Building (loud) portable speaker system

[Adam Froggatt]

Hello everyone.
I'm looking to build a replica version of the dubstep gun from the upcoming game Saints Row IV. Now, the actual body shaping and building is fine as is the lighting and such, but I'm looking to make it entirely functional by putting in a pair of working speakers.

However I have no idea where to start on building what is essentially a portable speaker system. It's shoulder mounted, so weight isn't too much of an issue, but as this thing is for dubstep, I'd like it to be real loud.

If anyone could advise on where to get the actual speakers and how I can make them run from a portable power supply (likely airsoft/RC battery nimh or lipo packs) it would be a great help.

I'm more than handy with a soldering iron, so it's fine if it's a self build guide kinda thing, I'm expecting I need to build an amp, and attach that and the speakers to a suitable power supply

And the bass would be dropped.

[Michael Erskine]

On 20 August 2013 10:46, Adam Froggatt <frogg...@gmail.com> wrote:
> It's shoulder mounted, so weight isn't too much of an issue

Weight not much of an issue? I challenge that statement!

http://www.instructables.com/id/800watt-12-long-16quot-diameter-Bass-Cannon/

[Adam Froggatt]

I wouldn't call that shoulder mounted.

However it is awesome.

Basically I just need a pointer, finding a cohesive guide is proving hard.

[Pat McDonald]

If it's and bassy loud then you are going to go through batteries like crazy. I can get maybe 3 hours out of fully charged car battery running a car stereo plus speakers... I don't regard car batteries as shoulder mounted, more like causes of hernias.

I am not questioning the idea (I do stuff like this), just mentioning it as a tradeoff between aesthetic beauty (it looks good) and functionality (it does the job it is supposed to).

 

[Michael Erskine]

Yes, you may need to work on bulking up your shoulders for this one :)

How much power can you get from airsoft LiPos? What size of DC amp
could be built on that power (or bought off the shelf). I'll have a
search around for the sort of rechargeable boom-box gadget that might
make a good basis.

> --
> You received this message because you are subscribed to the Google Groups "Nottingham Hackspace - Nottinghack" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to nottinghack...@googlegroups.com.
> For more options, visit https://groups.google.com/groups/opt_out.

[Michael Erskine]

A good starting point?

http://www.amazon.co.uk/RECHARGEABLE-PORTABLE-SPEAKER-BUILT-IN-SUITABLE/dp/B006BEWMHI

[Adam Froggatt]

That is a good starting point, thankyou.

The airsoft batteries can easily be chained to provide any level of power, I was thinking those as they provide an easily changeable and chargeable power source.

Also, it's for relatively short bursts of loud, not all nighter kind thing.

[Michael Erskine]

A bonus for hacking is that the product apparently arrives with the
speakers falling out!

I might get one for the kids and see how hackable it is. The speakers
on this one are 3 inch diameter - maybe a bit small. For a DIY affair,
we have various amp chips in the space. I dunno how to make an amp but
now's the time to learn!

[bruce]

I havnt done the sums, so this might not be workable, but....

If you can lay hands on a load of laptop batteries, you can strip them for the cells. There are usually 6 cells, type 18650,

about the size of a shotgun shell. They often are OKish. New, they might cost too much.

You could then power said audio set-up from a cartridge belt with maybe 20 or so, and it would fit comfortably around your

waist. Easier to carry than on your head!

HTH
bruce

[Michael Erskine]

On 20 August 2013 14:54, bruce <clothie...@gmail.com> wrote:
> You could then power said audio set-up from a cartridge belt with maybe 20
> or so, and it would fit comfortably around your waist.

That's a damn fine idea Bruce! http://en.wikipedia.org/wiki/Bandolier

[Kai Pays]

Context:

https://www.youtube.com/watch?v=QdCg5geZN3A&feature=youtube_gdata_player

[Adam Froggatt]

As fun as stripping down laptop batteries sounds, I'd rather not be strapping reclaimed piles of corrosive liquid across my chest.

Also it does all need to be contained within the dubstep gun itself, hence me going for the airsoft batteries.

To be honest, I'm struggling on the actual wiring of the speakers (and what kind are needed) more than the actual power right now.

[Kai Pays]

The only thing I can think of speaker wise that may be up to the task on a size vs loudness ratio are the bose accustimass cubes, not sure what they go for 2nd hand, but they have an awesome system that is essentially a really long tube coiled up and squeezed into a tiny cube, so you get for more air moving pressure for the size than a normal speaker.

