6th order bandpass ø phase question

[alinedgif]

I'm confused about the physics of the 6th order bandpass as it relates to phase.
I'm also Dyslexic so please excuse replaced or misspelt words.

Q. if I put a bass guitar amp on stage behind a sound system using 6th order bandpass enclosures are there any phase problems inherent in the design of the 6th order bandpass for the bassist?
Or the audience?

What I want to know is:
Q. Are the two chambers/ports of a 6th order bandpass out of phase with each other?
i.e does the phasing of a swept sine wave 'flip' as it passes the centre overlap point of the two resonant frequencies.

Q. if so would it matter which direction the two port exists are facing with regards to the bassist or audience?

I have made two 6th order bandpass systems for playback and loved their characteristics when used with horns.
I have read a lot and pondered a lot and i want to check before committing to a live sound build. It's for a renewables 24v setup.

 

[weltersys]

1) if I put a bass guitar amp on stage behind a sound system using 6th order bandpass enclosures are there any phase problems inherent in the design of the 6th order bandpass for the bassist?
Or the audience?
2) Are the two chambers/ports of a 6th order bandpass out of phase with each other?
i.e does the phasing of a swept sine wave 'flip' as it passes the centre overlap point of the two resonant frequencies.
3) if so would it matter which direction the two port exists are facing with regards to the bassist or audience?

1) Unless the bass guitar speaker was the same design, used the same amplification, and is located within 1/4 wavelength of the mains sub there will be "phase problems".
The 6th order BP won't present any more or less than another design of the same SPL (sound pressure level).
2) The outputs of both ports are "phase inverted" from the respective cone sides so there is a 180 degree phase "wrap" between the two, the LF being +90 degrees, the middle band being 0 degrees, the upper response -90 degrees.
3) Neither direction will be "in phase" with the mains. Reversing the polarity of the stage sub may (slightly) improve room response. You could use a pin 2/3 reverse XLR cable to experiment with if the mixing console does not have a polarity reverse switch.

Cheers,
Art

 

[TBTL]

It will not happen that both the FOH system and a bass guitar amplifier play at the same sound pressure level, so phase related stuff between the two is not an issue. Either the bass is routed through the FOH system and the bass guitar amplifier is turned down (just for monitoring for the player) or the bass is not routed through the FOH system altogether.

 

[alinedgif]

Thanks weltersys for explaining enough to get my head around some more of the physics. That was really usefull, and TBTL for reasuring me further.

Seperating (in my mind) phase problems that are large, and i may be able to negate of fix (cancelations or re-enfourcments from problems in design at source or close to source) from pahse problems that are small due to time differences, tone differences, direction and reflections differences that i can't really do anything about, really helped me to have confidence in a 6th order bandpass being workable for a 24v live sound rig.