Best/Cheapest way to power 6x9 speaker from PC line out ?

[alank2]

Hi,

Does anyone have a recommendation for the Best/Cheapest way to power 6x9 speaker from PC line out ?  I am planning on building a cab and it will have a regular 6x9 speaker in it.  Will I need to buy something and cut the amp out of it?  Any ideas?

Thanks,

Alan

[lokki]

Here is what I did.
I had a pair of powered speakers lying around with 16 watt AMP, (I read somewhere that 10 W should be more than enough for cabinet speakers).

One of the speakers is connected to the Sound Card, and I wired the cable that should go to the second speaker to the cabinet speaker.
I put the powerd speaker behind the coin do, (this speaker has the volume settings) so it is accesible to change the volume.
Has worked great for me.

I looked are removing the AMP from the speaker but it did not seem worth the effort.


Thanks

[SirPoonga]

not sure ont he specs of your speakers but radio shack has amp kits.

[grafixmonkey]

A really, really basic amplifier is simple to build with a few components, too.  Probably three or four components, on a board, costing $4 or $5 total, and you'd end up with a volume knob, one input and one speaker and that's it.

I've never tried building one myself, but if you wanna try it might be cool.

[alank2]

not sure ont he specs of your speakers but radio shack has amp kits.

I looked at www.radioshack.com but couldn't find any--can you post a link or two?

Thanks!!

Alan

[alank2]

A really, really basic amplifier is simple to build with a few components, too.  Probably three or four components, on a board, costing $4 or $5 total, and you'd end up with a volume knob, one input and one speaker and that's it.

I've never tried building one myself, but if you wanna try it might be cool.

What components?  Do you have a schematic?

Thanks,

Alan

[RedSquirrel]

yeah i was thinking the exact same thing now about powering some car speakers for my cab!

[SirPoonga]

hmm, radio shack use to have a nice 30W amp that almost anything could hook up to.


Well, next suggestion

http://www.partsexpress.com/webpage.cfm?&Webpage_ID=3&DID=7&CAT_ID=41&ObjectGroup_ID=200&SO=2

[grafixmonkey]

What components?  Do you have a schematic?

Thanks,

Alan

This is one I'd have to think through a bit, but it involves one resistor, one potentiometer, one op-amp, and I'm guessing I would have to add something else but we'll see.  The design I have in my head right now involves 10 or 11 solder connections.

Let me think about it a lil' bit...    the tricky part will be finding an op-amp that can supply the power you want.  I'm sure I can find one, just hafta look.

[Magnet_Eye]

Can't you just take some PC speakers or a PC sub and cut the wires and connect them to the speaker since it is amplified?

This is what I wanted to try. I have an old labtec subwoofer and the speakers plug into it. The sub is amped. So I though If i just cut the wires to the speakers and connect those to the 6x9 in my cab, it would work. YES? NO?

[nighthawk2099]

I don't think the PC speaker amp puts out enough juice for the 6x9's.  But I could be wrong...

[Magnet_Eye]

Hmmm. I guess i will just have to try it out. These things really pump, i dunno how many watts it puts out, but it is friggin LOUD for PC speakers.

it powers a 4" subwoofer and 2-2" speakers.

If it doesn't like the 6x9, i guess I will just mount the speakers inside somehow.

[RedSquirrel]

if i can find my old pc speakers im gonna try see if they can be hacked easily.

[Smittydc]

SI-5.com has a nice 15w/channel class-t amplifier that runs on 12v or batteries.  

It's a very nifty compact unit.

[jcoleman]

For my MAMEd Galaxian, I just ripped open an amplified external PC speaker, disconnected the driver and connected the cabinet's original 6x9.  Works like a charm.  If you don't have an original 6x9, get the cheapest one you can find from Radio Shack.  Your lowly PC speaker amp should drive that with no problem.  Sound quality is not really an issue, since most of the sounds from classics are beeps and boops anyway.  I doubt you'll be listening to Bach on your cab, right?  

John

[Edgedamage]

You could try what I did. This kit sells at electronic stores
with everything you need and it takes about 30min to put together. It runs off any 9v to 18v dc source.

[alank2]

You could try what I did. This kit sells at electronic stores
with everything you need and it takes about 30min to put together. It runs off any 9v to 18v dc source.

Yes, I've been looking at these, but there are many different versions.  Are you using the 7W kit like the one below?  Is it loud enough at 7W ?  Yours looks similar...

Thanks!

Alan



http://www.velleman-kit.com/

7W MONO AUDIO AMPLIFIER
Order Code:  K4001            

This small amplifier is constructed around the TDA2003 IC, capable of delivering 4Wrms at 4ohms. The IC is completely thermally and short-circuit protected. A conventional direct current can be connected as supply.

 
 Features

exists also in mounted version: M4001
 
 Specifications

music power output: 7W / 4ohm
RMS output: 3.5W / 4ohm or 2W / 8ohm
total harmonic distortion: 0.05% (1W / 1kHz)
frequency response: 20Hz to 20kHz (-3dB)
signal/noise ratio: 86dB (A weighted)
input sensitivity: 40mV / 150Kohm
overload and short-circuit protected
supply voltage: 15VDC (8 to 18VDC possible) / 0.5A
dimensions: 55 x 35mm (2.2" x 1.4")
recommended transformer: 1150080M
recommended adapter: PS1208 or PS1508
 
 

[zero-one]

You could try what I did. This kit sells at electronic stores
with everything you need and it takes about 30min to put together. It runs off any 9v to 18v dc source.