[Martin Farraway]

I have a old pair of Eltax monitor 7 speakers I getting rid of I you want them. The only thing wrong is one of the subs have gone. Them sound fine as the subs are none drirectional. They have all the cross overs all ready in them, also with one less sub for you to drive the power consumption will be greatly improved but still have sterio separation

[Bruce Clothier]

Thanks Mike,

But I insist he goes dressed like a goucho!

Bruce

--
You received this message because you are subscribed to a topic in the Google Groups "Nottingham Hackspace - Nottinghack" group.
To unsubscribe from this topic, visit https://groups.google.com/d/topic/nottinghack/ux_ZkapgVbA/unsubscribe.
To unsubscribe from this group and all of its topics, send an email to nottinghack...@googlegroups.com.

[Chunky]

Yo Adam,

I've built a few portable battery powered sound systems and speaker cabinets in the past.

As you probably already know:
Power is in watts hence speakers are all rated in watts output.
The power output of audio is a bit wierd though as the audio signal varies so much. Generally people rate sound output in terms of peak or of rms. For a decent sound system you want a speaker/amplifier system with an rms rating, as this means it is the root mean square which will be much louder than the peak.

Computer speakers are OK and quite loud even though they are small, but they are generally rated with peak values. The other issue is that they are sometimes mains powered - you should try and get ones with a DC regulator input - even better if they are 12V input.

Another issue is bass - this is what consumes the most power in a sound system as you must move a whole load of air to create the feeling of bass.
Also with decent bass you need air inlets. Proper speaker designers go to great lengths to get the resonance of a speaker cabinet which allows enough air to push in and out to provide resonance.

Then again you probably want it loud and cheap.

Sound is pretty amazing in the fact that only a few watts seems pretty darn loud to us.

I would personally go for 12V car audio equipment. Its cheap (and easy to find second hand), loud (as everyone want their car to be the loudest). You can then easily power from a 12V source - I would suggest a cheap 12V lead acid battery. Capacity would depend totally on how long you want to run it for.
I've not use lipo etc but they would be higher energy density (and so lighter), but more expensive and probably not directly wireable to 12V audio stuff.

So my suggestion is:
a 50W 12V car audio amplifier, maybe like these:
http://www.ebay.co.uk/itm/500W-2-CH-USB-Power-Stereo-AMP-Amplifier-Car-Boat-Motor/250810981222?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D286%26meid%3D704414966761190242%26pid%3D100005%26prg%3D1048%26rk%3D2%26rkt%3D5%26sd%3D261205631015%26

http://www.amazon.co.uk/TDA7850-Audio-Amplifier-Board-50W/dp/B008VOPYFS

http://www.ebay.co.uk/itm/300W-Stereo-Power-AMP-RCA-Amplifier-Car-Motorcycle-Bike-Free-DC-power-cord/250977226771?rt=nc&_trksid=p2047675.m1851&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D286%26meid%3D704414966761190242%26pid%3D100005%26prg%3D1048%26rk%3D3%26rkt%3D5%26sd%3D261205631015%26

Might be better to find a small second-hand car amp via gumtree if possible?

Then use some car audio speakers. They will be loud, smallish and with a relatively good frequency range. Example:

http://www.ebay.co.uk/itm/Sub-Zero-Car-or-Van-dash-door-shelf-Ice-4-150W-Coaxial-Audio-Stereo-Speakers-/350855144242?pt=UK_In_Car_Technology&hash=item51b098a332

Then you also need a 12V battery (I'd use a 7Ah gel cell which will give around 3-4 hours use even at high volumes). This way you can have corrosive liquid on your shoulder.

Anyway - there are my thoughts.
Let me know if you'd like any help with it. Its very easy to get loud sounds - making loud sounds that sound good to others is a bit harder.

Have fun,

Matt

[Bruce Clothier]

Adam,

You are, of course, free to do whatever you like, but what you say about laptop cells 

I'm sorry to say I regard as nonsense. I was given some discarded batteries and the cells within are as

 safe as houses. I don't know where you get the idea that they're full of corrosive liquid.

You can hack the can open and very little harm will come. I would guess, and it is only a guess, that you are more in danger from a floppy bag than a hermetically sealed tin. Own opinions only.

Maybe others can comment.

I also have a pile of speakers extracted from those big, old CRT TVs, should you want to look at them.

I'm probably going to be in the Space tomorrow and I'll bring them in if you like. Also a small box of audio

 chips. Let me know.

