3-Way Series Cross-Over
There are 2 basic ways
of implementing a 3-way series cross-over.
1.
Cascade
2. Linked
Some general
comments:
To get the best from
a 3-way you really need sim software, you really need to
watch your impedances carefully as well.
If you want to
do a 3-way series just using the 2-way spreadsheet with any
success (or the 3-way linked spreadsheet for that matter), you
have to follow some rules ..
1. mid sensitivity
needs to be pretty much the same as the woofer sensitivity,
a small amount below is ok! any above you may need to start
putting resistors across the mid/tweeter combo, ?!!!
2. x-o points
should differ by factor of about 10
3. mids should
have a wide smooth response with a smooth roll-off.
Method.
a) treat the top point first, using the normal procedure
for 2-way. aim at zeta 1
b) now
use the mids and their sensitivity and impedance do
the bottom x-o point. also aim at zeta 1
c)
join then together using either the linked or cascade
configuration. you may need a zobel on the mid,
but its unlikely one will be needed on the woofer
cos you are crossing well below any inductive impedance
rise.
Other
Comments
Designs
like an MtMWW 'could' cause real problems if
the mids and woofs are 8 ohm drivers and you
have them wired in parallel, the impedance could
drop to very low values. It would be essential
to try to work out the overall impedance in
the lower regions, especially if a zobel is
used on the mids. (this applies to both series
and parallel x-os)
Big
differences in impedance or sensitivity between
the woofs and mids will make doing it without
sim software quite difficult.
As
with any "by ear" design, its
is (IMO) very important to plan right from
the word go, especially driver selection
!!!!
using
just any drivers and hoping to combine
them effectively in a 3-way is a big ask
!!
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