Amplifying PC Audio

[Hiub]

Well, I managed to source some cool speakers for my arcade project. I got 2 4.5'' drivers from a friend of mine's car, and i bought a 10'' sub from ebay for about $15. I saw the write-up on Oscar's site about hacking a set of cheap-o speakers which I had laying around, but the board that came out of them really does not have enough power to drive the speakers properly. The speakers sound underpowered and just plain like poo. I've done some searching, and I found out that I can use a car amp hooked up to the computer's power supply. I couldn't get a clear answer as to wether I could use the same power supply powering the computer or if I needed another one, or if I needed to hook up several power supplies in series. Other than a car amp, is there any other alternative that may be a bit easier to use the speakers to their full potential?

Thanks in advance, Fred.

[dmish82]

Car amps are pretty expensive (At least $60 or more if you can find a great deal). for that price you could have bought some really nice computer speakers w/ a sub that are powered. If you look online there are circuits that you can build to "drive" the speakers to make them louder. That may be more work than it's worth though. Good luck.

[Hiub]

I can find some pretty cheap amps on eBay, so if that is the best route for about $20 I can get one. Oviously I do not need a 1000w amp for this thing, so anything small will do.

Thanks for the reply, Fred.

[daywane]

I do not have golden ears. I kan not hear some hiss noice like other people do. I just picked up some stereo's from yard sales then hooked up the pc into the cd ports. sound great to me. I am not talking about the book shelf type I am talking about the component type.
I get them for $25.00

[Hiub]

Not a bad idea, I was thinking I could go that route, as long as I find something cheap enough. I think I remember seeing some at the thrift store last time I went, hmm...

Thanks for the suggestion, Fred.

[bryan1945]

Hiub- asked my dad about car amps since he plays with 'em a bit, and they use a 12 volt power source.  So if your computer's power supply can provide the 12v power without exceeding it's rated limit, then you'll be ok powering the amp from the computer.  However, due to the transient nature of sound (lots of quick peaks rather than a constant norm) I would go with a separate power supply if you can.  

As an electrical engineer, putting power supplies in series-  pretty much a bad idea.  Fires, explosions, chaos, cats & dogs living together will result.  

An alternative is a home stereo amp.  They tend to be bigger, though cheaper.  If you have an old receiver/stereo, you can power your speakers through that.

Hope that helps.

B

[Hiub]

Man, I was reading on some random car audio forum how some guy had a 12 volt battery hooked up to a charger in his room, and that's how he powered his amp and speakers. Not a smart kid by any means. Thats the same place where they mentioned wiring the power supplies in series too, I guess I'm not going around there any more. I have a couple of power supplies laying around, I am going to get my hands on a cheap amp and give it a try. Also, like I said, I am going to scrounge up a home stereo amp, and see how that goes.

Thanks again for the heads up, Fred.

[seibu]

Two pieces of advice here:

1) Powering an amp from your PC's power supply can very often result in a ground loop. Several electrical people have told me that this is impossible, but I know what a ground loop sounds like! Any amp I power from my PC and then connect to the PC's sound card gives the classic ground loop buzz, which goes away when I put the PC sound signal through an external amp, or an external audio signal through the internal amp. Draw your own conclusions.

2) Remember that speakers depend on the resonance of the cabinet to make bass frequencies. At first I thought my speakers sounded weak and thin, because they were not screwed into anything. When screwed into the cab they sounded a lot better, and with the top fastened down (it's a cocktail) they sounded awesome!

[gap]

I used one of the amp kits mentioned above.

More info here:
http://www.mamegap.com/audio.htm

[Minwah]

Not neccessarily of use in this case, but SoundBlaster 16PCI's have a (small) built-in amp which outputs through the black 3.5mm jack - I just use this to power my (Happ) speakers.  Obviously not audiophile quality, but for old arcade games it does a great job

[RayB]

2) Remember that speakers depend on the resonance of the cabinet to make bass frequencies. At first I thought my speakers sounded weak and thin, because they were not screwed into anything. When screwed into the cab they sounded a lot better, and with the top fastened down (it's a cocktail) they sounded awesome!

Yeah tell me about it! Basically, your cabinet becomes a bass box. I am always impressed with the bass in my Galaga (it has a standard arcade speaker, probably the 5 watt 8 ohm variety) and I can feel the cab vibrate when there are bass sounds. No amp either. It's all straight off the game's circuit board amp.

Basically, a cheap little amplifying circuit is ALL you need. When I built my SNES cab ages ago, I used a cheap little one from Radio shack. Might have cost $10-$15. Car amps, car speakers... it's all overkill.

~Ray B.

[rchadd]

dont forget the car speakers are probably not shielded - not good if intend putting them in cab close to the monitor!

also it is desirable for speaker impedence to match the amps.

i got Happ shielded 12W 8ohm speakers connected to an amp i ripped out of a pair of 3(ish)W RMS PC speakers. they sound great even though the original pc speakers were tiny and 4 ohm. bass is especially nice probably due the large wooden box that is my cocktail cab.

http://www.arcadecontrols.org/yabbse/index.php?board=10;action=display;threadid=25687

i was originally worried that i should get a more powerful amp to match the speakers - but it is plenty load enough now!

however...anyone know of any good amp circuits or kits that are available? i enjoy a bit of soldering...

[gap]

however...anyone know of any good amp circuits or kits that are available? i enjoy a bit of soldering...

There's a 10x10 watt stereo amp that several builders here have used.  You can see my use of this amp on my website:

http://www.mamegap.com/audio.htm

Numerous places on the internet sell it.  I bought mine from circuitspecialists.com.  Others have purchased from electronickits.com.

[Darkstalker]

Two pieces of advice here:

1) Powering an amp from your PC's power supply can very often result in a ground loop. Several electrical people have told me that this is impossible, but I know what a ground loop sounds like! Any amp I power from my PC and then connect to the PC's sound card gives the classic ground loop buzz, which goes away when I put the PC sound signal through an external amp, or an external audio signal through the internal amp. Draw your own conclusions.

It isn't electrically impossible, they would be sharing a common ground, and the sound card would be picking up the noise from the amp.  It is best to set the amplifiers input level as low as possible. The best subjective S/N ratio is obtainable this way. Try to drive as high a signal level from the head unit as possible.  The only other problem I see with hooking car audio components to a PC is mixing impedance...

2) Remember that speakers depend on the resonance of the cabinet to make bass frequencies. At first I thought my speakers sounded weak and thin, because they were not screwed into anything. When screwed into the cab they sounded a lot better, and with the top fastened down (it's a cocktail) they sounded awesome!

That, and make sure you give your speakers some breathing holes behind the cone.  If you seal a speaker in a box you are limiting the sound potential.