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Originally Posted by oniman7  Ok. So when I consider amp power rating, would I add the two numbers to get total wattage. Do I have to run it differently?
Then again, maybe I shouldn't own this particular head if I don't understand it yet. |
No, you can't simply add the numbers up. The amp has a sort of bi-amping mode where the main amp provides a full range 700 watts. The 50 watt amp only amplifies the high frequency content of your sgnal (above 5Khz) and is used to drive a high frequency tweeter or horn.
Bi-amping can be a more efficient way of driving a full range rig because it always takes more power to amplify low frequencies than high ones (and high frequency drivers are also more efficient) so by having a thumping great power amp to drive the lows and another much smaller one to drive the highs makes sense. It also makes sense to do split the signal into low and high frequencies before they go to their separate power amps because then you're only dealing with small signals that can be handled by active electronic crossovers. If you amplify the full range signal into a cab such as a typical 410 with a tweeter then there has to be a high pass filter inside the cab to make sure that the tweeter only gets the highs. Doing this is fine, but it takes chunkier components and is less efficient.
The GK system is not proper bi-amping because with that a propoer crossover system, low frequencies and high frequencies have a crossover frequency (that is often adjustable) and the respective frequencies are attenuated quite severely around that point, so the lows won't go above that frequency, the highs won't see any sgnal below it.
In the GK system, 1 channel (700 watts) is full range the other gets the output via a 5kz hi pass filtered signal, so it will will only produce highs.
It's a myth that this will only work with a magical GK cable and GK cabs, it seems to be a standard 4 pole speakon arrangement where the lull range is just carried down one pair of conductors in a 4 core cable, the highs down the other pair (most probably wired 1+/1- for the full range, 2+/2- for the highs). It's also a myth that this will only work with GK cabs. If you have a little bit of savvy you should be able to use any cab with the full range signal (as long as it had the right impedance) and any high frequency drivers with the highs.
A typical use might be to run, say, a 215 cab with the full range. The high frequencies of the full range signal wil have started to drop off way before 5K anyway because the cab won't go that high, then run a horn or tweeter box from the 50 watt amp