Edgeamage, so where exactly did you get the kit and who made it?

[Edgedamage]

I got it at a little electronic store the kit is sold for $18. Here's the link to the web site that makes them http://kitsrus.com/kits.html#k47  
Also keep in mind that these kits are in almost every electronic parts store.

[Edgedamage]

All I can say is that I used one on a killer instinct cab using the line out from the sound card. And the volume pot starts at the 8:00 position for it's lowest setting. And the sound was nice and comfortable at the 9:00 position. And they also make stereo kits.

[RedSquirrel]

i opened up an old pair of pc speakers today, and made it so that it connected to some old car speakers i had lieing around. worked fine =) I wanna see if my 6x9's work with it, and whether or not ill need another pair of pc speakers to hack as these ones are only 3w rms.

edit..

i think perhaps it will be fine. they are quite loud even if they are 3w wrms. (the amp).

[OSCAR]

I seem to remember a similar discussion on RGVAC a while back...  Someone was going to build a very small amp that could be installed right into a jamma harness, probably based on a LM386 chip.  IIRC, the general consensus was that a 1W amp would be sufficient to drive a single cab speaker at normal gaming volume, but I don't know for sure.

If you search some electronics projects websites, I'm sure you can find plans for a very simple amp that can be built from readily available components from Radio Shack.

Here's a few cheap kits, anyway:

http://www.electronics123.com/amazon/catalogue/c3-3-1.htm

[RandyT]

Or take a look at the ones on this page.

Not kits.  Looks like at least one of them should work.

RandyT

[grafixmonkey]

If you think it'd be fun to try building one, this might be a good circuit to try.  You see a (?) ohms resistor because it's there in diagrams I look up, but I don't know why, and its value depends on the value of the other two.  Here's the equation, assuming the top left resistor is 100 ohms:

resistance = 1 / ( 1/100 + 1/(100*A) )

the thing is, A has a range of values, so I'd just make it about 80 to 90 ohms (about 80 to 90 percent of the top-left resistor's value.)

Now, about the A...  the A is the number that multiplies the input voltage.  If you have 1 volt going in, you will have -A volts going out.  This is where the potentiometer is.  I'm not sure what the voltage of an audio out jack is, but work out 'A' so that that voltage multiplied by A is the right voltage to send to your speaker.  

Say the speaker is 8 ohms, 10 watts...  then the maximum voltage you send to it should match (V^2 / < 10,

and your potentiometer's max resistance R should match  100 * A = R, so that (max input voltage * A) < V.

The connections P+ and P- in the drawing are the power supply to your amplifier.  (they connect to the op amp.)  For safety, you could make these match the maximum voltage your speaker can stand, and then the op amp will not be able to burn out your speaker.

Or, you could just throw some stuff together, and see if anything starts smoking.       That's what I do!!

However, unless you wanna build it for fun to see if it works, getting one of those pre-made amps RandyT posted would be a better solution by far.

EDIT:  forgot to attach the drawing!  

[alank2]

Yeah, I found two of them -- which one is recommended?  These come assembled with a volume control on them for about $14 plus $6 for shipping.

UK153 - 5W Audio Amplifier (Assembled)
http://www.canakit.com/Contents/Items/UK153.asp

UK193 - 20W Bridged Power Amplifier (Assembled)
http://www.canakit.com/Contents/Items/UK193.asp

I plan on using a 30 watt 6x9 8 ohm shielded speaker (from mikesarcade!) and I am leaning towards the 20W UK193.  The doc says that it can output 12W RMS @ 8 ohm at 18V input.  I plan to tap a PC power supply 12V instead of 18V, so I'm guessing that will drop my output to about 8W RMS @ 8 Ohm.

I'm guessing the UK153 is probably about 3.5W RMS @ 4Ohm, so maybe around 2-2.5W @ 8 Ohm.  I'm not sure this would be enough, but you tell me!

Thanks,

Alan

[grafixmonkey]

If you happen to have an old AT power supply from an ancient computer, or can get one, there's a 15v lead on the motherboard connector.  Several other voltages as well, I'd bet you could find an 18v difference among them.  (I think there's a -15v and I know there's a 3v...  that might do it)

[CthulhuLuke]

Well I'd have to say this is the easiest way and will involve the least amount of work, plus it might turn out to be the cheapest as well.  Buy these, or a similar pair for the same price,
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2755181453&category=3702
*actually just head down to a local wal-mart and pick em up, they should have a set*
   and cut the wires that are going to the speakers, remember which is left and which is right, and take out the amplifier board.  This is a stereo amplifier, I have one myself on my cab, and just splice the amplifier wires to your 6x9 speakers, I think they'll output a max of 15ws, which should be plenty for arcade speakers, dont expect to run your car system with em, but they work great for me.  The only thing you gotta make sure is that the chip doesnt overheat if your running em too loud, just place your pinky on top of the chip, and if it feels super hot, dont run it so loud.
      -Chu