The Boominator - another stab at the ultimate party machine

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#2,502
Wubbaz said:
So I calculated, according to this formula: Value of inductor=speaker impedance/(2*pi*crossover frequency), that I will be needing a 4,24 mH coil if I want a 150 hz low-pass filter for my HP-12W's.. does that sound wrong? It sounds a bit too simple to me.
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It's that simple. However, note the DC resistance of the coil you're using. You have to add that to the DCR of the driver so the coil used affects the cabinet calculation. So it affects Qts and sensitivity of the system.
 
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#2,504
#2,506
aaroe said:
Regarding solar panels, are there any better alternatives than 2 of these?
Solar Cell Huge - 5.2W - All you need to prototype

I know its monocrystalline - but I can't seem to find any any amorpheous that will fit within 300x900 mm... Are the monocrystalline that bad? - because 2 of these panels will fit perfectly - especially if the top of the boominator is routed.
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I used those panels last year on the festival. I didn't think that they were that effective. You need 2 connected in series to get the right voltage.

For next year I'm working on a solution that can carry the solar panels that are a little to big to fit on the top of the boominator. I'm thinking of some kind of frame that you can easily take off when the sun has gone away for the day at the festival.
 
#2,507
rubennn said:
I used those panels last year on the festival. I didn't think that they were that effective. You need 2 connected in series to get the right voltage.

For next year I'm working on a solution that can carry the solar panels that are a little to big to fit on the top of the boominator. I'm thinking of some kind of frame that you can easily take off when the sun has gone away for the day at the festival.
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Hmm... Allright, thanks for the input 😉
A larger external solarpanel is actually a good idea - the ability to disconnect it at sunset seems appealing. Besides that, it can be turned directly at the sun, for maximum efficiency...
 
#2,508
Saturnus said:
It accounted for. The Goldwood G1058 is a direct drop in replacement.
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Cool. The 120mm hole for the speaker magnets in your Sketchup drawing won't do for the speakers, but I hope anyone building the Boominator and using the GW1058s will notice that in a hurry.

Yeah, replicas are generally crap. The Monacor MPT-001 is a decent quality replica though so if you're on a very tight budget these can be used. But I'll reiterate that the original Motorolas are much better.
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Yup. I'll keep an eye out for CTS/Motorola bits. This box is turning out to be a bit expensive to make (I'm about to spend $60 CAD on paint) and I'd rather not shag up the whole thing because I cheaped out on the tweeters.

You'll have to notice that you'll probably need a steeper sub-cut filter than just adjusting the input cap to avoid excessive cone excursions if you don't use the intended port/handle design. The Boominator is intentionally designed to produce too high port air velocities at higher excursions because it limits air movement, and thereby helps protects against excessive excursions.

It hard to put an exact measure on the effect but from observations on actual compared to calculated cone excursions, I'd estimate it equal to adding at least another 1st order sub cut and probably more.

I also find it curious that you chose a 4" port. From an aesthetic point of view a 3" port would match the tweeter cut-out.
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Didn't really have a good reason for choosing 4" over 3". Looked alright in Sketchup so I went with it. I'm terrible at aesthetics 😉

Cone excursion limiting is one of the reasons why I'm working on the SigmaDSP based card. I can put in a very sharp highpass if I want.

Lately I've been experimenting with missing fundamental bass enhancement on the SigmaDSP eval card. It'll let the Boominator give apparent bass extension down to ~60Hz, at the expensive of some SQ, while keeping the speakers intact. I'll have to wait until the Boominator is built before I can say for sure, but on headphones so far it sounds pretty promising.

I'm also looking into multiband audio processing, similar to what radio stations do to make themselves sound loud on the air without exceeding modulation limits. Basically peak-to-average ratio reduction. For people that don't mind running bigger batteries, having larger solar panels or not running their systems for as long, this could be used to get a few dB more loudness without clipping their amps and damaging tweeters, etc.
 
