# AM I BEING STUPID....?

Discussion in 'Amps and Cabs [BG]' started by stompfrog, Sep 9, 2005.

1. ### stompfrog

Apr 12, 2004
hello

todays quiz....

one 8 ohm cab = 8 ohms resistance

two 8 ohm cabs in series = (8x8)/(8+8) = 4 ohms

am i right so far....?

three 8 ohm cabs in series = what??

(8x8x8)/(8+8+8) = 21.33 ohms?

2. ### strummer

Jul 27, 2005
Sweden
Hi

2x8 ohm cabs in series gives you 16 ohms, 3 will give you 24 ohms.
But I think you mean parallell, and then 2x8 ohms gives 4 ohms and 3x8 ohms will give you 2,67 ohms.

3. ### wildduck#7

Jul 5, 2005
Aachen, Germany
@ stompfrog

No,

the 2 basic formulas are (where Zx ist the impedance of one cab and Z is the resulting impedance):

Series: Z = Z1 + Z2 + ... + Zn

Parallel: Z = 1 / ( (1/Z1) + (1/Z2) + ... + (1/Zn))

Hope this helped.

4. ### stompfrog

Apr 12, 2004
Many Thanks. I guess I wont be having a 3 cab setup then.

Cheers

5. ### stompfrog

Apr 12, 2004
If you had a stereo head what happens then? A g**tar playing friend of mine has a H + K triamp with 2 (stereo) 16ohm outputs. if you connect a 16ohm cab to each is that still gonna give a total resistance of 8 ohms or is this now a parrallel connection so the total is 32?

hope that makes sense...

6. ### wildduck#7

Jul 5, 2005
Aachen, Germany
The TriAmp outputs are 2 paralleled mono outputs for connecting a stereo cabinet, not real stereo.
If you connect 2 pcs. 16 ohm cabs, your total impedance is 8 ohm, not 32, because they are paralleled internally, and paralleling 2 same cabs gives you half the impedance!!! (check the formulas)

7. ### stompfrog

Apr 12, 2004
This is so confusing...

just to check.... my warwick quad vi head has one speakon output that goes into a cab then out of that cab and into another cab. that is parallell right so its 8 + 8 = 4 which matches the head.

and... with the tri amp you would want to connect two 8ohm cabs to the 16 ohm stereo (paired mono) outputs to get everything working in perfect harmony.

thanks for your continued patience with my ignorance.

8. ### wildduck#7

Jul 5, 2005
Aachen, Germany
You are correct with your Warwick calculations.

To the Triamp:

The 2 (stereo) outputs are internally connected parallel to the 8 ohm tap of the output transformer. You should connect either one 8 ohm cab or 2 16 ohm cabs to this output / these outputs.
Common guitar cabs can be switched as mono with 8 ohm resulting impedance or as stereo with 2x 16 ohm (because when they are switched to mono, they are internally paralleled)

So connect either 1 pcs. 8 ohm mono cab to one of the outputs (and leave the other open) or connect 2 16 ohm cabs to the head (then internally paralled, resulting also to 8 ohms.