Ghetto speaker party! Woooo!

October 25, 2007 11:12 AM

Let's ghetto-rig some PA speakers! (Audio challenge inside :D)

We inherited some massive speakers a while back, but no amp/mixer/anything else you would need for a PA system. They are approximately 4ft high Soundtech PA Speakers. A photo of the input panel (the same in each speaker) can be found here.

So here's the challenge: we need a way to rig these to, y'know, play music this weekend for a Halloween party. We have at our disposal a car amplifier (of unknown wattage, but I can find out if necessary), a stereo receiver, plenty of ingenuity, and very little money. What we need are some very creative suggestions on how to get these to work.

Any crazy suggestion welcome. The obvious solution of "go rent some equipment" has already been thought over and discarded. We wouldn't know what we needed and probably wouldn't have the cash to go get it. Any other random equipment can probably be borrowed or finagled from friends. :D

posted by denimflavored to technology (15 comments total)

Ghetto style? Here's what I would do - expect some purists to shed a few tears over what I'm about to tell you.

Go buy one of these.
Chop the two 1/4" ends off.

Strip the wires and then splice on some longer speaker wires (anything you have will do). Attach the wire that is spliced to the center conductor of the 1/4" plug to the positive (red) terminal on the receiver.

Plus the 1/4" ends into either of the "Full Range" jacks on the bottom of your speaker input panels.

Turn it up and go.

The car stereo amp is more trouble than it's worth (trying to find a 12v power supply with enough amperage).

It may sound like crap, it may not.

Feel free to ask for clarification in thread.
posted by davey_darling at 11:26 AM on October 25, 2007

Wire up some speaker cables to some 1/4" phone jacks and plug them into one of the inputs labeled Full Range. The stereo receiver is probably your best bet.

On preview: what davey_darling said.
posted by zsazsa at 11:29 AM on October 25, 2007

Be wary of your resistance levels.
posted by nomisxid at 11:30 AM on October 25, 2007

They're 8 ohm speakers, so most amplifiers should have no problem driving them.
posted by pombe at 11:41 AM on October 25, 2007

Using the car audio amplifier has two problems:

1. Car amps accept 12V DC. House provides 120V AC

2. Car amps output 2 or 4 Ohms. Speakers are 8 Ohms.


You can get converters for the voltage problem, but they aren't cheap and struggle to provide sustained high power, which you will require. You chould try rounding up a bunch of your friend's car batteries and wire them in series, and see how long that lasts. Could be quite a while.

Problem Two is not as much of a problem. You can drive 8 ohm speakers with a two or four-ohm amplifier, it just wastes efficiency, since to acheive maximum power you need to impedence-match.

So yeah, hacking together wiring from your reciever directly to the speakers is your best bet.
posted by lohmannn at 12:01 PM on October 25, 2007

Crap, should be "wire them in parallel." Wiring a bunch of car batteries in series would be BAD.
posted by lohmannn at 12:02 PM on October 25, 2007

To clarify what davey_darling and zsazsa said about the "Full Range" jacks: you don't need the splitter that davey_darling suggested. The "PARALLEL INPUTS" label that's awkwardly split across the "FULL RANGE" label means that those 2 jacks are physically connected to each other inside the speaker. Presumably, there are 2 so that if you've got a bunch of speakers to connect and an amp that can handle a low-impedance load, you can just "daisy chain" them together by plugging each additional speaker into the spare jack of the one before it.

You say you have "some speakers," but don't specify how many If it's just 2, you can just hook one up to each of your receiver's left and right outputs and everything will work. If you need to drive more than two, things get a bit more complicated. Check your receiver's back panel/manual to see if it supports loads at a lower impedance than 8 Ohms. 8 is the standard for home stereo, but many receivers are capable of doing 4 as well, possibly selected by a switch near the speaker connections. If so, you can hook up 2 speakers per output. If not, or if you're trying to hook up more speakers, we'll need more details about your situation (number of speakers and receiver model or specs would be good to start)
posted by contraption at 12:08 PM on October 25, 2007

Contraption, I understand what you are saying, but you've misinterpreted me - I just told him to buy the splitter because it's probably the least expensive way to get two 1/4" plugs with wires already attached. I told him to cut the ends off and make speaker cables with them.
posted by davey_darling at 12:19 PM on October 25, 2007

Sorry, davey_darling, I didn't read your commment closely and thought you were recommending cutting off the jack end of the splitter and using the resulting bare wires to split the speaker outputs from the receiver, when in fact you were complying perfectly with the OP's guidelines. Reducing costs by cannibalizing the connectors from an adaptor is a ghetto-fabulous idea.
posted by contraption at 1:14 PM on October 25, 2007

1. Car amps accept 12V DC. House provides 120V AC

2. Car amps output 2 or 4 Ohms. Speakers are 8 Ohms.

Problem one can be solved with any old computer power supply - how to turn it on will depend on how old it is.

Problem two isn't really a problem at all, for the most part, though you may have to turn the volume/gain up a bit.

That said, hooking up to a bookshelf stereo system is probably the right way to go. The exact cable you need will depend on what you find, except that one end will be a 1/4" jack of course.
posted by Chuckles at 7:12 PM on October 25, 2007

a stereo receiver

Ah! Perfect alternative to bookshelf stereo system, though it isn't as "ghetto" :P

What kind of terminals does it use for speaker out? Probably spring terminals, I suppose, so you won't have to worry about the amp end at all.
posted by Chuckles at 7:24 PM on October 25, 2007

Thank you all for the replies. :D I'll best-answer someone as soon as we've got it all hooked up.

To clarify for anyone who's still interested, we've got 2 speakers. The receiver *does* have spring terminals. And I am definitely a she. ;)
posted by denimflavored at 5:27 AM on October 26, 2007

And I am definitely a she. ;)

Aww, sorry!
posted by davey_darling at 7:05 AM on October 26, 2007

Chuckles -- thanks for pointing that out. I had completely forgotten about using a computer power supply. I don't know how I overlooked it, as I have actually used a psu to power up and test a new head unit before!
posted by lohmannn at 10:59 AM on October 26, 2007

Haha, it's cool. :D
We got everything hooked up - I a friend of mine soldered some tips to some pretty heavy gauge speaker wire and now we're good to go. We even got the hookups to plug my MP3 player to the receiver. Hooray! Muchas gracias to all!
posted by denimflavored at 8:53 PM on October 26, 2007