[Primus_Boom]

I have been craving to build a Boom-Box/Ghetto Blaster for a while now and think it is time.
The problem is that I have never built anything on this scale, which is why I will need all the help and comments I can get.

To start off, let me show you the speakers that I have:
2 Kenwood JL-774 "3 Way Speaker System"
-Maximum Input Power: 140 W
-Impedance: 8 Ohms

The speakers are pretty large, but I want a THUMPING ghetto blaster.

Now I have been reading over DIY Boombox Project - bit-tech.net Forums and MetkuMods - Because you love your hardware!. I found some good information here but I still had a few questions:

-What type of amp would be ideal for my system?
-What type of battery/supply would be ideal for my system?
-Would I need to get special capacitors or crossovers or can I use what's included in the speaker cabinets?

Here are some pics of the speakers:

Here is a site I found with pretty cool amps:
41Hz audio amp kits. Sounds good to me! Tripath based amplifiers for DIY:ers.

I have been thinking about it and have came to a conclusion that this box will only be using 1 speaker, hence only needing 1 channel.

I appreciate whatever help i can get...
Thanks

 

[MASantos]

A Boombox is suposed to be an all in one case solution.

If you're building from scratch you should really get the separate drivers, build an enclosure, get an efficient amp and a battery, size depending on how much play time you're aiming for.

You should look for efficient speakers, which don't need much power and hence reducing the need of a big amplifier.

Class D amps are good if you're not aiming for the best sound quality, if you want this to sound better than average than you should look for class AB amps, like a gainclone.

20-40 Watts should give you lotsssss of thump with efficient drivers.

For the enclosure use MDF 1/2 or 3/4(will be heavier but probably less fragile)

Go over to DIYaudio.org and search for efficient drivers and speakers, browse the speaker building sites to look for ideias.

Now, if you really want to use those speakers, build a gainclone, get yourself the biggest battery you can afford and carry around and put it all together some way.

 

[gz76]

No DIY ghetto blaster is complete without a car stereo mounted on the front of it!

Good luck with your build.

 

[Nemo de Monet]

Car stereo? What kinda ghetto you from?

I'm thinking more a salvaged 4x beige CD-ROM drive, myself. That's ghetto.

(I've even occasionally toyed with the idea of making a really nerdy stereo out of an old external SCSI CD-ROM or tape-drive enclosure with internal power supply, like the old SUN 411 or 611 cases. It wouldn't be super-powerful, but it'd be nerdy as hell...)

 

[SiBurning]

Quote:

Originally Posted by Primus_Boom /img/forum/go_quote.gif -What type of amp would be ideal for my system? -What type of battery/supply would be ideal for my system? -Would I need to get special capacitors or crossovers or can I use what's included in the speaker cabinets?

Lots of choice in amps, and I don't have an opinion. The battery's the big issue. The speaker's crossover is already set up to do the right thing: just use it.

Trying to drive a 20W amp for any length of time requires some serious battery power and weight. You need to have a certain voltage, and that choice might limit the amp you choose. I see they have amps from 14.4V on up. A 15V battery pack would be convenient for one of the 14V amps. Need to take care in choosing it that you choose one that can supply the current you need. My guess is you'll have a hard time with anything other than lead-acid, which is a pain to work with, and doesn't like being drained. Lithium batteries are much lighter, and easier to work with, but they may not provide the power you need. Standard sized D batteries might be an option as well, either NiCd or NiMH.

Have you given thought to how you're going to use this? Small outdoor speakers would be ideal. Indoor speakers don't handle water, moisture, or change in temerature and humidity well. You also want grills over the speaker cones for protection. You might also want to do something to waterproof or seal the speaker connectors. At an outdoor party, a stereo pair of detachable speakers would be pretty cool, although a single speaker can be much larger, and will probably deliver deeper bass. Either way, you need to figure out how to mount the the speaker(s) to the main box, or vice verse.

Will it be set up to use alternate power sources? You might want to hook it up to the car or a generator or standard D batteries. There's also outputs to consider--or not--but even if you build a mono amp, it'll probably accept stereo inputs, so will it have outputs? Maybe you can set it up to have two amps, but have a switch that can either mix the two signals and only power one amp, or keep the signals separate and power two amps. Or just build and carry two of these pups.