Bruce

[Adam Froggatt]

Apologies Bruce, I'd misunderstood the components of laptop batteries somewhat. However it does all need to be packed inside the shoulder unit unfortunately, so bandoliers are right out for this one. If you could bring in the speakers, I'd be very happy with a few, thankyou.

Matt: That's all awesome info, thankyou. I think I need to finish drawing up the plan, but that's definitely the kind of thing I was after. It seems I need to finish the design, then I can select the right size speakers and batteries. You might get an email that reads "Would all this hook up together alright?" in the near future.

For anyone wondering, the dubstep gun looks like this:

http://images.vg247.com/current//2013/08/Saints_row_4_dubstep_gun.jpg

Current plan is to put the power supply (whatever it may be in the end) just behind the shoulder to counterbalance the speakers in the front.

[Kate Bolin]

I don't know the volume level on these babies, but they'd be a piece of cake to pop in and they're USB rechargeable:
http://www.tesco.com/direct/ihome-ihm61-portable-colour-changing-mini-speaker/215-0256.prd?recommendationId=6aaec1a9-776d-465c-9793-e21f787a87c8.0&skuId=215-0256

Plus, LED LIGHTS.

(Also, randomly, if you're looking for a good bluetooth speaker to just have in your house, we are delighted with this one:
http://www.tesco.com/direct/technika-barcelona-bluetooth-speaker/515-4294.prd?pageLevel=&skuId=515-4294)

--

You received this message because you are subscribed to the Google Groups "Nottingham Hackspace - Nottinghack" group.

To unsubscribe from this group and stop receiving emails from it, send an email to nottinghack...@googlegroups.com.

For more options, visit https://groups.google.com/groups/opt_out.

--
Kate Bolin
www.katebolin.com

[Pat McDonald]

I'd agree with Bruce, in that lead acid are the batteries with corrosive liquid in. The 7 AmpHour types are smaller than car batteries but still heavy.

If it's shoulder mount, then it will need straps anyway - so stacking up laptop cells is feasible, if expensive. They will still be heavy but more compact.

Ideally stacking LIon Lithiun Ion mobile phone batteries would give least weight, smallest size (for  given amount of AmpHour storage). A bit fiddly orking with them because they are so small.

The tricky bit with a strap or belt power pack is making it flexible yet tough.

The tricky bit with car audio is, tends to be greedy - last rig I lashed together drew 15 Amps at full volume.

Starting with the speakers and tying a couple of different amps would probably give the smoothest path to a working system, but dub step, being bass heavy, is especially prpblematic...

[Lionel]

I have a pair of decent car speakers if I can put my hands on them. I think they are in my sister's garage so I shall have to pop round there later.
I also have a pair of 10" speakers in 15" square boxes which used to be part of a PA system 50 years ago. They produce a lot of sound just plugged in to the headphone socket of a walkman type radio cassette player but are probably a bit large and heavy for your purpose. They were my PC speakers until the move from soundblaster to "modern" soundcard needed powered amplified speakers.

[Bruce Clothier]

Adam,

I'm glad Pat agrees with me! But I think he is also mistaken: apart from the automotive battery

( much, much too heavy to carry ) lead batteries are SLA ( sealed ), so no real worries. The 'bandolier' idea,  seems to have been misinterpreted. You certainly don't have to wear it round your shoulders like Santa Anna at the Alamo. I anticipated a waist-belt - discrete and easy to carry.

Another wheeze might be to use a small back-pack ( in addition to your massive head-gear ). It could be small and discrete, but easy hold a 7, 10 or more, AHr SLA. You wouldn't notice the weight ( you will if it's on your head ). Another wheeze would be to fit the speakers in the back-pack and have dummy speaker cones in the head-set. You could fit very heavy speakers in there and nobody would know: sound is like that.

HTH

Bruce

 

--

[Adam Froggatt]

Alright, huge reference posting so people know what I'm trying to build, feel free to chip components at me and I'm happy to throw you a few quid back:

Reveal video:

http://youtu.be/hDJOeCUYIqY

The real thing from the WAD WAD Edition of the game:

http://youtu.be/QdCg5geZN3A

http://images.vg247.com/current//2013/08/Saints_row_4_dubstep_gun.jpg

In-game shot:

http://hw1.pa-cdn.com/par/img/editorial/aokjgoiuw.1369313723.jpg

[Lionel]

Now that I have seen the pictures, I think these may be a bit heavy for you;

 Pioneer TS-160 160mm dual cone nom 8W max 20W 4ohm 10oz ceramic magnet.

I have tested them and shall bring them in tomorrow anyway.

