quick ohms question

[sonik]

I can't for the life of me figure out the ohms thing...so if someone could help me out...
I have a 2x10 cabinet which is rated "4 ohms"
Inside (opened it up today because I blew a speaker and am going to get it reconed), there are 2 8 ohm speakers...
this is normal, right?  By the way it is an Eden 210 XST.

I wonder because I've seen 4 ohm speakers for sale, which would, by the same logic, have to be for a 2 ohm cab, which is something i've never seen....

[blacktiger]

Depends on how you wire them, in series, or parallel (or with 4 or more series-parallel).  Most American amps tend to be wired in parallel, so two 8 ohm speakers would yield a 4 ohm load.  The same speakers wired in series would yield a 16 ohm load, common on amps like Vox AC30s.  To keep it simple, in a two speaker set-up wiring in parallel will give you a load that's half the impedance of what a single speaker is rated for.  Wiring in series will double the impedance of what a single speaker is rated for.  If you want to know about it in more depth than that, someone else will have to chime in.

[sonik]

okay, that sounds about right...thanks!

[danoisefactory]

ok, some more info from this thread:
index.php?topic=7794.15

Let's say you have two speakers:

there 25 watt, 8 ohm.

That means that wether you wire'm parallel or serial, the resulting cabinet is 50 watts.

When wired in parallel the ohmage is:

1/8 + 1/8 = 2/8 (then turn around, just lke resistors) = 8/2 = 4 ohm.

when wired in serial it is 8+8 = 16 ohm.

So if you get speakers there are 16 ohms, you can wire them parallel and you have 8 ohms!
If you have speakers that are 4 ohms: 4+4=8 ohms!

But if you have 8 ohm speakers, you can not make two of them become 8 ohms.

here is some info:
http://colomar.com/Shavano/speaker.html
http://colomar.com/Shavano/spkr_wiring_sp.html
http://colomar.com/Shavano/spkr_wiring.html
http://colomar.com/Shavano/stereocab.html

and more:
http://colomar.com/Shavano/construction.html