Soundcraft EFX12

[FunnyFellow]

Is the Soundcraft EFX12 a good board? Does it have bleedover and RF interference?

[FMEng]

It's probably safe to say it is as good as any other console in its size and price range. I'm curious about why you are asking about RF interference? Have you had problems in the past? Is there a radio tower nearby?

[FunnyFellow]

Originally Posted by FMEng

It's probably safe to say it is as good as any other console in its size and price range. I'm curious about why you are asking about RF interference? Have you had problems in the past? Is there a radio tower nearby?

On our school's portable mixer, even though there is no radio tower anywhere near, I get rf interference (it is some behringer board). not that I normally doubt Soundcraft, but as I am thinking of buying this for personal use, I just wanted a few opinions.

[FMEng]

I'd say the Soundcraft has a better chance at avoiding RF than the Behringer, but that is just a guess. Few manufacturers pay much attention this problem, and no published specs can tell us whether a piece of equipment is susceptible. Making equipment immune to RF costs money for a problem that few customers run into.

There are simple ways to get RF out of audio gear for modest cost. If you can listen to the interference and identify whether it is AM, FM, or two way radio, I can offer a few suggestions to get it out. Stations identify themselves within a few minutes of the top of the hour.

[Lightguy48]

The thing about higher end manufacturers is sometimes they re-use circuit designs from their higher lines to save production cost.

Considering Soundcraft makes high grade consoles I would put take their lowest end mic preamp/console any day over a Behringer.

But you also have to keep in mind not all RF issues are due to the console or it's preamps. An open sheild could cause an issue, an impedance mismatch, or low grade audio cable.

If I have RF problems I try switching to star-quad mic cable to see if it eliminates the issue. I've had microphones pick up RF going into well designed mic processors such as Symetrix and Valley People. Switching to star-quad mic cable eliminated the issue. (Of course having a major antenna farm a few miles away didn't help matters either)

[FunnyFellow]

It has got to be the board, because all of the cables are of extreme quality, and they are only 2 weeks old.

[Chris15]

Originally Posted by FunnyFellow

It has got to be the board, because all of the cables are of extreme quality, and they are only 2 weeks old.

Sounds like rather a large assumption to me. Have you confirmed that it is the board? I would consider confirmation to be interference with all external cabling disconnected...

[FMEng]

Originally Posted by Lightguy48

If I have RF problems I try switching to star-quad mic cable to see if it eliminates the issue. I've had microphones pick up RF going into well designed mic processors such as Symetrix and Valley People. Switching to star-quad mic cable eliminated the issue. (Of course having a major antenna farm a few miles away didn't help matters either)

Better quality cables may have helped, but it was more likely heavier, more complete shielding, not the star-quad.

Star-quad works by taking better advantage of the preamp's common mode rejection. The cable presents better balance of the common mode noise, which enables better electronic cancellation in the input stage.

BUT, the common mode rejection of most input stages is poor to non-existent above audio frequencies. Since that is the case, the fact that the cable was star-quad didn't help.

Better cable shielding only helps if the shield has a connection that shunts the RF away from the high-gain, preamp circuit traces. Good design often ties pin 1 of the XLR directly to the metal chassis or to a very wide ground plane instead of a whimpy little trace on the printed circuit board. In other words, if the mixer is badly made, no cable can save the day.

[FMEng]

Originally Posted by Chris15

Sounds like rather a large assumption to me. Have you confirmed that it is the board? I would consider confirmation to be interference with all external cabling disconnected...

Not necessarily. The cable is an antenna. Without cables connected, there may not be enough RF induced to create a problem even if the mixer is the culprit.

Manufacturers don't do much to deal with RF anyway, but the cheaper the product, the worse it can get because they cut even more corners.