[Michael Erskine]

Awesome! I'll help however I can. Tonight I found some car speakers in
the loft so I may be trying out a few portable audio
something-or-other hacks of my own in the coming months.

[Gazz]

you really don't want to be messing about with lead acid batteries this day
and age, they are ancient technology, extremely heavy and a very low power
density, only thing in their favor is price when you need to draw a 6 or 7
hundred amps for a few seconds from a 100Ah battery,

Li-po batteries weigh next to nothing (hence why they are used in electric
model planes), have very high power densities, and are pretty cheap
nowadays, tho they can be fragile... build them into a light weight box and
you should be ok, as they are in pouches wrapped in heat shrink, and you do
not want to puncture them.. of course there's tons of scare stories on
Utube, but most have them applying high voltages at high current
uncontrolled into the battery to make it light off, try that with a metal
cased cell and it'd explode,

or there's the LifePo4 batteries, these are cylindrical batteries that said
to be safer than li-po's, bit heavier but still a modern battery chemistry
with a good power density,
What you need to check is the C rating of the batteries, that's the amount
of current you can pull from them, the most common LifePo4's are at about
3C, that is you can safely pull 3 times the battery rating, which for 10Ah
cells is 30 amps,
Li-po's are available in the 100C ratings nowadays, but not needed by all
but the most power hungry applications.

i'm looking into batteries for my e-bike build, i was originally considering
these:
http://eclipsebikes.com/headway-lifepo4-40152s-15ah-p-1053.html
i'd need 12 of them (3.2 volts each cell) to get my required 36 volt pack,
but i assume your amplifier would run on around 12 volts?? then you'd need 4
of them to give 13.2 volts (absolutely fine for a car type amp, which runs
on 14.8 volts when the engine is running)

But then i re considered li-po's, as i could stuff them in my bikes frame
easier (my bike having a square top tube rather than round)
http://www.hobbyking.com/hobbyking/store/__21377__ZIPPY_Compact_5000mAh_10S_25C_Lipo_Pack.html
i'd need a 10 cell pack (3.7 volts per cell) to give 36 volts, 5AH is the
max i can get in this voltage, 25C, so i'd need 3 of them paralleled to give
me the 15Ah i want, but i could draw 125 amps if i wanted from them!,

But for your project, assuming 12 volt amplifier (if you can get/build one
that runs on nearer 36 volts it's be much more efficient) you'd prolly want
:
http://www.hobbyking.com/hobbyking/store/__32214__ZIPPY_Flightmax_8000mAh_3S1P_30C_UK_Warehouse_.html
or similar,
That gives you 11.1 volts (Will be a bit more when fully charged, but check
the amp will run at the slightly lower voltage) and 8 amp hours,

I presume you know what this amp hour lark is?? (i.e. if you pulled 1 amp
from the battery, you could run for 8 hours on the above pack, or if it
pulls 8 amps, run for one hour... tho you must not discharge these kinds of
batteries more than 80%, so say 6 hours run time, or 6 amps for an hour)

Anyhoo, i wouldn't hesitate to use li-po's for your application, yes you are
strapping bags of chemicals to your body, (downhill electric mountain bike
people put them in a rucksack all the time, many crashes and not one has
gone up in flames... yet :) but the newer nanophosphate li-po cells are much
much safer than the old type, it's the old type that are used in the dream
liner planes, amazing as they banned shipping of li-po cells in the hold of
passenger planes long ago, yet build a plane that uses the damn things for
electrical power!!

You will need a li-po charger, can be had for a tenner upwards, but if your
stuck, i have a fairly good computer controlled balance charger you can
borrow, but it is a standard hobby type charger, i.e. runs off 12 volts (so
it can be used to charge the batteries at the flying field from the car) so
you'd need a 12 volt psu for home use,

You'd also want a low voltage alarm, as the easiest way to kill any lithium
based battery is to over discharge it, all of �2.50:
http://www.hobbyking.com/hobbyking/store/__18588__Hobbyking_2_8S_Cell_Checker_with_Low_Voltage_Alarm.html

That should be your batteries sorted, tho would need to work out the exact
battery you should buy only once you have the amplifier power requirements
sorted,


--------------------------------------------------
From: "Bruce Clothier" <clothie...@gmail.com>
Sent: Tuesday, August 20, 2013 8:29 PM
To: <notti...@googlegroups.com>
Subject: Re: [Nottinghack] Re: Building (loud) portable speaker system

> You received this message because you are subscribed to the Google Groups

> "Nottingham Hackspace - Nottinghack" group.

