Topic: DIY Spaced Omni Bar - active capsules [BSC2s]

[Fried Chicken Boy]

Well done, Ian!  Between you, Gutbucket and the suggestions of others in this thread, I'm getting some tantalizing ideas for the outdoor concerts this summer. 

[fatstratcat]

I'm curious about the angle you have your mics at; playing around with the "Visualization of stereo microphone system" at http://www.sengpielaudio.com/Visualization-AB60-E.htm
It seems like you'd have the about the same stereo effect with the omnis at 0° as you would at 90° or 110°.
Does it really matter?

[Gutbucket]

Even omnidirectonal mics get somewhat directional at high frequencies.  The extent to which that happens, and the shape of that pattern is determined by the design of the microphone.  Generally the smaller the mic is, the higher in frequency it will retain it's omnidirectionality.  It's enough to hear a difference with many omnis.

In general its a good idea to point the mics at the source if you want to get those highest frequencies on your recording.  Sometimes people point them straight up for measurement purposes so the respose is uniform from all horizontal directions, or to pick up less of the highest frequencies from the source if that's what they want.

The virtual microphone configuration programs usually model an ideal omni, which doesn't take that aspect into account.  It would be difficult to display the relavant data anyway if they did, since it varies by model and doesn't make a difference for most of the audible frequency range. 

So in terms of Stereo Recording Angle it doesn't really matter how you point the omnis, only how much you space them.  How you point them is more of a timbre / high-frequency response thing.

[fatstratcat]

Even omnidirectonal mics get somewhat directional at high frequencies.  The extent to which that happens, and the shape of that pattern is determined by the design of the microphone.  Generally the smaller the mic is, the higher in frequency it will retain it's omnidirectionality.  It's enough to hear a difference with many omnis.

In general its a good idea to point the mics at the source if you want to get those highest frequencies on your recording.  Sometimes people point them straight up for measurement purposes so the respose is uniform from all horizontal directions, or to pick up less of the highest frequencies from the source if that's what they want.

The virtual microphone configuration programs usually model an ideal omni, which doesn't take that aspect into account.  It would be difficult to display the relavant data anyway if they did, since it varies by model and doesn't make a difference for most of the audible frequency range. 

So in terms of Stereo Recording Angle it doesn't really matter how you point the omnis, only how much you space them.  How you point them is more of a timbre / high-frequency response thing.

That helps a lot, thanks. I built an omni bar using an aluminum bar, not a pipe, and drilled holes in the ends to clip my mics into (painted the obligatory black, of course); so, I can only have my mics at 0° with it like it is. Of course, I could go up like you mentioned.
Simple, but it will do for now.

[fatstratcat]

Ian, thanks for the inspiration to do this. I like doing this kinda stuff. Now I just need to go to some shows.....

[Gutbucket]

That's the standard A-B spaced setup- mics parallel, pointing straight ahead.  You would probably only want to point them upwards if you are using omnis which have an accentuated high-frequency response and have them positioned rather close to the source, where they might sound overly bright if on-axis.

[JimmieC]

Thanks for all the omni info.  Just got a DR-680 and finally can do a comparison tonight (AKG ck32 3' split and ck61 PAS), and then I want to try the 3 mic (2 omnis and 1 cardioid) configuration.

[thunderbolt]

Thanks for all the omni info.  Just got a DR-680 and finally can do a comparison tonight (AKG ck32 3' split and ck61 PAS), and then I want to try the 3 mic (2 omnis and 1 cardioid) configuration.

I think we need to have a bastardized name for this, like DINa.  I nominate "DTCC" (Decca Tree with Center Cardioid).

Seriously, though, I'm gonna try it out this summer--thanks Gut. 

[thunderbolt]

Here's my GAKbar with a Busman CK-1 center...

[Gutbucket]

Here's my GAKbar with a Busman CK-1 center...

Shields up! All stop. Open a hailing channel.

[thunderbolt]

 

Tribbles.must.die.

[Chuck]

I like this idea so much I bought the parts to make one today.

I've had good luck with 24 - 28" spacing with my Audix Micro series omnis. So, I'm going to make mine shorter.

I'm wondering if I can grind down the bumps on the Wedge Anchors so the aluminum rod doesn't get so dis-formed when tighting the nut after it's inserted into the tube.

Do you keep the nuts on the ends after you tighten it? I might even pour some epoxy into the tube before inserting the anchor, just to make sure it won't come out again.

Thanks for posting this project. I can make good use of a lightweight spaced omni bar.

[kirk97132]

I have materials laying around that would allow building a bar that has approx, half the spacing (about 20 inches).  Is this width not adequate to do spaced omins with?  I could build it with zero outlay, but am I wasting my time? Is there any advantage to trying spaced omnis at this distance?  TIA

[Chuck]

I've made nice recordings with the 24" spacing using Audix Micro omnis.

[fatstratcat]

I made mine out of a 30" solid aluminum bar with holes drilled in the ends. I clip my omnis in the end. I used a piece of PVC that I epoxied in the center, and have that in a shock mount. I haven't used it yet for music.