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[Uwe Riemer2]

That was a good read. I found something at the end that I've never heard of.

"The Butterworth Tweak"

11. (Butterworth crossovers only). Apply the Butterworth Tweak. Increase or decrease the delay
by the following amount:
Crossover freq Tweak (mSec)
70 3.57
80 3.13
90 2.78
100 2.50
The rule about whether to increase or decrease the delay is a bit complicated. The best
procedure is to try both and choose whichever gives the best coverage.

Anyone know anything about this???

They are refering to 18dB/oct BW crossovers:
crossover frequency is defined at -3dB
phase difference for HP/LP with the same crossover point is 90 degree, so HP/LP summation on axis (perpendicular ) gives +3dB because of the phase difference.
Adding delay to one band which equals 90 degree at crossover frequency e.g. 80Hz 3.125ms will match phase at crossover point and give +6dB summation on axis.
Off axis and/or for other frequencies things might get difficult

Uwe

[Mark Wilkinson]

They are refering to 18dB/oct BW crossovers:
crossover frequency is defined at -3dB
phase difference for HP/LP with the same crossover point is 90 degree, so HP/LP summation on axis (perpendicular ) gives +3dB because of the phase difference.
Adding delay to one band which equals 90 degree at crossover frequency e.g. 80Hz 3.125ms will match phase at crossover point and give +6dB summation on axis.
Off axis and/or for other frequencies things might get difficult

Uwe

Yep.  EV's just recommending a 1/4 wave length shift. (with 18 BW opposing polarities)

I've always thought 18dB/oct BW's are a great bet when you don't know if polarities are right, and have no time to figure it out...
...cause like you say, they will be 90 deg apart either way...which could be a whole lot worse !

[Chris Grimshaw]

I'm targeting as low as 80; and as high as 120, but with the LR24 instead of what I chose (pretty much at random) last night, the BW6.  The PV 15's are rated to handle as low as 46hz.  Of course we all know how accurate all the ratings are in manufacturer spec listings.     @120 like I had it set last night with the long slope of the BW6 the 15's were still handling a lot of bass; I had planned to hit the web today for research to figure out the next plan of attack.  And you guys did NOT disappoint!!

The number in the crossover setting (eg, LR24, BW18, etc) is the number of decibels per octave that the crossover is attenuating by.

So, once the rolloff is in place, a 6dB per octave slope isn't much - 50Hz is only 6dB down on 100Hz. In fact, you need a 12dB/octave slope just to keep cone movement level as frequency decreases (if there was no crossover, the cone excursion would rapidly increase towards the bass, which is bad for drivers trying to cover the midrange).

I'd recommend 18dB/octave or 24dB/octave slopes for crossover use, and definitely 24dB/octave to protect the sub. Steeper slopes aren't necessary (24dB/oct kills things fast enough IME), but do add more group delay around the bottom end.

Chris

[Chrysander 'C.R.' Young]

I'm running stereo in to the AMP from the mixer; left channel out to (2) PV115 mains, right out to (2) previously mentioned 800w subs.  HI/LOW pass filters set at 120 on both - sending anything above 120 to the mains, below to the subs of course.  It asked what TYPE of pass filters to use, I just chose the first in a list of at least a half-dozen.  BUT6 is what I'm using on both Hi and Low pass.

Seriously?  My ears tell me otherwise.  The recording of Vehicle, by Ides of march, splits the vocals to the left, and the horns to the right (or vise versa) - so how I had been wiring my speakers in the past (only using the "LEFT" out of the mixer) left that song sounding VERY stupid.  I tested this song specifically last night because of this.  I heard everything for once. 

I am thinking you don't have your amp set in the way you think you do.  What mode is the amp in?  For your situation, you should be in Biamp1 or Biamp2 and feeding the amp a single mono full-range signal.

[Michael Hogeland]

The number in the crossover setting (eg, LR24, BW18, etc) is the number of decibels per octave that the crossover is attenuating by.

So, once the rolloff is in place, a 6dB per octave slope isn't much - 50Hz is only 6dB down on 100Hz. In fact, you need a 12dB/octave slope just to keep cone movement level as frequency decreases (if there was no crossover, the cone excursion would rapidly increase towards the bass, which is bad for drivers trying to cover the midrange).

I'd recommend 18dB/octave or 24dB/octave slopes for crossover use, and definitely 24dB/octave to protect the sub. Steeper slopes aren't necessary (24dB/oct kills things fast enough IME), but do add more group delay around the bottom end.

Chris

Chris - I set it up at 24 all around as recommended and sounds great.  Guys in the band really enjoyed the upgrade (one of which is a sound recording engineer, so good ears!)

I am thinking you don't have your amp set in the way you think you do.  What mode is the amp in?  For your situation, you should be in Biamp1 or Biamp2 and feeding the amp a single mono full-range signal.

Chrysander - Amp is in Bi-Amp2; L/R from mixer to Amp A/B.  iPod is done into a stereo channel with L/R 1/4" trs to 1/8" headphone jack  ::shrug::  I don't know a lot about the equipment admittedly, but I know what I did, and I know what I hear. 

Hearing someone in this group confused about it concerns me though. 

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