I had not even considered that...I thought that daisy chaining bins to run at 4 ohm was
standard practice. And that "bridging" was "combining" to make one BIG amp running at
4ohms..... not 2 amps running at 2ohm. Although that would explain why the bass amp runs
so much hotter than the top amp.
> the current draw will be the equivalent
of two ohms for each bridged channel.
To answer your crossover question, I go
from an Allen & Heath ZED 22FX desk into a Behringer FBQ3102, this has 3 outs. 2 for
the left and right tops and sub out for the bass bins.
I imagine it is cutting bass
frequencies to the tops if I use the sub out option. Are you suggesting I should use the
pass through, take a full range signal out and use the SUB option on the bass bin amp?
> yes, let the bass through, though I think the Behringer is doing that,
anyway. You can test this by not using the subs and listening to the tops on their own.
The tops are full-range devices; it would be a waste of those nice 15s not to use them for
That raises another question, I have been using both actually, the SUB
out from the FBQ and using the SUB option on the bass bin amp (a belts and braces approach
> Yes, just use the sub out from the Behringer. The less
processing the better, generally.
I also have a sweep on both the FBQ and the
amp itself, they both go from 20 to 200HZ. On the FBQ I left it full (at 200HZ) this lets
all the bass frequencies through (doesn't it?) and on the bass amp I just messed around
with it til I got a sound I was happy with.
> I'd start with a top
frequency of about 125 Hz on the sub outs. The subs will add a bit more punch to the
system, so you won't have to push the bottom-end of the speakers.
Am I doing this
all arse about tit? Overall I'm very happy with the sound, just slightly lacking in low
> Basically the tops should sound pretty good on their own,
full-range. Adding the subs will give more low-end welly, and if it's too high-bassy, you
can bring the crossover down to 80 or 60 Hz. Or, use a graphic and cut 60, 80 and 100 by 3
Db or so.
As for the polarity questions....I have no idea!
If the polarity is correct, the bass will go up when you fade up the bass-amp's send or
volume controls. You could use a 50 Hz tone for this. If the volume goes down, the
polarities will be fighting each-other, so reverse the banana plugs (if you use them) or
get a polarity (phase) reversing XLR adapter.
And if after all this, all is
correct and it's too bass-light, get two more subs...
-------------------- PA stuff on FB
Edited by Guy Johnson (23/02/12 01:40 PM)