View Single Post
Old 28th October 2019
Lives for gear

Originally Posted by Geoff Poulton View Post
What frequency would you aim for with that deedeeyeah? Or would it depend on.........?
yes, it depends...

short answer: the lf range as you experience the largest difference in level with the phase relationship off, the mids as there is simply the most 'traffic'/our ears are the most sensitive and the hf range which can make the stereofield more wide.


long answer: i mostly measure the room before i set up spaced mics and then decide on their spacing (although i hardly ever end up using spaced mics as mains but anyway):

let's assume you experience a 'room tone' at 100hz: you could almost cancel out this frequency by using a spacing of 83,5cm which would get you (up to) 90° degrees phase offset at 100hz while all other frequencies would have a less (or a less noticeable) phase offset.
then you set identical apf's on both tracks but invert phase on just one track until you get +90° one one side and -90° on the other side at the frequency which you want to cut down.
with multple apf's you can affect the phase relationship in multiple frequency areas - but also completly mess up things, so handle with care! :-)

i'm using a measurement mic, an fft to analyze and a speaker processors for precise alignment (and i record clave clicks right in front of the main mics). without fft, a goniometer and even a simple spl meter are also helpful (although way less precise).


p.s. i learned s few things from measuring and aligning large speaker systems and especially from designing and measuring subwoofer arrays: same principles on the way in as on the way out...

Last edited by deedeeyeah; 29th October 2019 at 12:34 AM.. Reason: edited twice for clarification and p.s. added