Creating a portable stereo out of car bits

alexthecheese

alexthecheese

alexthecheese

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Hi, I've got a thread in the motors forum with regard to this but would like some input on the actual acoustic design of a portable stereo that I intend to make this weekend out of a car stereo, car/leisure battery and car speakers. Basically a car stereo in a box.

As was mentioned by a nice chap in the other thread, I want to make it - within reason - as acoustically 'sound' as possible so I get as many decibels for my electric money, so it last as long as possible.

Does this involve making a soundbox for the speakers, so it's a separated enclosure from the battery and car stereo?
 
You're going to power it off a car battery? It's not going to run very long at all if that's the case.

Anyway the 6x9's should have sealed specifications but I would assume .5cf each is enough...so i would say start with around 2.0 cf of airspace and then stuff it with some polyfill til it suits your ear.
 
Seen dozenz of these done when I was camping, assuming this is what your going to use it for a sub can really help as you loose a lot of the base feel in the outside world.

have seen everything from small boxes made out of parts from car boot sales right up to some pretty hardcore stuff. My suggestion would be start simple and modify if it doesn't sound great.

Think seriously about power a normal car battery will do pretty well if just running a low power headunit with a few small speakers but much more than that and your going to need some more serious batteries, est I've seen were some old milk float batteries but they were seriously heavy and hard to come by! Maybe consider a wind turbine/solar power to re-charge the battery!
 
Not really using it as a sub as such, just as a stereo that will last for 5 days of use. We'll be taking it to Glastonbury this year so will need it from Wednesday until Sunday and without taking a load of batteries for a crap stereo I thought building it as a long-life replacement would be kinda cool. :)

I'm looking at getting soemthing like an 85ah/105ah battery, the latter should offer about 50 hours use I hope which should be about enough. It's just a 4 x 45watt head unit with 4 6x9 speakers, possibly just the two though.

What do you think of the solar chargers by the way? We can get them from eBay for about £20ish - do they actually do anything at all?
 
I'd be tempted by a cheap solar charger, not going to make a huge difference but every little counts!

My point about the Sub was that you loose a lot of base in the open air the 6x9's may well produce plenty of base in the back of your car but will lack a little punch in the outside world.

Don't forget an aerial it's cheap as chips and your bound to want to listen to it especially if you forgot the one! Go for a motorised one for extra coolness allthough not so good for the battery!

Make sure the box you build is strong enough to stand/sit on as people inevitably will and you don't want it to colapse. If it's for Glastonbury keep it smallish as you going to want to stash it away in your tent when you off listening to the bands and you don't want it to cripple you!

Final advice give it a good test session before you go! There is nothing worse than showing up dragging out you shiny new stereo and it not working or the battery going flat after 10 minutes (I've seen both and it was pretty embarassing!)
 
I know what you mean, it will be thoroughly tested next week when we're off to the Norfolk Broads! I will get it in the ear from my mates if it doesnt last a good number of hours as it took me ages to convince them to put their money into it! ;)

What do you mean about the polyfiller gurusan? Just so it's a completely sealed enclosure?

Actually, speaking of which... I'm going to nail/screw and no-nails the thing together, with some support blocks on each corner to keep it strong - like you say, no doubt people will want to sit on the thing so it needs to be strong! But what about sealing the thing so it's airtight as much as possible? Any ideas how I could do that?

An aerial too... didn't think of that. Reckon I could mount in on the inside of the box so it's not on the outside and won't get broken off?

Fingers crossed the car stereo will arrive tomorrow so we'll be able to get cracking. I'll take some pics of construction this week weather permitting. Really looking forward to getting stuck in!
 
alexthecheese said:
What do you mean about the polyfiller gurusan? Just so it's a completely sealed enclosure?

Actually, speaking of which... I'm going to nail/screw and no-nails the thing together, with some support blocks on each corner to keep it strong - like you say, no doubt people will want to sit on the thing so it needs to be strong! But what about sealing the thing so it's airtight as much as possible? Any ideas how I could do that?

An aerial too... didn't think of that. Reckon I could mount in on the inside of the box so it's not on the outside and won't get broken off?
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I think Gurusan means stuff it with foam type stuff until you like the way it sounds, it's an easy way to alter the internal size and altering the sound without having to rebuild the box!

Make sure you have at least one panel that is screwed on, if you glue and nail the whole thing you know that you going to need to get inside it and have to smash it up!

Aerial will probably need a bit of trial and error but I think it will need to be external, the thing is going to be pretty low to the ground so a proper aerial will improve reception no end. Get a telescopic one you'll only need it up when in use and they are pretty cheap to replace if it does get wrecked!

Enjoy it most of these I've been involved with have started out life as projects like this and then just grown and grown, I've seen multi-box affairs that were loud enough to put most bad boy racers to shame!
 
Well here we are mate, after a day's ******* about and some money well-spent.... here she is!!

Festival Stereo 1
Festival Stereo 2
Festival Stereo 3

We've got 2 cheap 6x9's hooked up and 2 x 5 1/4 Kenwood speakers. It's a cheapo Sony head unit but does the trick. That's plugged into a 85ah leisure battery that will keep it going for a good few hours!

Really does sound great - apart from a small hole where the speaker cables go into the speaker enclosure it's properly air tight and the bass is great! Gonna pimp it up tomorrow with some sanding and spray paint and we'll be well away.

Very chuffed indeed. :cool:
 
You could try a using a ups for a longer battery life, they are designed for desktop pcs, so they should last a long time.
 
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I dont think we need any more to be honest, I've just been checking how much current it takes with my Dad and he reckons about 1 amp on average playing a cd at a decent volume.

The battery is 85ah so it should be at least 70 hours play, and over 5 days of glastonbury that's 14 hours a day (WHICH WE HAVE JUST GOT TICKETS FOR :D )... which should be plenty. ;)
 
Update:

Painted it, put some handles on and started stickering it up. Not very happy with the painting (makes it look so amateur!) so bit disappointed with that, hence the stickers. Hopefully it'll be covered with them soon.

Here's a few pics:

Painted 1
Top bit

Personally I think the handles make it look really cool. ;)
 
alexthecheese said:
I've just been checking how much current it takes with my Dad and he reckons about 1 amp on average playing a cd at a decent volume.
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You realise that 1amp is equivalent to 12 Watts of continuous power, right?

And at high/max volume, the amp is likely to be pushing 15-20W RMS per channel. I don't want to urinate on your bonfire, but make sure you know how long it lasts before you go off to glastonbury all excited. :o :p
 
daz said:
I don't want to urinate on your bonfire, but make sure you know how long it lasts before you go off to glastonbury all excited. :o :p
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Agreed having been there and done that it's not pretty, allthough being a mini driver at the time I was more than willing to donate my battery for extended listening. Also don't forget to knock it about a bit before you go to check for loose conection and give it that authentic beatup look.
 
daz said:
You realise that 1amp is equivalent to 12 Watts of continuous power, right?

And at high/max volume, the amp is likely to be pushing 15-20W RMS per channel. I don't want to urinate on your bonfire, but make sure you know how long it lasts before you go off to glastonbury all excited. :o :p
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That's fine, my bonfire wasn't that great anyway. ;)

Seriously though, he's got a multimeter and we whopped it up to a decent volume (listenable, nothing overly loud) and it was taking anywhere between 0.8 and about 1.3 amps. So, hopefully it will last a decent length of time. Also, running it at full volume is seriously loud and I doubt we'd ever need it that high. We tested it in my garden and 100ft away it was easily still loud enough!
 
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