> To unsubscribe from this group and stop receiving emails from it, send an

[Gazz]

Saw someone else say that the lifepo4 batteries found in most laptops are
not corrosive, i guess that depends on what it comes into contact with,

they do contain fluoric acid, which isnt 'that' dangerous, you are advised
to wash it off with lots of soap and water, it is extremely toxic tho,

But then again so is most of the stuff inside any battery, the 'danger' with
recycling old cells is puncturing the casing when you are removing the tabs,
but as long as you are carefull you can make up a nice pack for peanuts,

Personally i'd just buy a ready made up li-po pack new, they are cheap
enough nowadays, and the modern chemistries are really getting somewhere
regards to life and performance,
plus a new pack will have easy to connect to discharge leads, and the
balance taps terminated in the jst connector that's almost standard
nowadays, it'd be about as close to plug and play as you could get.



--------------------------------------------------
From: "Adam Froggatt" <frogg...@gmail.com>
Sent: Tuesday, August 20, 2013 3:06 PM

To: <notti...@googlegroups.com>
Subject: Re: [Nottinghack] Re: Building (loud) portable speaker system

[Matt Lloyd]

although the chemicals in any on of the lithium batteries might not be as bad as car batteries or SLA

they should all be treaded with a level of respect, see the video

Lithium Ion Batteries - Fire and Explosions

It may look like some of the packs above are just kicking out white smoke but they are doing that at about 600-1200c

For the paranoid, think about this, this is the batter tech that keeps your phone in your pocket running all day long!

Adam just grab your self a LiPo pack from http://www.componentshop.co.uk/batteries/airsoft/li-po-packs.html

nice cost vs performance, just follow the handling charging guides with respect

'RepRap' Matt

[Gazz]

I rekon all power sources should be treated with respect, they all have a
way to harm you if mistreated,
It's just that lithium polymer type technology is still fairly new, it's
come on leaps and bounds from the days of 0.5 C charge rates and 2 or 3C
discharge max,

i bet if we put a modern mobile phone battery in a turn of the century phone
(say nokia 3310) it'd last months between charges, it's just that as soon as
lighter, more powerful and smaller batteries come out, the phones get more
and more features that suck the power even faster,

That vid makes a change from the people who connect a car battery to a 7.4
volt li-po, then video it venting and flaming (for all of 5 seconds before
it goes out on it's own), and claim it happened with normal use, if i
dumped a few hundred amps into a certain part of their anatomy i bet it'd do
the same :)

That same part of the anatomy that most people lay a laptop near... which
have similar batteries, there's already been a case of a bloke who burnt his
winkie whilst surfing the net naked with the laptop resting on his belly
(the lifepo4 batteries can get pretty warm in normal use)

To be honest i'd expect similar results if you drilled through a metal cased
cell, only with more of a fragmentation grenade imitation, they are after
all shorting out a cell that can deliver 100 amps or more, if you shorted
out a li-po via the discharge wires rather than drilling through it, the
interconnect tabs would open, as they act like a fuse on completed packs.


Re: the airsoft battery, almost the exact same thing can be had for �6.69 at
hobbyking:
http://www.hobbyking.com/hobbyking/store/__9167__Turnigy_1600mAh_3S_20C_Lipo_Pack.html

it's �17.95 at the airsoft shop, but that kind of thing is normal in trade,
if it's a 'specialist' application they are selling for, double the price :)

Just you really want a bit more than 1.6 amp hours if you want to use the
dub step gun for more than a few seconds,

BTW, i am recommending Hobbyking as they were the pioneers with li-po's, and
are very good on price, they are a chinese company that make the batteries,
and basically sell direct via their warehouses, one of em being in the uk,

There are apparently only a couple of factories that make li-po cells, so in
95% of the cases, they are all the exact same thing just with a different
sticker on the outer shrink wrap,

--------------------------------------------------
From: "Matt Lloyd" <dps...@gmail.com>
Sent: Wednesday, August 21, 2013 7:54 AM

[Adam Froggatt]

It's starting to seem that as I'll ideally be carrying this thing around all day with no access to charger, the larger 7Ah cells are going to be best. Although future upgrades may see the smaller airsoft ones being used as 'ammo' to go in a slot in the side!

Thanks everyone, now it's time to get the electrics together, and get this thing built for March.

[Adam Froggatt]

Michael Erskine has kindly provided me with a pair of speakers, so now it's just a case of getting the power source and amp all hooked up. Thanks to everyone for their advice!