Greg, the low- and high-pass outs are for bi-amping and driving those signals thru two (bi- . . .) amps, or the two sides of a single power amp, into cabinets for lows and cabinets for highs.
This sort of thing came about in the old days once people began to realize that Voice of the Theaters and Shure VocalMasters could NOT keep up with louder and louder bands in bigger and bigger venues, especially when back then a BIG power amp was 200 or 300 watts a side and the passive crossovers of the day would distort much more easily in the cabs. Having to mic kick drums and bass REALLY drove this.
So we'd take an active crossover of some sort, run the lo-pass thru 15' or 18's with as much juice as we could get because those lows are what takes diesel-strength power to push, and run a small conventional cab or horn bins for the top, which typically took maybe 1/3 the power to be as loud. Lot of rigs with DC300's for bass and D75's for highs. It just takes more juice to push those long bass wavelengths.
Bass players jumped on this back in the day. IF you weren't satisified with a big Acoustic or SVT, then you bought a bass preamp with or without a crossover, a power amp and a separate crossover if required, and lots of guys would push a folded horn or front loaded 18 or 15 for lows and 10's or 12's or 15's for highs. Then you just added as many power amps as needed and off you went. The cigar-box-sized, 1000 watt amps and Neo-cabs we have today were only dreams in the 70's.
Think about the two cabs you're buying. A crossover circuit card inside those cabinets is dividing the incoming speaker wattage into the low-pass (the bass part of the signal) into the 12 woofer. The remaining mids and highs are being sent to that 6 speaker. This circuit card inside the cab is general called a 'passive' crossover, in that it's a fixed-value circuit.
On the F1X, the crossover is doing the same function, but since there are variable controls (the crossover frequency, and the hi freq level), this would be an 'active' crossover, inasmuch as you have control over some of the parameters.
If you think about, say, a good computer audio system or the surround sound-type television rig, we see a subwoofer for the lows and smaller cabs for the highs. This would be your basic '2-way' system where those dedicated cabinets split the sound into two into specific cabinets for their load.
So, on the F1X, for example, say you set the crossover on the front panel for 150hz. At the back panel, the signal out of the lo-pass would only be 150hz and down and the hi-pass would be signal only from 150hz and up.
Commercial sound often begins this way, with flying concert sytems even tri- and quad- amped systems.
With the amp and cabinets you're getting this won't work for bi-amping: The Avatars have a full-range-only input.
In other words, the inputs on the cabs would be marked hi-pass and lo-pass where you would be plugging those same signals from the F1X into each side of the XLS and passing thru to those inputs on the cabs. One side of the XLS would drive the 12's and the other side would drive the 6's, IF the inputs on the Avatars allowed for this. They don't.
The passive vs. direct crossover argument has raged for years, and in the good cases, passives can be fine: Acme's range of cabs work just fine, for instance. Generally, for most commercial sound, active crossovers rule.
To hear the difference vs. the full-range operation I mapped out previously, plug your bass into the F1X, and set the front panel crossover at 150hz. Take the lo-pass out of the F1x and run into Ch A of the XLS(reset for normal stereo operation) and hook one Avatar speaker to that channel. Repeat with the hi-pass into the XLS ChB and into the other Avatar. Again, be SURE the crossover function in the XLS is turned OFF, or this will get REAL confusing ! The 'volume' knob on the F1X will control both of the outputs.
Do this a low or medium volume one channel at a time only and you'll hear the division immediately: The ChA tone will be like organ pedals or the dead-est tape wounds you ever heard, and ChB will sound like an AM radio. Combine them and you'll begin to get the idea. A lot of times, in a biamp rig, most of your tone is just where the crossover happens, and how much high end you add or subtract volume-wise: This is why the F1X smartly includes that 'HF Level' control, you just dial in as much hi-pass you want to suit.
Full-range cabs like you have are obviously not the preferred way to go for a bi-amp rig. However, since you're almost there, it would be easy enough to add a single 15 Avatar (15 only, no hi-driver in the cab) and use it for the lo-pass and the 12 cab you have for the hi-pass. Simple.
For the type of gigs you mention, the Avatars full range should work fine. And later, if you join a metal band, you can just expand out from there !
I ran bi-amped rigs once or twice back in the day, and for LOUD stuff it was great, not so hot at reasonable levels. I always wanted to try ELF, but probably won't get a round too-it.
Wolf or anybody else out there, what did I miss?
Joey
(Message edited by bigredbass on October 02, 2015)
