FAQ: Connecting your Car PC's Power and Speakers - Page 3

blk02si · 07-23-2006, 06:32 PM

Quote: Originally Posted by Red GTi VR6

again, most amps are 2 ohm stereo stable...it should be fine!

Most amps are only 2 ohm stable in mono. Meaning the channels are bridged to power 1 speaker. There are a limited number of very high end 2 channel amps that are 2 ohm stable on each channel in stereo (think $800+). You will run hot and possibily clip your signal at high volume with 2 ohm load on each channel in stereo. Do your speakers a favor to aviod blowing them via a clipped signal, wire them in series. Anyway, The real solution here is a 4 channel amp.

This is coming from someone who has a crossover and 2 seperate amps hooked up to tweeters, midranges and a 12" sub with the PC pushing everything. I like my cars to sound like a live concert just rolled by.

Crazy · 05-15-2007, 09:57 PM

I've been doing this insanity 4 a long time now. These are 2 key items 2 keep in mind:

1) ALL wires and cables should ALWAYS be able to handle the load it feeds 2 or from regardless of distance. Eg. 18 guage power cable 2 feed an amp with a 3000 Wrms output can only do 2 things, under power your amp and burn your car down.

2) In Ohm's law, lower resistance =higher load/output.But some people may not know this also means higher power draw/consumption.Eg. If 100Wrms @ 4 ohms
uses 16 amps, @2 ohms you'd get approx.140Wrms but you'd be using close to
28 amps.

Hope i helped someone.

Crazy · 05-15-2007, 10:12 PM

1 downside to series wiring. A serious loss of output power. the overheating from wiring in parallel is greatly reduced by using speakers of a higher resistance. 8 ohms is good.

blk02si · 05-16-2007, 04:31 PM

Pushing 8 ohm loads on the amp for midrange and tweeters is fine these usually only draw 125 watts max any way. If you wire subs in series you will see a great loss in the pushing power as larger speakers will obviously draw more watts due to the large voice coils of the subs. But again it all has to do with your hardware and best thing to do when hooking up any pc to other equipment is do the research on your connections and do the math on your input and output loads.

Crazy · 05-16-2007, 09:48 PM

Actually 3 spkrs/tweets of 8 ohm impedance wired in para creates a load of approx 2.6 ohms,so if each channel is 125Wrms out @ 4 ohms you'd end up with about 200Wrms @ said resistance.So 3 midrange 8 ohm spkrs on ch 1= 2.6 ohm load, 3 tweets @ 8 ohm on ch 2 = 2.6ohm load.So if using a 4 ch amp you'd still have 2 chs free, just waiting to be bridged down to 2 ohms for a decent sub.

blk02si · 05-17-2007, 12:10 PM

crazy have you ever blown up an amp?

Crazy · 05-17-2007, 06:28 PM

Judging by the question it would seem you're doubtful it's possible.So I'll try to post pics or video so you can see for yourself. And you might laugh when you see it's an old Pyramid amp.

Black98Cobra · 05-19-2007, 01:12 AM

Quote: Originally Posted by blk02si

Most amps are only 2 ohm stable in mono. Meaning the channels are bridged to power 1 speaker. There are a limited number of very high end 2 channel amps that are 2 ohm stable on each channel in stereo (think $800+).

Id have to disagree, any amp worth buying will rate is stability on each independant channel. If your paying $800+ for an amp, it better be stable below one ohm. I paid $450 for my RF Power 650 and its rock solid running 2 Ohms per speaker. With the ribbon tweeters, Im sure it dips below one ohm at certain frequencies. Ill agree that you get what you pay for but an $800 car amp better have some serious specs.

Quote:

Do your speakers a favor to aviod blowing them via a clipped signal, wire them in series. Anyway, The real solution here is a 4 channel amp.

If you look at the crossover networks in almost any box speaker, youll find that the speakers are run in parallel. Running speakers in series will add harmonics and artifacts to the speakers behind the first driver caused by the inductance and resistance of the moving voice coil of the first driver. If you do this with a tweeter and a large woofer, youll hear the effect. Also, you have no reliable way to control the volume difference between the two speakers since they are not receiving power from the amplifier at the same impedance. Granted, you get the most control running a single speaker from a single channel, but careful planning and understanding of automotive acoustics will allow you to calculate the proper crossover levels to accomplish what you want with a minimum number of amplifier bricks.

pate60 · 05-19-2007, 05:41 AM

no one has mentioned about keeping the speakers in phase!!!

when wiring up the speakers make sure that you have the + and - terminals around the right way for all speakers. if you mix these up you'll end up with flat sounding music with no bass. common trap for newbies.

2k1Toaster · 05-19-2007, 05:43 AM

Quote: Originally Posted by Crazy

[IMG]file:///C:/Documents%20and%20Settings/Administrator/Desktop/Image002.jpg[/IMG]

Your desktop isnt a server.

Use imageshack or something. Or just upload it as a pic

Crazy · 05-19-2007, 08:50 PM

Thanks for mentioning the phase aspect of this topic And you are very right.Get these two reversed and you'll get bass that sounds like dropping rocks into a bucket. Meanwhile I'm waiting for my 4 MMATS Class D 2900.05 bricks and Juggernaut 12's to arrive for this Subaru I'm supposed to work on. Any ideas would be considered and appreciated. And I need to apologize for my mistake with trying to post that pic that way.Check out the pics i uploaded and you'll see what i did.Only thing i couldn't show was the 3rd tweeter because it's behind the center speaker.