#2,509
aaroe said:
Regarding solar panels, are there any better alternatives than 2 of these?
Solar Cell Huge - 5.2W - All you need to prototype

I know its monocrystalline - but I can't seem to find any any amorpheous that will fit within 300x900 mm... Are the monocrystalline that bad? - because 2 of these panels will fit perfectly - especially if the top of the boominator is routed.
Click to expand...
I'm considering four of these in series/parallel for mine, giving 21 chinawatts of solar power. They lack the connector "box" that the Sparkfun panel has which makes routing the top a bit easier:

5W Monocrystal Solar Panel 12V Battery Charge 5.3 Watt [5.2W] - $30.26 : Zen Cart!, The Art of E-commerce

I'm also considering bare 3x6" solar panels embedded in the top. You could fit 15 in the top, giving close to 30 watts. Maximum power voltage will be ~7.5V so you'll need a boost mode MPPT charger like a ST SPV1020.

There's also lots of 20W monocrystalline panels kicking around that'll fit the top, eg:

http://www.instapark.com/solar-pane...-solar-panel-with-12v-charger-controller.html
 
#2,510
gmarsh, you can get away with using mono/poly-crystalline panels because Canada is very far south compared to Denmark. Halifax is over 1100 km south of Copenhagen and is comparable to southern France, northern Italy in terms of latitude which is the important factor. Normally, you'd consider 45 degrees North or South the barrier for poly/mono-crystalline panels. Higher and you need amorphous/thin film panels because they have much higher efficiency in diffuse light which dominates at these latitudes.
 
#2,511
Saturnus said:
Actually the amp6 (or any other TA2020, TA2021 or TA2024) uses about 360mA

The calculation is pretty simple, it just assumes an average music level at -10dB (-9dB dynamic gaussian signal normalized to -1dB). So it's just V^2/(Z*10) to have the power consumption of both channels at full music power output. That's 300mA. To that you add the quiescent current consumption which for the TA2020/2021/2024 is 60mA, so 360mA total (assuming the amp has no LED to indicate power, otherwise add 20mA).

For the above amp, assuming the same battery, the output will be the same since the supply voltage is the same so the load consumption is also the same at 300mA but quiescent for the TP2050 chipset is 185mA plus the LEDs beside the potentiometer which uses 40mA so 525mA total.

So about 50% more consumption at the same maximum power output. However, the interesting thing is that the idle consumption is totally different; amp6 in idle uses 60mA, the above amp uses 225mA in idle. Almost 4 times as much.
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thank you very much! again 😉
 
#2,512
gmarsh said:
Cool. The 120mm hole for the speaker magnets in your Sketchup drawing won't do for the speakers, but I hope anyone building the Boominator and using the GW1058s will notice that in a hurry.
Click to expand...

You'll also notice that you don't need the magnet cut-out with the GW1058s because they're shallower than the original HP10Ws so they wont actually reach the center brace 😉

You should cut-out a piece of wood to put on either side of the center brace, 12mm (0.5") so that the magnet is in direct contact with center brace on the GW1058s. This can be done from the speaker cut-outs you have left from the sides.
 
#2,513
gmarsh said:
I'm considering four of these in series/parallel for mine, giving 21 chinawatts of solar power. They lack the connector "box" that the Sparkfun panel has which makes routing the top a bit easier:

5W Monocrystal Solar Panel 12V Battery Charge 5.3 Watt [5.2W] - $30.26 : Zen Cart!, The Art of E-commerce

I'm also considering bare 3x6" solar panels embedded in the top. You could fit 15 in the top, giving close to 30 watts. Maximum power voltage will be ~7.5V so you'll need a boost mode MPPT charger like a ST SPV1020.

There's also lots of 20W monocrystalline panels kicking around that'll fit the top, eg:

20W Mono-Crystalline Solar Power Panel with 12V Charger Controller - Solar Power Panels
Click to expand...

That China-panel has the perfect dimentions to fit the boominator 🙂 only problem is, that its monocrystal. I think I'll stick to a larger external amorpheous panel as mentioned earlier.
 
#2,514
Btw, I forgot to ask you guys, what kind of glue is recommended around the edge between the speaker, speaker grid and the cabinet, if you understand...?

Besides the glue, I'm planning on using unbraco or torx bolts through the cabinet, tightened with a nut on the back side. This should hold the speaker in place, so the main purpose for the glue is actually just to make the jointing airtight.
 
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