Stereo Audio With Beachtek
 

Hey guys-
I'm in a pickle. I've captured some footage on my GL2 with two external mics through a Beachtek DXA-6 (one left channel and one right channel). When I put the video on my G5 (using Final Cut Express HD), I can't edit the channels individually. Is this possible? To edit the left channel separately from the right channel? Or am I just lost in the sauce? I know a lot of you probably dont use FCEHD, but does any other program let you do this (i.e. Vegas, FCPHD?) Someone please shed some light.
Thanks!

Hi Brett!

Off topic:
Many of the DXA-6 records the stereo signal out of phase. This was corrected about 2-3 months ago by BeachTek. Combining a stereo signal with each channel recorded out of phase is a catastrof.

If your DXA-6's volume controls has 10 steps it will record the stereo signal out of phase.
If your DXA-6's volume controls has 30 steps it records the signal in perfect phase.

This phase problem can be fixed easily by any electronic technician or by BeachTek so that it records in perfect phase. And if you have a DXA-6 that records out of phase you can correct it in a audio editing application, so it can be solved anyway.

On topic:
I use Premiere Pro and can edit both channels individually by either using a function called Break Out To Mono in Premiere Pro or duplicate the two stereo tracks and edit, or use a audio edit application and create two mono files out of the stereo file.

/Roger :)

Thanks Roger-
What is the difference between a track that is recorded "in phase" and one that is recorded "out of phase"? Is there any audible difference?
Thanks.

Yes, there is a audiable difference. I am not the right man to explain "how" it sounds but the sound "looses" it's low frequencies and sounds "hollow". If you play a stereo signal that is out of phase through a mono system most of the signal dissapears... (Somebody else can probably give a better explanation...)

There is no audiable difference when you play either left or right, but when you play left and right at the same time you will here the difference.

Here is a short sample of two files, one are in perfect shape and one is out of phase:
http://members.chello.se/averdahl/phase.zip

/Roger

Ha! That's a hoot!

I guess their faces were pretty red.

Out of Phase (better termed Reversed Polarity) is that condition in which the positive peaks and negative peaks of one channel are reversed on the second channel. (Usually by a pair of wires being reversed)

As the sound peaks positive on channel one, it's peaking negative on channel 2. Although there are some folks who can identify absolute polarity, most folks hearing each channel separately can't tell the difference.

HOWEVER!!!, whe you add the two together in MONO, the positive peaks cancel the negative peaks and in doing so the sound is reduced and sounds pretty weird.

This "effect" is what is used in Vocal Scrapers to remove vocals from records. One channel has its polarity reversed and the two are then combined to mono. Because the vocal is usually panned to the center of a mix, it will cancel out. Kick drum and bass also usually are in the middle of the stereo spectrum and they also cancel out. Sometimes you hear the vocal reverb, but not the main vocal. That's because there are slight timing differences between the two channels, so cancellation doesn't happen as completely.

How's that?

Ty Ford

Wow guys, thanks for the replies! I understand now :) So if I call Beachtek, will they fix my DXA-6 for me? It is the older style one. Anyway, thanks again.

If it's still under warranty BeachTek will fix it, but you have to pay for the shipment to and from BeachTek in Canada. :( (send them a mail and ask how they can solve it since the DXA-6 had a faulty design.)

If it is not under warranty i am sure Mr Kaufmann will fix your DXA-6. More info: http://www.beachtek.com/questions.html (take a look at the question "How do I get my adapter repaired?")

It is very easy to fix the problem, so a local electronic technichian will fix it easy. It will take just a couple of minutes and will save you money.

At last, Mr Kaufmann at BeachTek has been very co-operative regarding this matter from day 1 when i first told him about my findings. :)

/Roger

if you're getting an out of phase recording, just resolder your connections on your XLR cable. i believe you swap the red and white? (the two that are not the ground). resolder them on both ends that way you have two different microphone cables... one normal one and one set for out of phase conditions... make sure you mark the out of phase one.

Um, if you resolder both ends of the same cable, (swapping the connections), you're right back where you started.

Regards,

Ty Ford

Roger-
What has to be done to fix the Beachtek? I have a friend that is an Electrician, and I know he could fix it if I were to tell him what to do. He is also very good with Audio equipment, so he might not even need me to tell him what to do, but for my sake, could you please kinda give me a run down of the process?
Thanks a ton!
-Brett

Hi Brett!

I made a simple homepage with two pics of my DXA-6 and a simple "how-to-do" guide. If you have any questions, just post them here! :)

My box was modified by Mr Kaufmann at BeachTek before i bought it.

http://members.chello.se/averdahl/dxa6fix

/Roger

Wow thanks Roger! You rock!
-Brett

You're welcome Brett! :)

/Roger

My DXA-6 is the VERY original version, it only has phantom power for one channel. It uses a totally different switch layout so hopefully it doesn't have the same circuit pathways. I'll have to test it when I get a moment. I've never done true stereo through it, only single and dual channel mono.
I already have a phase reversal cable handy since one of my Chinese mics has reversed polarity. You can also buy an inline barrel phase reverse switch from Shure and others, I think I have a couple of those too.

Roger-
I noticed in your graphics, that only one side is talked about. Do I have to do that procedure to both XLR inputs, or just the one you've shown?

Also: I have the DXA-6 that has Phantom power on only ONE side. Does this make a difference? I asked the question about doing the procedure to both sides because one XLR input has power (a red wire) going to it. What will happen if I switch the wires?
Thanks.