Saturday, September 29, 2012

Dave Rat Blog - Up Down and Side to Side

San Antonio Texas and a cool hotel on the Riverwalk. Show day of the 4th gig of the tour leg. San Diego, Glendale AZ, and Denver so far with Dallas and New Orleans still ahead.

I continue to ponder the deficiencies in the methods typically used to setup and measure the implementation of live audio systems and question whether a truly accurate and useful method even exists. Primarily the aspect I am focused on has to do with the inability of measurement systems to adequately differentiate between comb-filtering issues occurring in the horizontal versus the vertical domains.

With two horizontally spaced sources, like our home stereo or a typical live sound system setup, the comb filtering that results is not really a negative issue to our ears yet common measurement methods will typically indicate the interaction from the output of the two sources as undesirable, not flat and a series of summations and cancellations known as comb-filtering.

With identical vertically spaced sources conventional measurement methods will measure the same issues from any single point as with the horizontal sources mentioned above, yet sonically  perception-wise to our ears, the sound is far from the same. Horizontally spaced sources covering the same area sound 'stereo' and so desirable that we strive set up sound systems this way, comb-filtering and all. With vertically spaced sources covering the same area we do not enjoy the perceptual benefits of that 'stereo' sound so all we are left with is determining whether the resulting comb-filtering is an issue or not.

Is vertical comb-filtering less important to our ears than horizontal comb filtering? Is that why variable angle line arrays are always vertical? Is horizontal comb-filtering desirable from spaced sources (stereo) and an issue from horizontal sources in close proximity? Yet with vertical sources in in close proximity, are our ears less likely to here the issues associated with the multiple sources reproducing the same signal?  If any or all of the above are true, then differing amounts of relevance would need to be attributed to comb-filtering issues depending on whether the sources are horizontally spaced or vertically spaced and also one the spacing distances as well.

Does the method you use to measure, calibrate and EQ a live sound system have the ability to tell you effectively "OK, these horizontal issues are no big deal and these horizontal issues are a big deal where as these same vertical issues are no big deal and these vertical issues are a concern."?

And on to sharing a few pics:

This blog is focused on the audio and adventure side of tour but a bit of love and recognition for my friends and the band who has me join them on these worldly adventures.

My view from FOH

It was great to see the band OFF! opening for Peppers in Los Angeles. Long history with old friends, yay!

And where I left off last blog was in Beirut, we then headed to Istambul and WOW! What and absolutely amazing city.  Truly magic and I can not recommend enough a visit there added to your adventuring dream list.

And doing Dave Rat seminars in cool places is so darn cool! Another group of wonderful sound nerds. Thank you for hanging out with me and being such gracious hosts!

Here is the Istambul gig

This was the last show with us for Ulf whom came to join us and assist with the stadium sized Peppers show. A true pleasure and honor working with you and see you soon I hope.

Finally, to sign off with a bit of curiosity, here is a pic I snapped out the van window as we drove into Tel Aviv

Oh my

OK, more to come and off to do a show in San Antonio, rocking!