P.A. question outputs

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bassbashr99

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i have a pretty interesting question but FIRST.......

a while ago i read in bassgear magazine in the DIY section they wear splitting outputs in the back of power amps to go into multiple cabinets. the book is long gone so i cannot refer to it for details..
I have a gallien krueger 400RB-111 with 2 outputs in the back.. one is being used by the combo amps 2x10 and the other is being used by my supplied 2x10 ,both are 8ohms (i was looking around for 4x10 cabinets and there were some that were also 8ohms)

now what my question is can i split one of those outputs to go to a 4x10 cab if i wanted.. keeping in mind that a 4x10 is 8ohms and that is basically what i have right now.. just in 2 seperate cabinets..

the capacity of the amp is either 1 4ohm or 2 8ohm
 
if you add a third speaker it will be 2.67 ohms i believe.
 
If you put speaker in series, the impedance of the speakers is the sum.
R = R1 + R2

If you put 'em in parallel, you gotta use this formula:
R = 1 / R1 + 1 / R2

With R being the total impedance of your speakers. The idea here is that you gotta keep the impedance of your speakers above the lowest impedance your amp can handle. So you can use 8 ohm speakers on 4 ohm output. Or 4 ohm speakers on a 4 ohm output. But no 4 ohm speakers on an 8 ohm output.
 
i believe the formula for parallel would be r=1/(1/r1)+1/(1/r2) etc.

if it were the other way 1/r1 + 1/r2 two 8 ohm circuits in parallel would be 1/4 ohms. its really 4 ohms.
 
POWER <1% THD
240W@4ohm,150W@8ohm, 1 kHz.
(150W Into Internal Speakers.)
what does that mean.....

if u can tell i have no idea what the lowest load my amp can take
 
tyler657recpro said:
shit i screwed up

its R=1/[(1/r1)+(1/r2)+(1/r etc.)]
Click to expand...

Damn. Ofcourse...
It was meant to be:
1 / R = 1 / R1 + 1 / R2

My apologies. :o Even the smartest man can make mistakes...
 
Roel said:
Damn. Ofcourse...
It was meant to be:
1 / R = 1 / R1 + 1 / R2

My apologies. :o Even the smartest man can make mistakes...
Click to expand...
Apology accepted, but now you have to realize that we don't think you're SMART anymore!!! :p ;)
 
Roel said:
Damn. Ofcourse...
It was meant to be:
1 / R = 1 / R1 + 1 / R2

My apologies. :o Even the smartest man can make mistakes...
Click to expand...

Wow, that is so much easier to type. lol
 
wtf!

how do i find the minimum impedence for my amp?!?!?!?!?!?!?!
 
the capacity of the amp is either 1 4ohm or 2 8ohm
Click to expand...

I think this actually means that the 2 outputs on yer amp are connected in parallel. So the minimal impedance your amp can handle is 4 Ohms.

If you put in 2 speakers of 8 Ohms, they are connected in parallel, which gives you 4Ohms using that almighty formule.
 
bah

death comes to mind when i think of how easy and how much cheaper it could have been buying a seperate power amp and a 4X10
 
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