Re: oh yeaahhh
dvsDave said:
"Will six eighteen inch subs do the job?" asks the tech
8O my reaction exactly
followed by
8) ohhh yeaah
I have a couple of really good sharp thunder cracks from a surround sound fx library. no issue there... but I think running the deep effects is going to take a careful setup
thru a
pitch shifter and carefully set crossovers... speaking of crossovers, with 6 subs, should I set them at different frequencies or have all of them driving the same sound?
For the new techs who may not know about Crossovers: Crossovers take an audio signal and split the freuqency's between the cabinets to better have the cabinets/drivers/speakers run the frequency ranges they were designed for, best and most effeciently..and the new Digital processors and Xovers allow you to boost or cut certain frequencys to compensate for manufactuerers processors that may not be with the cabinets. It also allows you to do precision time alignment for the drivers and cabinets to keep things in
phase and time delays if you space things out. Since sound is something that moves in air at a specific speed, offsetting drivers can cause "
phase" and time alighment problems that can
effect the sound. Typically--you cannot hear most time alignment differences up to about 8-10 milliseconds, so some analyzers (like
SMAART, TEF, SIMM
etc) are used to
nail the delays precisely or close to it while analyzing a
system signal & room response. How you would set these depends a
bit on the
speaker cabinets, amps and frequency range. You can do some cool time alignment and "
phase" tricks with these.
Phase is something that if done correctly will make signals additive, or completely cancel out, or give a psychoacoustic
effect depending on the delay lengths. Ok..enough class lecture to whet the appitite for now =)
Overall to answer your question--if your subs have a very low range (not all 18" subs are created equal--are they reflex, ported or hornloaded?) your placement will vary how you delay them. If you have them side by side or separate--overall then your xover frequency should match for the most part--again tho this is pending the response of the cabinets and the rest of your
system. IOW if your subs are
x-over to about 120hz, but your mids don't
pick up below say 250 hz--there is a noticable gap between 120hz and 250hz you will want to try to fill or compensate for or the sound can be empty in that range. Changing the
x-over frequency's between cabinets is not going to accomplish much except limit the range the cabinet--one, two or all, will reproduce. Won't do much to help your idea or
effect if the rest of your
system cannot compensate for the "gap" you leave between subs and mids
IMO. Unless you had something waay cool like a few Servo-Drive cabinets that do the subsonic frequency's, and some other 18" subs, I would keep all your xover frequency's the same.
hope this helps...
-wolf
PS--almost done with the first "what is sound" tutorial...u should see it by labor day. proof read it and see if its too vague or too technical..and I'll adjust it. -w