great loss.

Cabinet size I would aim for with 4 of these would be 24x24x60cm

But this one might actually be better, and it's 6½" and cheaper to boot ... http://www.hifikit.org/index.php?id=284

 

[Brytnardz]

bipolar?

I don´t realy understand this with bipolar design and in what order you connect wires, rigtht/left, +/- to the amp? How does it work and how do you calculate cabinet size for a bipolar design.

I have been following this tread from the start with most excitement. And of course I am also into building lightweigt BIG sound.

My latest idea is to put one B&C 10HPL 64 in a 20l BR together with a compression driver. Mono but loud.

 

[v-bro]

Hi,

it's not a Boominator, but I just thought it would be nice to show you guys my latest creation:

http://41hz.com/Forums/topic.asp?TOPIC_ID=1917

 

[NED 209]

gorgeous Vincent. im gagging for one of your macaronies... i wonder how international airports would view them though.. as a suspicious looking device?

Saturnus one thing thats puzzling me bout the boominator - amp six, a two channel amp, is running all 8 drivers? could you explain how this is done please?

 

[v-bro]

Thanks Brian! I have taken the Macaroni to England and back by airplane, there was just one question about what it is. I explained and it was OK.

I guess it depends on the people checking it... I can imagine it can give trouble, but I took the risk...

I think Saturnus has series/parallel connected a few of the drivers....

 

[Saturnus]

Saturnus one thing thats puzzling me bout the boominator - amp six, a two channel amp, is running all 8 drivers? could you explain how this is done please?

Hmmm ... there's 4 woofers and 4 tweeter in each essentially making it 4 speakers. The 2 in each volume is paralleled to make it 4 Ohm. Pretty standard.

V-bro, very nice work as usual from you. But why the amp11 this time?

 

[v-bro]

Hi,

thanks man!

Sorry to come barging in your thread this way, but I thought it would be interesting for the readers here...

AMP11 is an excellent amp, it has lots of headroom and extremely wide voltage range (I modded it to work from 9Vdc to 32Vdc!) extremely low distortion....lots of space and holes for any kind of input cap....

It is also very nice that it's a mono module and it's single supply, so easy to operate on a battery. I also like the black PCB and all modules I made worked right away!

AND there's a new chip coming up that works up to 50V! It is pin compatible and when you only change a few caps on the AMP11 it can output up to ~200W! More about that later...

Short: AMP11 is one of my favorites for sure!!

 

[jchillerup]

woop woop, received the speakers.

I've decided to go for just the two for now, but I need some help designing a case. I hear that its dimensions are pretty important. So what data do we need? I'll try to provide as much as I know for now.

The case is going to be made with 20mm plywood, the arrangements inside it will be left - battery - right speaker. That is, the good ol' design for a boombox.

I sincerely hope the bass will be more clear when it's all installed in a case

 

[MortenJ]

>>Jchilerup: If the woofers are not placed in a cabinet the soundwaves from the front of the speaker are cancelled out by the waves from the back, especially in the lowest frequencies. So it will sound a lot better in a cabinet.

My boombox is almost ready now, the paint is drying up now so it should be finished in a few days. I went for two 6.5" woofers and two piezo tweeters powered by an Amp6 Basic from a 12V, 12 Ah sla battery. Can't wait for it to be finished.

>>Saturnus: I'm up for a small competition.

Morten

 

[m4gnus]

So cool project - but could we please get some dimentions?? What size is the box, how tall, deep and long is it? And don't you have som photos from inside it? It could be nice to see how close the magnets are..
Thanks

 

[Saturnus]

The magnets are pressed together. And the dimensions you can find in this thread.

 

[Peter M.]

@Janoch

The magnet to magnet construction focuses the magnet fields in the driver and gives a slight increase in sensitivity of roughly ½dB per driver, resulting in a 1dB sensitivity increase per speaker pair ... that may not sound like a lot but 1dB is 25% more output for the same power input.

Hi Saturnus.
You gain only 0,5db combined if each speaker is 0,5db more efficient I think.

ex: If you have two 90db speakers you get 93db combined, if you have two 90,5db speakers you`ll get 93,5db.

Regards,
Peter

 

[Saturnus]

That's very possible, and in that case I get a 1dB boost just by putting the magnets together. Measurements don't lie.

 

[Peter M.]

That's very possible, and in that case I get a 1dB boost just by putting the magnets together. Measurements don't lie.

1db boost for free is good


Great idea to use the speaker basket as a part of the structural design. Saving weight and adding strength at the same time, and it also cancels out vibrations.
Very cool

 

[jchillerup]

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

 

[m4gnus]

Where can I find that Qbox system thing?? And is it important?

 

[Saturnus]

Where can I find that Qbox system thing?? And is it important?

Qbox is the resulting Q a system has when a driver is placed in an enclosure volume (a box) whether it's an open baffle, closed, or reflex system. You need the formulae or a speaker software to calculate it. Most free speaker design software doesn't let you adjust Q though, so professional software is needed.

Read this to understand the basics:

http://www.geocities.com/kreskovs/Box-Q.html