What about the sources? Would you be connecting portable CD players and MP3 players? If so, how will they stay on? Perhaps a protective top cabinet with some velcro straps. If you decide to build it into the existing speaker cabinet, you'll change the acoustics, and probably won't like the results, so you'll need to do some speaker design. Easire to mount the hardware outside.

Finally, if you're gonna call this a portable, you're gonna get a lot of flac from people around here about how it's only transportable.

 

[Primus_Boom]

Quote:

Originally Posted by SiBurning /img/forum/go_quote.gif Lots of choice in amps, and I don't have an opinion. The battery's the big issue. The speaker's crossover is already set up to do the right thing: just use it. Trying to drive a 20W amp for any length of time requires some serious battery power and weight. You need to have a certain voltage, and that choice might limit the amp you choose. I see they have amps from 14.4V on up. A 15V battery pack would be convenient for one of the 14V amps. Need to take care in choosing it that you choose one that can supply the current you need. My guess is you'll have a hard time with anything other than lead-acid, which is a pain to work with, and doesn't like being drained. Lithium batteries are much lighter, and easier to work with, but they may not provide the power you need. Standard sized D batteries might be an option as well, either NiCd or NiMH. Have you given thought to how you're going to use this? Small outdoor speakers would be ideal. Indoor speakers don't handle water, moisture, or change in temerature and humidity well. You also want grills over the speaker cones for protection. You might also want to do something to waterproof or seal the speaker connectors. At an outdoor party, a stereo pair of detachable speakers would be pretty cool, although a single speaker can be much larger, and will probably deliver deeper bass. Either way, you need to figure out how to mount the the speaker(s) to the main box, or vice verse. Will it be set up to use alternate power sources? You might want to hook it up to the car or a generator or standard D batteries. There's also outputs to consider--or not--but even if you build a mono amp, it'll probably accept stereo inputs, so will it have outputs? Maybe you can set it up to have two amps, but have a switch that can either mix the two signals and only power one amp, or keep the signals separate and power two amps. Or just build and carry two of these pups. What about the sources? Would you be connecting portable CD players and MP3 players? If so, how will they stay on? Perhaps a protective top cabinet with some velcro straps. If you decide to build it into the existing speaker cabinet, you'll change the acoustics, and probably won't like the results, so you'll need to do some speaker design. Easire to mount the hardware outside. Finally, if you're gonna call this a portable, you're gonna get a lot of flac from people around here about how it's only transportable.

As for the case, I am drawing up sketches and will come up with better results once i find out what size battery and amp would be hooked up to this. One of my friends is really good with woodwork and has a woodshop which would probably be ideal for constructing this thing.
I will post up more pictures once I take this person apart and scan some sketches that will be drawn.

I like your idea with the stereo input to mono output, that's what I was looking for. I want to have a line input for say an mp3 player (will probably make some sort of stand for it). As for battery, I was going for something rechargeable with a life (more than 5 hrs). Problem is, I'm not too sure as to which amp would be the most "efficient" for this speaker along with a battery that would be ideal to power the amp. I am looking for it to be LOUD, but clear as well. I am mainly going to keep this box indoors for it is going to be more of an experiment, but I do want to bring it up to my rooftop for when I have parties.

 

[Nemo de Monet]

IMO, if you want five hours' battery life out of it, and want it to be party-loud, you're best off looking at a different, more efficient pair of speakers. I've some indoor/outdoor (waterproof!) bookshelf speakers from KLH that are 40W, pretty efficient (89Db/1W), and don't sound too bad for what they are. (Or just hunt through a thrift store until you find an old pair of high-efficiency speakers - 15-20W Technics or Pioneers.) Couple them with a $30 TA2024 amplifier board, and a $35 12V, 18AH lead-acid battery, and you should have a whole world of loud, semi-portable music for six to eight hours at a time.

 

[Primus_Boom]

Quote:

Originally Posted by Nemo de Monet /img/forum/go_quote.gif IMO, if you want five hours' battery life out of it, and want it to be party-loud, you're best off looking at a different, more efficient pair of speakers. I've some indoor/outdoor (waterproof!) bookshelf speakers from KLH that are 40W, pretty efficient (89Db/1W), and don't sound too bad for what they are. (Or just hunt through a thrift store until you find an old pair of high-efficiency speakers - 15-20W Technics or Pioneers.) Couple them with a $30 TA2024 amplifier board, and a $35 12V, 18AH lead-acid battery, and you should have a whole world of loud, semi-portable music for six to eight hours at a time.

That sounds like a pretty good idea. I will look more into this idea