Topic: Split Omni Mic Bar?

[skotdee]

Anyone got any suggestions for creating a mic bar to run split omnis? Im thinking around 36". Not sure if such a thing can be bought, or if I need to build it myself...

[BC]

I think people usually use 2 stands for running split omnis at shows.

[Javier Cinakowski]

Posthorn.com sells meter long hex bars for the sabra-som t-bar...   You can get 6' lengths of round aluminum bar (similar diameter) at Home Depot.

[taylordb]

I bought a 3/16" diameter aluminum bar from Home depot.  Then I took a file and filed the each end so that it was flat (so I could clip my mics to it easier).  I duct taped the bar to my small stereo bar and monted it on my stand.  I have Church Audio ST-11 mics which are very small, so this won't work if you have bigger (heavier) mics.

[Belexes]

Check out this DIY bar made with PVC:

http://taperssection.com/index.php/topic,114163.0.html

[flipp]

custom fabricated omni bar

http://taperssection.com/index.php/topic,77869.0.html

[manitouman]

How far of a split is ideal? What's the smallest split that can be used without the J-disk? My curiosity is starting my wheels turning...

[SmokinJoe]

How far of a split is ideal? What's the smallest split that can be used without the J-disk? My curiosity is starting my wheels turning...

I've read that the laws of physics/acoustics say that somewhere in 36-39" is ideal.  I can't provide the source off the top of my head, I just remember logging that information as a good starting point in a brain cell and marking it "do not destroy". 

I intend to use some particular steel tube I have, 3/8" id... just because I happen be able to weld steel and I can do what i want.  If you are more into nuts/bolts/glue, go with aluminum.  That bar that flipp linked to... that looks cool.  I would have thought it would sag like hell with those 414s, but apparently not.

[ilduclo]

How far of a split is ideal? What's the smallest split that can be used without the J-disk? My curiosity is starting my wheels turning...

I read, somewhere, probably on here, or ? that the distance should be 1/2 the distance to the stage. That is, for 5' from the stage a 2.5 split? Does this seem reasonable? I did split omnis once from a ceiling mount, using that concept, seemed to sound pretty good....that is, until one of the mics fell due to a little kid running into the wire......

[skotdee]

I've only tried it a couple times, but each time I did approx 36" and I was very pleased with the result. But don't take my word, hear for yourself: http://www.archive.org/details/dumpstaphunk2008-11-15.AKG482.FLAC16

Im not really interested in 15, 20, or even 30 foot splits, thats just nuts. I don't have that much xlr cable, and I like to keep closer tabs on my mics than that!

So yeah, a 36" split bar would suit me fine. The bar that flipp linked to looks SWEET, I wonder if he would still make them?

[ShawnF]

No, he doesn't make them, anymore.  Though if he does, I have dibs, as he twice promised me one he had already fabricated . . .    It is a cool design, though.

There was a guy from Switzerland on Gearslutz making something similar, but it was fairly expensive.  I'm sure if you do a search there you'll come across it, and Mark contributed to that thread, also.

[Belexes]

Im not really interested in 15, 20, or even 30 foot splits, thats just nuts. I don't have that much xlr cable, and I like to keep closer tabs on my mics than that!

I remember reading that for a P Floyd show in '87 in Chicago a taper bought up a whole row of seats for split mics, I assume omnis.
That's epic.

[drpro]

You might also take a look at 8020, they make a number of products.  The 10 series product is great for making mic bars and Decca Trees, plus they will cut it to size for you.

David

[taylordb]

Only run split omnis once and used a 36" spread:
http://www.archive.org/details/UM2008-04-20.CA_ST-11_omni.flac16

[Gutbucket]

Depends on how heavy your mics are.  I use black telescopic TV aerial arms to split 4060s up to 5'.  The adjustability, single stand, low visible profile and compact breakdown is really nice, but that obviously wouldn't support my TLs.

As for the spacing itself, I find 1 meter (~39") a personal sweet spot for amplified outdoor concerts.  For me the spacing determines the tone and openess of the lower midrange as much as the nature of the stereo spread. More than 3' can work with mono PAs and really decorrelates the ambience and crowd sound nicely, but also risks a hole in the middle. 

You can refer to the Stereo Zoom charts for the specific SRA (stereo recording angle) of various spacings, especially for non PA amplified music where most of the sound comes from the actual sources.  Those charts are based on data from tests of various mic spacings and the resulting recording angle - which ever recording angle you choose off the chart should be then fill the reproduction angle of a standard 60 degree playback speaker triangle.  The charts only cover spacings of ~14-20" in metric measures from 37cm (+/- 90 degrees) to 50 cm (+/- 50 degrees).. I extrapolated the chart data out to 100cm (39") and got a figure of +/- 20 degrees, FWIW.  I haven't confirmed this with a 'walk around' record & playback test but I'd like to some day.

1m also generally works well at the stagelip but I use various spacing there more often since the sound sources are so close, spread out and since level differences come into play much more.