Battery-Powered Sound System... HOW BIG MUST MY BATTERY BE? - AVS Forum
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post #1 of 7 Old 03-03-2014, 07:40 PM - Thread Starter
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I am quite aware that this will sound like absolute buffoonery, but bare with me for just a moment. You see, I am one of them nerdy weird chicks that enjoys cosplay. Why does that matter? You'll see.

 

This is Hatsune Miku, and the pink things on her hips are what appear to be speakers. On the back, some renditions of the character feature a third speaker (presumably a subwoofer). I would really like to make a cosplay with a functional audio system mounted on the belt. Now I'm used to dealing with electronics--have a 3-foot Tesla coil to show for it--and I know enough about sound to create a basic schematic of what I want. My knowledge fails me, though, on the basis of power delegation in battery-operated systems.

 

 

I have selected a few components that will fit both the feel of the costume and the relatively small amount of space I have to work with. (Feel free to give me feedback on my choice in equipment; I am basically going in blind here.)

 

-For the two side speakers, I plan on using two Boss CH6530 3-way 6-inch speakers. (300-500W max power)

-As far as the sub goes, I've been looking into the Pyle PLPW6D 6.5-inch. (<300W max power)

-My power of choice (mostly because of space optimization) is the MTX TD-500.1D.

-If necessary, I will add to my wonderful plethora of goodies a little old crossover that my friend handed down to me.

 

The amp and the speakers will all be fitted onto a fiberglass frame much like Miku's (the character) belt (which I have yet to build because I have also yet to buy any of my equipment). Hopefully my creative side will be able to take over from there and I'll be able to construct a well-suited belt-thingy...

 

Moving on.

 

Seeing as how this system is going to be entirely mobile, it would only make sense that I either attach a giant solar panel to my head and hope it converts enough power to run my little system, or I get a battery. Either way, I run into problems. Solar panels are a little bit heavy, and it would be difficult to carry a solar panel around a 3-day convention (not to mention I'd look like an idiot and probably have to hobble my way back home with a compressed disk). On the same note, I'm not sure how a battery would fare.

 

I've scoured the interwebs in search of the holy grail of all batteries; but alas, I have found nothing to shed light upon my withered hopes and dreams.

 

And it doesn't help that I'm not too knowledgeable about DC electronics and batteries and such.

 

So long story short: I have a system that will need to be ran off of a battery. What voltage will this battery  have to be, and how many ampere-hours will it require to actually run for a decent amount of time at full power before recharging?

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post #2 of 7 Old 03-04-2014, 05:45 AM
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A couple of questions/notes:

1) Are you looking to do stereo or mono audio?
2) Why do you need to have 500W of amplifier power? ( I assume by the MTX amp information this is a 500W class D mono amplifier?)
3) To fit the profile you are looking at I would think something like this would work with cost/size savings http://www.mtx.com/portable-speaker
4) #3 above could be driven with any MP3 or phone music system, amps are built into each speaker, and the batteries are integrated into the speaker package.

Let me know what you think

My Home Theater Site:

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post #3 of 7 Old 03-04-2014, 05:46 AM
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Your question has a lot of different answers.

First the voltage depends on the electronics used and what they require. Since you are talking about a car amp-12V would be fine.

How much weight are you wiling to carry around-battery-amps etc?

How long the battery will last is determined by how loud you play it. The louder it is-the shorter the battery life-simple as that. So you can go longer at a quieter level.

"Full power" when talking about audio is a term that there is no easy answer for. Since audio is very dynamic in its "power" and different types of music have different dynamic ranges-that will greatly affect how long the battery lasts.

If you are using highly compressed music the battery will not last as long as if you were playing uncompressed classical music.

So there are a lot of variables involved here.

I would start with the size/weight issues-then go from there. I really don't think you want to be carrying around a car battery-it would kinda ruin the look

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post #4 of 7 Old 03-04-2014, 06:03 AM - Thread Starter
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Mono and stereo... Hmm. It would be kinda neat to go stereo, but I have to consider the purpose of my setup, so it may not be very different from just doing a mono setup. The reason I chose the MTX TD-500.1D is because of its compact size and relatively decent power.

 

To clarify, it is a 500W class D amp. I don't necessarily NEED 500W of power, but it would be pretty cool to show off at the con. I've pretty much set a budget high enough to build 4 of these things, so I'm not too worried at this point about cost-effectiveness; that, and my DIY nature will not allow me to buy something prefabricated. (Teehee~) However, on the subject of prefabricated things, I've seen some really powerful portable systems that lasted on batteries for hours on end turned all the way up. I'm curious as to what sort of battery they use.

 

Let's assume, then, that I have the exact system listed in my previous post, playing Dream Theatre on 50% of the amp's potential power. My goal is to optimize the amount of run time with respect to the weight of the battery. (Gosh... It would be helpful if the website listed the minimum and maximum power draw of the amp... Or maybe it does, but I dunno.)

 

What about a li-ion cell?

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post #5 of 7 Old 03-04-2014, 10:26 AM
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Lithium ion cells would IMHO be the best way to go. They have the highest energy density of anything reasonably accessible. Combine them in series to give the voltage you need and in parallel to give the play time you need. The voltage you need will depend on the electronics used. But you may find NiMH batteries a better way to go. You can get them in standard sizes and chargers are cheap and plentiful.

I think this project is doable. Kids used to run ghetto blasters on eight alkaline D-cells at levels loud enough to annoy people around them. It is just a matter of finding the right components. If I were doing it, I would just design a small, simple amplifier to do the job. But you can certainly cobble together something from existing components. You might want to see what kind of amplifier modules are available from electronic surplus suppliers.

Look for speakers intended for automotive use with the highest sensitivity.

I think it would be best not to think in hundreds of watts. You aren't going to be able to build something that rocks a convention center. You wouldn't want to be close to it if it could. And event organizers probably wouldn't appreciate it.
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post #6 of 7 Old 03-04-2014, 10:34 AM - Thread Starter
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I think I just peed a little. Ghetto blasters. Oh my gosh.

 

I do see your point though. So instead of something with hundreds of watts, looking for a setup that would be in the double-digits is what you suggest?

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post #7 of 7 Old 03-04-2014, 10:59 AM
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Quote:
Originally Posted by cookieworks View Post

Ghetto blasters...
Come to think of it, scavenging one might be a good way to go about it.

Yeah, 10s of watts.
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