Audio Static in Cultural Hall

[russellhltn]

Originally, you said it was when you were using a HDMI cable. Has further testing shows that to be false?

The metal stand could be a factor, but it's a bit "out there". (But then I have a few "war stories" of "out there" problems. Like a computer keyboard that didn't like metal desks.)

[Hilohi]

Originally, you said it was when you were using a HDMI cable. Has further testing shows that to be false?

The metal stand could be a factor, but it's a bit "out there". (But then I have a few "war stories" of "out there" problems. Like a computer keyboard that didn't like metal desks.)

In all cases I was using an HDMI cable to connect my computer via a USB hub to the projector. It was only when I experienced audio static that I started to troubleshoot and noticed that it was when I connected the HDMI cable to my computer and projector that the static started (connecting the power cable, the dvd drive, 3.5mm adapter did not introduce static). The variable when I had static and didn't have static was when I placed my laptop on the metal projector stand, so I just thought I'd mention that in case that might have been a significant factor (which, based on your last message, it looks like it isn't).

[russellhltn]

Testing beats theory. Repeat the experiment with the exact same setup, but place the equipment on a non-metallic surface.

You can also try just lifting the laptop off the surface as a test.

[Hilohi]

Testing beats theory. Repeat the experiment with the exact same setup, but place the equipment on a non-metallic surface.

You can also try just lifting the laptop off the surface as a test.

At this point, I'll just use the crab box

[russellhltn]

If that works, that's a win.

[dave.swartz]

Our preferred setup for this application is Laptop ->HDMI Cable -> Projector -> Projector Audio Output jack -> Crab Box -> Cultural Center Microphone Jack. Don't forget to turn up the projectors volume. As has been mentioned the Crab box should provide isolation of ground loops and or phantom power as well as attenuation. This nice thing about using the output jack on the projector instead of the laptop audio jack it that for a windows computer when you plug in the HDMI cable it will switch all audio output to HDMI cable automatically. There will be no need to manually select the built-in computer audio jack after the HDMI cable is plugged in.

The transformer in the crab box will help prevent a ground loop. As you have alluded to in your post you can still provide a ground path through your audio cables if the XLR connectors are metal, the cart is metal, and say your power strip is also metal. Just be careful that you don't introduce an alternative ground path. We had static once just by an XLR connector for the chapel podium mic resting against a section of conduit in the podium. Simply by moving off the conduit the noise went away.

[Hilohi]

I tested the crab box with a DVD player and my computer and there's no static. Yay! It would be great if the volume were a tad bit louder, but at least there's no static.

[russellhltn]

It would be great if the volume were a tad bit louder, but at least there's no static.

I'll bet you have the gray box EJ-10. See the thread Modifying the EJ-10 Crab box. Not only will you get more volume but it will be clearer as well.

[Hilohi]

It would be great if the volume were a tad bit louder, but at least there's no static.

I'll bet you have the gray box EJ-10. See the thread Modifying the EJ-10 Crab box. Not only will you get more volume but it will be clearer as well.

You're right - we got the EJ-10. I had to order a new crab box (which I just got last week), so I'm looking into whether we can exchange our EJ-10 for the EJ-8.

Thanks for the mod instructions. If we can't exchange the EJ-10, how difficult is it to mod it? It's been a minute since I've soldered anything.

[russellhltn]

how difficult is it to mod it? It's been a minute since I've soldered anything.

As far as soldering goes, it's not hard. Not like it has surface mounted devices or anything like that.

I'm kind of surprised they still push the EJ-10. The main difference from the EJ-8 is that it supports connecting to phone lines. Eons ago, that would have helped to get the Priesthood session of conference via long-distance phone call (before the satellite system was installed). Today, it might be a backup plan if the internet fails on a webcast. But there's a fair chance your chapel doesn't even have a phone line anymore which kind of makes it pointless.