amp question? need help

[slashgnr88]

ok so I have a 100watt solid state head running through a 4x12 8ohm cab. my question is can I use this head to run another 8ohm cab.

on the back of the amp it reads......OUTPUT: 100 watts rms into 4ohms.

and under the double speaker out it reads.....minimum total 1mp-4ohms


so can I run two 8ohms cabs with this head???

 

[Rouse]

Yes, Two 8ohms=4ohms, just make sure you run them in parallel

"In series, they add normally.  Two 8 ohm = 16 ohm, etc.etc.  Parallel is more common and practical because there are no special chords or wiring, but the formula is more confusing.
This is just a little different from Mayfly's, but the formula is actually 1/((1/L1)+(1/L2)) = L total.  When adding in parallel, the total ohm load is always smaller than either of the separate values.  Two 8 ohms is 4.  4 is smaller than 8.  An 8 ohm and 4ohm = 2.666', which is smaller than 4.

The easiest way is to just put two of the same value together and divide one of them by two.  Two 8s is 4, two 16s are 8, two 4s are 2, etc."

-Super Turbo Deluxe Custom

 

[slashgnr88]

Bad A....Thanks a Ton!!! :headbang1:

 

[Patrick from Davis]

You can also use a voltmeter to check if the two cabs are in parallel.  A 4 ohm load should read approximately 3.2 ohms or resistance at rest.  Move the speakers and everything goes haywire, but the resistance is usually about 70-80% of the impedance value, even though they have quite different physical meanings.  Just put the black lead from a multimeter on the sleeve of the cable going to the cabinets, and the red on the tip and look at the mutlimeter.  Remember it is not exact, but it should give you what you need to know.  If it says something around 12-13 ohms, it is in series...
Patrick