Stereo Audio With Beachtek

Jay Massengill · October 21st, 2005, 03:46 PM

I've quickly tested my very early DXA-6 (with phantom on only one channel). The two XLR connectors are out of phase with each other.
I would have to do further testing to say which side is reversed and which side is correct without opening my box. You would only modify one side to correct this problem. Correcting either one will make it right as far as the BeachTek is concerned, but if you change the good side to match the out of phase side, then you'd be making your camera wrong when combined with another recording device. Since any of these devices that we'd be recording with can't be locked together precisely enough to maintain an in-phase or out-of-phase condition it wouldn't be a total disaster. We already know you're not even going to try to lock two copies of the same audio from different devices, like multiple feeds from a mixer except to obtain sync and then use just one copy for final audio. However, it would be a lot easier to work with two pieces of equipment that are in phase rather than out. It's easier to sync by listening to a boosted and phasy signal rather than one that cancels to nothing some of the time.
It would be easier to just change the non-phantom side, since you wouldn't have to worry about the extra power connection, but I'm not sure whether that's the good or the bad side.
Since I will rarely have this problem, I think I'll rely on an external reverser. I'll let you know when I have a chance to find out which side is in and which side is out. Maybe that's already known by one of these posters or you can tell by looking inside your own BeachTek.
I think the error occurred because the two XLR connectors are rotated 180 degrees apart in order to make them easier to unplug. The circuit traces also needed to run opposite of each other to match this physical arrangement.
For other owners wanting to do a quick test on their BeachTek, you don't even need to actually record anything. Use a tone generator or a single output from a CD player, either Left or Right. Input this signal to a mixer and keep the input Pan Centered. Take the two outputs from the mixer into your BeachTek, set for Line Level. Set the BeachTek switch to Mono. If you can't hear anything while monitoring your camera until you pan the mixer input left or right, then your BeachTek XLR inputs are out of phase with each other. This assumes your two mixer outputs and the two cables are all correct.

Cody Dulock · October 21st, 2005, 05:42 PM

oops my mistake! phase reversing a cable is pin 1 to pin 1, pin 2 to pin 3, pin 3 to pin 2.

Roger Averdahl · October 22nd, 2005, 08:06 AM

Quote:

Originally Posted by Brett Whited

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?

Hi Brett!

If you fix both channels you are back at square one! You should only modify one of the channels. Right channel is the easiest to modify on the DXA-6 and is the channel BeachTek fixes.

The phantom power is not affected on my DXA-6. But the only cables you should change is the cables where the audio signal passes. Do not modify the cables from the phantom power.

The modification done at my DXA-6 by BeachTek did not affect the phantom power supply on my DXA-6, phantom power works at both channels. :)

/Roger

Roger Averdahl · October 22nd, 2005, 08:20 AM

Quote:

Originally Posted by Jay Massengill

I've quickly tested my very early DXA-6 (with phantom on only one channel). The two XLR connectors are out of phase with each other.
I would have to do further testing to say which side is reversed and which side is correct without opening my box.

Hi Jay!

I tested a faulty DXA-6 in july 2005 and compared the channels with a Panasonic camera XLR-inputs and i am almost 100% sure of that it is the left channel that actually is the channel that is out of phase on the DXA-6's and should be repaired. It should be very interesting to see your test results Jay.

/Roger

Brett Whited · October 22nd, 2005, 06:57 PM

Quote:

Originally Posted by Roger Averdahl

Hi Brett!

If you fix both channels you are back at square one! You should only modify one of the channels. Right channel is the easiest to modify on the DXA-6 and is the channel BeachTek fixes.

The phantom power is not affected on my DXA-6. But the only cables you should change is the cables where the audio signal passes. Do not modify the cables from the phantom power.

The modification done at my DXA-6 by BeachTek did not affect the phantom power supply on my DXA-6, phantom power works at both channels. :)

/Roger

Thanks for all the advice Roger and everyone else! So let me get this strait... I should only modify my Right channel (the one without the Phantom power). And all I have to do is to switch the connections on Pin 2 and Pin 3 (connect Pin 2 to where Pin 3 was and vise versa)? Is this correct?
Thanks again.
-Brett

Roger Averdahl · October 23rd, 2005, 08:17 AM

Quote:

Originally Posted by Brett Whited

So let me get this strait... I should only modify my Right channel (the one without the Phantom power). And all I have to do is to switch the connections on Pin 2 and Pin 3 (connect Pin 2 to where Pin 3 was and vise versa)? Is this correct?

