GK 700RBII Total Power Question??

[jrsmiles]

I'm a little confused on the two speaker outputs in the back and how that will affect the total power.

Scenario 1 - Hook up one cab to one output in the back of the amp. This gives you an 8ohm load.

Scenario 2 - Hook up two cabinets, one to each output on the back of the amp. This gives you a 4ohm load.

Is that correct?

When hooking up two cabs via the two output jacks, does this give 480w to each cabinet, or 240w to each?

AND, if only using one cabinet (8ohms) do you only get 320w to one cab?

Thanks!

 

[FretlessMainly]

The overall impedence is a function of the impedence of the cabinet(s) and how they are connected. If you use a single 8-ohm cabinet, the impedence is 8 ohms and the 700RB-II pushes 320W. If you then add a second 8-ohm cabinet in parallel (i.e., using both speaker jacks on the amp), the overall system impedence is now 4 ohms and the 700RB-II pushes a total of 480W - as 240W to each cabinet (more or less). Because you are moving twice as much air (assuming that the cabinets have the same speaker configurations), this is noticeably louder than one cab at 320W.

It's important that you only use 8-ohm cabinets in this case, because the total impedence for wiring in parallel is calculated from:

impedence = 1/(1/impedence cab 1 + 1/impedence cab 2).

= 1/ (1/8 + 1/8) = 1/(1/4) = 4 ohms

Using one 8 ohm and one 4 ohm cabinet in parallel gives less than 4 ohms impedence (2.67 ohms to be exact) and you'll burn out your head.

I would add that the wattages are for normal operation (called rms, I believe) - peak wattages can be higher, and the 700RB-II is a loud head.

 

[jrsmiles]

Good point, I should have specified only 8ohm cabinets are in question here.

Thanks for the reply.

 

[B-string]

First the speaker cab provides the impedance to the amp (assuming here you are talking two 8 ohm cabs).
You can use both speaker outs or daisy chain one cab from the other, the end result is the same 8+8 ohm cabs in parallel is a 4 ohm load.
The two cabs will share the 480 watts (240 each)
Yes you will get 320 watts to one 8 ohm cab, you can also have 480 watts into one cab if that cab is 4 ohm impedance.

 

[DrewGK]

i personally bought my Neo 212 in a 4ohm version so it gets the full 480+50 form the head

so yeah theres always that option

 

[B-string]

i personally bought my Neo 212 in a 4ohm version so it gets the full 480+50 form the head

so yeah theres always that option

With two 8 ohm 212's you would get 480+75 from the amp head.

 

[4001]

Not sure, so before I do....can I use the 700RB II without hooking up cabs??
You know, for recording direct??

 

[Marton]

Not sure, so before I do....can I use the 700RB II without hooking up cabs??
You know, for recording direct??

IIRC, they tell in the instructions manual that its OK to do so.

 

[B-string]

Yes you don't need to hook up a speaker cab or dummy load to run the amp.

 

[4001]

Thanks! I was too lazy to look for the manual last night.
I thought so, but wasn't 100% sure.