Speaker OHMS Question - TranceAddict Forums

TranceAddict Forums (www.tranceaddict.com/forums)
- DJ Booth
-- Speaker OHMS Question

Posted by Jarvmeister on Aug-03-2009 16:24:

Speaker OHMS Question

I need it explained.

If I have an amp that delivers, say, 250w @ 8ohms then what are my options?

Say I have a pair of 4 ohm speakers, what are the implications? Do I need two pairs of 4 ohms to make 8 ohms?

Essentialy, what I'm, trying to understand is how many pairs of speakers I can safely attach to a given amplifier, and what the logic is behind this.

Cheers all.

Posted by dark_Omens on Aug-03-2009 17:46:

Basically, if you put the speakers in parallel, it will half the impedance. Put them in series, and it will double.

Typically, an amp that delivers 250W at 8 ohms will deliver 500W at 4 ohms (I assume you're dealing with solid state here as opposed to tubes). Much below 4 ohms though, and the amp will shut off if it has circuit protection, as a short circuit will essentially be made due to the lack of resistance.

If the speakers operate at 8 ohms, then you should be able to put 2 sets in parallel and run the amp at 4 ohms. Should look like this:

S--S--Amp--S--S

Posted by n3lly on Aug-03-2009 17:57:

It all depends on how you wire the speakers. If you wire them in series or parallel your amp will work at a different load.

I could have this wrong because I'm used to wiring up subs and from what i can remember they were Dual Voice Coil subs so it might have different implications.

From what i gathered back when i installed my system in my car wiring in series you add the impedence of the speakers together. In this case 4+4=8ohm. Which would run your amp at 8ohm (250rms).

If you were to wire them in series then you half the impedence. So if you were to wire your speakers in parallel then you'd be giving your amp a 2ohm load. Which I probably wouldn't suggest as I'm not sure whether your amp would be able to cope under that stress.

Again I'm not sure about this and someone will no doubt come along and answer the question better than i have. But here is a diagram of speakers wired in parallel and series to help a little.

If you'd like I know a bunch of a lads on another site that I can ask for you if you need the answer asap.

Let me know if you'd like me to ask my mates.

nelly

Posted by n3lly on Aug-03-2009 18:04:

dark_Omens explained it a lot better I think lol..

The only thing I would add though is that if you're going to apply this setup to a gig situation I'm not sure how long your amp would be happy on a 4ohm load if you're pushing the amp hard.

You could instad wire the speakers in Parallel+series. Rather than try and explain I think i'll just show you this website which does a good job of explaining it I think.

http://www.speakermonger.com/tech_corner.htm

HTH..

Posted by epdarks on Aug-03-2009 18:32:

If this is a home setup just run the speakers and don't worry about it. Unless you're over-driving your amp you'll be fine.

If you're going to add a second pair of speakers, I would personally run them in parallel.

Posted by TranceOwnsLol on Aug-04-2009 06:17:

(R1*R2)/(R1+R2) = Total ohms for resistors in parallel

Posted by Jarvmeister on Aug-05-2009 15:02:

Cheers all.