Yes, thats correct! :)

/Roger

Jay Massengill · October 24th, 2005, 07:49 AM

On my particular DXA-6, the Left channel is IN phase and the Right channel is OUT of phase, at least when comparing with Sony cameras. This is good because I don't have to worry with the phantom circuit at all since it doesn't go to the right channel.
Interestingly I had the materials to test right in front of me. I'm currently editing a project where I used a BeachTek-equipped D8 camera to record a visual reference of the projection screen so I could lay in the rendered .png PowerPoint slides easily in post. I was sending a feed of the podium mic to the left channels of both the DSR-390 DVCAM main camera and the TRV-103 D8. They were in phase with each other.
Two more points of interest. There was enough difference in the frequency response of the two cameras that they only had minimal cancellation (about 2db) even when one was purposely inverted.
They also held sync amazingly well, drifting less than one frame in about 53 minutes. Too bad it didn't matter, the D8 footage will be deleted as soon as the slides are in position.
I also tested both the Left and Right of the D8 camera against each other visually in a separate test. This also showed the Left channel of the BeachTek was in phase and the right was out.
All this assumes that the Rode and Sennheiser mics, the Mackie and Peavey mixer outputs, and all the cables used were in phase.
One last note about the BeachTek. Keep in mind that the Left input is directly behind the Right control when viewing from the front. I know I should have been looking at the labels more closely, but when I first hooked up the BeachTek long ago I confused myself until I checked the labels more closely when looking at the input (back) end. I made certain to double-check them for these tests.

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October 21st, 2005, 03:46 PM	#16
Jay Massengill Trustee Join Date: Jul 2003 Location: Burlington Posts: 1,976	I've quickly tested my very early DXA-6 (with phantom on only one channel). The two XLR connectors are out of phase with each other. I would have to do further testing to say which side is reversed and which side is correct without opening my box. You would only modify one side to correct this problem. Correcting either one will make it right as far as the BeachTek is concerned, but if you change the good side to match the out of phase side, then you'd be making your camera wrong when combined with another recording device. Since any of these devices that we'd be recording with can't be locked together precisely enough to maintain an in-phase or out-of-phase condition it wouldn't be a total disaster. We already know you're not even going to try to lock two copies of the same audio from different devices, like multiple feeds from a mixer except to obtain sync and then use just one copy for final audio. However, it would be a lot easier to work with two pieces of equipment that are in phase rather than out. It's easier to sync by listening to a boosted and phasy signal rather than one that cancels to nothing some of the time. It would be easier to just change the non-phantom side, since you wouldn't have to worry about the extra power connection, but I'm not sure whether that's the good or the bad side. Since I will rarely have this problem, I think I'll rely on an external reverser. I'll let you know when I have a chance to find out which side is in and which side is out. Maybe that's already known by one of these posters or you can tell by looking inside your own BeachTek. I think the error occurred because the two XLR connectors are rotated 180 degrees apart in order to make them easier to unplug. The circuit traces also needed to run opposite of each other to match this physical arrangement. For other owners wanting to do a quick test on their BeachTek, you don't even need to actually record anything. Use a tone generator or a single output from a CD player, either Left or Right. Input this signal to a mixer and keep the input Pan Centered. Take the two outputs from the mixer into your BeachTek, set for Line Level. Set the BeachTek switch to Mono. If you can't hear anything while monitoring your camera until you pan the mixer input left or right, then your BeachTek XLR inputs are out of phase with each other. This assumes your two mixer outputs and the two cables are all correct.

October 21st, 2005, 05:42 PM	#17
Cody Dulock Major Player Join Date: Sep 2004 Location: arlington, texas Posts: 420	oops my mistake! phase reversing a cable is pin 1 to pin 1, pin 2 to pin 3, pin 3 to pin 2.

October 24th, 2005, 07:49 AM	#22
Jay Massengill Trustee Join Date: Jul 2003 Location: Burlington Posts: 1,976	On my particular DXA-6, the Left channel is IN phase and the Right channel is OUT of phase, at least when comparing with Sony cameras. This is good because I don't have to worry with the phantom circuit at all since it doesn't go to the right channel. Interestingly I had the materials to test right in front of me. I'm currently editing a project where I used a BeachTek-equipped D8 camera to record a visual reference of the projection screen so I could lay in the rendered .png PowerPoint slides easily in post. I was sending a feed of the podium mic to the left channels of both the DSR-390 DVCAM main camera and the TRV-103 D8. They were in phase with each other. Two more points of interest. There was enough difference in the frequency response of the two cameras that they only had minimal cancellation (about 2db) even when one was purposely inverted. They also held sync amazingly well, drifting less than one frame in about 53 minutes. Too bad it didn't matter, the D8 footage will be deleted as soon as the slides are in position. I also tested both the Left and Right of the D8 camera against each other visually in a separate test. This also showed the Left channel of the BeachTek was in phase and the right was out. All this assumes that the Rode and Sennheiser mics, the Mackie and Peavey mixer outputs, and all the cables used were in phase. One last note about the BeachTek. Keep in mind that the Left input is directly behind the Right control when viewing from the front. I know I should have been looking at the labels more closely, but when I first hooked up the BeachTek long ago I confused myself until I checked the labels more closely when looking at the input (back) end. I made certain to double-check them for these tests.